Methods for Tracking Cosmic-Ray Spectral Changes Using Neutron Monitors at High Cutoff Rigidity
1
Issued Date
2025-05-01
Resource Type
ISSN
0004637X
eISSN
15384357
Scopus ID
2-s2.0-105003558829
Journal Title
Astrophysical Journal
Volume
984
Issue
1
Rights Holder(s)
SCOPUS
Bibliographic Citation
Astrophysical Journal Vol.984 No.1 (2025)
Suggested Citation
Khamphakdee S., Nuntiyakul W., Banglieng C., Seripienlert A., Yakum P., Sáiz A., Ruffolo D., Evenson P., Munakata K., Komonjinda S. Methods for Tracking Cosmic-Ray Spectral Changes Using Neutron Monitors at High Cutoff Rigidity. Astrophysical Journal Vol.984 No.1 (2025). doi:10.3847/1538-4357/adc5f9 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/109935
Title
Methods for Tracking Cosmic-Ray Spectral Changes Using Neutron Monitors at High Cutoff Rigidity
Corresponding Author(s)
Other Contributor(s)
Abstract
Neutron monitors are a standard tool for high-precision monitoring of changes in the Galactic cosmic ray (GCR) flux that occur as a result of variations of the heliospheric conditions and solar storms. In Thailand, we have developed a mobile neutron monitor named “Changvan” based on the 3NM64 design, except that the middle counter lacks lead producer rings, so we call it a semileaded neutron monitor. From 2021 April to 2023 April, the Changvan operated at the Science and Technology Park, Mae Hia, Chiang Mai, Thailand, at an altitude of about 340 m above sea level, with a vertical cutoff rigidity of 16.7 GV, which is near the highest value observed globally. With a similar cutoff rigidity, the nearby Princess Sirindhorn Neutron Monitor is an 18NM64 at the summit of Doi Inthanon, the highest mountain in Thailand, at 2560 m above sea level. We examine how count rates at different altitudes with similar cutoffs, count rates from the unleaded versus leaded counters, and the leader fraction measured from time-delay histograms all reflect GCR spectral differences, thus providing a variety of techniques for tracking cosmic-ray spectral changes. Applied at high cutoff rigidity, these methods extend the reach of the worldwide neutron monitor network to even higher rigidity.