1. A first look of the 10” High QE PMT Shigeru Yoshida for Yuusuke Hasegawa and Mina Inaba Dep. of Physics, Chiba University “Super Bialkali” photocathode

2. Which is which? Our IceCube PMT Super Bialkali PMT The Graduate Student

3. DOM Reference PMT Absolutely calibrated NDfilter LED Slit 1mm X-stage QE×CE Absolute calibration Systematic error ~7% @ room Photocathode calibration Reflectivity : 14.5%±0.73 Transmission : 50.7%±2.54 LED motor PMT

4. Absolute QE×CE IceCube PMT IceCube PMT

5. PMT 2D Uniformity Scan Averaged PMT 2D CEMap(~94PMTs) The direction of the first dynode

6. 17.8% 18.1%15.5% 16.0%18.7% 15.0%16.7% 17.9% TA1895TA2026 TA2086TA2146TA2182 TA2259TA2349 TA2374 Systematic error ～ 8% 20 0 -0.15m 0.15m @337nm 2D QE x CE Map of PMT

7. 70nse c CAMAC Crate Controller Crate Controller ADC GP-IB Function Generator Function Generator NIM PCI Card CAMAC Interface CAMAC Interface GP-IB Interface GP-IB Interface Gate Generator Gate Generator LinuxPC Sync. PMT Freezer(-35 ℃ ) Gate Signal Discriminator TTL-NIM Converter TTL-NIM Converter 2kHz, ~ 0.01 photo- electron/shot 4 ~ 6nse c 375 nm UV LED diffus er ~ 100ns The Test bench

8. Freezer -35 ℃ The Test Bench Diffuser attached to the UV LED 375nm UV LED In the Freezer box 2kHz, ~ 0.01 photo- electron/shot

9. HV dependence of the PMT gain Gain (x10 7 ) 10 7 Gain Super PMT

10. @5x10 7 - 35C SPE Charge Historgram pedestalSPE Our IceCube PMTSuper Bialkali PMT

11. P/V Gain (x10 7 ) Peak/Valley -35C Super PMT

12. Charge Resolution Gain (x10 7 )  q /q0 -35C 30% line Super PMT

13. The IceCube PMT charge response Average over 118 PMTs One measurement Peak of gaussian ~ 1 p.e. Charge resolution 29% Mean 15% less

14. Now “Super” PMT case Average over 118 PMTs One measurement

15. Dark Rate Temperature [C] Dark Rate [Hz] Discri. threshold 0.25 p.e. 1kHz Super PMT

16. Summary QE ~ 35 % @ 365 nm (IceCube PMT – 25%) Charge response, cathode uniformity comparable with the IceCube PMTs – P/V is even better. Dark Rate ~ 1kHz @ -35 C (IceCube PMT ~ 600Hz)

17. Backup slides

18. 18.3% 16.3% 16.4% 15.4% 11.3% 10.4% 4.88% 3.96% Keno_Inuzaka(TA1056)Daikaku_Inumura(TA1176) 16.6% 15.7% 15.0% 12.5% 10.6% 9.70% 4.69% 4.30% 16.0% 13.3% 13.2% 14.2% 9.14% 8.93% 4.23% 3.74% Red : measured at 24 ℃ Blue : measured at -32 ℃ lower QE measured at -32 ℃ tend to 5~10% lower than measured at 24 ℃ However, they agree within the systematic error. Sosuke_Inukawa(TA1181) Absolute QE