*4.2. Research Results Using the Synchrotron*

In the X/gamma ray astronomy field, various X/gamma ray detectors and electronic circuits dedicated to the detectors, which are durable in space, have been developed. One of the detectors uses a CMOS (complementary metal-oxide semiconductor) imaging sensor. The CMOS sensor can be driven with a small power consumption since the signal transmission is not accompanied by charge transfer and high voltage analog circuits are not needed, such as CCD (charge-coupled device) sensors. The CMOS sensor is chip-integrable together with its peripheral circuit; therefore, it is possible to reduce the size and cost of the detector. For such a reason, the CMOS image sensor has been adopted especially for usage in small space probes.

HiZ-GUNDAM [32] is a future satellite mission for the exploration of the early universe by detecting high-redshift gamma-ray bursts by using the wide-field X-ray detector. The Kanazawa University group will adopt a CMOS image sensor GSENSE6060BSI fabricated by Gpixel Inc. for the detection of soft X-ray [17]. The radiation tolerance test was conducted using GSENSE400BSI-TVISB, which is close in pixel size and has the same resistivity and epilayer thickness as GSENSE6060BSI. The test for the sensor was performed by the irradiation of a 100 MeV proton with a flux of 1 <sup>×</sup> <sup>10</sup><sup>7</sup> cm−<sup>2</sup> s <sup>−</sup><sup>1</sup> and a fluence of 4.8 <sup>×</sup> <sup>10</sup><sup>10</sup> cm−<sup>2</sup> , which corresponds to the absorbed dose of 5 krad during 6 years in orbit. After the irradiation, the energy spectra of Mn-K<sup>α</sup> and K<sup>β</sup> X-ray were obtained at temperatures of +20 ◦C and −20 ◦C (Figure 9). Although the significant damage appears as the increase in the dark noise and the worsening of the energy resolution, the background tail of the low energy side caused by the dark noise is reduced in the operation at −20 ◦C (Figure 9, right). Although the MOS structure seems to be affected by TID, the increase in dark current noise is considered to be caused by bulk damage from DDD.

A986(2021) 164673).

*Quantum Beam Sci.* **2021**, *5*, x FOR PEER REVIEW 12 of 18

**Figure 9.** Comparison of the Mn-Kα and Kβ spectra obtained before and after the 100 MeV proton irradiation. Although the noise tail appears on the low-energy side at +20 °C, after cooling of sample to −20 °C, contribution of dark noise is significantly reduced. (Reprint Figure 10 in p.5 of N. Ogino **Figure 9.** Comparison of the Mn-K<sup>α</sup> and K<sup>β</sup> spectra obtained before and after the 100 MeV proton irradiation. Although the noise tail appears on the low-energy side at +20 ◦C, after cooling of sample to −20 ◦C, contribution of dark noise is significantly reduced. (Reprint Figure 10 in p.5 of N. Ogino et al., Nucl. Inst. and Methods in Phys. Research, A987(2021) 164843). to −20 °C, contribution of dark noise is significantly reduced. (Reprint Figure 10 in p.5 of N. Ogino et al*.*, Nucl. Inst. and Methods in Phys. Research, A987(2021) 164843)*.*  The Hiroshima University group has chosen a system of a CsI(Tl) scintillator and a

et al*.*, Nucl. Inst. and Methods in Phys. Research, A987(2021) 164843)*.*  The Hiroshima University group has chosen a system of a CsI(Tl) scintillator and a silicon photomultiplier (Si-PM) for the X/gamma ray detector onboard CubeSats. The Si-PM is a kind of avalanche photodiode (APD) and the multi pixelated Si-PM (Multi Pixel Photon Counter, MPPC) were supplied by Hamamatsu Photonics K.K. (HPK). Two types of MPPCs (S13360-6050CS and S14160-6050HS) were irradiated with a 200 MeV proton beam. Figure 10 shows the comparison between the gamma ray spectra obtained several minutes and 7 months after the 300 rad irradiation. Just after the irradiation, the 22.2 keV photo peak from 109Cd (blue line) disappears in the spectrum and the threshold level rises. The Hiroshima University group has chosen a system of a CsI(Tl) scintillator and a silicon photomultiplier (Si-PM) for the X/gamma ray detector onboard CubeSats. The Si-PM is a kind of avalanche photodiode (APD) and the multi pixelated Si-PM (Multi Pixel Photon Counter, MPPC) were supplied by Hamamatsu Photonics K.K. (HPK). Two types of MPPCs (S13360-6050CS and S14160-6050HS) were irradiated with a 200 MeV proton beam. Figure 10 shows the comparison between the gamma ray spectra obtained several minutes and 7 months after the 300 rad irradiation. Just after the irradiation, the 22.2 keV photo peak from <sup>109</sup>Cd (blue line) disappears in the spectrum and the threshold level rises. In the gamma ray spectrum measured after the MPPC that was left at room temperature for 7 months, the recovery of 22.2 keV photo peak can be found in the spectrum. It is a certain annealing effect against the irradiation for the MPPC [18]. silicon photomultiplier (Si-PM) for the X/gamma ray detector onboard CubeSats. The Si-PM is a kind of avalanche photodiode (APD) and the multi pixelated Si-PM (Multi Pixel Photon Counter, MPPC) were supplied by Hamamatsu Photonics K.K. (HPK). Two types of MPPCs (S13360-6050CS and S14160-6050HS) were irradiated with a 200 MeV proton beam. Figure 10 shows the comparison between the gamma ray spectra obtained several minutes and 7 months after the 300 rad irradiation. Just after the irradiation, the 22.2 keV photo peak from 109Cd (blue line) disappears in the spectrum and the threshold level rises. In the gamma ray spectrum measured after the MPPC that was left at room temperature for 7 months, the recovery of 22.2 keV photo peak can be found in the spectrum. It is a certain annealing effect against the irradiation for the MPPC [18].

In the gamma ray spectrum measured after the MPPC that was left at room temperature

**Figure 10.** Gamma-ray spectra with MPPC S13360-6050CS at –30˚C. Left figure is acquired at several minutes after 300 rad irradiation and right figure shows the spectra measured at 7 months after irradiation. (Reprint Figure 4 in p.3 of N. Hirade et al**.**, Nucl. Inst. and Meth. in Phys. Research **Figure 10.** Gamma-ray spectra with MPPC S13360-6050CS at −30 ◦C. Left figure is acquired at several minutes after 300 rad irradiation and right figure shows the spectra measured at 7 months after irradiation. (Reprint Figure 4 in p.3 of N. Hirade et al., Nucl. Inst. and Meth. in Phys. Research A986(2021) 164673).

**Figure 10.** Gamma-ray spectra with MPPC S13360-6050CS at –30˚C. Left figure is acquired at several minutes after 300 rad irradiation and right figure shows the spectra measured at 7 months after irradiation. (Reprint Figure 4 in p.3 of N. Hirade et al**.**, Nucl. Inst. and Meth. in Phys. Research A986(2021) 164673). Not only radiation detectors but also electronic devices such as a power module, integrated circuits used in an analog amplifier, a logic gate, a microcomputer, etc. have to be evaluated for the radiation tolerance. The gate oxide structure of MOSFET (metal-oxide Not only radiation detectors but also electronic devices such as a power module, integrated circuits used in an analog amplifier, a logic gate, a microcomputer, etc. have to be evaluated for the radiation tolerance. The gate oxide structure of MOSFET (metal-oxide semiconductor field effect transistor) and IGBT (insulated gate bipolar transistor) used in the power module is subject to the TID effect. SEE may also be observed as the single event upset (SEU) in the switching device by the charged particle-induced ionization in the de-Not only radiation detectors but also electronic devices such as a power module, integrated circuits used in an analog amplifier, a logic gate, a microcomputer, etc. have to be evaluated for the radiation tolerance. The gate oxide structure of MOSFET (metal-oxide semiconductor field effect transistor) and IGBT (insulated gate bipolar transistor) used in the power module is subject to the TID effect. SEE may also be observed as the single event upset (SEU) in the switching device by the charged particle-induced ionization in the depletion layer. Especially, SEE in IGBT in the power module and CMOS in the logic gate with a parasitic thyristor in themselves may generate single event latchup (SEL),

the power module is subject to the TID effect. SEE may also be observed as the single event upset (SEU) in the switching device by the charged particle-induced ionization in the depletion layer. Especially, SEE in IGBT in the power module and CMOS in the logic gate with a parasitic thyristor in themselves may generate single event latchup (SEL), causing causing the thermal runaway. Once SEE occurs in the gate region of power MOS-FET or IGBT, the destruction of the gate may cause another thermal runaway, i.e., single event burnout (SEB).

The Tokyo Institute of Technology group has developed APD X-ray detectors and their dedicated ASIC (application-specific integrated circuit). The 0.35 µm CMOS technology is used for the developed ASIC. The ASIC has dual interlock cell (DICE) circuits with a master– slave flip-flop's scheme to prevent malfunction due to the distortion or the noisy clock signal and the accidental activation of CMOS, i.e., an SEU event. The evaluation test of the radiation tolerance was performed for the ASIC with 90 MeV protons because the threshold and saturation energies for the cross section of SEE in the logic device have been reported to be set at around 10 MeV and 100 MeV, respectively. The proton beam was directly irradiated on the ASIC with a flux of 4.8 <sup>×</sup> <sup>10</sup><sup>7</sup> s −1 cm−<sup>2</sup> and a fluence of 1.0 <sup>×</sup> <sup>10</sup><sup>11</sup> cm−<sup>2</sup> , which corresponds to the total dose for 160 years in the International Space Station (ISS) orbit [19]. During the irradiation, the currents from the positive and negative power supplies for the charge sensitive amplifier (CSA) on the ASIC were monitored in order to check whether an SEL event occurred or not. The digital bit data of DICEs were duplicated on a copy register in order to detect SEU events during the irradiation. There was no indication of an SEL event and any SEU events were not obtained either. The ASIC has 1030-bit registers; therefore, the SEU cross-section is estimated to be 2.2 <sup>×</sup> <sup>10</sup>−<sup>14</sup> cm2bit−<sup>1</sup> at most.

The Kyushu Institute of Technology group has tried to obtain the excitation function of the SEE cross section by the variation of kinetic energy of proton [20]. The measurements were conducted for the microchips of PIC16F877, Raspberry Pi Zero and Raspberry Pi 3B. The obtained excitation function shows that the threshold energy for SEE in the integrated circuits may be set at around 10 MeV.

The Aoyama Gakuin University and Nagoya University group have paid attention to the radiation effect on the detectors in space from the radioactivation point of view. A gamma-ray detector using new scintillator LaBr<sup>3</sup> (Ce) has been developed for the CALorimetric Electron Telescope (CALET) experiment on ISS. LaBr<sup>3</sup> (Ce) detectors were irradiated with 20, 70, and 140 MeV protons with fluences of 7.9 <sup>×</sup> <sup>10</sup>10, 7.1 <sup>×</sup> <sup>10</sup><sup>9</sup> , and 5.0 <sup>×</sup> <sup>10</sup><sup>9</sup> cm−<sup>2</sup> , respectively [21]. After the irradiation, the activation of the scintillators was investigated by measuring gamma-ray energy spectra by Ge detectors.
