Bremsstrahlung effects in energetic particle detectors

Abstract

The energetic charged particles of the Earth's magnetosphere are routinely detected by solid‐state satellite instruments. Quantitative data are increasingly required for engineering dose calculations and for space weather science. However, the design of some energetic particle detectors can be severely constrained. Background effects must be accurately modeled in such cases to extract quantitative information. In particular, bremsstrahlung radiation from electrons impacting the detector and the satellite often dominates the background noise. Numerical tools are presented here to calculate total bremsstrahlung effects in energetic electron detectors. The calculations are illustrated for the low‐energy particle detector of current Global Positioning System satellites.

The Global Positioning System constellation as a space weather monitor: Comparison of electron measurements with Van Allen Probes data

“…While performing this work, systematic offsets between the expected and observed counts were found, in particular for the lowest five energy channels. These energy channels are from the Low Energy Particle (LEP) component of the CXD instrument [ Cayton , ], and the sense of the offset was consistent with an underestimate of the Bremsstrahlung contribution [ Tuszewski et al , ]. A constant scaling was applied to the Bremsstrahlung component of the instrument response, which was found to improve agreement with the expected counts; however, applying a constant scaling to the full energy dependent response both improved the median error and reduced the spread of count ratios.…”

“…Various sampling rates can be commanded, though the typical sampling rate is 240 s. Each of these sensors also provides proton measurements, and the proton data will be the subject of future work. Details of the instrument design, including the integrated X‐ray sensors, are given by Distel et al [], and more details on the LEP sensor are given by Tuszewski et al [].…”

“…Since late 2000, two new series of instruments have been flown on the GPS constellation: The BDD‐IIR detector [ Cayton et al , ], which is significantly different to the BDD‐II described above, and the Combined X‐ray Dosimeter (CXD), which is an entirely new design [ Cayton , ; Tuszewski et al , ].…”

On the Role of Last Closed Drift Shell Dynamics in Driving Fast Losses and Van Allen Radiation Belt Extinction

“…Figure shows that in the first three events (March 2013, 2015, and September 2014) the radiation belt loss happened on a time scale which is too short to be fully resolved along the orbit of the Van Allen Probes mission, the orbital period being too long to provide an explicit picture of what happened. Thus, in this paper, we additionally focus on GPS satellite electron flux measurements from the Combined X‐ray Dosimeter (Tuszewski et al, ). Combined data from 11 to 17 satellites, depending on the year, delivers high (∼30 min) temporal resolution and explicitly shows the dropout patterns even in fast loss events.…”

Global Prompt Proton Sensor Network: Monitoring Solar Energetic Protons Based on GPS Satellite Constellation

“…The latest instrument is the Combined X-ray Dosimeter (CXD), replacing the previous version of Burst Detector Dosimeter for Block II-R (BDD-IIR, Cayton et al, 1998). A detailed description of the CXD instrument is given by Tuszewski et al (2004), and we briefly recap here. Besides measuring electrons (see Morley et al, 2016), the CXD instrument also measures protons with energies from ~6 MeV up to greater than 75 MeV within five channels using three sensors: the lowenergy particle sensor containing two proton channels 6-10 MeV (P1) and 10-50 MeV (P2), the first high-energy X-ray and particle detector with one proton channel 16-128 MeV (P3), and the second high-energy X-ray and particle detector with two proton channels 57-75 MeV (P4) and >75 MeV (P5).…”