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arXiv · 1509.02385

A magnetic diverter for charged particle background rejection in the SIMBOL-X telescope

D. Spiga·V. Fioretti·A. Bulgarelli·E. Dell'Orto·L. Foschini·G. Malaguti·G. Pareschi·G. Tagliaferri·A. Tiengo
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Abstract

Minimization of charged particle background in X-ray telescopes is a well known issue. Charged particles (chiefly protons and electrons) naturally present in the cosmic environment constitute an important background source when they collide with the X-ray detector. Even worse, a serious degradation of spectroscopic performances of the X-ray detector was observed in Chandra and Newton-XMM, caused by soft protons with kinetic energies ranging between 100 keV and some MeV being collected by the grazing-incidence mirrors and funneled to the detector. For a focusing telescope like SIMBOL-X, the exposure of the soft X-ray detector to the proton flux can increase significantly the instrumental background, with a consequent loss of sensitivity. In the worst case, it can also seriously compromise the detector duration. A well-known countermeasure that can be adopted is the implementation of a properly-designed magnetic diverter, that should prevent high-energy particles from reaching the focal plane instruments of SIMBOL-X. Although Newton-XMM and Swift-XRT are equipped with magnetic diverters for electrons, the magnetic fields used are insufficient to effectively act on protons. In this paper, we simulate the behavior of a magnetic diverter for SIMBOL-X, consisting of commercially-available permanent magnets. The effects of SIMBOL-X optics is simulated through GEANT4 libraries, whereas the effect of the intense required magnetic fields is simulated along with specifically-written numerical codes in IDL.

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D. Spiga, V. Fioretti, A. Bulgarelli, E. Dell'Orto, L. Foschini, G. Malaguti, G. Pareschi, G. Tagliaferri, A. Tiengo. 2015-09-08. A magnetic diverter for charged particle background rejection in the SIMBOL-X telescope. https://doi.org/10.1117/12.789917

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