The new PMT generation with very high quantum efficiency is very attractive for their potential to improve energy resolution, in particular for applications involving new scintillation crystals with high light yield. Furthermore recent development of new devices, like silicon photomultipliers (SiPMs), with high gain and quantum efficiency have raised the competition between silicon and standard photomultiplier device in particular for application where high energy resolution may improve the imaging response of the detector. Hamamatsu has recently developed a new prototype PMT R7600-200 with an Ultra BiAlkali (UBA) photocathode (QE=42%). To evaluate the improvement, we compared the energy resolution obtained by R7600-200 PMT with ones from a standard R7600 PMT (QE=22%); the results from both PMTs was obtained with a standard and a tapered divider circuit respectively. We compared also the data from a MA-PMT H8500 and from a PMT R6231, representing a gold standard. A LaBr3:Ce scintillator crystal (½” diam. x ½” thick) was coupled to all PMTs. Preliminary results show an energy resolution improvement with UBA photocathode of about 30% @122keV with respect to R7600, close to what expected from the higher quantum efficiency (40%). On the contrary they agree with ones from R6231 PMT, thought its lower QE. This result is probably due to the different collection efficiency of first dynode stage related to different dynode structure of tubes. Furthermore an energy resolution improvement smaller than expected resulted from H8500 MA-PMT. Thought the same dynode structure, this result is not well understood and it could probably due to the larger size of MAPMT photocathode, involving a better light collection. In any case, the improvement of 30% between UBA e No-UBA PMT is not in agreement with the expected one (20%), considering the intrinsic energy resolution of LaBr3:Ce (4.4%@ 140 keV). This behavior is not well explained at moment and is matter of next investigations.
Gamma Ray Spectroscopy with LaBr3:Ce Scintillation Crystals Coupled to an Ultra High Quantum Efficiency PMT
S. Lo Meo;BALDAZZI, GIUSEPPE;NAVARRIA, FRANCESCO LUIGI;
2008
Abstract
The new PMT generation with very high quantum efficiency is very attractive for their potential to improve energy resolution, in particular for applications involving new scintillation crystals with high light yield. Furthermore recent development of new devices, like silicon photomultipliers (SiPMs), with high gain and quantum efficiency have raised the competition between silicon and standard photomultiplier device in particular for application where high energy resolution may improve the imaging response of the detector. Hamamatsu has recently developed a new prototype PMT R7600-200 with an Ultra BiAlkali (UBA) photocathode (QE=42%). To evaluate the improvement, we compared the energy resolution obtained by R7600-200 PMT with ones from a standard R7600 PMT (QE=22%); the results from both PMTs was obtained with a standard and a tapered divider circuit respectively. We compared also the data from a MA-PMT H8500 and from a PMT R6231, representing a gold standard. A LaBr3:Ce scintillator crystal (½” diam. x ½” thick) was coupled to all PMTs. Preliminary results show an energy resolution improvement with UBA photocathode of about 30% @122keV with respect to R7600, close to what expected from the higher quantum efficiency (40%). On the contrary they agree with ones from R6231 PMT, thought its lower QE. This result is probably due to the different collection efficiency of first dynode stage related to different dynode structure of tubes. Furthermore an energy resolution improvement smaller than expected resulted from H8500 MA-PMT. Thought the same dynode structure, this result is not well understood and it could probably due to the larger size of MAPMT photocathode, involving a better light collection. In any case, the improvement of 30% between UBA e No-UBA PMT is not in agreement with the expected one (20%), considering the intrinsic energy resolution of LaBr3:Ce (4.4%@ 140 keV). This behavior is not well explained at moment and is matter of next investigations.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
