Speaker
Description
Polarization observations of X-rays and γ-rays are an important method to investigate the radiation mechanisms of high-energy astrophysical sources. However, such observations are difficult to perform, and there are few observational examples. CMOS image sensors are detectors with superior spatial resolution compared to CCDs. CMOS sensors are sensitive to optical light through X-rays, but have limited sensitivity to γ-rays.On the other hand, scintillator detectors are sensitive to γ-rays but lack spatial resolution. However, recent research has focused on scintillators with excellent spatial resolution of several micrometers. By combining these detectors, it may be possible to detect the electron tracks resulting from the scattering and absorption of X-rays and γ-rays, thereby enabling the detection of X-ray and γ-ray polarization. In this study, we used the IU233N5-Z CMOS detector manufactured by Sony. The IU233N5-Z is a CMOS detector for optical light with the smallest pixel size of 1.12 µm square. The basic characteristics of the IU233N5-Z for X-rays were reported at HSTD13. In this presentation, γ-ray sources 137Cs and 241Am were irradiated onto a CsI(Tl) scintillator without a microstructure, and the resulting scintillation light was detected by the IU233N5-Z. At 662 keV for 137Cs, a change in image brightness was observed depending on the presence or absence of the source, confirming that the CMOS detector can detect scintillation light. Furthermore, by attaching a lens to the IU233N5-Z, it was possible to detect scintillation light generated by α-rays from 241Am and scintillation light generated by γ-rays separately.
