Calculations of neutron flux spectra induced in the Earth's atmosphere by galactic cosmic rays

Armstrong, T. W.; Chandler, K.C.; Barish, J.

doi:10.1029/ja078i016p02715

Cited by 165 publications

(117 citation statements)

References 28 publications

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“…During float, the counting rate remains reasonably constant except for a 45 minute interval during which a 20 cm diameter by 10 cm thick block ing crystal was moved in front of the aperture, and during the Crab nebula transit. The isotropic atmospheric fluxes of neutrons and > 100 MeV protons drop by a factor of several, depending upon the particle and upon energy, betweenPfotzer maximum and float (Armstrong, et al, 1973 andWebber, 1959). …”

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confidence: 99%

Gamma-ray spectroscopy in astrophysics

Ramaty

Kline

Weaver

1978

Nature

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This was the first symposium devoted entirely to spectroscopy in gamma ray astronomy. Its purposes were to bring together most of the scientists contributing to all the aspects, experimental and theoretical, of this new field and to discuss and compare ideas, measurements, calcu lations and technical experience in what we confidently expect to be a very important new discipline in high energy astrophysics.This goal was achieved, we feel, in that a very large fraction of all that is known about gamma ray spectroscopy in astrophysics was indeed presented or discussed at the Symposium, yet many of these results are new, presented here for the first time. Further, the discipline is on the brink of moving to the next level of development within the coming year, with a number of satellite experiments and major balloon experiments in gamma ray spectroscopy and in related astrophysical sciences about to be launched. We therefore felt that we should publish the Proceedings as soon as possible, without the delays involved in reformatting the manuscripts and extensive editing. We hope that the information that will thus become available will prove to be useful to all workers in these fields.We have ordered the papers approximately as presented, with experimental and theoretical papers combined in each session. The introductory session is followed by the sessions on solar, stellar, and planetary gamma ray spectroscopy, and on cosmic gamma ray spectroscopy, with the technical discussions and previews of new experiments in the last two sessions.The Symposium was organized by the editors of these proceedings, T. L. Cline and R. Ramaty. We wish to thank the Symposium Session Chairmen, D. D. Clayton, and M. M. Shapiro, and the Workshop Session Chairmen, G. J. Fishman and N. S. Wall, for their assistance. We are grateful to R. C. Reedy for supplying us the manuscript on Planetary Gamma Ray Spectro scopy which was not presented at the Symposium. This paper is taken from the Proceedings of the Ninth Lunar and Planetary Science Conference (Pergamon Press 1978, with permission). We are also indebted to R. W. Bussard and R. P. Weaver for their help in running the conference. We thank F. B. McDonald for his continued support of this Symposium, and R. S. Cooper for his interest and his contribution. We thank Barbara Pratt in particular for her excellent secretarial help with both the organization of the Symposium and the preparation of this document. It is a pleasure for me to be here and welcome you all to the Goddard Space Flight Center. I noticed from the agenda that we have speakers from all the major groups that are interested in high energy astronomy and in particular in gamma ray astronomy virtually in the entire free world. The agenda is particularly interesting to me and I intend to spend as much of my time here over the next day as I can. I would like to make a couple of points. The people here at Goddard know that when they give me an oppor tunity to come and welcome you, the potential is always there for me to say something...

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confidence: 99%

Gamma-ray spectroscopy in astrophysics

Ramaty

Kline

Weaver

1978

Nature

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“…Thus, we tried to examine the effects of the variability of unfolding results on the default spectrum. Figure 9 shows cosmic-ray neutron spectra over a wide energy range as neutrons cm À2 s À1 MeV À1 at 11.8 km altitude (200 g cm À2 in atmospheric depth) calculated by Armstrong et al 26) and measured by Hess et al,27) and at 11.28 km altitude measured by Nakamura and coworkers. 12,22) In reference to Fig.…”

Section: (2) Comparison With Calculationsmentioning

confidence: 99%

Measurements of Cosmic-Ray Neutron Energy Spectra from Thermal to 15 MeV with Bonner Ball Neutron Detector in Aircraft

Yajima¹,

Yasuda²,

Takada³

et al. 2010

Journal of Nuclear Science and Technology

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Cosmic-ray neutron energy spectra from thermal to 15 MeV were measured with a multimoderator spectrometer known as the Bonner Ball Neutron Detector (BBND) at aviation altitude (9-11 km). Four flights were carried out around Nagoya Airport in Japan. The measured data were unfolded using the maximum entropy deconvolution code MAXED, and the derived spectra agreed with the calculated results using the PHITS-based analytical radiation model in the atmosphere (PARMA). The results of the in-flight measurement verified the accuracy of model calculation in regard to the neutrons within a certain energy range.

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“…The neutron flux used in the simulation is from a model proposed by Armstrong et al [41] for an atmospheric depth of 5 g/cm 2 . The angular distribution is assumed to be isotropic, but we note that according to Armstrong et al [42], the upward and downward fluxes are typically 80% and 20% of the isotropic flux, respectively.…”

Section: Background Simulationmentioning

confidence: 99%

PoGOLite – A high sensitivity balloon-borne soft gamma-ray polarimeter

Kamae

Andersson

Arimoto

et al. 2008

Astroparticle Physics

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We describe a new balloon-borne instrument (PoGOLite) capable of detecting 10% polarisation from 200 mCrab point-like sources between 25 keV and 80 keV in one 6 hour 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 field of view (FWHM = 1.25 msr, 2.0 degrees × 2.0 degrees) obtained with detector cells and the use of thick background shields warrant a large effective area for polarisation measurements (∼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 ∼100 mCrab source between 25 keV and 50 keV. A 6 hour observation of the Crab pulsar will differentiate between the Polar Cap/Slot Gap, Outer Gap, and Caustic models with greater than 5σ 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.Key words: Instrumentation: detectors, Techniques: polarimetric, Pulsars: general, X-ray: binaries, Stars: neutron, Galaxies: active PACS: 95.30. Gv, 95.55.Ka, 95.55.Qf, 95.75.Hi, 95.85.Pw, 97.60Gv, 97.60.Lf, 97.80.Jp, 98.54.Cm

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Calculations of neutron flux spectra induced in the Earth's atmosphere by galactic cosmic rays

Cited by 165 publications

References 28 publications

Gamma-ray spectroscopy in astrophysics

Gamma-ray spectroscopy in astrophysics

Measurements of Cosmic-Ray Neutron Energy Spectra from Thermal to 15 MeV with Bonner Ball Neutron Detector in Aircraft

PoGOLite – A high sensitivity balloon-borne soft gamma-ray polarimeter

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