1. XL-Calibur – a second-generation balloon-borne hard X-ray polarimetry mission.
- Author
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Abarr, Q., Awaki, H., Baring, M.G., Bose, R., De Geronimo, G., Dowkontt, P., Errando, M., Guarino, V., Hattori, K., Hayashida, K., Imazato, F., Ishida, M., Iyer, N.K., Kislat, F., Kiss, M., Kitaguchi, T., Krawczynski, H., Lisalda, L., Matake, H., and Maeda, Y.
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HARD X-rays , *X-rays , *CADMIUM zinc telluride , *POLARIMETRY , *POLARISCOPE , *BALLOONING - Abstract
XL-Calibur is a hard X-ray (15-80 keV) polarimetry mission operating from a stabilised balloon-borne platform in the stratosphere. It builds on heritage from the X-Calibur mission, which observed the accreting neutron star GX 301 - 2 from Antarctica, between December 29th 2018 and January 1st 2019. The XL-Calibur design incorporates an X-ray mirror, which focusses X-rays onto a polarimeter comprising a beryllium rod surrounded by Cadmium Zinc Telluride (CZT) detectors. The polarimeter is housed in an anticoincidence shield to mitigate background from particles present in the stratosphere. The mirror and polarimeter-shield assembly are mounted at opposite ends of a 12 m long lightweight truss, which is pointed with arcsecond precision by WASP – the Wallops Arc Second Pointer. The XL-Calibur mission will achieve a substantially improved sensitivity over X-Calibur by using a larger effective area X-ray mirror, reducing background through thinner CZT detectors, and improved anticoincidence shielding. When observing a 1 Crab source for t day days, the Minimum Detectable Polarisation (at 99% confidence level) is ∼ 2 % · t day − 1 / 2 . The energy resolution at 40 keV is ∼ 5.9 keV. The aim of this paper is to describe the design and performance of the XL-Calibur mission, as well as the foreseen science programme. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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