Radioactivity induced background noise in space-borne astronomical gamma-ray telescopes employing inorganic scintillation spectrometers

Dean, Anthony J.; Lei, F.; Byard, Kevin; Goldwurm, A.; Hall, Christopher

doi:10.1007/bf00414794

Cited by 13 publications

(8 citation statements)

References 4 publications

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“…Most of the properties of the atmospheric gammarays were obtained with balloon experiments, mainly launched from Palestine (Texas, USA). Empirical models of the atmospheric gamma-ray emission, based on observational results, were worked out by various authors (Peterson 1975;Ling 1975;Dean et al 1989). From these observations, it can be seen that the gamma-ray emission properties depend on various parameters, like the geomagnetic latitude, the energy band, the direction of emission (downward, upward) and the altitude from the Earth.…”

Section: B1 the Past Measurementsmentioning

confidence: 99%

“…Thus its spectral properties, specially at low energies (>10 keV), are expected to be different from those observed inside the atmosphere. Measurements of the X-ray albedo radiation are reported in Schwartz & Peterson (1974) for photon energies in the 10-300 keV band, and in Imhof et al (1976) above 40 keV, while for energies higher than 150 keV see, e.g., Letaw et al (1986) and Dean et al (1989).…”

Section: B1 the Past Measurementsmentioning

confidence: 99%

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The Cosmic X‐Ray Background and the Population of the Most Heavily Obscured AGNs

Frontera¹,

Orlandini²,

Landi³

et al. 2007

ApJ

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We report on an accurate measurement of the CXB in the 15-50 keV range performed with the Phoswich Detection System (PDS) instrument aboard the BeppoSAX satellite. We establish that the most likely CXB intensity level at its emission peak (26-28 keV) is ≈40 keV cm −2 s −1 sr −1 , a value consistent with that derived from the best available CXB measurement obtained over 25 years ago with the first High Energy Astronomical Observatory satellite mission (HEAO-1;Gruber et al. 1999), whose intensity, lying well below the extrapolation of some lower energy measurements performed with focusing telescopes, was questioned in the recent years. We find that 90% of the acceptable solutions of our best fit model to the PDS data give a 20-50 keV CXB flux lower than 6.5 × 10 −8 erg cm −2 s −1 sr −1 , which is 12% higher than that quoted by Gruber et al. (1999) when we use our best calibration scale. This scale gives a 20-50 keV flux of the Crab Nebula of 9.22 × 10 −9 erg cm −2 s −1 , which is in excellent agreement with the most recent Crab Nebula measurements and 6% smaller than that assumed by Gruber et al. (1999). In combination with the CXB synthesis models we infer that about 25% of the intensity at ∼ 30 keV arises from extremely obscured, Compton thick AGNs (absorbing column density N H > 10 24 cm −2 ), while a much larger population would be implied by the highest intensity estimates. We also infer a mass density of supermassive BHs of ∼ 3 × 10 5 M ⊙ Mpc −3 . The summed contribution of resolved sources (Moretti et al. 2003) in the 2-10 keV band exceeds our best fit CXB intensity extrapolated to lower energies, but it is within our upper limit, so that any significant contribution to the CXB from sources other than AGNs, such as star forming galaxies and diffuse Warm-Hot Intergalactic Medium (WHIM), is expected to be mainly confined below a few keV.

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Section: B1 the Past Measurementsmentioning

confidence: 99%

Section: B1 the Past Measurementsmentioning

confidence: 99%

The Cosmic X‐Ray Background and the Population of the Most Heavily Obscured AGNs

Frontera¹,

Orlandini²,

Landi³

et al. 2007

ApJ

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show abstract

“…Cosmic ray interactions in the atmosphere radiate gamma-rays isotropically. This emissivity depends solely on the intensity of the incident cosmic rays and the atmospheric depth (Dean et al 1989). An angle-averaged spectrum of this albedo flux is also presented by Gehrels (1991).…”

Section: North-south Albedo Gamma-ray Excessmentioning

confidence: 99%

Evidence of polarisation in the prompt gamma-ray emission from GRB 930131 and GRB 960924

Willis

Barlow

Bird

et al. 2005

A&A

Self Cite

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Abstract. The true nature of the progenitor to GRBs remains elusive; one characteristic that would constrain our understanding of the GRB mechanism considerably is gamma-ray polarimetry measurements of the initial burst flux. We present a method that interprets the prompt GRB flux as it Compton scatters off the Earth's atmosphere, based on detailed modelling of both the Earth's atmosphere and the orbiting detectors. The BATSE mission aboard the CGRO monitored the whole sky in the 20 keV-1 MeV energy band continuously from April 1991 until June 2000. We present the BATSE Albedo Polarimetry System (BAPS), and show that GRB 930131 and GRB 960924 provide evidence of polarisation in their prompt flux that is consistent with degrees of polarisation of Π > 35% and Π > 50% respectively. While the evidence of polarisation is strong, the method is unable to strongly constrain the degree of polarisation beyond a systematics based estimation. Hence the implications on GRB theory are unclear, and further measurements essential.

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“…So the flux of albedo gamma radiation strongly depends on the relative position and pointing direction of HXMT. The spectrum can be obtained by combining the measurements of atmospheric gamma rays from several instruments (Imhof et al 1976;Ryan et al 1979), the emissivity of the earth's atmosphere (Dean et al 1989), and the atmosphere model. 3…”

Section: Albedo Gammamentioning

confidence: 99%

Simulation of the in-flight background for HXMT/HE

Xie

Zhang

Song

et al. 2015

Astrophys Space Sci

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The Hard X-ray Modulation Telescope (HXMT) is a broad-band X-ray astronomical satellite from 1 to 250 keV. Understanding the X-ray background in detail will help to achieve a good performance of the instrument. In this work, we make use of the mass modeling technique to estimate the background of High Energy Telescope (HE) aboard HXMT. It consists of three steps. First, we built a complete geometric model of HXMT. Then based on the investigation about the space environment concerning HXMT low-earth orbit, in our simulation we considered cosmic rays, cosmic X-ray background (CXB), South Atlantic Anomaly (SAA) trapped particles, the albedo gamma, and neutrons from interaction of cosmic rays with the Earth's atmosphere. Finally, the Shielding Physics List supplied by Geant4 collaborations was adopted. According to our simulation, (1) the total background of HXMT/HE is about 540 count/s on average over 20-250 keV energy band after 100 days in orbit; (2) the delayed component caused by cosmic rays and SAA trapped particles dominates the full energy band of HXMT/HE; (3) some emission lines are prominent in the background continuum spectrum and will be used for inorbit calibration; (4) the estimated sensitivity is ∼0.1 mCrab at 50 keV with an exposure of 10 6 s.

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Radioactivity induced background noise in space-borne astronomical gamma-ray telescopes employing inorganic scintillation spectrometers

Cited by 13 publications

References 4 publications

The Cosmic X‐Ray Background and the Population of the Most Heavily Obscured AGNs

The Cosmic X‐Ray Background and the Population of the Most Heavily Obscured AGNs

Evidence of polarisation in the prompt gamma-ray emission from GRB 930131 and GRB 960924

Simulation of the in-flight background for HXMT/HE

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