Variation of secondary cosmic gamma ray flux during lunar eclipse S. Roy* , S. Chatterjee , S. Chakraborty** , S. Biswas , S. Das , S. K. Ghosh , S. Raha Department of Physics (CAPSS), Bose Institute, Kolkata, India. E-mail:
[email protected] Introduction Astronomical events such as Solar eclipses and Lunar eclipses provide the opportunity for studying the disturbance produced in the atmosphere and its effect on cosmic ray intensity. There are earlier reports on decrease in secondary cosmic gamma ray (SCGR) flux during solar eclipse and enhancement of the same during lunar eclipse [1-4]. We have measured the variation of SCGR flux during two lunar eclipses that took place in India in the year 2018, one on 31st of January and the other on 27th of July. Both the measurements have been carried out in the Detector laboratory of Bose Institute, Kolkata, India, using NaI (Tl) scintillator detector. We observed slight increment of SCGR during the lunar eclipse of January. We did not observe any significant changes in SCGR during lunar eclipse of July. Experimental Setup ❖ NaI(Tl) scintillator detector is used. Size of the crystal: 5.1cm × 5.1cm ❖ Gamma ray sources used for detector calibration: 137Cs (662 keV), ❖ PMT bias: +600V. Signals are amplified and shaped before sending 60Co (1173 keV and 1332 keV) and 22Na (551 keV) them to MCA for energy spectrum accumulation ORTEC-556 ORTEC-671 Schematic of the signal processing electronics Picture of the experimental setup Gamma ray spectra with different configurations of lead shielding ADC