A Compton polarimeter using scintillators read out with MPPCs through Citiroc ASICShow others and affiliations
2019 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 943, article id 162376Article in journal (Refereed) Published
Abstract [en]
In recent years, a number of purpose-built scintillator-based polarimeters have studied bright astronomical sources for the first time in the hard X-ray band (tens to hundreds of keV). The addition of polarimetry can help data interpretation by resolving model-dependent degeneracies. The typical instrument approach is that incident X-rays scatter off a plastic scintillator into an adjacent scintillator cell. In all missions to date, the scintillators are read out using traditional vacuum tube photo-multipliers (PMTs). The advent of solid-state PMTs (“silicon PM” or “MPPC”) is attractive for space-based instruments since the devices are compact, robust and require a low bias voltage. We have characterised the plastic scintillator, EJ-248M, optically coupled to a multi-pixel photon counter (MPPC) and read out with the Citiroc ASIC. A light-yield of 1.6 photoelectrons/keV has been obtained, with a low energy detection threshold of ≲5 keV at room temperature. We have also constructed an MPPC-based polarimeter-demonstrator in order to investigate the feasibility of such an approach for future instruments. Incident X-rays scatter from a plastic-scintillator bar to surrounding cerium-doped GAGG (Gadolinium Aluminium Gallium Garnet) scintillators yielding time-coincident signals in the scintillators. We have determined the polarimetric response of this set-up using both unpolarised and polarised ∼50 keV X-rays. We observe a clear asymmetry in the GAGG counting rates for the polarised beam. The low-energy detection threshold in the plastic scintillator can be further reduced using a coincidence technique. The demonstrated polarimeter design shows promise as a space-based Compton polarimeter and we discuss ways in which our polarimeter can be adapted for such a mission.
Place, publisher, year, edition, pages
Elsevier, 2019. Vol. 943, article id 162376
Keywords [en]
Compton polarimetry, GAGG, Gamma/X-ray detector, MPPC, Plastic scintillator, Scintillator, Application specific integrated circuits, Electron tubes, Ellipsometry, Ionization, Phosphors, Photomultipliers, Photons, Polarimeters, X rays, Astronomical sources, Coincidence techniques, Multi-pixel photon counters, Purpose built scintillators, Scintillation counters
National Category
Subatomic Physics
Research subject
Physics, Atomic, Subatomic and Astrophysics
Identifiers
URN: urn:nbn:se:kth:diva-263519DOI: 10.1016/j.nima.2019.162376ISI: 000504926900001Scopus ID: 2-s2.0-85070208746OAI: oai:DiVA.org:kth-263519DiVA, id: diva2:1374273
Note
QC 20191204
2019-11-292019-11-292025-02-14Bibliographically approved