Abstract
Low energy protons (< 300 keV) can enter the field of view of X-ray telescopes, scatter on their mirror surfaces at small incident angles, and deposit energy on the detector. This phenomenon can cause intense background flares at the focal plane decreasing the mission observing time (e.g. the XMM-Newton mission) or in the most extreme cases, damaging the X-ray detector. A correct modelization of the physics process responsible for the grazing angle scattering processes is mandatory to evaluate the impact of such events on the performance (e.g. observation time, sensitivity) of future X-ray telescopes as the ESA ATHENA mission. The Remizovich model describes particles reflected by solids at glancing angles in terms of the Boltzmann transport equation using the diffuse approximation and the model of continuous slowing down in energy. For the first time this solution, in the approximation of no energy losses, is implemented, verified, and qualitatively validated on top of the Geant4 release 10.2, with the possibility to add a constant energy loss to each interaction. This implementation is verified by comparing the simulated proton distribution to both the theoretical probability distribution and with independent ray-tracing simulations. Both the new scattering physics and the Coulomb scattering already built in the official Geant4 distribution are used to reproduce the latest experimental results on grazing angle proton scattering. At 250 keV multiple scattering delivers large proton angles and it is not consistent with the observation. Among the tested models, the single scattering seems to better reproduce the scattering efficiency at the three energies but energy loss obtained at small scattering angles is significantly lower than the experimental values. In general, the energy losses obtained in the experiment are higher than what obtained by the simulation. The experimental data are not completely representative of the soft proton scattering experienced by current X-ray telescopes because of the lack of measurements at low energies (< 200 keV) and small reflection angles, so we are not able to address any of the tested models as the one that can certainly reproduce the scattering behavior of low energy protons expected for the ATHENA mission. We can, however, discard multiple scattering as the model able to reproduce soft proton funnelling, and affirm that Coulomb single scattering can represent, until further measurements at lower energies are available, the best approximation of the proton scattered angular distribution at the exit of X-ray optics.
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References
Agostinelli, S., et al.: Geant4–a simulation toolkit. NIM A 506, 250–303 (2003)
Allison, J., et al.: Geant4 developments and applications. IEEE Trans. Nucl. Sci. 53(1), 270–278 (2006)
Allison, J., et al.: Recent developments in GEANT4. NIM A 835, 186–225 (2016). https://doi.org/10.1016/j.nima.2016.06.125
Briel, U.G., et al.: In-orbit performance of the EPIC-PN CCD camera on board XMM-Newton. Proc. SPIE 4012, 154–164 (2000)
Bulgarelli, A., et al.: BoGEMMS: the Bologna Geant4 multi-mission simulator. Proc. SPIE, 845335 (2012). https://doi.org/10.1117/12.926065
Burrows, D.N., et al.: The swift X-ray telescope. Space Sci. Rev. 120, 165–195 (2005). https://doi.org/10.1007/s11214-005-5097-2
Carter, J.A., Read, A.M.: The XMM-Newton EPIC background and the production of background blank sky event files. A&A 464, 1155–1166 (2007). https://doi.org/10.1051/0004-6361:20065882
Conti, G., et al.: X-ray characteristics of the Italian X-Ray Astronomy Satellite (SAX) flight mirror units. Proc. SPIE 2279, 101–109 (1994)
Cusumano, G., et al.: In-flight calibration of the Swift XRT effective area. AIPC 836, 664–667 (2006). https://doi.org/10.1063/1.2207972
De Luca, A., Molendi, S.: The 2-8 keV cosmic X-ray background spectrum as observed with XMM-Newton. A&A 419, 837–848 (2004). https://doi.org/10.1051/0004-6361:20034421
Diebold, S., et al.: Soft proton scattering efficiency measurements on X-ray mirror shells. Exp. Astron. 39, 343–365 (2015). https://doi.org/10.1007/s10686-015-9451-4
Fioretti, V., et al.: Monte Carlo simulations of gamma-ray space telescopes: a BoGEMMS multi-purpose application. Proc. SPIE 9144, 91443N (2014). https://doi.org/10.1117/12.2056442
Garmire, G.P., et al.: Advanced CCD imaging spectrometer (ACIS) instrument on the Chandra X-ray observatory. Proc. SPIE 4851, 28–44 (2003). https://doi.org/10.1117/12.461599
Ivanchenko, V., et al.: Validation of Geant4 10.3 simulation of proton interaction for space radiation effects. Exp. Astron. 835, 186–225 (2017). https://doi.org/10.1007/s10686-017-9556-z
Ivanchenko, V.N., et al.: Geant4 models for simulation of multiple scattering. J. Phys. Conf. Ser. 219, 032045 (2010). https://doi.org/10.1088/1742-6596/219/3/032045
Jansen, F., et al.: XMM-Newton observatory. I. The spacecraft and operations. A&A 365, L1–L6 (2001). https://doi.org/10.1051/0004-6361:20000036
Kimura, K., Hasegawa, M., Mannami, M.H.: Energy loss of MeV light ions specularly reflected from a SnTe(001) surface. Phys. Rev. B 36, 7–12 (1987). https://doi.org/10.1103/PhysRevB.36.7
Lei, F., et al.: Update on the use of Geant4 for the simulation of low-energy protons scattering off X-ray mirrors at grazing incidence angles. IEEE Trans. Nucl. Sci. 51, 3408–3412 (2004). https://doi.org/10.1109/TNS.2004.839160
Lumb, D.H., et al.: X-ray background measurements with XMM-Newton EPIC. A&A 389, 93–105 (2002). https://doi.org/10.1051/0004-6361:20020531
Mashkova, E.S., et al.: Small-angle particle reflection from random solids: theory and experiments. Rad. Effects p. 85 (1983)
Mineo, T., et al.: Validation of the ray-tracing code: A first evaluation of the proton transmission of XMM-Newton optics. INAF Tech. Report INAF-XIFU-TM-2015-1 (2015)
Mitsuda, K., et al.: The X-ray observatory Suzaku. PASJ 59, 1–7 (2007). https://doi.org/10.1093/pasj/59.sp1.S1
Nandra, K., et al.: The hot and energetic universe: a white paper presenting the science theme motivating the Athena+ mission. ArXiv e-prints (2013)
Nartallo, R., et al.: Low-angle scattering of protons on the XMM-Newton optics and effects on the on-board CCD detectors. IEEE Trans. Nucl. Sci. 48(6), 1815–1821 (2001)
Predehl, P., et al.: eROSITA on SRG. Proc. SPIE 9144, 91441T (2014). https://doi.org/10.1117/12.2055426
Remizovich, V.S., Ryazanov, M.I., Tilinin, I.S.: Energy and angular distributions of particles reflected in glancing incidence of a beam of ions on the surface of a material. Sov. J. Exp. Th. Phys. 52, 225 (1980)
Spiga, D., et al.: A magnetic diverter for charged particle background rejection in the SIMBOL-X telescope. Proc. SPIE 7011, 70112Y (2008). https://doi.org/10.1117/12.789917
Villa, G.E., et al.: Epic system onboard the ESA XMM. Proc. SPIE 2808, 402–413 (1996)
Weisskopf, M.C., et al.: Chandra X-ray observatory (cxo): overview. Proc. SPIE 4012, 2–16 (2000)
Wentzel, G.: Zwei Bemerkungen uber die Zerstreuung korpuskularer Strahlen als Beugungserscheinung. Z. Phys. 40, 590 (1927)
Willingale, R.: An electron diverter for the Swift telescope. XRT-LUX-RE-011/1Technical Report (2000)
Acknowledgements
This work is supported by the ESA Contract No 4000116655/16/NL/BW. The AHEAD project (grant agreement n. 654215) which is part of the EU-H2020 programm is acknowledged for partial support.
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Appendices
Appendix A: Scattering efficiency
Appendix B: Energy losses
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Fioretti, V., Mineo, T., Bulgarelli, A. et al. Geant4 simulations of soft proton scattering in X-ray optics. Exp Astron 44, 413–435 (2017). https://doi.org/10.1007/s10686-017-9559-9
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DOI: https://doi.org/10.1007/s10686-017-9559-9