11:00 AM - 11:15 AM
△ [14a-E204-7] Investigation of Lower-Energy Distribution of Environmental Cosmic-Ray Muon
Keywords:Cosmic-Ray Muon, Soft Error
Recently, the cosmic-ray muons are also considered to be sensitive to soft errors in the state-of-the-art high-integration devices. Especially since low energy muon can deposit sufficient energy even in the small sensitive region, single event upsets are expected to be caused. Therefore, its intensity is important to estimate the soft error rate accurately, but no measurement have been reported below 100 MeV.
We have developed a muon detector system consists of plastic scintillators (PSs) to measure the low-energy cosmic-ray muon energy spectrum. The main PS, 20 x 20 x 20 cm3, was sandwiched by two thin PSs. The upper one was used as coincidence detector not to detect natural background radiation and electric noises. The bottom one was used as a veto detector to reject the muons penetrating the main PS. The detector system can detect only the muons stopped in the main PS which have their kinetic energies from 10 to 75 MeV. The detectable zenith angular range was limited from 0 to 45 degrees.
The first experiment with the detector system was carried out at Chikushi Campus of Kyushu University (LAT 33.5oN, LNG 130.5oE). The spectrum was measured in the energy range below 75 MeV. The measured spectrum is in good agreement with the calculated one with EXPACS around 75 MeV in magnitude and shape. However, the measured flux intensity is larger than the EXPACS calculation in lower muon energy range. One of the reasons for the disagreement is possibly due to background electrons that cannot be completely rejected.
We have developed a muon detector system consists of plastic scintillators (PSs) to measure the low-energy cosmic-ray muon energy spectrum. The main PS, 20 x 20 x 20 cm3, was sandwiched by two thin PSs. The upper one was used as coincidence detector not to detect natural background radiation and electric noises. The bottom one was used as a veto detector to reject the muons penetrating the main PS. The detector system can detect only the muons stopped in the main PS which have their kinetic energies from 10 to 75 MeV. The detectable zenith angular range was limited from 0 to 45 degrees.
The first experiment with the detector system was carried out at Chikushi Campus of Kyushu University (LAT 33.5oN, LNG 130.5oE). The spectrum was measured in the energy range below 75 MeV. The measured spectrum is in good agreement with the calculated one with EXPACS around 75 MeV in magnitude and shape. However, the measured flux intensity is larger than the EXPACS calculation in lower muon energy range. One of the reasons for the disagreement is possibly due to background electrons that cannot be completely rejected.