Gating PMT M. Aoki

Hodoscope – Trigger – TOF 3e4 hits/plane/pulse by the prompt burst. – 3e3 hits/bar/pulse. Standard PMT will be saturated. Gating-PMT worked in the beam test in 2009 with 3e3 hits/PMT/pulse.

gating PMT Designed by T. Taniguchi

Snapshot of PMT signal B1 Plas. Scinti. gating B2 Plas. Scinti. gating B3 Plas. Scinti. normal PMT ND filtered Baseline distortion due to delayed fluorescence from plastic scintillator. Individual hits by real particles can be seen on the baseline.

5 Gating PMT by Taniguchi Raise Focus and Dy3. Originally developed for an extinction monitor for COMET. Designed by Taniguchi (KEK), tested at Osaka U. Rise time: 60 ns, Fall time 20 ns Very fast switching PMT : R (Hamamatsu) 2-inch, 12 dynodes, linear focus with focus grid. Switching Part 2 3 VOLT DYNODE K 1... F 4 >100V

6 Off On Off On Timing of light PMT signal Gate signal Gating PMT No signal during the off state. 400-ns length of the switching noise: need to be improved. Ground shielding 400ns

7 Cutoff Ratio Scan by changing the timing of laser light. Off region: 10 9 photons/pulse On region: 10 3 photons/pulse Time (μs) Cutoff Ratio = 7x10 -7 R H.V.1500V 1kHz Gate : 1μs

Summary A prototype of the gating-PMT for DeeMe Horoscope already exists. The prototype showed very good performance in the beam test – Need to reduce the switching noise, probably by improving ground shielding (shield casing?) Good R&D item for university collaborators.