Seasonal and Lunar Month Periods Observed in Natural Neutron Flux at High Altitude

Abstract

Air radon concentration measurement is useful for research on geophysical effects, but it is strongly sensitive to site geology and many geophysical and microclimatic processes such as wind, ventilation, air humidity and so * Corresponding author: Xinhua Ma, Key Laboratory of Particle Astrophysics, Institute of High energy Physics, Chinese Academy of Sciences, P.O.Box 918(3), Yuquan Road 19(B), Beijing 100049, China E-mail: maxh@ihep.ac.cn 1 on that induce very big fluctuations on the concentration of radon in air. On the contrary, monitoring the radon concentration in soil by measuring the thermal neutron flux reduces environmental effects. In this paper we report some experimental results on the natural thermal neutron flux as well as the concentration of air radon and its variations at 4300 m a.s.l. These results were obtained with unshielded thermal neutron scintillation detectors (en-detectors) and radon monitors located inside the ARGO-YBJ experimental hall. The correlation of these variations with the lunar month and 1-year period is undoubtedly confirmed. A method for earthquakes prediction provided by a global net of the en-detectors is currently under study.

Measurement of secondary cosmic-ray neutrons near the geomagnetic North Pole

“…We found that variations in the measured neutron counts on the order of 10% were observed when the moisture changed from 100% saturated to 94% saturated. (Stenkin et al, 2017) measured the effect of the seasonal rainfall on thermal neutron count rates indoors high elevation, finding that the ground-moisture effect on the count rate should be ~10%. This effect is not, however, included in the model prediction of the neutron count rate vs. atmospheric pressure or elevation.…”

“…We found that variations in the measured neutron counts on the order of 10% were observed when the moisture changed from 100% saturated to 94% saturated. (Stenkin et al, 2017) measured the effect of the seasonal rainfall on thermal neutron count rates indoors high elevation,…”

“…There is also a second, albeit much lower flux, source of background neutrons: alpha particles emitted by nuclides in the uranium and thorium decay chains interacting with the nuclei of lighter elements in the Earth's crust (Be, F, Al, Si, etc. ) and producing neutrons that escape into the atmosphere (Stenkin et al, 2017;Kuzhevskij et al, 2002).…”

EAS Thermal Neutron Detector Array to Add into LHAASO

“…The existence of periodical variations both seasonal and related to the moon month are confirmed for the first time at high altitude. In particular, for synodic moon month the 4th harmonic with amplitude of about 0.5% and maximum with a delay of about 1 day after syzygies is found [12]. It indicates that the EN-detectors can be used to monitor seismic activity.…”

Study of the EN-Detectors Array in Tibet

“…Mao-Yuan Liu Sun-Moon-Earth system [9] and earthquakes [10], which can periodically changes thermal neutron flux.…”