Lead-Free Gulmarg Neutron Monitor

A lead-free neutron monitor predominantly sensitive to a few MeV energy secondary neutrons produced by the cosmic ray interactions with the earth’s atmosphere is described in this paper. The monitor was originally aimed at recording neutron bursts supposedly produced in the atmospheric lightning discharges. Besides operating in the integral counting mode to record neutron background in the atmosphere the monitor is also configured to record rates of neutron bunches, in pre-determined small time intervals of 50 ms duration, that are produced in the atmosphere due to cosmic ray interaction. The monitor is seen to compare very well with the existing conventional neutron monitors in responding to transient solar modulation. However, the data on neutron bunches indicate large scale reduction in their occurrences at the time of solar events. Such variations have never been recorded by the conventional neutron monitors.