The recent R&D status of a large photocathode HAPD

1. The recent R&D status of a large photocathode HAPD T. Abe, H. Aihara, M. Iwasaki, H. Nakayama (Univ. of Tokyo) M. Tanaka, (KEK) Y. Kawai, H. Kyushima, M. Suyama (HPK) M. Shiozawa (ICRR)

2. Introduction • We believe HAPD is the photon detector for the next generation water-Cherenkov detector (i.e. Hyper Kamiokande, 2km detector for T2K). • We have developed large (13-inch) HAPD. • In this talk, we present the R&D status of the HAPD.

3. 190ps σ Theme • Excellent HAPD performance than PMT’s • Single photon sensitivity • Single photon time resolution ~ 190ps (s) • Readout system development dedicated for HAPD • Possible application to other field

4. Bombardment: x4500@20kV Ne/sNe=67 Avalanche Gain: X30 Total Gain:~105 Principle of HAPD Operation HAPD PMT 1st Dynode Gain: x5 Ne/sNe=2.2 Incident Light Incident Light Photoelectron Photoelectron Large gain @ 1st mult. stage  good single photon detection 10~20kV Dynodes Avalanche Diode No Dynodes (No TTS)  large HAPD with good time resolution Total Gain:~107 Total Gain:~105

5. Property of HAPD • Single photon sensitivity large gain at the first stage of multiplication • Good time resolution No TTS in dynodes • Cost reduction and easy Quality control simple structure without dynodes • Lower gain Need a dedicated readout system

6. t f HAPD system (Q, T) QP.H. TTime ≥1Gsps MOF 13-inch HAPD Pre-amplifier ASIC (Low noise) Waveform sampling (Fast sampling) +Digital filter (Noise Suppression) HAPD performances are evaluated using this system

7. 13inch HPD performances • Energy measurement related items • Comparison between HAPD and PMT • Dynamic range • Position dependence of relative gain • Timing measurement related items • Comparison & # of P.E. dependence • HV dependence • Dark rate

8. HPD and PMT 1P.E. 2P.E. 3P.E. 4P.E. 1P.E. 5P.E. 2P.E.(?) HPD（HV=12ｋV bias=330V) PMT(13inch)

9. :Sample A :Sample B :Sample C Dynamic range (no preamplifier) 3000p.e. equivalent input 110 HV=+20kV, Bias=290V for Sample A 370V for Sample B 390V for Sample C Light Source: Pulsed Laser (PW: ~70ps, λ: ~400nm) 100 90 80 Output/input [%] 70 60 -3% Deviation at Output Charge of 100pC (~3000p.e. input signal intensity equivalent at total gain of ~2x105) 50 40 1 10 100 1000 Output Charge [pC]

10. 18cm ~65deg. Position dependence of gain for photons<5 Gain uniformity:s~2%

11. 45 deg 70 deg Time resolution (large HAPD) Time resolution = Transit time variation Timing resolution Center

12. Timing resolution Spot Laser illuminated HV=12ｋV bias=330V Better st No dependence of # of p.e. 190ps

13. Photoelectron transit time Center Bias=290V Light Source: Pulsed Laser (PW: ~70ps, λ: ~400nm) 45 deg 70 deg Position dep. of Transit time < 1 nsec

14. Dark rate Dark rate quickly goes down below ~17 kV. Sample#1 20inch PMT dark rate @ room temp Sample#2 After modification of HPD, Dark rate HPD@20kV~20inch PMT Dark count : 15kHz HAPD

15. HAPD vs. PMT

16. Under development f MOF 1Gsps AMC t Pre-amplifier ASIC Analog memory cell (AMC) + FPGA for Digital Filter f HPD electronics status (Q, T) ≥1Gsps MOF

17. Front-end electronics Intrinsic noise: 2000electron tfilter：30nsec Rise time ：＜1nsec Dynamic range：２V Power consumption : ~4mW/ch (depends on driving capability)

18. Analog memory cell 512nsec • Sampling period : 1Gsps • Dynamic range : 3.5V • Integral nonlinearity 0.1% for 2.5V • Uniformity of sampling period <100ps • 50mW/ch

19. Possible application to other fields • We are seeking possible HAPD application to other fields. • Excellent single photon sensitivity of HAPD might be useful for environment science. • We try to measure photons from photo protein (single photon events).

20. Filter output of photo protein events The origin of photon source is same as fireflies.

21. Photon measurement from photo protein noise signals

22. Summary • We develop a 13inch HAPD and confirm • Excellent single photon st~190ps. • Excellent single photon sE~44%. • Total gain of > 2X105. • We develop a dedicated readout electronics for the HAPD. • HAPD might be useful for other fields.

23. Backup slides

24. HPD system in the next step • In the next step (after several modifications) • Stability for temperature (for general purpose) • Evaluation of long term stability • Optimization of manufacturing process for production cost • Photocathode formation • Low cost material • Quality check during production …. • Customization of electronics/system for HK Multi-SK Large-SK HK

25. t t MOF MOF 1Gsps AMC 1Gsps AMC f f Two directions • Similar to SK • On HPD Digital data through Ethernet Ethernet Development of common devices After determination of timing I/F(i.e. trigger, clock ..) Multi-chip module or deep submicron ASIC (blue rectangle part) will be developed as a building block of the readout system.

26. EB and Avalanche Gain AD Bias=30V(fixed), HV=Swept HV=+10kV(fixed), Bias=Swept Gain=~4700 @20kV Gain=~50 @390kV

27. Incorporated Avalanche Diode and its C-V Characteristics Capacitance: ~40pF over bias voltage of 120V (assembled on the base) Assembled Bare Chip Backside Illumination Avalanche Diode Effective Area: 5mm in dia.

28. Photoelectron Collection Efficiency and Effect of Magnetic Field (Simulation) Photoelectron Collection Efficiency as a function of HV (No Magnetic Field) Collection Efficiency as a function of Magnetic Field (at HV of +20kV)