Unexpected enhancement in secondary cosmic ray flux during the total lunar eclipse of December 10, 2011

TL;DR

This study observed an unexpected 8.1% increase in secondary cosmic ray flux during the December 2011 lunar eclipse, suggesting unknown factors influencing SCR flux beyond known environmental and geomagnetic effects.

Contribution

It reports the first observation of flux enhancement during a lunar eclipse, challenging existing understanding of cosmic ray modulation.

Findings

SCR flux increased by 8.1% during the lunar eclipse

Weather and geomagnetic factors did not explain the flux enhancement

Eclipse-related factors may influence cosmic ray flux in new ways

Abstract

Temporal variation of secondary cosmic rays (SCR) flux was measured during the total lunar eclipse on December 10, 2011 and the subsequent full moon on January 8, 2012. The measurements were done at Department of Physics, University of Mumbai, Mumbai (Geomagnetic latitude: 10.6 N), India using NaI (Tl) scintillation detector by keeping energy threshold of 200 KeV. The SCR flux showed approximately 8.1% enhancement during the lunar eclipse as compared to the average of pre- and post-eclipse periods. Weather parameters (temperature and relative humidity) were continuously monitored and their correlations with temporal variation in SCR flux were examined. The influences of geomagnetic field, interplanetary parameters and tidal effect on SCR flux were considered. Qualitative analysis of SCR flux variation indicates that the known factors affecting SCR flux fail to explain observed enhancement during the eclipse. This enhancement during lunar eclipse and widely reported decrease during solar eclipses may unravel hitherto unnoticed factors modulating SCR flux.