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Publications (10 of 193) Show all publications
Xie, F., Pearce, M. & SPHiNX, C. (2018). A Study of Background Conditions for Sphinx-The Satellite-Borne Gamma-Ray Burst Polarimeter. Galaxies, 6(2), Article ID 50.
Open this publication in new window or tab >>A Study of Background Conditions for Sphinx-The Satellite-Borne Gamma-Ray Burst Polarimeter
2018 (English)In: Galaxies, E-ISSN 2075-4434, Vol. 6, no 2, article id 50Article in journal (Refereed) Published
Abstract [en]

SPHiNX is a proposed satellite-borne gamma-ray burst polarimeter operating in the energy range 50-500 keV. The mission aims to probe the fundamental mechanism responsible for gamma-ray burst prompt emission through polarisation measurements. Optimising the signal-to-background ratio for SPHiNX is an important task during the design phase. The Geant4 Monte Carlo toolkit is used in this work. From the simulation, the total background outside the South Atlantic Anomaly (SAA) is about 323 counts/s, which is dominated by the cosmic X-ray background and albedo gamma rays, which contribute similar to 60% and similar to 35% of the total background, respectively. The background from albedo neutrons and primary and secondary cosmic rays is negligible. The delayed background induced by the SAA-trapped protons is about 190 counts/s when SPHiNX operates in orbit for one year. The resulting total background level of similar to 513 counts/s allows the polarisation of similar to 50 GRBs with minimum detectable polarisation less than 30% to be determined during the two-year mission lifetime.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
polarimeter, Compton scattering, GRB, background
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:kth:diva-232265 (URN)10.3390/galaxies6020050 (DOI)000436552000012 ()2-s2.0-85047239209 (Scopus ID)
Note

QC 20180719

Available from: 2018-07-19 Created: 2018-07-19 Last updated: 2018-07-19Bibliographically approved
Chauvin, M., Florén, H.-G., Friis, M., Jackson, M., Kamae, T., Kataoka, J., . . . Pearce, M. (2018). Accretion geometry of the black-hole binary Cygnus X-1 from X-ray polarimetry [Letter to the editor]. Nature Astronomy, 2(8), 652-655
Open this publication in new window or tab >>Accretion geometry of the black-hole binary Cygnus X-1 from X-ray polarimetry
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2018 (English)In: Nature Astronomy, ISSN 2397-3366, Vol. 2, no 8, p. 652-655Article in journal, Letter (Refereed) Published
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.

Place, publisher, year, edition, pages
Nature Publishing Group, 2018
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:kth:diva-228215 (URN)10.1038/s41550-018-0489-x (DOI)2-s2.0-85051090128 (Scopus ID)
Note

QC 20180521

Available from: 2018-05-18 Created: 2018-05-18 Last updated: 2018-08-22Bibliographically approved
Munini, R., Boezio, M., Bruno, A., Christian, E. C., Nolfo, G. A., Felice, V. D., . . . Potgieter, M. S. (2018). Evidence of Energy and Charge Sign Dependence of the Recovery Time for the 2006 December Forbush Event Measured by the PAMELA Experiment. Astrophysical Journal, 853(1), Article ID 76.
Open this publication in new window or tab >>Evidence of Energy and Charge Sign Dependence of the Recovery Time for the 2006 December Forbush Event Measured by the PAMELA Experiment
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2018 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 853, no 1, article id 76Article in journal (Refereed) Published
Abstract [en]

New results on the short-term galactic cosmic-ray (GCR) intensity variation (Forbish decrease) in 2006 December measured by the PAMELA instrument are presented. Forbush decreases are sudden suppressions of the GCR intensities, which are associated with the passage of interplanetary transients such as shocks and interplanetary coronal mass ejections (ICMEs). Most of the past measurements of this phenomenon were carried out with groundbased detectors such as neutron monitors or muon telescopes. These techniques allow only the indirect detection of the overall GCR intensity over an integrated energy range. For the first time, thanks to the unique features of the PAMELA magnetic spectrometer, the Forbush decrease, commencing on 2006 December 14 and following a CME at the Sun on 2006 December 13, was studied in a wide rigidity range (0.4-20 GV) and for different species of GCRs detected directly in space. The daily averaged GCR proton intensity was used to investigate the rigidity dependence of the amplitude and the recovery time of the Forbush decrease. Additionally, for the first time, the temporal variations in the helium and electron intensities during a Forbush decrease were studied. Interestingly, the temporal evolutions of the helium and proton intensities during the Forbush decrease were found to be in good agreement, while the low rigidity electrons (<2 GV) displayed a faster recovery. This difference in the electron recovery is interpreted as a charge sign dependence introduced by drift motions experienced by the GCRs during their propagation through the heliosphere.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2018
Keywords
cosmic rays, Sun: coronal mass ejections (CMEs), Sun: heliosphere, Sun: particle emission
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-222300 (URN)10.3847/1538-4357/aaa0c8 (DOI)000423361100012 ()2-s2.0-85041112562 (Scopus ID)
Funder
Swedish National Space BoardSwedish Research Council
Note

QC 20180206

Available from: 2018-02-06 Created: 2018-02-06 Last updated: 2018-02-19Bibliographically approved
Menn, W., Bogomolov, E. A., Simon, M., Vasilyev, G., Adriani, O., Barbarino, G. C., . . . Zampa, N. (2018). Lithium and Beryllium Isotopes with the PAMELA Experiment. Astrophysical Journal, 862(2), Article ID 141.
Open this publication in new window or tab >>Lithium and Beryllium Isotopes with the PAMELA Experiment
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2018 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 862, no 2, article id 141Article in journal (Refereed) Published
Abstract [en]

The cosmic ray (CR) lithium and beryllium (Li-6, Li-7, Be-7, Be-9, Be-10) isotopic composition has been measured with the satellite-borne experiment PAMELA, which was launched into low-Earth orbit on board the Resurs-DKJ satellite on 2006 June 15. The rare lithium and beryllium isotopes in CRs are believed to originate mainly from the interaction of high-energy carbon, nitrogen, and oxygen nuclei with the interstellar medium (ISM), but also on "tertiary" interactions in the ISM (i.e., produced by further fragmentation of secondary beryllium and boron). In this paper, the isotopic ratios Li-7/Li-6 and Be-7/(Be-9 + Be-10), measured between 150 and 1100 MeV n(-1) using two different detector systems from 2006 July to 2014 September, will be presented.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2018
Keywords
astroparticle physics, cosmic rays
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-233280 (URN)10.3847/1538-4357/aacf89 (DOI)000440621800003 ()
Note

QC 20180822

Available from: 2018-08-22 Created: 2018-08-22 Last updated: 2018-08-22Bibliographically approved
Martucci, M., Munini, R., Boezio, M., Di Felice, V., Adriani, O., Barbarino, G. C., . . . Raath, J. L. (2018). Proton Fluxes Measured by the PAMELA Experiment from the Minimum to the Maximum Solar Activity for Solar Cycle 24. Astrophysical Journal Letters, 854(1), Article ID L2.
Open this publication in new window or tab >>Proton Fluxes Measured by the PAMELA Experiment from the Minimum to the Maximum Solar Activity for Solar Cycle 24
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2018 (English)In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 854, no 1, article id L2Article in journal (Refereed) Published
Abstract [en]

Precise measurements of the time-dependent intensity of the low-energy (<50 GeV) galactic cosmic rays (GCRs) are fundamental to test and improve the models that describe their propagation inside the heliosphere. In particular, data spanning different solar activity periods, i.e., from minimum to maximum, are needed to achieve comprehensive understanding of such physical phenomena. The minimum phase between solar cycles 23 and 24 was peculiarly long, extending up to the beginning of 2010 and followed by the maximum phase, reached during early 2014. In this Letter, we present proton differential spectra measured from 2010 January to 2014 February by the PAMELA experiment. For the first time the GCR proton intensity was studied over a wide energy range (0.08-50 GeV) by a single apparatus from a minimum to a maximum period of solar activity. The large statistics allowed the time variation to be investigated on a nearly monthly basis. Data were compared and interpreted in the context of a state-of-the-art three-dimensional model describing the GCRs propagation through the heliosphere.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2018
Keywords
astroparticle physics, cosmic rays, Sun: heliosphere
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-223499 (URN)10.3847/2041-8213/aaa9b2 (DOI)000424238600002 ()2-s2.0-85042130192 (Scopus ID)
Note

QC 20180223

Available from: 2018-02-23 Created: 2018-02-23 Last updated: 2018-02-23Bibliographically approved
Friis, M., Kiss, M., Mikhalev, V., Pearce, M. & Takahashi, H. (2018). The PoGO+ balloon-borne hard X-ray polarimetry mission. Galaxies, 6(1), Article ID 30.
Open this publication in new window or tab >>The PoGO+ balloon-borne hard X-ray polarimetry mission
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2018 (English)In: Galaxies, E-ISSN 2075-4434, Vol. 6, no 1, article id 30Article in journal (Refereed) Published
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. 

Place, publisher, year, edition, pages
MDPI AG, 2018
Keywords
Attitude control, Compton polarimeter, Crab, Cygnus X-1, Hard X-rays, Payload design, Scientific ballooning
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-227400 (URN)10.3390/galaxies6010030 (DOI)000428554900030 ()2-s2.0-85043362309 (Scopus ID)
Note

Export Date: 9 May 2018; Article; Correspondence Address: Kiss, M.; KTH Royal Institute of Technology, Department of PhysicsSweden; email: mozsi@kth.se; Funding details: Knut och Alice Wallenbergs Stiftelse; Funding details: JSPS, Japan Society for the Promotion of Science; Funding details: TRC, The Research Council; Funding details: SNSB, Swedish National Space Board; Funding details: DST, Department of Science and Technology, Ministry of Science and Technology; Funding details: CASIS, Center for the Advancement of Science in Space; Funding text: Acknowledgments: This research was supported in Sweden by The Swedish National Space Board, The Knut and Alice Wallenberg Foundation, and The Swedish Research Council. In Japan, support was provided by the Japan Society for Promotion of Science and ISAS/JAXA. SSC are thanked for providing expert mission support and launch services at Esrange Space Center. DST Control developed the PoGO+ attitude control system under the leadership of J.-E. Strömberg. Contributions from past collaboration members and students are acknowledged. QC 20180529

Available from: 2018-05-29 Created: 2018-05-29 Last updated: 2018-06-25Bibliographically approved
Mikhailov, V. V., Adriani, O., Bazilevskaya, G. A., Barbarino, G. C., Bellotti, R., Bogomolov, E. A., . . . Yurkin, Y. T. (2018). Trapped Positrons and Electrons in the Inner Radiation Belt According to Data of the PAMELA Experiment. Physics of Atomic Nuclei, 81(4), 515-519
Open this publication in new window or tab >>Trapped Positrons and Electrons in the Inner Radiation Belt According to Data of the PAMELA Experiment
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2018 (English)In: Physics of Atomic Nuclei, ISSN 1063-7788, E-ISSN 1562-692X, Vol. 81, no 4, p. 515-519Article in journal (Refereed) Published
Abstract [en]

Measurements of secondary-electron and secondary-positron fluxes below the geomagnetic cutoff in near-Earth space were performed by means of the PAMELA magnetic spectrometer installed on board the Resurs-DK1 satellite launched on June 15, 2006, in an elliptical orbit of inclination 70A degrees and altitude 350 to 600 km. This spectrometer permits measuring the fluxes of electrons and positrons over a wide energy range, as well as determining their spatial distributions to a precision of about 2A degrees. A calculation of particle trajectories in the geomagnetic field makes it possible to separate electrons and positrons originating from cosmic-ray interactions in the Earth's magnetosphere. The spatial distributions of quasitrapped, trapped, and short-lived albedo positrons and electrons of energy above 70 MeV in the radiation belt were analyzed. The ratio of the electron-to-positron fluxes and the energy spectra of the electrons and positrons in question are indicative of different productionmechanisms for stably trapped and quasitrapped secondary particles.

Place, publisher, year, edition, pages
PLEIADES PUBLISHING INC, 2018
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-234208 (URN)10.1134/S1063778818040129 (DOI)000441871000012 ()2-s2.0-85051714633 (Scopus ID)
Note

QC 20180906

Available from: 2018-09-06 Created: 2018-09-06 Last updated: 2018-09-06Bibliographically approved
Adriani, O., Barbarino, G. C., Bazilevskaya, G. A., Bellotti, R., Boezio, M., Bogomolov, E. A., . . . Zampa, N. (2018). Unexpected Cyclic Behavior in Cosmic-Ray Protons Observed by PAMELA at 1 au. Astrophysical Journal Letters, 852(2), Article ID L28.
Open this publication in new window or tab >>Unexpected Cyclic Behavior in Cosmic-Ray Protons Observed by PAMELA at 1 au
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2018 (English)In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 852, no 2, article id L28Article in journal (Refereed) Published
Abstract [en]

Protons detected by the PAMELA experiment in the period 2006-2014 have been analyzed in the energy range between 0.40 and 50 GV to explore possible periodicities besides the well known solar undecennial modulation. An unexpected clear and regular feature has been found at rigidities below 15 GV, with a quasi-periodicity of similar to 450 days. A possible Jovian origin of this periodicity has been investigated in different ways. The results seem to favor a small but not negligible contribution to cosmic rays from the Jovian magnetosphere, even if other explanations cannot be excluded.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2018
Keywords
cosmic rays, Sun: heliosphere
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-221941 (URN)10.3847/2041-8213/aaa403 (DOI)000419785000004 ()2-s2.0-85040668902 (Scopus ID)
Note

QC 20180130

Available from: 2018-01-30 Created: 2018-01-30 Last updated: 2018-01-30Bibliographically approved
Chauvin, M., Friis, M., Jackson, M., Kawano, T., Kiss, M., Mikhalev, V., . . . Pearce, M. (2017). Calibration and performance studies of the balloon-borne hard X-ray polarimeter PoGO. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 859, 125-133
Open this publication in new window or tab >>Calibration and performance studies of the balloon-borne hard X-ray polarimeter PoGO
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2017 (English)In: 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) Published
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.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2017
Keywords
X-ray, Polarisation, Compton scattering, Scientific ballooning, Crab, Cygnus X-1, Monte Carlo simulations
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-219572 (URN)10.1016/j.nima.2017.03.027 (DOI)000402464700018 ()2-s2.0-85018696451 (Scopus ID)
Note

QC 20171207

Available from: 2017-12-07 Created: 2017-12-07 Last updated: 2018-05-21Bibliographically approved
Bruno, A., Adriani, O., Barbarino, G. C., Bazilevskaya, G. A., Bellotti, R., Boezio, M., . . . Zampa, N. (2017). Geomagnetically trapped, albedo and solar energetic particles: Trajectory analysis and flux reconstruction with PAMELA. Advances in Space Research, 60(4), 788-795
Open this publication in new window or tab >>Geomagnetically trapped, albedo and solar energetic particles: Trajectory analysis and flux reconstruction with PAMELA
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2017 (English)In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 60, no 4, p. 788-795Article in journal (Refereed) Published
Abstract [en]

The PAMELA satellite experiment is providing comprehensive observations of the interplanetary and magnetospheric radiation in the near-Earth environment. Thanks to its identification capabilities and the semi-polar orbit, PAMELA is able to precisely measure the energetic spectra and the angular distributions of the different cosmic-ray populations over a wide latitude region, including geomagnetically trapped and albedo particles. Its observations comprise the solar energetic particle events between solar cycles 23 and 24, and the geomagnetic cutoff variations during magnetospheric storms. PAMELA's measurements are supported by an accurate analysis of particle trajectories in the Earth's magnetosphere based on a realistic geomagnetic field modeling, which allows the classification of particle populations of different origin and the investigation of the asymptotic directions of arrival.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Cosmic-rays, Radiation belts, Albedo particles, Geomagnetic cutoff, Solar energetic particles
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-211588 (URN)10.1016/j.asr.2016.06.042 (DOI)000405975700005 ()2-s2.0-85002846984 (Scopus ID)
Funder
Swedish National Space BoardSwedish Research Council
Note

QC 20170815

Available from: 2017-08-15 Created: 2017-08-15 Last updated: 2017-08-15Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-7011-7229

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