Speaker
Description
The main threat to electronics at the ground level is well-known as the secondary-cosmic-ray-induced soft error. The soft error is caused by an upset of the memory information due to an energy deposition by an energetic ionizing radiation. Among the cosmic-ray species, the muon has recently drawn attention as a new cause of the soft error due to the reduction of the critical charge of the static random-access memory. Our previous works [1] reported that the negative muon has much more serious effect on the occurrence of soft errors compared to the positive one because of the emission of light ions (hydrogen and helium) from the nuclear muon capture reaction in the silicon nuclei. In this work, we performed the experiment to accumulate the basic data of the fundamental physical process of muon-induced soft error, i.e., the light ion from the nuclear muon capture reaction, to improve the accuracy of the simulation of the muon-induced soft error. In addition to the experiment, a validation of the model calculation implemented in Particle and Heavy Ions Transport code System (PHITS) [2] was made by comparing the experimental data and the simulation.
The experiment was performed at the M1 muon beam line of Muon Science Innovative muon beam Channel [3] in Research Center for Nuclear Physics, Osaka University, Japan. The pions, which is a source of muons, were generated through the nuclear reaction between a 392-MeV proton beam and a graphite target. The produced pions almost decayed into muons in a superconducting solenoid magnet. The polarity and the momentum of the muon were selected by the solenoid magnet and the selected muons were transported to a vacuum chamber which was connected to the beam exit of the M1 beam line. The momentum of 36 MeV/c was chosen to maximize the number of stopping muons. A 100 µm thick silicon target was mounted at the center of the chamber at a tilt angle of 45° to the beam direction. The size of the target is 10 cm × 5 cm. Two forward plastic scintillators with the size of 5 cm × 7 cm × 0.5 cmt were set to count the number of incident muons and make the triggers for the data acquisition. Two telescopes were mounted parallelly to the target at both the upstream and downstream of the target to detect the secondary ions and measure their kinetic energies. The energies of the ions were determined by a ΔE-E method by using a 325 µm silicon detector (ΔE) and 25 mm thick CsI detector (E).
The energy spectra of proton, deuteron and triton were successfully measured in the energy range from 8 MeV to 35 MeV. The proton and deuteron spectra in the energy range of 8-15 MeV and the triton spectrum were first measured in this work. The measured proton and deuteron spectra were compared to those of the past work [4]. The comparison demonstrated the consistency between the present and past data. Next, a benchmark test of the PHITS calculation was performed. The nuclear muon capture reaction is described with the quantum molecular dynamics (QMD) [5] or modified QMD (MQMD) [6] for the dynamic process plus the generalized evaporation model (GEM) for statistical decay process [7]. The test indicated that the MQMD plus GEM has larger yields of deuteron and triton than the QMD plus GEM. However, both models still significantly underestimated the measured spectra in the high emission energy region.
[1] S. Manabe et al., IEEE Trans. Nucl. Sci., 65:8, 1742-1749 (2018).
[2] T. Sato et al., J. Nucl. Sci. and Technol., 55:5-6, 684-690 (2018).
[3] Y. Matsumoto et al., Proc. of 6th International Particle Accelerator Conference (IPAC), 2537-2540 (2015).
[4] S. E. Sobottka and E. L. Wills, Phys. Rev. Lett., 20:12, 596-598 (1968).
[5] K. Niita et al., Phys. Rev. C, 52:26, 2620-2635 (1995)
[6] Y. Watanabe and D. Kadrev, in Proc. of International Conference on Nuclear Data for Science and Technology 2007 (2008)
[7] S. Furihata et al., Japan Atomic Energy Research Institute; 2001. (JAERI-Data/Code 2001-015).
