Atmospheric water vapor and attenuation of the cosmic-ray nucleonic component

Abstract

This communication presents some experimental results that seem to indicate that the barometric pressure coefficient customarily employed to correct terrestrial neutron monitor intensities is subject to variations in magnitude that are apparently related to changes of atmospheric water vapor content above the site of measurement. An aluminum container was placed above one section of the IGY standard neutron monitor at the University of Denver, Denver, Colorado (1600‐meter altitude, 2.93 Gv/c Quenby‐Wenk threshold). The container was filled to different depths of water for various intervals of time, and the corresponding attenuation of the nucleonic intensity was determined. Preliminary results of a statistically reliable nature have been obtained for four different water levels. The results are indicated m the table below.

Neutron monitors and muon detectors for solar modulation studies: Interstellar flux, yield function, and assessment of critical parameters in count rate calculations

“…As discussed in Bercovitch and Robertson (1965) and in Chasson et al (1966), an increase of atmospheric water vapour content attenuates the intensity of secondaries seen by a NM. To take into account this effect, they proposed a correction of the barometric coefficient β.…”

The Effect of Atmospheric Water Vapor on Neutron Count in the Cosmic-Ray Soil Moisture Observing System

“…Although early studies have attempted to identify the effect of water vapor on thermal (Bethe et al 1940;Lockwood and Yingst 1956) and high-energy neutrons (Bercovitch and Robertson 1965;Chasson et al 1966), no study has yet attempted to determine the fast neutron sensitivity to water vapor. In this paper we identify and evaluate the sensitivity of cosmic-ray probes to the hydrogen present as water vapor in the near-surface atmosphere.…”