Predictions of induced radioactivity for spacecraft in low Earth orbit

Armstrong, T. W.; Colborn, B. L.

doi:10.1016/1359-0189(92)90089-e

Cited by 27 publications

(7 citation statements)

References 17 publications

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“…At a recent Houston workshop, it was concluded that the fraction of dose equivalent from neutrons for the ISS may lie between ∼30% and 50% depending on the assumed quality factor for the high-energy neutrons [8]. Studies during the 1990s continued to indicate that the majority of neutrons are generated as secondary radiation and that about half of the neutron dose equivalent comes from neutrons with energy > 15 MeV [9,10].…”

Section: Introductionmentioning

confidence: 99%

Bubble detector characterization for space radiation

Green

Andrews²,

Bennett

et al. 2005

Acta Astronautica

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Section: Introductionmentioning

confidence: 99%

Bubble detector characterization for space radiation

Green

Andrews²,

Bennett

et al. 2005

Acta Astronautica

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“…In addition, the AC placed inside the passive shielding could reduce the passive material induced delayed emission. However, the detectors would also be reached by the AC induced decays, and the inorganic scintillators are proven to be intense sources of delayed emission [33]. The best choice could be represented by a combination of the two types, a plastic and inorganic AC, to fully exploit their performances.…”

Section: Discussionmentioning

confidence: 98%

“…A strong dependance on the magnetic latitude, i.e. on the geomagnetic cut-off, is instead found: in [47], from ∼ 40 • to the equator the flux is 3 times lower, a value confirmed by [33]. We compare the fit to the COMPTEL neutron measurement [34], computed at λ m ∼ 40 • , with the model of [33], after normalizing for the different altitude.…”

Section: Albedo Neutronsmentioning

confidence: 89%

“…The most recent measurement has been made by the COMPTEL instrument onboard the CGRO mission [43] in 1991-1994, while the majority of the studies regarding the atmospheric neutrons refer to the late 60s and 70s, performed on board rocket [44] and balloon [45] flights, the Salyut and MIR space stations [46] and the OGO-6 satellite [47,40]. Among the Monte Carlo simulations of the expected neutron flux, the model by [33], at solar minimum for λ m = 42 • and an altitude of 45 km, is the most widely used thanks to its extended energy coverage and the accurate validation. The solar activity influences the neutron flux only for high latitudes [44].…”

Section: Albedo Neutronsmentioning

confidence: 99%

“…1 (right panel, thin lines), are consistent. We extrapolate the albedo neutron flux from the [33] model, which covers a wider energy range, after correcting for the different altitude (550 km) and latitude (geomagnetic equator).…”

Section: Albedo Neutronsmentioning

confidence: 99%

See 2 more Smart Citations

The low Earth orbit radiation environment and its impact on the prompt background of hard x-ray focusing telescopes

Fioretti

Bulgarelli

Malaguti

et al. 2012

High Energy, Optical, and Infrared Detectors for Astronomy V

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The background minimization is a science-driven necessity in order to reach deep sensitivity levels in the hard X-ray band, one of the key scientific requirements for hard X-ray telescopes (e.g. NuSTAR, ASTRO-H). It requires a careful modeling of the radiation environment and new concepts of shielding systems. We exploit the Bologna Geant4 Multi-Mission Simulator (BoGEMMS) features to evaluate the impact of the Low Earth Orbit (LEO) radiation environment on the prompt background level for a hybrid Si/CdTe soft and hard X-ray detection assembly and a combined active and passive shielding system. For each class of particles, the spectral distribution of the background flux is simulated, exploring the effect of different materials (plastic vs inorganic active scintillator) and configurations (passive absorbers enclosing or surrounded by the active shielding) on the background count rate. While protons are efficiently removed by the active shielding, an external passive shielding causes the albedo electrons and positrons to be the primary source of background. Albedo neutrons are instead weakly interactive with the active shielding, and they cause an intense background level below 10 keV via elastic scattering. The best shielding configuration in terms of background and active shielding count rates is given by an inorganic scintillator placed inside the passive layers, with the addition of passive material to absorb the intense fluorescence lines of the active shielding and avoid escape peaks on the CdTe detector.

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Background simulations for the Large Area Detector onboard LOFT

et al. 2013

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The Large Observatory For X-ray Timing (LOFT), currently in an assessment phase in the framework the ESA M3 Cosmic Vision programme, is an innovative medium-class mission specifically designed to answer fundamental questions about the behaviour of matter, in the very strong gravitational and magnetic fields around compact objects and in supranuclear density conditions. Having an effective area of ~10 m^2 at 8 keV, LOFT will be able to measure with high sensitivity very fast variability in the X-ray fluxes and spectra. A good knowledge of the in-orbit background environment is essential to assess the scientific performance of the mission and optimize the design of its main instrument, the Large Area Detector (LAD). In this paper the results of an extensive Geant-4 simulation of the instrument will be discussed, showing the main contributions to the background and the design solutions for its reduction and control. Our results show that the current LOFT/LAD design is expected to meet its scientific requirement of a background rate equivalent to 10 mCrab in 2-30 keV, achieving about 5 mCrab in the most important 2-10 keV energy band. Moreover, simulations show an anticipated modulation of the background rate as small as 10% over the orbital timescale. The intrinsic photonic origin of the largest background component also allows for an efficient modelling, supported by an in-flight active monitoring, allowing to predict systematic residuals significantly better than the requirement of 1%, and actually meeting the 0.25% science goal.Comment: 31 pages, 18 figures. Accepted for publication in Experimental Astronom

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Predictions of induced radioactivity for spacecraft in low Earth orbit

Cited by 27 publications

References 17 publications

Bubble detector characterization for space radiation

Bubble detector characterization for space radiation

The low Earth orbit radiation environment and its impact on the prompt background of hard x-ray focusing telescopes

Background simulations for the Large Area Detector onboard LOFT

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