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  • 1.
    Anghel, Ionut Gheorghe
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Anglart, Henryk
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Hedberg, Stellan
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Rydström, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Experimental Investigation of the Influence of Flow Obstacles on Post-Dryout Heat Transfer in an Annulus2009In: ICONE 17: PROCEEDINGS OF THE 17TH INTERNATIONAL CONFERENCE ON NUCLEAR ENGINEERING, VOL 3, NEW YORK: AMER SOC MECHANICAL ENGINEERS , 2009, p. 277-286Conference paper (Refereed)
    Abstract [en]

    This paper describes the experimental setup, instrumentation and procedures which have been developed in the thermal-hydraulic laboratory at the Royal Institute of Technology (KTH), Stockholm, Sweden, to perform new post-dryout heat transfer investigations in an annulus with flow obstacles. Previous investigations performed in the same laboratory indicated that flow obstacles had a considerable influence on the post-CHF heat transfer. The measured heat transfer enhancement was significantly under-predicted by existing models. However, the net effect of obstacles could not be deduced from the measurements, since reference - obstacle-free measurements- had not been performed. In addition, the number of thermocouples that could be installed inside the heated rod was limited to 8. These deficiencies have been removed in the current approach. Firstly, the present design of the test section allows for measurements both with and without flow obstacles. In this way the net effect of the obstacles will be captured. Secondly, a newly developed technique allowed the installation of 40 thermocouples inside of the heated rod. An additional 40 thermocouples have been installed on the external wall of the heated tube. Therefore, a significant improvement of the accuracy of measurements can be expected. The present arrangement of instrumentation is suitable to perform measurements of heat transfer under both steady-state and transient conditions.

  • 2.
    Anglart, Henryk
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Bergagio, Mattia
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Hedberg, Stellan
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Rydström, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Frid, Wiktor
    Swedish Radiation Safety Authority.
    Measurement of Wall Temperature Fluctuations during Thermal Mixing of Non-isothermal Water Streams2015In: Proceedings of the 16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-16), American Nuclear Society, 2015Conference paper (Refereed)
    Abstract [en]

    This paper is dealing with measurement of temperature fluctuations during mixing of two water streams in an annular test section at BWR operational conditions. The experiments are simulating conditions existing in a guide tube of BWR control rods, where relatively cold water at about 333 K is mixing with hot water at ~550 K. It is shown that the mixing is causing high amplitude temperature fluctuations in the solid walls of the control rod extender. Using new movable multi-sensors it became possible to obtain a large experimental database, containing wall temperature measurements at 8 azimuthal and 5 axial positions, with 13 thermocouples at each position. In total 520 temperature readings were performed, each lasting about 2 minutes and recording transient temperature with frequency of at least 100 samples per second and with estimated non-calibrated uncertainty less than 3.9 K. The present experimental results can be used to analyze the governing phenomena during thermal mixing and also to validate CFD conjugate heat transfer models of thermal mixing applied to actual reactor geometries.

  • 3.
    Bergagio, Mattia
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Anglart, Henryk
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Hedberg, Stellan
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Rydström, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Instrumentation for Temperature and Heat Flux Measurement on a Solid Surface under BWR Operating Conditions2015In: Proceedings of the 16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-16), American Nuclear Society , 2015, p. 5962-5975Conference paper (Refereed)
    Abstract [en]

    A new experimental facility has been developed at KTH Royal Institute of Technology to measure temperature and heat flux propagations in solid walls due to mixing of non-isothermal water streams in their vicinity. The main purpose of the measurements has been to obtain a high-precision experimental database suitable for validation of Computational Fluid Dynamics (CFD) codes. Consequently, a set of experiments have been performed in a test section simulating the annular region in the BWR control-rod guide tubes. Since preliminary CFD results implied that 0.1-1 Hz temperature oscillations were to be expected, this experimental research intends to assess the magnitude of temperature fluctuations within the abovementioned frequency range. To this end, water and wall temperatures have been measured in the innermost part of the test-section annulus, with a variety of boundary conditions. As thermocouples would otherwise be available at few axial and azimuthal coordinates only, the tube they are installed on has been lifted, lowered and rotated by a software-controlled motor to record temperature fluctuations in the whole mixing region. At each measurement point, data have been collected over a time long enough to detect the existence of the aforesaid fluctuations. Moreover, an uncertainty analysis has been carried out concerning water temperatures. Thermocouples meant to monitor these temperatures have been modelled with a finite-element method for this very purpose. The wall heat flux has also been estimated using experimental data, thanks to a corrected finite-difference Crank-Nicolson scheme.

  • 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. Hidvégi, A.
    et al.
    Geler, P.
    Rehlich, K.
    Bohm, C.
    Rydström, Stefan
    KTH, School of Engineering Sciences (SCI), Physics.
    A system for distributing high-speed synchronous high-precision clock and trigger data over large distances2008Conference paper (Refereed)
    Abstract [en]

    The distribution of precise timing throughout the European X-ray Free Electron Laser project [1] (XFEL) and its triggering system is a very challenging part of the system design. ADCs in data acquisition systems and DACs in control systems will require very high precision clocks. The clocks need to be synchronous to each other, both in frequency and phase, with a jitter performance better than 5 ps (RMS). At some high-speed ADCs it might even need a precision down to 0.1 ps. The frequencies that must be available are the main 1.3 GHz and some frequencies below, which are all derived from the main frequency. The phase needs to be adjustable to allow synchronization between separate devices. Triggering information needs to be distributed over the system, so that controlling instructions can be carried out at a very precise time. This is very important since the beam will travel with the speed of light, and there is no possibility for information to be sent back and forth. This requires an absolute timing to be distributed over the system. Both the main clock and triggering information will be transmitted over the same fiber cable, one to each device. An advanced synchronization method needs to be developed to synchronize the phases of the clocks throughout the whole system. The delay through the cable can change with temperature, and due to long cables the total change through a single cable can be significant. It is essential that the clocks are stable and not drifting away from each other. Therefore a continuous calibration method is needed, ensuring that the clocks are synchronous throughout the whole system. A prototype of such a system is being developed and a first version is expected to be completed in 2009 Ql.

  • 7.
    Hofverberg, Petter
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Johansson, H.
    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, Particle and Astroparticle Physics.
    First results from the Stockholm Educational Air Shower Array (SEASA)2005In: Proceedings of the 29th International Cosmic Ray Conference Vol 8: HE 1.5, 2005, p. 271-274Conference paper (Refereed)
    Abstract [en]

    The 'Stockholm Educational Air Shower Array' (SEASA) project is establishing a network of time-synchronised scintillator detector stations at high-schools in the Stockholm region. High school students are contributing to the construction, installation, testing and running of the detector station placed on the roof of their school. This initiative aims to increase the students' interest in science and technology subjects by exposing them to modem research. Each station is equipped with three plastic scintillator detectors (each 0.3 m(2)) arranged in a triangular formation. Signals from GPS satellites are used to time-synchronise signals from the widely separated detector stations, allowing cosmic ray air showers to be identified and studied. A low-cost and highly scalable data acquisition system has been produced using embedded Linux processors which communicate station trigger and monitoring data to a central database. Air shower data and the performance of each detector station can be visualised in real-time via a web browser. The status of the project is presented along with first results from the observation of air showers over Stockholm.

  • 8.
    Hofverberg, Petter
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Johansson, H.
    KTH, School of Engineering Sciences (SCI), Physics.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics.
    Rydström, Stefan
    KTH, School of Engineering Sciences (SCI), Physics.
    Wikström, Christian
    KTH, School of Engineering Sciences (SCI), Physics.
    The data acquisition system of the Stockholm educational air shower array2005Conference paper (Refereed)
    Abstract [en]

    The Stockholm Educational Air Shower Array (SEASA) project is deploying an array of plastic scintillator detector stations on school roofs in the Stockholm area. Signals from GPS satellites are used to time synchronise signals from the widely separated detector stations, allowing cosmic ray air showers to be identified and studied. A low-cost and highly scalable data acquisition system has been produced using embedded Linux processors which communicate station data to a central server running a MySQL database. Air shower data can be visualised in real-time using a Java-applet client. It is also possible to query the database and manage detector stations from the client. In this paper, the design and performance of the system are described.

  • 9.
    Hofverberg, Petter
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Johansson, H.
    KTH, School of Engineering Sciences (SCI), Physics.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics.
    Rydström, Stefan
    KTH, School of Engineering Sciences (SCI), Physics.
    Wikström, Christian
    KTH, School of Engineering Sciences (SCI), Physics.
    The data acquisition system of the Stockholm Educational Air Shower Array2005In: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 52, no 6, p. 2801-2809Article in journal (Refereed)
    Abstract [en]

    The Stockholm Educational Air Shower Array (SEASA) project is deploying an array of plastic scintillator detector stations on school roofs in the Stockholm area. Signals from GPS satellites are used to time synchronise signals from the widely separated detector stations, allowing cosmic ray air showers to be identified and studied. A low-cost and highly scalable data acquisition system has been produced using embedded Linux processors which communicate station data to a central server running a MySQL database. Air shower data can be visualised in real-time using a Java-applet client. It is also possible to query the database and manage detector stations from the client. In this paper, the design and performance of the system are described.

  • 10.
    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.

  • 11.
    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.

  • 12. Kole, Merlin
    et al.
    Chauvin, Maxime
    Fukazawa, Y.
    Fukuda, K.
    Ishizu, S.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics.
    Kamae, T.
    Kawaguchi, N.
    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.
    Moretti, Elena
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Rydström, Stefan
    Takahashi, H.
    Yanagida, T.
    Neutron background detection for a hard X-ray balloon-borne polarimeter2014In: Proceedings of Science, Proceedings of Science (PoS) , 2014Conference paper (Refereed)
    Abstract [en]

    PoGOLite is a balloon-borne hard X-ray polarimeter. It determines polarisation by measuring the azimuthal angular distribution of Compton scattered photons in a plastic scintillator array. The use of an all-plastic target yields a relatively large, low-mass detection area. The dominant source of background for these measurements has been shown, through Geant4 simulations, to originate from high energy (MeV range) atmospheric neutrons. Neutrons can pass the instrument's Bismuth Germanium Oxide (BGO) anti-coincidence shield undetected and subsequently scatter between plastic scintillator elements to produce a polarisation signature. A passive 15 cm thick polyethylene shield surrounding the polarimeter reduces the neutron induced background by an order of magnitude. The background level remains however significant, prompting the need for active monitoring of the continuously changing neutron flux. For this purpose PoGOLite makes use of a phoswich scintillator cell. The phoswich cell consists of a 5 mm thick Lithium Calcium Aluminium Fluoride (LiCAF) scintillator, used for neutron detection. The LiCAF is surrounded by a BGO anti-coincidence system. This small light weight detector can therefore be used to measure the neutron flux even in high radiation environments. This type of neutron detector was tested on a separate dedicated stratospheric balloon mission in March 2013, called PoGOLino, prior to the PoGOLite flight which took place in July 2013. Results from the test flight and implications for the measurements performed on the PoGOLite flight will be discussed.

  • 13.
    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.

  • 14.
    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.

  • 15.
    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.

  • 16. 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.

  • 17. 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.

  • 18. 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.

  • 19. 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.

1 - 19 of 19
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