Speaker
Laura Cardani
(ROMA1)
Description
The direct detection of rare alpha decays is very challenging, as
detectors like gas counters or semiconductors can not achieve a sufficient sensitivity to study these processes.
The background suppression against beta and gamma decays, which is a crucial issue for the disentanglement of the alpha peak, can be easily obtained by means of scintillating bolometers.
These detectors can be sketched as a main bolometer plus a light detector. The energy measured by the main bolometer, that acts as an almost perfect calorimeter, is independent of the nature of the particle. However, the scintillation yield of alpha particles is significantly lower that the one of electrons of the same energy. Therefore, the simultaneous measurement of the scintillation light allows to identify the nature of the interacting particle and to reject the background due to electrons, providing a very high sensitivity on the alpha decay.
We present the results obtained using this technique in the study of $^{209}$Bi, $^{204}$Pb, $^{206}$Pb and $^{208}$Pb decays.
For the first time, the $^{209}$Bi alpha decays to the ground and to the first excited states were unambiguously observed in a BGO scintillating bolometer.
A PbWO4 crystal was analyzed in the framework of the optimization of the light detectors for the LUCIFER experiment. Thanks to this measurement, the rare decays of the lead isotopes were studied with an unprecedented sensitivity. No signal was detected, providing a lower limit on the half life of these isotopes.
Optional extended abstract
For the first time, the 209Bi alpha decays to the ground and to the first excited states were unambiguously observed in a BGO scintillating bolometer.
The same technique was used to study the rare alpha decays of 204Pb, 206Pb and 208Pb with an unprecedented sensitivity, providing a lower limit on the half life of these isotopes.
Primary author
Laura Cardani
(ROMA1)
