Elio Giroletti, Irene Bolognino, Claudio Cattaneo, Giuseppe Liguori, Paola Salvini, Piero Vallania, Carlo Vigorito
The ARGO-YBJ experiment is a full coverage air shower array; its lowest
energy threshold is reached using the "scaler mode technique". Working in this
mode, the signals generated by any particle hitting each cluster are put in
coincidence every 150 ns and read by four independent scaler channels, giving
the counting rates of multiplicity \geq1, \geq2, \geq3 and \geq4 (C1, C2, C3
and C4, respectively). The study of these counting rates pointed out a
different behaviour of C1 respect to C2, C3 and C4, suggesting that C1 is
detecting not only cosmic rays. This work shows that the radon (222Rn) gamma
emitter daughters present in the ARGO-YBJ building air are contributing to C1
counts at the level of 1 Hz each Bq/m3 of radon. The uncertainty about this
contribution is great, because of the high variability of 222Rn concentration
and the building ventilation. The radon monitoring will allow the C1 correction
improving the sensitivity of the ARGO-YBJ experiment at its lowest energy
threshold.
View original:
http://arxiv.org/abs/1112.4305
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