Photodetector developement CBM October 2008 Piotr Koczoń,GSI CBM-RICH: Photodetector developement P.Koczoń, C.Höhne, A.Braem C.Joram, M. van Stenis

Photodetector for RICH CBM October 2008 Piotr Koczoń,GSI Photodetector for RICH - Wavelength Shifter technologies - Single photon capability of H8500 WLS on a H8500 - Outlook/Plans

Photodetector for RICH CBM October 2008 Piotr Koczoń,GSI Photodetector for RICH - Array photomultiplier: H8500 (H9500?) - Why wavelength shifter? And what type? (Tetra Phenyl Butadiene = TPB, meta-P-terphenyl = pTer, pTer on teflon) - WLS gain measured immediately after coating and after 3 months in CO2 atmosphere thickness studies 75/100/125 µg/cm2 for pTer pTer/teflon WLS

H8500 8x8 pads 5.8 x 5.8 mm each 89% packing density U=1100 V but CBM October 2008 Piotr Koczoń,GSI H8500 8x8 pads 5.8 x 5.8 mm each 89% packing density U=1100 V but borosilicate window and low QE for UV

H8500: room for QE improvements CBM October 2008 Piotr Koczoń,GSI H8500: room for QE improvements WLS coating: technology, measurements, results absorbtion emission

Monochromator Vacuum deep UV relative QE QE Test Bench (HPD) Air CBM October 2008 Piotr Koczoń,GSI Monochromator Vacuum deep UV relative QE QE Test Bench (HPD) Air 200 nm cut off abs. QE measurement

QE for XP3102 @ far UV with WLS CBM may 2008 Piotr Koczoń,GSI QE for XP3102 @ far UV with WLS for TPB PM1 – X3102 number 1 235 ug/cm2 – coating thickness For these tests a set of Photonis XP3102 was used. for p-Ter

QE gain for XP3102 @ far UV with WLS CBM may 2008 Piotr Koczoń,GSI QE gain for XP3102 @ far UV with WLS for TPB Gain: 10 - 80 for p-Ter Gain: 8 - 80

after 3 months in CO2 normal pressure CBM October 2008 Piotr Koczoń,GSI QE of XP3102 @ UV with p-Ter after 3 months in CO2 normal pressure F8 – measured in Feb 2008 J8 – measured in Juni 2008 Ageing almost not visible (within error bar)

Accuracy of QE measurement CBM October 2008 Piotr Koczoń,GSI Accuracy of QE measurement After rebuilding of absolute QE monochromator a new adjustment and callibration was needed

Gain factor for XP3102 @ UV with pTer CBM October 2008 Piotr Koczoń,GSI Gain factor for XP3102 @ UV with pTer Thickness study for p-Ter

Gain dependency on p-Ter thickness CBM October 2008 Piotr Koczoń,GSI Gain dependency on p-Ter thickness Results at exacltly 100μg/cm2 not quite understood pTer thickness 90 – 125 μg/cm2 is an optimum

WLS results & conclusions CBM October 2008 Piotr Koczoń,GSI WLS results & conclusions pTer layer can increase the quantum efficiency of an photomultiplier considerably in far UV TPB less suitable (other materials?) Ageing of pTer in CO2 not visible after 3 months 90 to 125 μg/cm2 seems to be an optimal thickness Other technologies (pTer spraying) not examined yet

pTer/teflon WLS made in RU CBM October 2008 Piotr Koczoń,GSI pTer/teflon WLS made in RU 250 µg/cm2 pTer on 50 µm thin teflon foil Courtesy of V.Rykalin

pTer/teflon WLS made in RU CBM October 2008 Piotr Koczoń,GSI pTer/teflon WLS made in RU

CBM October 2008 Piotr Koczoń,GSI pTer/teflon made in RU

pTer/teflon in Vacuum Gain of pTer on teflon in vacuum & ABS CBM October 2008 Piotr Koczoń,GSI pTer/teflon in Vacuum Gain of pTer on teflon in vacuum & ABS pTer on teflon seems to be mechanically less stable than directly evaporated on the entrance window of the PM

pTer on teflon Gain of pTer on teflon appreciably high CBM October 2008 Piotr Koczoń,GSI pTer on teflon Gain of pTer on teflon appreciably high Teflon foils are not flat (heat treatment?) pTer on teflon mechanically unstable

pTer on H8500 100 µg/cm2 pTer evaporated directly on H8500 entrance CBM October 2008 Piotr Koczoń,GSI pTer on H8500 100 µg/cm2 pTer evaporated directly on H8500 entrance window (50%)

pTer on H8500 in the vacuum monochromator CBM October 2008 Piotr Koczoń,GSI pTer on H8500 in the vacuum monochromator 8 x Signal HV Air instead of Ar introduces a cut off at 190 nm

pTer on H8500 + coated * illuminated Anode current Wavelength [nm] CBM October 2008 Piotr Koczoń,GSI pTer on H8500 + coated * illuminated Anode current Wavelength [nm]

GAIN of pTer on H8500 + coated * illuminated CBM October 2008 Piotr Koczoń,GSI GAIN of pTer on H8500 + coated * illuminated Only coated AND illuminated pixels show enhanced gain (>1)

Conclusions – Part 1 WLS improves QE in UV region CBM October 2008 Piotr Koczoń,GSI Conclusions – Part 1 WLS improves QE in UV region pTer is better WLS than TPB 100μg/cm2 of pTer is an optimum ageing of pTer almost not visible (3 mon. in CO2) WLS on teflon works astonishingly well WLS on H8500 works as well

H8500 opto-electronical properties: CBM October 2008 Piotr Koczoń,GSI H8500 opto-electronical properties: Single Photon Counting: measurements, results

Single photon counting capability (setup) CBM October 2008 Piotr Koczoń,GSI Single photon counting capability (setup) HV Light guide bundle LED PM grey filters Light tight box PulseGenerator signal Pico FADC gate

Single photon counting capability (reality) CBM October 2008 Piotr Koczoń,GSI Single photon counting capability (reality) Light guide bundle LED Light tight box grey filter HV signal Pulse generator (a bad one)

Single photon counting capability - results CBM October 2008 Piotr Koczoń,GSI Single photon counting capability - results Using a PC+PicoScope (2 channels, 1 GS 8 bit FADC)

Single photon counting capability - results CBM October 2008 Piotr Koczoń,GSI Single photon counting capability - results X2020 Hamamatsu 2“ X2020 is known as a SPC PM H8500 Thermal Electrons noise Photons SP = Photons „-“ noise Encouraging!!!

Single photon counting capability - results CBM October 2008 Piotr Koczoń,GSI Single photon counting capability - results Counts Signal Width Amplitude Amplitude/Charge Counts Counts Single Photons Time [ns] Amplitude/Charge quite convincing

Single photon counting capability - results CBM October 2008 Piotr Koczoń,GSI Single photon counting capability - results Pretty sure!

Single photon counting capability: CBM October 2008 Piotr Koczoń,GSI Single photon counting capability: H8500 is able to register single photons

Newest results: WLS on H8500: measurement of a H8500 CBM October 2008 Piotr Koczoń,GSI Newest results: WLS on H8500: measurement of a H8500 coated with 100μg/cm2 of pTer using PANDA/HADES/FAIR TRB Data Acquisition System

WLS on H8500 (PANDA TRB DAQ) Schematic view of the HV CBM October 2008 Piotr Koczoń,GSI WLS on H8500 (PANDA TRB DAQ) HV Schematic view of the first multiparameter measurement of WLS/H8500 properties UV LED H8500 20 cm Light tight box PulseGenerator signal PANDA TRB DAQ gate

PANDA TRB DAQ Courtesy of C.Sfienti & M.Traxler CBM October 2008 Piotr Koczoń,GSI PANDA TRB DAQ A General Purpose Trigger and Readout Board for HADES and FAIR-Experiments Frohlich, I.; Kajetanowicz, M.; Korcyl, K.; Krzemien, W.; Palka, M.; Salabura, P.; Schrader, C.; Skott, P.; Strobele, H.; Stroth, J.; Tarantola, A.; Traxler, M.; Trebacz, R.; Yurevich, S. Nuclear Science, IEEE Transactions on Volume 55, Issue 1, Feb. 2008 Page(s):59 - 66 Digital Object Identifier 10.1109/TNS.2007.913487 Courtesy of C.Sfienti & M.Traxler

WLS on H8500 (PANDA TRB DAQ) High light intensity Piotr Koczoń,GSI CBM October 2008 Piotr Koczoń,GSI WLS on H8500 (PANDA TRB DAQ) High light intensity

WLS on H8500 (PANDA TRB DAQ) low light intensity – single photons CBM October 2008 Piotr Koczoń,GSI WLS on H8500 (PANDA TRB DAQ) low light intensity – single photons

WLS on H8500 (PANDA TRB DAQ) 100μg/cm2 pTer Multipin connectors CBM October 2008 Piotr Koczoń,GSI WLS on H8500 (PANDA TRB DAQ) 100μg/cm2 pTer Multipin connectors (only two sixteen-fold cables were available)

PRELIMINARY WLS on H8500 (PANDA TRB DAQ) counts Time [ns] CBM October 2008 Piotr Koczoń,GSI WLS on H8500 (PANDA TRB DAQ) PRELIMINARY counts Time [ns] Channel number

PRELIMINARY WLS on H8500 (PANDA TRB DAQ) Counts Channel#->Pixel# CBM October 2008 Piotr Koczoń,GSI WLS on H8500 (PANDA TRB DAQ) PRELIMINARY Counts Channel#->Pixel#

Cross-talks – future plans CBM October 2008 Piotr Koczoń,GSI Cross-talks – future plans WLS can add an additional cross-talk between neighbouring pixels when a photon falls inclined or undergoes absorbtion-reemision in the WLS layer on PMs entrance window Hamamatsu claims for H8500: cross talk < 3% Photon transformed in WLS Inclined photon Propagation in WLS WLS Borosilicate Window (1mm) PM structure

Cross-talks - setup HV Light guide bundle LED grey filter Light CBM October 2008 Piotr Koczoń,GSI Cross-talks - setup HV Light guide bundle LED H8500 grey filter Light tight box XY-table PulseGenerator signal DAQ TRB gate

CBM October 2008 Piotr Koczoń,GSI Cross-talks - setup

WLS on H8500 – no conclusions yet, but: CBM October 2008 Piotr Koczoń,GSI WLS on H8500 – no conclusions yet, but: Using PANDA DAQ and 32 parameters WLS gain effect on H8500 can be confirmed cross-talk investigations possible/necessary nXyter readout urgently needed!!!

CBM October 2008 Piotr Koczoń,GSI Thank You !