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  • 1. Arimoto, M.
    et al.
    Kanai, Y.
    Ueno, M.
    Kataoka, J.
    Kawai, N.
    Tanaka, T.
    Yamamoto, K.
    Takahashi, H.
    Mizuno, T.
    Fukazawa, Y.
    Axelsson, Magnus
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Marini Bettolo, Cecilia
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Carlson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Klamra, Wlodzimierz
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Chen, P.
    Craig, B.
    Kamae, T.
    Madejski, G.
    Ng, J. S. T.
    Rogers, R.
    Tajima, H.
    Thurston, T. S.
    Saito, Y.
    Takahashi, T.
    Gunji, S.
    Bjornsson, Ca.
    Larsson, S.
    Ryde, Felix
    Bogaert, G.
    Varner, G.
    Performance assessment study of the balloon-borne astronomical soft gamma-ray polarimeter PoGOLite2007In: Physica. E, Low-Dimensional systems and nanostructures, ISSN 1386-9477, E-ISSN 1873-1759, Vol. 40, no 2, p. 438-441Article in journal (Refereed)
    Abstract [en]

    Measurements of polarization play a crucial role in the understanding of the dominant emission mechanism of astronomical sources. Polarized Gamma-ray Observer-Light version (PoGOLite) is a balloon-borne astronomical soft gamma-ray polarimeter at the 25-80 keV band. The PoGOLite detector consists of a hexagonal close-packed array of 217 Phoswich detector cells (PDCs) and side anti-coincidence shields (SASs) made of BGO crystals surrounding PDCs. Each PDC consists of a slow hollow scintillator, a fast scintillator and a BGO crystal that connects to a photomultiplier tube at the end. To examine the PoGOLite's capability and estimate the performance, we conducted experiments with the PDC using radioisotope 241Am. In addition, we compared this result with performance expected by Monte Carlo simulation with Geant4. As a result, we found that the actual PDC has the capability to detect a 100 m Crab source until 80 keV.

  • 2. Axelsson, Magnus
    et al.
    Engdegard, Olle
    KTH, School of Engineering Sciences (SCI), Physics.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Larsson, S.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Hjalmarsdotter, L.
    Kiss, Mószi
    KTH, School of Engineering Sciences (SCI), Physics.
    Bettolo, C. Marini
    KTH, School of Engineering Sciences (SCI), Physics.
    Arimoto, M.
    Bjornsson, C. I.
    Carlson, Per
    KTH, School of Engineering Sciences (SCI), Physics.
    Fukazawa, Y.
    Kamae, T.
    Kanai, Y.
    Kataoka, J.
    Kawal, N.
    Klamra, Wlodzimierz
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Madejski, G.
    Mizuno, T.
    Ng, J.
    Tajima, H.
    Takahashi, T.
    Tanaka, T.
    Ueno, M.
    Varner, G.
    Yamamoto, K.
    Measuring energy dependent polarization in soft gamma-rays using compton scattering in PoGOLite2007In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 28, no 3, p. 327-337Article in journal (Refereed)
    Abstract [en]

    Linear polarization in X-and gamma-rays is an important diagnostic of many astrophysical sources, foremost giving information about their geometry, magnetic fields, and radiation mechanisms. However, very few X-ray polarization measurements have been made, and then only mono-energetic detections, whilst several objects are assumed to have energy dependent polarization signatures. In this paper, we investigate whether detection of energy dependent polarization from cosmic sources is possible using the Compton technique, in particular with the proposed PoGOLite balloon-experiment, in the 25-100 keV range. We use Geant4 simulations of a PoGOLite model and input photon spectra based on Cygnus X-1 and accreting magnetic pulsars (100 mCrab). Effective observing times of 6 and 35 h were simulated, corresponding to a standard and a long duration flight, respectively. Both smooth and sharp energy variations of the polarization are investigated and compared to constant polarization signals using chi-square statistics. We can reject constant polarization, with energy, for the Cygnus X-1 spectrum (in the hard state), if the reflected component is assumed to be completely polarized, whereas the distinction cannot be made for weaker polarization. For the accreting pulsar, constant polarization can be rejected in the case of polarization in a narrow energy band with at least 50% polarization, and similarly for a negative step distribution from 30% to 0% polarization.

  • 3.
    Chauvin, Maxime
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, SE-10691 Stockholm, Sweden.
    Floren, H. -G
    Stockholm Univ, Dept Astron, SE-10691 Stockholm, Sweden.
    Friis, Mette
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, SE-10691 Stockholm, Sweden..
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kamae, T.
    Univ Tokyo, Dept Phys, Tokyo 1130033, Japan..
    Kataoka, J.
    Waseda Univ, Res Inst Sci & Engn, Tokyo 1698555, Japan..
    Kawano, T.
    Hiroshima Univ, Dept Phys Sci, Hiroshima 7398526, Japan..
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, SE-10691 Stockholm, Sweden..
    Mikhalev, Victor
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, SE-10691 Stockholm, Sweden..
    Mizuno, T.
    Hiroshima Univ, Dept Phys Sci, Hiroshima 7398526, Japan..
    Tajima, H.
    Nagoya Univ, Inst Space Earth Environm Res, Nagoya, Aichi 4648601, Japan..
    Takahashi, H.
    Hiroshima Univ, Dept Phys Sci, Hiroshima 7398526, Japan..
    Uchida, N.
    Hiroshima Univ, Dept Phys Sci, Hiroshima 7398526, Japan..
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, SE-10691 Stockholm, Sweden..
    The PoGO plus view on Crab off-pulse hard X-ray polarization2018In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 477, no 1, p. L45-L49Article in journal (Refereed)
    Abstract [en]

    The linear polarization fraction (PF) and angle of the hard X-ray emission from the Crab provide unique insight into high-energy radiation mechanisms, complementing the usual imaging, timing, and spectroscopic approaches. Results have recently been presented by two missions operating in partially overlapping energy bands, PoGO+ (18-160 keV) and AstroSat CZTI (100-380 keV). We previously reported PoGO+ results on the polarization parameters integrated across the light curve and for the entire nebula-dominated off-pulse region. We now introduce finer phase binning, in light of the AstroSat CZTI claim that the PF varies across the off-pulse region. Since both missions are operating in a regime where errors on the reconstructed polarization parameters are non-Gaussian, we adopt a Bayesian approach to compare results from each mission. We find no statistically significant variation in off-pulse polarization parameters, neither when considering the mission data separately nor when they are combined. This supports expectations from standard high-energy emission models.

  • 4.
    Chauvin, Maxime
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Floren, H. -G
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kamae, T.
    Kawano, T.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kole, Merlin
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Mikhalev, Victor
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Moretti, Elena
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. Max Planck Institute for Astrophysics, Germany.
    Olofsson, G.
    Rydström, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Takahashi, H.
    Iyudin, A.
    Arimoto, M.
    Fukazawa, Y.
    Kataoka, J.
    Kawai, N.
    Mizuno, T.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Tajima, H.
    Takahashi, T.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Observation of polarized hard X-ray emission from the Crab by the PoGOLite Pathfinder2016In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 456, no 1, p. L84-L88Article in journal (Refereed)
    Abstract [en]

    We have measured the linear polarization of hard X-ray emission from the Crab in a previously unexplored energy interval, 20-120 keV. The introduction of two new observational parameters, the polarization fraction and angle stands to disentangle geometrical and physical effects, thereby providing information on the pulsar wind geometry and magnetic field environment. Measurements are conducted using the PoGOLite Pathfinder - a balloon-borne polarimeter. Polarization is determined by measuring the azimuthal Compton scattering angle of incident X-rays in an array of plastic scintillators housed in an anticoincidence well. The polarimetric response has been characterized prior to flight using both polarized and unpolarized calibration sources. We address possible systematic effects through observations of a background field. The measured polarization fraction for the integrated Crab light curve is 18.4(-10.6)(+9.8) per cent, corresponding to an upper limit (99 per cent credibility) of 42.4 per cent, for a polarization angle of (149.2 +/- 16.0)degrees.

  • 5.
    Chauvin, Maxime
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Florén, H. -G
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kamae, T.
    Kawano, T.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kole, Merlin
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. Univ Geneva, Switzerland.
    Mikhalev, Victor
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Moretti, Elena
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Olofsson, G.
    Rydström, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Takahashi, H.
    Lind, J.
    Strömberg, J. -E
    Welin, O.
    Iyudin, A.
    Shifrin, D.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    The design and flight performance of the PoGOLite Pathfinder balloon-borne hard X-ray polarimeter2016In: Experimental astronomy (Print), ISSN 0922-6435, E-ISSN 1572-9508, Vol. 41, no 1, p. 17-41Article in journal (Refereed)
    Abstract [en]

    In the 50 years since the advent of X-ray astronomy there have been many scientific advances due to the development of new experimental techniques for detecting and characterising X-rays. Observations of X-ray polarisation have, however, not undergone a similar development. This is a shortcoming since a plethora of open questions related to the nature of X-ray sources could be resolved through measurements of the linear polarisation of emitted X-rays. The PoGOLite Pathfinder is a balloon-borne hard X-ray polarimeter operating in the 25-240 keV energy band from a stabilised observation platform. Polarisation is determined using coincident energy deposits in a segmented array of plastic scintillators surrounded by a BGO anticoincidence system and a polyethylene neutron shield. The PoGOLite Pathfinder was launched from the SSC Esrange Space Centre in July 2013. A near-circumpolar flight was achieved with a duration of approximately two weeks. The flight performance of the Pathfinder design is discussed for the three Crab observations conducted. The signal-to-background ratio for the observations is shown to be 0.25 ±0.03 and the Minimum Detectable Polarisation (99 % C.L.) is (28.4 ±2.2) %. A strategy for the continuation of the PoGOLite programme is outlined based on experience gained during the 2013 maiden flight.

  • 6.
    Chauvin, Maxime
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, Stockholm, Sweden.
    Florén, Hans-Gustav
    Friis, Mette
    KTH, School of Engineering Sciences (SCI), Physics. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, Stockholm, SwedenThe Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, Stockholm, Sweden.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics.
    Kamae, Tuneyoshi
    Kataoka, Jun
    Kawano, Takafumi
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Mikhalev, Victor
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Mizuno, Tsunefumi
    Ohashi, Norie
    Stana, Theodor
    KTH, School of Engineering Sciences (SCI), Physics.
    Tajima, Hiro
    Takahashi, Hiromitsu
    Uchida, Nagomi
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics.
    Accretion geometry of the black-hole binary Cygnus X-1 from X-ray polarimetry2018In: Nature Astronomy, ISSN 2397-3366, Vol. 2, no 8, p. 652-655Article in journal (Refereed)
    Abstract [en]

    Black hole binary (BHB) systems comprise a stellar-mass black hole and a closely orbiting companion star. Matter is transferred from the companion to the black hole, forming an accretion disk, corona and jet structures. The resulting release of gravitational energy leads to the emission of X-rays1. The radiation is affected by special/general relativistic effects, and can serve as a probe for the properties of the black hole and surrounding environment, if the accretion geometry is properly identified. Two competing models describe the disk–corona geometry for the hard spectral state of BHBs, based on spectral and timing measurements2,3. Measuring the polarization of hard X-rays reflected from the disk allows the geometry to be determined. The extent of the corona differs between the two models, affecting the strength of the relativistic effects (such as enhancement of the polarization fraction and rotation of the polarization angle). Here, we report observational results on the linear polarization of hard X-ray emission (19–181 keV) from a BHB, Cygnus X-14, in the hard state. The low polarization fraction, <8.6% (upper limit at a 90% confidence level), and the alignment of the polarization angle with the jet axis show that the dominant emission is not influenced by strong gravity. When considered together with existing spectral and timing data, our result reveals that the accretion corona is either an extended structure, or is located far from the black hole in the hard state of Cygnus X-1.

  • 7.
    Chauvin, Maxime
    et al.
    KTH, School of Engineering Sciences (SCI), Physics. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91, Stockholm, Sweden.
    Florén, H.-G.
    Friis, Mette
    KTH, School of Engineering Sciences (SCI), Physics. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91, Stockholm, Sweden.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics. School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA, UK.
    Kamae, T.
    Kataoka, J.
    Kawano, T.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91, Stockholm, Sweden.
    Mikhalev, Victor
    KTH, School of Engineering Sciences (SCI), Physics. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91, Stockholm, Sweden.
    Mizuno, T.
    Ohashi, N.
    Stana, Theodor-Adrian
    KTH, School of Engineering Sciences (SCI), Physics. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91, Stockholm, Sweden.
    Tajima, H.
    Takahashi, H.
    Uchida, N.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91, Stockholm, Sweden.
    Shedding new light on the Crab with polarized X-rays2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, no 7816, p. 1-6Article in journal (Refereed)
    Abstract [en]

    Strong magnetic fields, synchrotron emission, and Compton scattering are omnipresent in compactcelestial X-ray sources. Emissions in the X-ray energy band are consequently expected to be linearlypolarized. X-ray polarimetry provides a unique diagnostic to study the location and fundamentalmechanisms behind emission processes. The polarization of emissions from a bright celestial X-raysource, the Crab, is reported here for the first time in the hard X-ray band (~20–160 keV). The Crab isa complex system consisting of a central pulsar, a diffuse pulsar wind nebula, as well as structures inthe inner nebula including a jet and torus. Measurements are made by a purpose-built and calibratedpolarimeter, PoGO+. The polarization vector is found to be aligned with the spin axis of the pulsar for apolarization fraction, PF = (20.9 ± 5.0)%. This is higher than that of the optical diffuse nebula, implyinga more compact emission site, though not as compact as, e.g., the synchrotron knot. Contrary tomeasurements at higher energies, no significant temporal evolution of phase-integrated polarisationparameters is observed. The polarization parameters for the pulsar itself are measured for the first timein the X-ray energy band and are consistent with observations at optical wavelengths.

  • 8.
    Chauvin, Maxime
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Friis, Mette
    KTH, School of Engineering Sciences (SCI), Physics.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics.
    Kawano, T.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Mikhalev, Victor
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ohashi, N.
    Stana, Theodor-Adrian
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Takahashi, H.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91 Stockholm, Sweden.
    Calibration and performance studies of the balloon-borne hard X-ray polarimeter PoGO2017In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 859, p. 125-133Article in journal (Refereed)
    Abstract [en]

    Polarimetric observations of celestial sources in the hard X-ray band stand to provide new information on emission mechanisms and source geometries. PoGO+ is a Compton scattering polarimeter (20-150 keV) optimised for the observation of the Crab (pulsar and wind nebula) and Cygnus X-1 (black hole binary), from a stratospheric balloon-borne platform launched from the Esrange Space Centre in summer 2016. Prior to flight, the response of the polarimeter has been studied with polarised and unpolarised X-rays allowing a Geant4-based simulation model to be validated. The expected modulation factor for Crab observations is found to be M-Crab = (41.75 +/- 0.85)%, resulting in an expected Minimum Detectable Polarisation (MDP) of 7.3% for a 7 day flight. This will allow a measurement of the Crab polarisation parameters with at least 5 sigma statistical significance assuming a polarisation fraction similar to 20% - a significant improvement over the PoGOLite Pathfinder mission which flew in 2013 and from which the PoGO+ design is developed.

  • 9.
    Chauvin, Maxime
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova University Centre, Sweden.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova University Centre, Sweden.
    Kawano, T.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova University Centre, Sweden.
    Kole, Merlin
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova University Centre, Sweden.
    Mikhalev, Victor
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova University Centre, Sweden.
    Moretti, Elena
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova University Centre, Sweden.
    Takahashi, H.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova University Centre, Sweden.
    Optimising a balloon-borne polarimeter in the hard X-ray domain: From the PoGOLite Pathfinder to PoGO2016In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 82, p. 99-107Article in journal (Refereed)
    Abstract [en]

    PoGOLite is a balloon-borne hard X-ray polarimeter dedicated to the study of point sources. Compton scattered events are registered using an array of plastic scintillator units to determine the polarisation of incident X-rays in the energy range 20-240 keV. In 2013, a near circumpolar balloon flight of 14 days duration was completed after launch from Esrange, Sweden, resulting in a measurement of the linear polarisation of the Crab emission. Building on the experience gained from this Pathfinder flight, the polarimeter is being modified to improve performance for a second flight in 2016. Such optimisations, based on Geant4 Monte Carlo simulations, take into account the source characteristics, the instrument response and the background environment which is dominated by atmospheric neutrons. This paper describes the optimisation of the polarimeter and details the associated increase in performance. The resulting design, PoGO+, is expected to improve the Minimum Detectable Polarisation (MDP) for the Crab from 19.8% to 11.1% for a 5 day flight. Assuming the same Crab polarisation fraction as measured during the 2013 flight, this improvement in MDP will allow a 5 sigma constrained result. It will also allow the study of the nebula emission only (Crab off-pulse) and Cygnus X-1 if in the hard state.

  • 10.
    Chauvin, Maxime
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. Oskar Klein Centre for Cosmoparticle Physics, Sweden.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kawano, T.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. Oskar Klein Centre for Cosmoparticle Physics, Sweden.
    Kole, Merlin
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. Oskar Klein Centre for Cosmoparticle Physics, Sweden.
    Mikhalev, Victor
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. Oskar Klein Centre for Cosmoparticle Physics, Sweden.
    Moretti, Elena
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. Oskar Klein Centre for Cosmoparticle Physics, Sweden.
    Takahashi, H.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. Oskar Klein Centre for Cosmoparticle Physics, Sweden.
    Preflight performance studies of the PoGOLite hard X-ray polarimeter2016In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 72, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Polarimetric studies of astrophysical sources can make important contributions to resolve the geometry of the emitting region and determine the photon emission mechanism. PoGOLite is a balloon-borne polarimeter operating in the hard X-ray band (25-240 key), with a Pathfinder mission focussing on Crab observations. Within the polarimeter, the distribution of Compton scattering angles is used to determine the polarisation fraction and angle of incident photons. To assure an unbiased measurement of the polarisation during a balloon flight it is crucial to characterise the performance of the instrument before the launch. This paper presents the results of the PoGOLite calibration tests and simulations performed before the 2013 balloon flight. The tests performed confirm that the polarimeter does not have any intrinsic asymmetries and therefore does not induce bias into the measurements. Generally, good agreement is found between results from test data and simulations which allows the polarimeter performance to be estimated for Crab observations.

  • 11.
    Friis, M.
    et al.
    KTH, School of Engineering Sciences (SCI), Physics. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Center, 106 91 Stockholm, Sweden.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Center, 106 91 Stockholm, Sweden.
    Mikhalev, Victor
    KTH, School of Engineering Sciences (SCI), Physics. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Center, 106 91 Stockholm, Sweden.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics. The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Center, 106 91 Stockholm, Sweden.
    Takahashi, H.
    The PoGO+ balloon-borne hard X-ray polarimetry mission2018In: Galaxies, E-ISSN 2075-4434, Vol. 6, no 1, article id 30Article in journal (Refereed)
    Abstract [en]

    The PoGO mission, including the PoGOLite Pathfinder and PoGO+, aims to provide polarimetric measurements of the Crab system and Cygnus X-1 in the hard X-ray band. Measurements are conducted from a stabilized balloon-borne platform, launched on a 1 million cubic meter balloon from the Esrange Space Center in Sweden to an altitude of approximately 40 km. Several flights have been conducted, resulting in two independent measurements of the Crab polarization and one of Cygnus X-1. Here, a review of the PoGO mission is presented, including a description of the payload and the flight campaigns, and a discussion of some of the scientific results obtained to date. 

  • 12.
    Jackson, Miranda
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Klamra, Wlodzimierz
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Mallol, Pau
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Bettolo, Cecilia Marini
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Rydström, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Varner, G.
    Yoshida, H.
    PoGOLite: a balloon-borne soft gamma-ray polarimeter2009In: 2009 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-5  / [ed] Yu B, 2009, p. 449-453Conference paper (Refereed)
    Abstract [en]

    PoGOLite is a balloon-borne X-ray polarimeter, designed to measure the polarization of 25-80 keV X-rays. It is scheduled for a pathfinder flight in August 2010. This paper outlines the scientific motivation and the status of preparations of the payload.

  • 13. Kamae, Tuneyoshi
    et al.
    Andersson, Viktor
    KTH, School of Engineering Sciences (SCI), Physics.
    Arimoto, Makoto
    Axelsson, Magnus
    Bettolo, Cecilia Marini
    KTH, School of Engineering Sciences (SCI), Physics.
    Björnsson, Claes-Ingvar
    Bogaert, Gilles
    Carlson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Craig, William
    Ekeberg, Tomas
    KTH, School of Engineering Sciences (SCI), Physics.
    Engdegård, Olle
    KTH, School of Engineering Sciences (SCI), Physics.
    Fukazawa, Yasushi
    Gunji, Shuichi
    Hjalmarsdotter, Linnea
    Iwan, Bianca
    KTH, School of Engineering Sciences (SCI), Physics.
    Kanai, Yoshikazu
    Kataoka, Jun
    Kawai, Nobuyuki
    Kazejev, Jaroslav
    KTH, School of Engineering Sciences (SCI), Physics.
    Kiss, Mozsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Klamra, Wlodzimierz
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Larsson, Stefan
    KTH, School of Engineering Sciences (SCI), Physics.
    Madejski, Grzegorz
    Mizuno, Tsunefumi
    Ng, Johnny
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Rydé, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Suhonen, Markus
    KTH, School of Engineering Sciences (SCI), Physics.
    TaJima, Hiroyasu
    Takahashi, Hiromitsu
    Takahashi, Tadayuki
    Tanaka, Takuya
    Thurston, Timothy
    Ueno, Masaru
    Varneri, Gary
    Yamamoto, Kazuhide
    Yamashita, Yuichiro
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics.
    Yoshida, Hiroaki
    PoGOLite - A high sensitivity balloon-borne soft gamma-ray polarimeter2008In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 30, no 2, p. 72-84Article in journal (Refereed)
    Abstract [en]

    We describe a new balloon-borne instrument (PoGOLite) capable of detecting 10% polarisation from 200 mCrab point-like sources between 25 and 80 keV in one 6-h flight. Polarisation measurements in the soft gamma-ray band are expected to provide a powerful probe into high energy emission mechanisms as well as the distribution of magnetic fields, radiation fields and interstellar matter. Synchrotron radiation, inverse Compton scattering and propagation through high magnetic fields are likely to produce high degrees of polarisation in the energy band of the instrument. We demonstrate, through tests at accelerators, with radioactive sources and through computer simulations, that PoGOLite will be able to detect degrees of polarisation as predicted by models for several classes of high energy sources. At present, only exploratory polarisation measurements have been carried out in the soft gamma-ray band. Reduction of the large background produced by cosmic-ray particles while securing a large effective area has been the greatest challenge. PoGOLite uses Compton scattering and photo-absorption in an array of 217 well-type phoswich detector cells made of plastic and BGO scintillators surrounded by a BGO anticoincidence shield and a thick polyethylene neutron shield. The narrow Held of view (FWHM = 1.25 msr, 2.0 deg x 2.0 deg) obtained with detector cells and the use of thick background shields warrant a large effective area for polarisation measurements (similar to 228 cm(2) at E = 40 keV) without sacrificing the signal-to-noise ratio. Simulation studies for an atmospheric overburden of 3-4 g/cm(2) indicate that neutrons and gamma-rays entering the PDC assembly through the shields are dominant backgrounds. Off-line event selection based on recorded phototube waveforms and Compton kinematics reduce the background to that expected for a similar to 100 mCrab source between 25 and 50 keV. A 6-h observation of the Crab pulsar will differentiate between the Polar Cap/Slot Gap, Outer Gap, and Caustic models with greater than 5 sigma significance; and also cleanly identify the Compton reflection component in the Cygnus X-1 hard state. Long-duration flights will measure the dependence of the polarisation across the cyclotron absorption line in Hercules X-1. A scaled-down instrument will be flown as a pathfinder mission from the north of Sweden in 2010. The first science flight is planned to take place shortly thereafter.

  • 14. Kanai, Y.
    et al.
    Kataoka, J.
    Klamra, Wlodzimierz
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Rydstrom, S.
    Takahashi, T.
    Thurston, T. S.
    Varner, G.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Marini Bettolo, Cecilia
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Larsson, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    A Monte Carlo method for calculating the energy response of plastic scintillators to polarized photons below 100 keV2009In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 600, no 3, p. 609-617Article in journal (Refereed)
    Abstract [en]

    The energy response of plastic scintillators (Eljen Technology EJ-204) to polarized soft gamma-ray photons below 100 keV has been studied, primarily for the balloon-borne polarimeter, PoGOLite. The response calculation includes quenching effects due to low-energy recoil electrons and the position dependence of the light collection efficiency in a 20 cm long scintillator rod. The broadening of the pulse-height spectrum, presumably caused by light transportation processes inside the scintillator, as well as the generation and multiplication of photoelectrons in the photomultiplier tube, were studied experimentally and have also been taken into account. A Monte Carlo simulation based on the Geant4 toolkit was used to model photon interactions in the scintillators. When using the polarized Compton/Rayleigh scattering processes previously corrected by the authors, scintillator spectra and angular distributions of scattered polarized photons could clearly be reproduced, in agreement with the results obtained at a synchrotron beam test conducted at the KEK Photon Factory. Our simulation successfully reproduces the modulation factor, defined as the ratio of the amplitude to the mean of the distribution of the azimuthal scattering angles, within similar to 5% (relative). Although primarily developed for the PoGOLite mission, the method presented here is also relevant for other missions aiming to measure polarization from astronomical objects using plastic scintillator scatterers.

  • 15.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Measurements of astrophysical polarization using Compton scattering2011In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 648, p. 313-316Article in journal (Refereed)
    Abstract [en]

    The Polarized Gamma-ray Explorer (PoGOLite) is a balloon-borne instrument designed to measure polarization in the energy range 25–80 keV from many classes of astronomical objects, including pulsars, accretion discs and astrophysical jets. Using coincident detection of Compton scattering and photoelectric absorption in an array of 217 detector cells, the modulation in scattering angles can be determined. By this technique, the instrument will be able to measure as low as 10% polarization from a 200 mCrab source in a 6-h flight at an altitude of 40 km.

    The maiden flight of a 61-unit “pathfinder” instrument is scheduled to take place from the Esrange ballooning facility in northern Sweden in mid-2011. This flight will focus on measuring polarization from the Crab nebula and possibly Cygnus X-1, as well as to study the in-flight background caused by cosmic ray particles, X-ray and gamma-ray photons, and albedo neutrons. In order to reject such background, the instrument features a combination of active and passive shielding, as well as both active and passive collimation of the incident photons.

    Here, the design and status of the PoGOLite pathfinder instrument will be reviewed. Pre-flight calibration and performance tests will also be presented.

  • 16.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Pre-Flight Development of the PoGOLite Pathfinder2011Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The Polarized Gamma-ray Observer (PoGOLite) is a balloon-borne instrument that will measure gamma-ray polarization in the energy range 25-80 keV from astronomical sources such as pulsars, accretion discs and jets from active galacticnuclei. The two additional parameters provided by such observations, polarizationangle and degree, will allow these objects to be studied in a new way, providing information about their emission mechanisms and geometries.

    The instrument measures azimuthal scattering angles of photons within a closepacked array of phoswich detector cells (PDCs) based on coincident detection of Compton scattering and photoelectric absorption. Each PDC comprises three different scintillating components and combines photon detection, active collimation and bottom anticoincidence into one single unit. The three parts are viewed by a photomultiplier tube (PMT) and pulse shape discrimination is used to identify signals from dierent parts. Surrounding the detector array is a segmented side anticoincidence shield (SAS) made of BGO crystals.

    The detector elements of the instrument (PDCs, SAS units, PMTs) have been characterized, resulting in a placement scheme which details where within the detector array each element should be placed in order to maximize the instrument sensitivity and response uniformity. Suitable operating parameters for flight, suchas threshold settings and PMT voltages, have also been dened.

    Geant4 Monte Carlo simulations have shown that a polyethylene shield is needed around the detector array in order to sufficiently reduce the background from atmospheric neutrons. To validate these simulations, a simple detector array with four plastic scintillators and three BGO crystals shielded with polyethylene was irradiated with 14 MeV neutrons. Measured results were accurately recreated i nsimulations, demonstrating that the treatment of neutron interactions in Geant4 is reliable.

    A Pathnder version of the PoGOLite instrument has been constructed and tested with unpolarized and polarized photon beams, and results have been compared with simulations. The Pathnder is being prepared for a maiden flight from northern Sweden in mid-2011. A circumnavigation is foreseen at an altitude of up to 40 km, whereby the instrument travels westwards over Greenland and Canada and returns over Russia after a period of about 20 days. The main observational targets for this flight will be the Crab system and Cygnus X-1.

  • 17.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Studies of neutron background rejection in the PoGOLite polarimeter2010In: X-ray Polarimetry: A New Window in Astrophysics / [ed] Ronaldo Bellazzini, Enrico Costa, Giorgio Matt, Gianpiero Tagliaferri, Cambridge University Press, 2010, p. 299-304Conference paper (Refereed)
    Abstract [en]

    The Polarized Gamma-ray Observer (PoGOLite) is a balloon-borne polarimeter based on measuring anisotropy in the azimuthal scattering angle distribution of photons in the energy range 25-80 keV. This is achieved through coincident detection of Compton scattering and photoelectric absorption within a close-packed array of phoswich detector cells (PDCs). Each PDC contains a plastic scintillator rod (main detector component), a plastic scintillator tube (active collimator) and a BGO crystal (anticoincidence shield).

    A significant in-flight background is expected from atmospheric neutrons as well as from neutrons produced by interactions of cosmic rays with mechanical structures surrounding the instrument. Although this background can be reduced by introducing suitable shielding materials such as polyethylene, the shield geometry must be optimized through simulations in order to yield sufficient shielding with an acceptable increase in weight.

    Geant4-based Monte Carlo simulations have shown that a 10 cm thick polyethylene shield surrounding the PoGOLite instrument is required to sufficiently reduce the background, i.e. fake polarization events, from atmospheric neutrons. In order to validate these simulations, a beam test was carried out, at which 14 MeV neutrons were used to irradiate a simple detector array with four plastic scintillators and three BGO crystals. The array was configured to mimic the PoGOLite detector geometry and also featured a polyethylene neutron shield. Here, we present details of the neutron beam test and our simulation thereof, which demonstrate that the treatment of neutron interactions within the Geant4 framework is reliable. Such simulations can therefore be used to assess in-flight neutron background in balloon-borne instruments, such as the PoGOLite polarimeter.

  • 18.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Studies of PoGOLite performance and background rejection capabilities2008Licentiate thesis, monograph (Other scientific)
    Abstract [en]

    The Polarized Gamma-ray Observer (PoGOLite) is a balloon-borne instrument capable of measuring as low as 10% polarization from a 200 mCrab source in a sixhour °ight. A wide array of sources can be studied, including pulsars, neutron stars, accretion discs and jets from active galactic nuclei. The two new observational parameters provided by such measurements, polarization angle and degree, will allow these objects to be studied in a completely new way, providing information both about the emission mechanisms and the geometries of the emitting objects. The instrument measures anisotropies in azimuthal scattering angles of gammarays with a close-packed array of 217 well-type phoswich detector cells (PDCs) by coincident detection of Compton scattering and photoelectric absorption. Each PDC comprises a \slow" plastic scintillator tube, a \fast" plastic scintillator rod and a BGO crystal. The fast scintillator is the main detector component, whereas the slow scintillator and the BGO crystal act as an active collimator and a bottom anticoincidence shield, respectively. The three parts are viewed by a single photomultiplier tube (PMT) and pulse shape discrimination is used to identify signals from each part.

    The detector array is surrounded by a 54-segment side anticoincidence shield (SAS) made of BGO crystals. Each segment is 60 cm long and consists of three crystals. A total of 187 crystals have been procured and tested for light yield, energy resolution, dimensions and surface ¯nish. All crystals have been found to be of excellent quality and measured characteristics have been within speci¯ed limits. The performance of the instrument has also been evaluated in several beam tests with polarized synchrotron photons irradiating a prototype detector array. Front-end electronics have been tested and a modulation in the observed scattering angles has been observed in line with expectations. Geant4-based Monte Carlo simulations of the instrument performance have shown that a 10 cm thick polyethylene shield is required around the detector array in order to su±ciently reduce the background from atmospheric neutrons. To validate these simulations, a simple detector array with four plastic scintillators and three BGO crystals was irradiated with 14 MeV neutrons. The array was shielded with polyethylene, mimicking the PoGOLite instrument design. Measured results could be accurately recreated in Geant4 simulations, demonstrating that the treatment of neutron interaction processes in Geant4 is reliable.

  • 19.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    The PoGOLite balloon-borne soft gamma-ray polarimeter2008In: Astroparticle, Particle and Space Physics, Detectors and Medical Physics Applications: Proceedings of the 10th Conference / [ed] Michele Barone, Andrea Gaddi, Claude Leroy, Larry Price, Pier-Giorgio Rancoita, Randal Ruchti, World Scientific, 2008, p. 886-890Conference paper (Refereed)
    Abstract [en]

    PoGOLite is a balloon-borne experiment that will measure the polarization of soft gamma-rays between 25 keV and 80 keV through detection of coincident Compton scattering and absorption in a close-packed array of 217 well-type phoswich detector cells. The potential observation targets include pulsars, accreting compact objects and astrophysical jets. The polarization properties of such radiation can reveal important new information on the geometry, magnetic fields and emission mechanisms of these sources.

  • 20.
    Kiss, Mózsi Bank
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    PoGOLite: Opening a new window on the universe with polarized gamma-rays2007In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 580, no 2, p. 876-879Article in journal (Refereed)
    Abstract [en]

    PoGOLite (the Polarized Gamma-ray Observer, light-weight version) is a balloon-borne instrument that will measure the polarization of soft gamma-rays in the energy range 25-100keV from various astronomical sources such as pulsars, active galactic nuclei, galactic X-ray binaries and accreting black holes. The polarization properties of such radiation can reveal important new information about the geometry, magnetic fields and the emission mechanisms of the observed sources. The first flight is scheduled for 2009. In this paper, we present the current state of the project.

  • 21.
    Kiss, Mózsi
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Larsson, S.
    Arimoto, M.
    Axelsson, A.
    Marini Bettolo, Cecilia
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Bogaert, G.
    Floren, H. -G
    Fukazawa, Y.
    Gunji, S.
    Hjalmarsdotter, L.
    Kamae, T.
    Kanai, Y.
    Kataoka, J.
    Kawai, N.
    Klamra, Wlodzimierz
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kurita, K.
    Madejski, G.
    Mizuno, T.
    Olofsson, G.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Rydström, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Tajima, H.
    Takahashi, H.
    Takahashi, T.
    Tanaka, T.
    Ueno, M.
    Umeki, Y.
    Varner, G.
    Yoshida, H.
    The PoGOLite balloon-borne soft gamma-ray polarimeter2008In: COOL DISCS, HOT FLOWS: THE VARYING FACES OF ACCRETING COMPACT OBJECTS / [ed] Axelsson, M, 2008, Vol. 1054, p. 225-232Conference paper (Refereed)
    Abstract [en]

    Linearly polarized radiation in the hard X-ray/soft gamma-ray band is expected from a large variety of astronomical sources. We discuss the importance of polarimetric studies for several classes of sources - pulsars, accreting black holes. magnetic neutron stars and jets from active galaxies - and then describe PoGOLite, a balloon-borne instrument which is currently under construction and will be able to measure the polarization of electromagnetic radiation from such extra-solar objects in the energy range 25-80 keV.

  • 22.
    Kole, Merlin
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Chauvin, Maxime
    KTH, School of Engineering Sciences (SCI), Physics.
    Fukazawa, Yasushi
    Fukuda, Kentaro
    Ishizu, Sumito
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics.
    Kamae, Tune
    Kawaguchi, Noriaki
    Kawano, Takafumi
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Moretti, Elena
    KTH, School of Engineering Sciences (SCI), Physics.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Rydström, Stefan
    KTH, School of Engineering Sciences (SCI), Physics.
    Takahashi, Hiromitsu
    Yanagida, Takayuki
    PoGOLino: A scintillator-based balloon-borne neutron detector2015In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 770, p. 68-75Article in journal (Refereed)
    Abstract [en]

    PoGOLino is a balloon borne scintillator-based experiment developed to study the largely unexplored high altitude neutron environment at high geomagnetic latitudes. The instrument comprises two detectors LhaL make use of LiCAF, a novel neutron sensitive scintillator, sandwiched by [GO crystals for background reduction. The experiment was launched on March 20th 2013 from the [orange Space Centre, Northern Sweden (geomagnetic latitude of 65 degrees), for a three hour flight during which the instrument Look data up loan altitude of 30.9 km. The detector design and ground calibration results are presented together with the measurement results from the balloon flight.

  • 23.
    Kole, Merlin
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kiss, Mozsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Moretti, Elena
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Rydström, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Yanagida, Takayuki
    et, al
    A balloon-borne measurement of high latitude atmospheric neutrons using a licaf neutron detector2013In: 2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), IEEE conference proceedings, 2013, , p. 8p. 6829591-Conference paper (Refereed)
    Abstract [en]

    PoGOLino is a scintillator-based neutron detector. Its main purpose is to provide data on the neutron flux in the upper stratosphere at high latitudes at thermal and nonthermal energies for the PoGOLite instrument. PoGOLite is a balloon borne hard X-ray polarimeter for which the main source of background stems from high energy neutrons. No measurements of the neutron environment for the planned flight latitude and altitude exist. Furthermore this neutron environment changes with altitude, latitude and solar activity, three variables that will vary throughout the PoGOLite flight. PoGOLino was developed to study the neutron environment and the influences from these three variables upon it. PoGOLino consists of two Europium doped Lithium Calcium Aluminium Fluoride (Eu:LiCAF) scintillators, each of which is sandwiched between 2 Bismuth Germanium Oxide (BGO) scintillating crystals, which serve to veto signals produced by gamma-rays and charged particles. This allows the neutron flux to be measured even in high radiation environments. Measurements of neutrons in two separate energy bands are achieved by placing one LiCAF detector inside a moderating polyethylene shield while the second detector remains unshielded. The PoGOLino instrument was launched on March 20th 2013 from the Esrange Space Center in Northern Sweden to an altitude of 30.9 km. A description of the detector design and read-out system is presented. A detailed set of simulations of the atmospheric neutron environment performed using both PLANETOCOSMICS and Geant4 will also be described. The comparison of the neutron flux measured during flight to predictions based on these simulations will be presented and the consequences for the PoGOLite background will be discussed.

  • 24.
    Marini Bettolo, Cecilia
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kiss, Mózsi Bank
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Klamra, Wlodzimierz
    KTH, School of Engineering Sciences (SCI), Physics.
    Siegl, Martin
    KTH, School of Engineering Sciences (SCI), Physics.
    The BGO anticoincidence system of the PoGOLite balloon-borne soft gamma-ray polarimeter2007In: Proceedings of the 30th International Cosmic Ray Conference, ICRC 2007 / [ed] Rogelio Caballero, Juan Carlos D’Olivo, Gustavo Medina-Tanco, Lukas Nellen, Federico A. Sánchez, José F. Valdés-Galicia, Universidad Nacional Autonoma de Mexico , 2007, Vol. 2, p. 483-486Conference paper (Refereed)
    Abstract [en]

    The PoGOLite balloon-borne experiment applies well-type phoswich detector technology tomeasurements of soft gamma-ray polarization in the 25 keV - 80 keV energy range. The polarization isdetermined using Compton scattering and photoelectric absorption in an array of 217 plastic scintillators.This sensitive volume is surrounded by a segmented bismuth germanate oxide (BGO) anticoincidenceshield, designed to reduce background from charged cosmic rays, primary and atmospheric gamma-rays,and atmospheric and instrumental neutrons. A total of 379 BGO crystals with three different geometriesare used, giving an overall mass of approximately 250 kg. Tests of the BGO crystals are described andthe overall design of the anticoincidence shield is reviewed.

  • 25. Mizuno, T.
    et al.
    Arimoto, M.
    Axelsson, Magnus
    Stockholm University.
    Björnsson, C. -I
    Bogaert, G.
    Carlson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Craig, W.
    Fukazawa, Y.
    Gunji, S.
    Hjalmarsdotter, L.
    Kamae, T.
    Kanai, Y.
    Kataoka, J.
    Katsuta, J.
    Kawai, N.
    Kiss, Mózsi Bank
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Klamra, Wlodzimierz
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Larsson, S.
    Madejski, G.
    Bettolo, Cecilia M.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ng, J.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Tajima, H.
    Takahash, H.
    Takahashi, T.
    Tanaka, T.
    Thurston, T.
    Ueno, M.
    Varner, G.
    Yoshida, H.
    High sensitivity balloon-borne hard X-ray/soft Gamma-Ray Polarimeter PoGOLite2007In: Nuclear Science Symposium Conference Record, 2007. NSS ’07. IEEE, IEEE , 2007, Vol. 4, p. 2538-2544Conference paper (Refereed)
    Abstract [en]

    The Polarized Gamma-ray Observer - Lightweight version (PoGOLite) is a new balloon experiment capable of detecting 10% polarization from a 200 mCrab source in the 25-80 keV energy range in a single 6-hour flight for the first time. Polarization measurements of hard X-rays and soft gamma-rays are expected to provide a powerful probe into high-energy emission mechanisms as well as source geometries. PoGOLite uses Compton scattering and photo-absorption to measure polarization in an array of 217 well-type phoswich detector cells made of plastic and BGO scintillators. The adoption of a well-type phoswich counter concept and a thick polyethylene neutron shield provides a narrow field-of-view (1.25 msr), a large effective area ( gt; 250 cm2 at 40-50 keV), a high modulation factor (more than 25%) and the low background ( 100 mCrab) required to conduct high-sensitivity polarization measurements. Through tests in laboratories and accelerator facilities of a scaled-down prototype with the front-end electronics of flight design and an extensive study by Monte Carlo simulation, we have demonstrated high instrument performance. PoGOLite will be ready for a first engineering flight in 2009 and a science flight in 2010, during which polarization signals from the Crab Nebula/pulsar, Cygnus X-1 and other objects will be observed.

  • 26.
    Pearce, M.
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Eliasson, L.
    KTH, School of Engineering Sciences (SCI), Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Iyer, N.
    KTH, School of Engineering Sciences (SCI), Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Kiss, M.
    KTH, School of Engineering Sciences (SCI), Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Kushwah, R.
    KTH, School of Engineering Sciences (SCI), Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Larsson, Josefin
    KTH, School of Engineering Sciences (SCI), Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Lundman, C.
    KTH, School of Engineering Sciences (SCI), Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Mikhalev, V.
    KTH, School of Engineering Sciences (SCI), Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Ryde, F.
    KTH, School of Engineering Sciences (SCI), Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Stana, T. -A
    KTH, School of Engineering Sciences (SCI), Physics.
    Takahashi, H.
    Hiroshima Univ, Dept Phys Sci, Hiroshima 7398526, Japan..
    Xie, E.
    KTH, School of Engineering Sciences (SCI), Physics. KTH Royal Inst Technol, Dept Phys, S-10691 Stockholm, Sweden.;AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Science prospects for SPHiNX - A small satellite GRB polarimetry mission2019In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 104, p. 54-63Article in journal (Refereed)
    Abstract [en]

    Gamma-ray bursts (GRBs) are exceptionally bright electromagnetic events occurring daily on the sky. The prompt emission is dominated by X-/gamma-rays. Since their discovery over 50 years ago, GRBs are primarily studied through spectral and temporal measurements. The properties of the emission jets and underlying processes are not well understood. A promising way forward is the development of missions capable of characterising the linear polarisation of the high-energy emission. For this reason, the SPHiNX mission has been developed for a small-satellite platform. The polarisation properties of incident high-energy radiation (50-600 keV) are determined by reconstructing Compton scattering interactions in a segmented array of plastic and Gd3Al2Ga3O12(Ce) (GAGG(Ce)) scintillators. During a two-year mission, similar to 200 GRBs will be observed, with similar to 50 yielding measurements where the polarisation fraction is determined with a relative error <= 10%. This is a significant improvement compared to contemporary missions. This performance, combined with the ability to reconstruct GRB localisation and spectral properties, will allow discrimination between leading classes of emission models. 

  • 27.
    Pearce, Mark
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Arimoto, M.
    Axelsson, Magnus
    Stockholm University, Sweden.
    Björnsson, C. -I
    Bogaert, G.
    Carlson, Per
    KTH, School of Engineering Sciences (SCI), Physics.
    Craig, W.
    Fukazawa, Y.
    Gunji, S.
    Hjalmarsdotter, L.
    Kamae, T.
    Kanai, Y.
    Kataoka, J.
    Katsuta, J.
    Kawai, N.
    Kazejev, Jaroslav
    KTH, School of Engineering Sciences (SCI), Physics.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics.
    Klamra, Wlodzimierz
    KTH, School of Engineering Sciences (SCI), Physics.
    Larsson, S.
    Madejski, G.
    Marini Bettolo, C.
    Mizuno, T.
    Ng, J.
    Nomachi, M.
    Odaka, H.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics.
    Tajima, H.
    Takahashi, H.
    Takahashi, T.
    Tanaka, T.
    Thurston, T.
    Ueno, M.
    Varner, G.
    Yoshida, H.
    Yuasa, T.
    PoGOLite: A balloon-borne soft gamma-ray polarimeter2007In: Proceedings of the 30th International Cosmic Ray Conference, ICRC 2007, Universidad Nacional Autonoma de Mexico , 2007, Vol. 2, no OG PART 1, p. 479-482Conference paper (Refereed)
    Abstract [en]

    Polarized gamma-rays are expected from a wide variety of sources including rotationpowered pulsars, accreting black holes and neutron stars, and jet-dominated active galaxies. Polarization measurements provide a powerful probe of the gamma-ray emission mechanism and the distribution of magnetic and radiation fields around the source. No measurements have been performed in the soft gamma-ray band where non-thermal processes are expected to produce high degrees of polarization. The PoGOLite experiment applies well-type phoswich detector technology to polarization measurements in the 25 - 80 keV energy range. The instrument uses Compton scattering and photoabsorption in an array of 217 phoswich detector cells made of plastic and BGO scintillators, and surrounded by active BGO shields. A prototype of the flight instrument has been tested with polarized gammarays and background generated with radioactive sources. The test results and computer simulations confirm that the instrument can detect 10% polarization of a 200 mCrab source in one 6 hour balloon observation. In flight, targets are constrained to within better than 5% of the field-of-view (~5 degrees squared) in order to maximize the effective detection area during observations. The pointing direction on the sky is determined by an attitude control system comprising star trackers, differential GPS receiver system, gyroscopes, accelerometers and magnetometers which provide correction signals to a reaction wheel and torque motor system. Additionally, the entire polarimeter assembly rotates around its viewing axis to minimize systematic bias during observations. Flights are foreseen to start in 2009- 2010 and will target northern sky sources including the Crab pulsar/nebula, Cygnus X-1, and Hercules X-1. These observations will provide valuable information about the pulsar emission mechanism, the geometry around the black hole, and photon transportation in the strongly magnetized neutron star surface, respectively. Future goals include a long duration balloon flight from the Esrange facility in Northern Sweden to Canada.

  • 28.
    Pearce, Mark
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Eliasson, Linda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Iyer, Nirmal
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kushwah, Rakhee
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Larsson, Josefin
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Lundman, Christoffer
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Mikhalev, Victor
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Stana, Theodor-Adrian
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Takahashi, H.
    Xie, Fei
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Science prospects for SPHiNX – A small satellite GRB polarimetry mission2019In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 104, p. 54-63Article in journal (Refereed)
    Abstract [en]

    Gamma-ray bursts (GRBs) are exceptionally bright electromagnetic events occurring daily on the sky. The prompt emission is dominated by X-/γ-rays. Since their discovery over 50 years ago, GRBs are primarily studied through spectral and temporal measurements. The properties of the emission jets and underlying processes are not well understood. A promising way forward is the development of missions capable of characterising the linear polarisation of the high-energy emission. For this reason, the SPHiNX mission has been developed for a small-satellite platform. The polarisation properties of incident high-energy radiation (50–600 keV) are determined by reconstructing Compton scattering interactions in a segmented array of plastic and Gd3Al2Ga3O12(Ce) (GAGG(Ce)) scintillators. During a two-year mission, ∼ 200 GRBs will be observed, with ∼ 50 yielding measurements where the polarisation fraction is determined with a relative error ≤ 10%. This is a significant improvement compared to contemporary missions. This performance, combined with the ability to reconstruct GRB localisation and spectral properties, will allow discrimination between leading classes of emission models.

  • 29.
    Pearce, Mark
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Eliasson, Linda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Iyer, Nirmal
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Kushwah, Rakhee
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Larsson, Josefin
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Lundman, Christoffer
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Mikhalev, Victor
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Stana, Theodor-Adrian
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Takahashi, H.
    Hiroshima Univ, Dept Phys Sci, Hiroshima 7398526, Japan..
    Xie, Fei
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, S-10691 Stockholm, Sweden..
    Science prospects for SPHiNX - A small satellite GRB polarimetry mission2019In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 104, p. 54-63Article in journal (Refereed)
    Abstract [en]

    Gamma-ray bursts (GRBs) are exceptionally bright electromagnetic events occurring daily on the sky. The prompt emission is dominated by X-/gamma-rays. Since their discovery over 50 years ago, GRBs are primarily studied through spectral and temporal measurements. The properties of the emission jets and underlying processes are not well understood. A promising way forward is the development of missions capable of characterising the linear polarisation of the high-energy emission. For this reason, the SPHiNX mission has been developed for a small-satellite platform. The polarisation properties of incident high-energy radiation (50-600 keV) are determined by reconstructing Compton scattering interactions in a segmented array of plastic and Gd3Al2Ga3O12(Ce) (GAGG(Ce)) scintillators. During a two-year mission, similar to 200 GRBs will be observed, with similar to 50 yielding measurements where the polarisation fraction is determined with a relative error <= 10%. This is a significant improvement compared to contemporary missions. This performance, combined with the ability to reconstruct GRB localisation and spectral properties, will allow discrimination between leading classes of emission models.

  • 30.
    Pearce, Mark
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Florén, H. -G
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kamae, T.
    Kiss, Mózsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kole, Merlin
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Moretti, Elena
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Olofsson, G.
    Rydström, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strömberg, J. -E
    Takahashi, H.
    Balloon-borne hard X-ray polarimetry with PoGOLite2012In: 2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC), IEEE , 2012, p. 1885-1892Conference paper (Refereed)
    Abstract [en]

    PoGOLite is a hard X-ray polarimeter operating in the 25-100 keV energy band. The instrument design is optimised for the observation of compact astrophysical sources. Observations are conducted from a stabilised stratospheric balloon platform at an altitude of approximately 40 km. The primary targets for first balloon flights of a reduced effective area instrument are the Crab and Cygnus-X1. The polarisation of incoming photons is determined using coincident Compton scattering and photo-absorption events reconstructed in an array of plastic scintillator detector cells surrounded by a bismuth germanate oxide (BGO) side anticoincidence shield and a polyethylene neutron shield. A custom attitude control system keeps the polarimeter field-of-view aligned to targets of interest, compensating for sidereal motion and perturbations such as torsional forces in the balloon rigging. An overview of the PoGOLite project is presented and the outcome of the ill-fated maiden balloon flight is discussed.

  • 31. Sofitta, P
    et al.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Axelsson, M.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Chauvin, Maxime
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Burgess, Michael
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kiss, Moszi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Larsson, Josefin
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Xie, F
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Zoghbi, A.
    et al.,
    XIPE the X-ray Imaging Polarimetry Explorer2016In: Proceedings of SPIE, SPIE - International Society for Optical Engineering, 2016, Vol. 9905, article id UNSP 990515Conference paper (Refereed)
    Abstract [en]

    XIPE, the X-ray Imaging Polarimetry Explorer, is a mission dedicated to X-ray Astronomy. At the time of writing XIPE is in a competitive phase A as fourth medium size mission of ESA (M4). It promises to reopen the polarimetry window in high energy Astrophysics after more than 4 decades thanks to a detector that efficiently exploits the photoelectric effect and to X-ray optics with large effective area. XIPE uniqueness is time-spectrally-spatially- resolved X-ray polarimetry as a breakthrough in high energy astrophysics and fundamental physics. Indeed the payload consists of three Gas Pixel Detectors at the focus of three X-ray optics with a total effective area larger than one XMM mirror but with a low weight. The payload is compatible with the fairing of the Vega launcher. XIPE is designed as an observatory for X- ray astronomers with 75% of the time dedicated to a Guest Observer competitive program and it is organized as a consortium across Europe with main contributions from Italy, Germany, Spain, United Kingdom, Poland, Sweden.

  • 32. Takahashi, H.
    et al.
    Matsuoka, M.
    Umeki, Y.
    Yoshida, H.
    Tanaka, T.
    Mizuno, T.
    Fukazawa, Y.
    Kamae, T.
    Madejski, G.
    Tajima, H.
    Kiss, Mózsi Bank
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Klamra, Wlodzimierz
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Larsson, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Bettolo, Cecilia Marini
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Rydström, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kurita, K.
    Kanai, Y.
    Arimoto, M.
    Ueno, M.
    Kataoka, J.
    Kawai, N.
    Axelsson, Magnus
    Stockholm University.
    Hjalmarsdotter, L.
    Bogaert, G.
    Gunji, S.
    Katsuta, J.
    Takahashi, T.
    Varner, G.
    Yuasa, T.
    The Polarized Gamma-Ray Observer, PoGOLite2010In: Transactions of the Japanese Society for Artificial Intelligence, Aerospace Technology Japan, Vol. 8Article in journal (Refereed)
    Abstract [en]

    The Polarized Gamma-ray Observer, PoGOLite, is a balloon experiment with the capability of detecting 10% polarization from a 200 mCrab celestial object in the energy-range 25–80 keV. During a beam test at KEK-PF in 2008, 19 detector units and one anti-coincidence detector were assembled, and a 50 keV X-ray beam with a polarization degree of ∼90% was irradiated at the center unit. Signals from all 20 units were fed into flight-version electronics consisting of six circuit boards (four waveform digitizer boards, one digital I/O board and one router board) and one microprocessor (SpaceCube), which communicate using a SpaceWire interface. One digitizer board, which can associate up to 8 detectors, outputs a trigger signal. The digital I/O board handles the trigger and returns a data acquisition request if there is no veto signal (upper or pulse-shape discriminators) from any detector unit. This data acquisition system worked well, and the modulation factor was successfully measured to be ∼34%. These results confirmed the capabilities of the data-acquisition system for a “pathfinder” flight planned in 2010.

  • 33. Takahashi, H.
    et al.
    Matsuoka, M.
    Umeki, Y.
    Yoshida, H.
    Tanaka, T.
    Mizuno, T.
    Fukazawa, Y.
    Kamae, T.
    Madejski, G.
    Tajima, H.
    Kiss, Mózsi Bank
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Klamra, Wlodzimierz
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Larsson, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Marini Bettolo, Cecilia
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Rydstrom, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kurita, K.
    Kanai, Y.
    Arimoto, M.
    Ueno, M.
    Kataoka, J.
    Kawai, N.
    Axelsson, M.
    Hjalmarsdotter, L.
    Bogaert, G.
    Gunji, S.
    Takahashi, T.
    Varner, G.
    Yuasa, T.
    Beam test results of the polarized gamma-ray observer, PoGOLite2008In: 2008 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (2008 NSS/MIC), VOLS 1-9, 2008, p. 732-736Conference paper (Refereed)
    Abstract [en]

    The Polarized Gamma-ray Observer, PoGOLite, is a balloon experiment with the capability of detecting 10% polarization from a 200 mCrab celestial object in the energy range 25 #x2013;80 keV. During a beam test at KEK-PF in February 2008, 20 detector units were assembled, and a 50 keV X-ray beam with a polarization degree of #x223C;90% was irradiated at the center unit. Signals from all 20 units were fed into flightversion electronics consisting of six circuit boards (four waveform digitizer boards, one digital I/O board and one router board) and one microprocessor (SpaceCube), which communicate using a SpaceWire interface. One digitizer board, which can associate up to 8 PDCs, outputs a trigger signal. The digital I/O board handles the trigger and returns a data acquisition request if there is no veto signal (upper or pulse-shape discriminators) from any detector unit. This data acquisition system worked well, and the modulation factor was successfully measured to be #x223C;34%. These results confirmed the capabilities of both detector and data-acquisition system for a pathfinder flight planned in 2010.

  • 34. Takahashi, H.
    et al.
    Yonetani, M.
    Matsuoka, M.
    Mizuno, T.
    Fukazawa, Y.
    Yanagida, T.
    Fujimoto, Y.
    Yokota, Y.
    Yoshikawa, A.
    Kawaguchi, N.
    Ishizu, S.
    Fukuda, K.
    Suyama, T.
    Watanabe, K.
    Tajima, H.
    Kanai, Y.
    Kawai, N.
    Kataoka, J.
    Katsuta, J.
    Takahashi, T.
    Gunji, S.
    Axelsson, Magnus
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kiss, Mózsi Bank
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Klamra, Wlodzimierz
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kole, Merlin
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Larsson, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Mallol, Parera Pau
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Rydström, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Olofsson, G.
    Floren, H.
    Kamae, T.
    Madejski, G.
    Varner, G.
    A thermal-neutron detector with a phoswich system of LiCaAlF6 and BGO crystal scintillators onboard PoGOLite2010In: 2010 IEEE Nuclear Science Symposium, Medical Imaging Conference, NSS/MIC 2010 and 17th International Workshop on Room-Temperature Semiconductor X-ray and Gamma-ray Detectors, RTSD 2010, 2010, p. 32-37Conference paper (Refereed)
    Abstract [en]

    To measure the flux of atmospheric neutrons and study the neutron contribution to the background of the main detector of the PoGOLite (Polarized Gamma-ray Observer) balloon-borne experiment, a thermal-neutron detector with a phoswich system of LiCaAlF6 (Eu) and BGO crystal scintillators is developed. The performance to separate thermal-neutron events from those of gamma-rays and charged particles is validated with 252Cf on ground. The detector is attached to the PoGOLite instrument and is launched in 2011 from the Esrange facility in the North of Sweden. Although the emission wavelength of the LiCaAlF6 (Ce) is 300 nm and overlaps with the absorption wavelength of the BGO, the phoswich capability of the LiCaAlF6 (Ce) with the BGO is also confirmed with installing a waveform shifter.

  • 35. Takahashi, Hiromitsu
    et al.
    Chauvin, Maxime
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Fukazawa, Yasushi
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kamae, Tuneyoshi
    Kawano, Takafumi
    Kiss, Mozsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kole, Merlin
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Mikhalev, Victor
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Mizuno, Tsunefumi
    Moretti, Elena
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Rydström, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Data acquisition system and ground calibration of polarized gamma-ray observer (PoGOLite)2014In: Proceedings of SPIE - The International Society for Optical Engineering, SPIE - International Society for Optical Engineering, 2014Conference paper (Refereed)
    Abstract [en]

    The Polarized Gamma-ray Observer, PoGOLite, is a balloon experiment with the capability of detecting 10% polarization from a 200 mCrab celestial object between the energy-range 25-80 keV in one 6 hour flight. Polarization measurements in soft gamma-rays are expected to provide a powerful probe into high-energy emission mechanisms in/around neutron stars, black holes, supernova remnants, active-galactic nuclei etc. The pathfinder flight was performed in July 2013 for 14 days from Sweden to Russia. The polarization is measured using Compton scattering and photoelectric absorption in an array of 61 well-type phoswich detector cells (PDCs) for the pathfinder instrument. The PDCs are surrounded by 30 BGO crystals which form a side anti-coincidence shield (SAS) and passive polyethylene neutron shield. There is a neutron detector consisting of LiCaAlF6 (LiCAF) scintillator covered with BGOs to measure the background contribution of atmospheric neutrons. The data acquisition system treats 92 PMT signals from 61 PDCs + 30 SASs + 1 neutron detector, and it is developed based on SpaceWire spacecraft communication network. Most of the signal processing is done by digital circuits in Field Programmable Gate Arrays (FPGAs). This enables the reduction of the mass, the space and the power consumption. The performance was calibrated before the launch.

  • 36. Tanaka, T.
    et al.
    Arimoto, M.
    Axelsson, Magnus
    Stockholm University.
    Bjornsson, C. -I
    Bogaert, G.
    Carlson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Cooney, M.
    Craig, W.
    Engdegård, Olle
    KTH, School of Engineering Sciences (SCI), Physics.
    Fukazawa, Y.
    Gunji, S.
    Hjalmarsdotter, L.
    Kamae, T.
    Kanai, Y.
    Kataoka, J.
    Katsuta, J.
    Kawai, N.
    Kazejev, Jaroslav
    KTH, School of Engineering Sciences (SCI), Physics.
    Kiss, Mozsi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Klamra, Wlodzimierz
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Larsson, Stefan
    Madejski, G.
    Bettolo, Cecilia Marini
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Mizuno, T.
    Ng, J.
    Nomachi, M.
    Odaka, H.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ruckman, L.
    Ryde, F.
    Tajima, H.
    Takahashi, H.
    Takahashi, T.
    Thurston, T.
    Ueno, M.
    Varner, G.
    Ylinen, T.
    Yoshida, H.
    Yuasa, T.
    Data acquisition system for the PoGOLite astronomical hard X-ray polarimeter2007In: 2007 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-11, 2007, Vol. 1, p. 445-449Conference paper (Refereed)
    Abstract [en]

    The PoGOLite is a new balloon-borne instrument to measure the polarization of hard X-rays / soft gamma-rays in the 25-80 keV energy range for the first time. In order to detect the polarization, PoGOLite measures the azimuthal angle asymmetry of Compton scattering and the subsequent photo- absorption in an array of detectors. This array consists of 217 well-type phoswich detector cells (PDCs) surrounded by a side anti-coincidence shield (SAS) composed of 54 segments of BGO crystals. At balloon altitude, the intensity of backgrounds due to cosmic-ray charged particles, atmospheric gamma-rays and neutrons is extremely high, typically a few hundred Hz per unit. Hence the data acquisition (DAQ) system of PoGOLite is required to handle more than 270 signals simultaneously, and detect weak signals from astrophysical objects (lOOmCrab, 1.5 cs-1 in 25-80 keV ) under such a severe environment. We have developed a new DAQ system consisting of front-end electronics, waveform digitizer, field programmable gate array (FPGA) and a microprocessor. In this system, all output signals of PDC / SAS are fed into individual charge-sensitive amplifier and then digitized to 12 bit accuracy at 24MSa/s by pipelined analog to digital converters. A DAQ board for the PDC records waveforms which will be examined in an off-line analysis to distinguish signals from the background events and measure the energy spectrum and polarization of targets. A board for the SAS records hit pattern to be used for background rejection. It also continuously records a pulse-height analysis (PHA) histogram to monitor incident background flux. These basic functions of the DAQ system were verified in a series of beam tests.

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