A first look of the 10” High QE PMT

Shigeru Yoshida forYuusuke Hasegawa and Mina Inaba

Dep. of Physics, Chiba University

“Super Bialkali” photocathode

Which is which?

Our IceCube PMT Super Bialkali PMT

The Graduate Student

DOM

Reference PMT Absolutely calibrated

NDfilterLED

Slit 1mm

X-stage

QE×CE Absolute calibration

Systematic error ~7% @ room

Photocathode calibration

Reflectivity : 14.5%±0.73Transmission : 50.7%±2.54

LED

motor

PMT

Absolute QE×CE

IceCubePMT

IceCubePMT

PMT 2D Uniformity ScanAveraged PMT

2D CEMap(~94PMTs)

The direction of the first dynode

17.8%

18.1% 15.5%

16.0% 18.7%

15.0% 16.7%

17.9%

TA1895 TA2026

TA2086 TA2146 TA2182

TA2259 TA2349

TA2374

Systematic error ～ 8%

20

0-0.15m 0.15m

@337nm

2D QE x CE Map of PMT

70nsec

CAMACCAMACCrate

ControllerCrate

Controller

ADCADC

GP-IBGP-IBFunction

GeneratorFunction

Generator

NIMNIM

PCI CardPCI CardCAMAC

InterfaceCAMAC

Interface

GP-IBInterfaceGP-IB

Interface

GateGenerator

GateGenerator

LinuxPCSync.Sync.

PMTPMT

Freezer(-35℃)

Gate

Signal

DiscriminatorDiscriminator

TTL-NIM ConverterTTL-NIM Converter

2kHz, ~0.01 photo-electron/shot

4~6nsec

375 nmUV LED

diffuser

~100ns

The Test bench

Freezer -35℃

The Test Bench

Diffuser attached to the UV LED

375nmUV LED

In the Freezer box

2kHz, ~0.01 photo-electron/shot

HV dependence of the PMT gainG

ain

(x

107

)

107 Gain

Super PMT

@5x107 -35C

SPE Charge Historgram

pedestal SPE

Our IceCube PMTSuper Bialkali PMT

P/V

Gain (x107)

Pe

ak/V

alle

y -35C

Super PMT

Charge Resolution

Gain (x107)

q/q

0-35C

30% line

Super PMT

The IceCube PMT charge response

Average over 118 PMTs

One measurement

Peak of gaussian Peak of gaussian ~ 1 p.e.~ 1 p.e.

Charge resolution 29%

Mean 15% lessMean 15% less

Now “Super” PMT case

Average over 118 PMTs

One measurement

Dark Rate

Temperature [C]

Da

rk R

ate

[Hz]

Discri. threshold 0.25 p.e.

1kHz

Super PMT

Summary

• QE ~ 35 % @ 365 nm (IceCube PMT – 25%)• Charge response, cathode uniformity compar

able with the IceCube PMTs

– P/V is even better.• Dark Rate ~ 1kHz @ -35 C

(IceCube PMT ~ 600Hz)

Backup slides

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℃

QE measured at -32℃　 tend to 5~10% lowerlower than measured at 24℃However, they agree within the systematic error.

Sosuke_Inukawa(TA1181)

Absolute QE