Speaker
Description
Photomultiplier tube (PMT) is one of the best best candidate device as the photo sensor for rare event search experiments, such as dark matter particle interactions and neutrinoless double beta decay events.
For future experiments, one of the issue that needs to be addressed is its relatively large RI amount due to large amount of material used for the device.
R13111 is a very low-background PMT developed during XMASS experiment for such future experiments.
Low radioactivity was achieved mainly by three components: (1) the low-radioactive-contamination glass; (2) the photocathode with 39K-enriched potassium; and (3) the purest grade of aluminum vacuum seal. Achieved amount of RIs are about 0.4 mBq of 226Ra, less than 2 mBq of 238U, 0.3 mBq of 228Ra, 2 mBq of 40K and 0.2 mBq of 60Co.
Together with such low level RI, good performance, large angular acceptance with high collection efficiency, good timing resolution, and long-term stable operation were also realized.
