Quenching factors measurements & WIMP class of DM candidates investigated by PSA in devoted exposure

  • 1996 - Quenching factors mesurements In order to avoid the activation of low background set-ups operating deep underground, the routine energy calibrations have to be performed with gamma sources. In case the WIMP class of Dark Matter particle candidates is investigated by their scattering on target nuclei, the knowledge of the quenching factor for the given nucleus in the given detector is necessary. It strongly depends for whatever kind of detector on its specific features; see for example the summary table X of Riv. N. Cim. 26 n.1 (2003)1. In particular for NaI(Tl) it depends on dopant concentration, gowth method, etc.

    The Na and I quenching factors (amount of light induced by a Na or a I recoil nucleus to the amount of light induced by an electron of the same kinetic energy) have been measured in the 2-20 keV energy range with the same method as K. Fushimi et al., PRC47(1993)R425.

    For this purpose a crystal built with the same growing technique, tallium concentration, etc., than those used deeply underground and a 252Cf neutron source shielded by a suitable thick moderator in order to investigate the energy interval of interest have been used.

    The values of 0.30 and 0.09 (with error equal to 0.01) have been obtained for Na and I respectively in our crystals. For results and comparisons see PLB389(1996) 757-766 and the summary table X of Riv. N. Cim. 26 n.1 (2003)1.

  • 2007 - The role of the channeling effect in crystals, wich can not be pointed out by neutron measurements for the reason described in literature, has been discussed and accounted for.