Characterization of Hamamatsu R12199 PMTs Oleg Kalekin KM3NeT Meeting CPPM, Marseille

O. Kalekin: R12199 PMTs test results 2 KM3NeT specification for 3” PMTs 470nm > 20% HV for 5x10 6 gain V TTS <2ns sigma Dark rate <1kHz Peak-to-valley ratio >3

O. Kalekin: R12199 PMTs test results 3 Hamamatsu R PMTs 80mm diameter Hemispherical (mushroom) shape 200 PMTs delivered and under tests in Nikhef, ECAP and LNS Catania Test results for 56 PMTs are presented Resistor base according to recommended voltage ratio

O. Kalekin: R12199 PMTs test results 4 Quantum efficiency 470nm > 20%

O. Kalekin: KM3NeT: R12199 PMTs test results 5 Single photoelectron parameters Fast LED (Picoquant): <0.8ns FWHM, 470nm; phe/pulse Waveform at 1Gs/s with a Lecroy Waverunner oscilloscope Charge and time parameters are derived from saved waveforms

O. Kalekin: KM3NeT: R12199 PMTs test results 6 Gain HV for 5x10 6 gain: V

O. Kalekin: KM3NeT: R12199 PMTs test results 7 Transit time spread TTS: <2ns sigma

O. Kalekin: KM3NeT: R12199 PMTs test results 8 TT & DEvs HV (gain) 4x10 6 (1100V) 12x10 6 (1300V) Detection efficiency increase >10% with gain increase from 4x10 6 to 7x10 6

O. Kalekin: R12199 PMTs test results 9 Late pulses Integration time window 10-50ns after main TT peak

O. Kalekin: R12199 PMTs test results 10 Dark rate Dark rate <1kHz3 PMTs with high rates: 8, 20, 25 kHz

O. Kalekin: R12199 PMTs test results 11 Effective area R QE: monochromator DE: 470nm fast LED, optical fiber, XY-scanner Effective diameter ~76mm X

O. Kalekin: R12199 PMTs test results 12 Time-over-threshold 23 active bases with ToT discriminator soldered Recommended thr=B0too low thr=84

O. Kalekin: R12199 PMTs test results 13 Time-over-threshold Threshold scan

O. Kalekin: R12199 PMTs test results 14 Time-over-threshold Threshold scan

Catania Preliminary results from measurements on 3 inch Hamamatsu PMT performed by INFN Catania S. Aiello, V. Giordano, E. Leonora, A. Grimaldi, D. Sciliberto

16 Measurements Condition PMT conditions: - Total darkness. - Dark conditioned for about 3 hours without supply voltage. - After dark adaption, PMT switched ON at the nominal voltage declared by Hamamatsu, and maintained for 30 min to stable the gain - Gain condition of 5 E6 - Powered by a base produced by Erlangen Light source condition: Laser pulsed at 10 kHz. Wavelength of 410 nm. Width of 50 ps as FWHM. Attenuated up to the single photo electron condition. Ratio between the PMT response and the laser frequency about 0.01 Whole photocathode illuminated

Dark counts and Charge measurememts Dark Count: Measured by counter NIM CAEN at a threshold of 1/3 of s.p.e Charge measurements PMT signals acquired by Le Croy waverunner 1 GHz oscilloscope and elaborate in ROOT gain 5 E6 [V] DC rate [Hz] P/V ZB ZB ZB ZB Preliminary results show P/V values lower than those declared by Hamamatsu …we are investigating about that! Typical charge spectrum in spe condition

Transit Time Spread and spurious pulses Spurious pulses are noise pulses time-correlated with the main PMT response -Pre-pulses (P.P.), appear ns before the main pulse. Due to direct photo-effect on the first dynode. - Delayed pulse (D.P.), appear ns after the main pulse, in the place of it. Due to photoelectron backscattering on the first dynode. - After pulse (AP), appear 10ns – 10 us after the main pulse. - Short AP: due to luminous reaction on the electrodes. - Long AP : due to the ionization of the residual gas in the PMT. Transit Time Spread (TTS) measured as FWHM of the TT spectrum acquired by FAST NIM Time Ampitude Converter. Laser in spe condition. 10 kHz. PMT response≈ 100Hz. Threshold 1/3 of spe.

19 Typical distribution and timing results Typical time distribution of after pulse Typical time distribution of delayed pulse TTS (FWHM) (ns) Pre-pulse (%) Delayed- pulse (%) After- pulse (%) ZB ZB ZB ZB Ratio between number of spurious events on number of PMT main pulses was calculated