Speaker
Dr
Valentina Giordano
(INFN - Catania)
Description
A great number of large area photomultipliers are widely used in neutrino and
astroparticle detector to measure Cherenkov light in medium like water or ice. The
key element of these detectors are the so-called “optical module”, which consist in
photodetectors closed in a transparent pressure-resistant glass sphere to protect it
and ensure good light
transmission. The noise pulses present on the anode of each photomultiplier affect
strongly the performance of the detector so a large study was conducted on noise
pulses of photomultipliers by HAMAMATSU of 10 inch (used in NEMO Phase-2) and 3
inch diameter (multiPMT OM), considering time and charge distributions of dark
pulses, pre-pulses, delayed pulses, and after pulses. In particular an analysis on
multiple after pulses was done on both models of photomultipliers. In order to study
these events, the digital oscilloscope was used to acquire all the pulses after the
main pulse for 16 microseconds. Hence an off-line analysis follows the acquisition in
order to obtain charge and time spectra and a correlation between the arrival times
and the charge of each after pulse.
Primary author
Dr
Valentina Giordano
(INFN - Catania)
Co-authors
Dr
Emanuele Leonora
(INFN - Catania)
Dr
Sebastiano Aiello
(INFN - Catania)
