Investigation of cosmic ray intensity variation at primary rigidity above 1.7 TV
. Investigation of cosmic ray intensity variation
at primary rigidity above 1.7 TV'
submitted by LEE Yiu-wa
for the degree of Master of Philosophy
at the University of Hong Kong
in November, 1986.
A telescope has been set up in an underground
laboratory to study the cosmic ray intensity variations at
The intensity weighted average depth of
the laboratory is found to be 587 hg cm-2 which
corresponds to a mean muon threshold energy of about 147
GeV and a median rigidity about 1750 GV.
The telescope is composed of triple layers of
proportional counters, each layer of area about 3.65m x 2m
and their separation o. Sm.
Event selection is achieved by
triple coincidence of the counter layers and by software
Arrival direction histograms are
accumulated and recorded hourly.
The counters are
continuously checked by a monitor spectrum.
Data in the period from November 1983 to February
1986 are analysed.
The duty cycle is about 81% and a
total of 1. 98x1 07 are accumulated.
The total barometer
coefficients for the above period is found to be
(0. 00677?. 00475) % mb- l.
The result obtained so far in
the first and second harmonics in sidereal frequency are
+5.4 7.9 -5.9
4. 2:!:1 .7
1. 7:!:3. 6
where the confidence limits for the amplitudes are 5% and
95% and those for the phases are 68%. The calculation is
based on the non-Gaussian distribution.
The first and second harmonics in anti-sidereal
frequency are found to be statistically insignificant.
The result is consistent with recent measurements in other
School:The University of Hong Kong
School Location:China - Hong Kong SAR
Source Type:Master's Thesis
Keywords:cosmic ray variations tunnel detection aberdeen
Date of Publication:01/01/1987