photonis

Revisiting the optimum PMT size for water-Cherenkov megaton detectors: 

Revisiting the optimum PMT size for water-Cherenkov megaton detectors Esso Flyckt, Christophe Fontaine, Pascal Lavoute and Carole Marmonier Photonis, Brive, France NNN05 workshop Aussois 2005-04-08

Overview: 

Overview PHOTONIS Physics is challenging Traditional PMTs Optimal size andlt;=andgt; cost Capacity andamp; investments Sub-conclusions Discussion Randamp;D prospects

Brive: 

Brive

PHOTONIS: 

PHOTONIS Photomultipliers Image intensifiers Streak tubes Microchannel plates Single-channel electron multipliers Neutron detectors

PMTs: 

PMTs Nuclear medicine (~80%) gamma cameras PET scanners Analytics/industrial (~10%) Physics (~10%)

H.E.S.S. in Namibia(very-low after-pulse PMT): 

H.E.S.S. in Namibia (very-low after-pulse PMT)

Veritas in Arizona: 

Veritas in Arizona

Auger in Argentina: 

Auger in Argentina

Traditional PMTs: 

Traditional PMTs Hemispherical 5', 8', 9', 10.6', 12', 15'

Very many PMTs Example: UNO >50,000x 20“: 

Very many PMTs Example: UNO andgt;50,000x 20' PMT size andlt;=andgt; cost Embedded inside water volume Sensitivity Timing SE pulse-height resolution Granularity

PMT size <=> cost: 

PMT size andlt;=andgt; cost Diameter 20' andlt;=andgt; (20')17' andlt;=andgt; 12' projected area 1660 1450 615 cm² QE(typ) 20 20 24 % CE 60 60 70 % Cost 2500 2500 800 € Cost/cm² per useful PEU= cost/(cm²xQExCE) 12.6 14.4 7.7 €/PEU/cm²

Timing-Weight : 

Timing-Weight Weight (kg) 8 8 2.2

Single-electron resolution : 

Single-electron resolution Need good P/V for exact gain calibration: 20' difficult? (P/V = 1.1 - 1.7:1) 17' P/V = 1.5 - 2.5:1 (reality better) 12' P/V = 1.5 - 2.3:1 (reality better)

Quantities and total cost: 

Quantities and total cost 20' 50,000 x € 2500 = € 125M 17' 57,200 x € 2500 = € 143M 12' 135,000 x € 800 = € 108M

New pump capacity needed?: 

New pump capacity needed? Delivery over 6 years 300 working days/year 20' tube 50,000/6/300 =andgt; 28 good tubes x yield 0.7 = 40 starts/day (1 start/pump/day) =andgt; 40 pumps ( € 7M or so) 12' tube 135,000/6/300 =andgt; 75 good tubes x yield 0.7 = 110 starts/day. A multi-array computerised pump at Photonis handles 20 starts/day =andgt; 6 pumps ( € 2M or so)

+ Sub-conclusions: 

+ Sub-conclusions 12' seems much better than 20'/17' cost per useful photoelectron andamp; total PMT cost timing single-electron resolution (17' equal) granularity weight and handling implosion risk investments and start-up

- Sub-conclusions: 

- Sub-conclusions cost of more cables and electronics 12' tubes may also need a shield at 60 m depth (or thicker glass?)

Discussion: 

Discussion The 12' tube is a cost-optimum for Photonis pumping systems - maybe other cost-optima in 8' - 15' for other suppliers? Can be made by at least 4 suppliers - without major Randamp;D! Photonis is willing, able and prepared up to 15' However, non-industry investments needed!

Optimise!Cost/cm² per useful PEU= cost/(cm²xQExCE): 

Optimise! Cost/cm² per useful PEU= cost/(cm²xQExCE)

Invest in QE now!: 

Invest in QE now! Instead of investing € 7M (or so) for 20' it is better to invest € 2M (or so) for 12' and another € 0.5M in getting the QE up to andgt; 30 % Photonis has such a QE programme Characterisation with French institutes

„Smart“ PMTs so far: 

„Smart' PMTs so far „smart' =andgt; PHR =andgt; elimination of single PE noise (for DUMANDs) Patented by Philips (Photonis) Copied (faster mushrom shape) by INR, Moscow, into the „QUASAR' Philips (spherical)

Slide22: 

anode target was YSO single-crystal at +25-30 kV =andgt; photocathode at ground potential! partly sensitive from the back

Pulse-height resolution: 

Pulse-height resolution S/N 8 andamp; 10 deployed in Lake Baikal

Status „smart“ PMTs: 

Status „smart' PMTs Philips/Photonis made ~ 30; invested 1M €! 200 QUASARs operating for many years in Lake Baikal =andgt; proof of concept as to life time! No ongoing production! Could be made (and improved) again!

Possible „smart“ PMTs: 

Possible „smart' PMTs Reproduce and improve former tubes Redesign (target) Better scintillator (LSO, ZnO:Ga, ...) Si diode/Si diode array APD/APD array Multianode multiplier Quadrant PMT (inside/outside) ??

On-going R&D: 

On-going Randamp;D „smart' 8 =andgt; 12' tubes with: electron-bombarded scintillator in a preamplifier tube, read-out by a small, fast PMT electron-bombarded Si diode as the anode Both will resolve 1, 2, 3, several photoelectrons but - need to stand andgt; 15 - 20 kV Is such „smartness' worth a factor 2-3 in cost?

Photonis has all the technical capability needed!R&D cooperation: detailed & intensive talks are going on with the MEMPHYS collaboration to define a balanced programmeWorkshop planned in the spring: 

Photonis has all the technical capability needed! Randamp;D cooperation: detailed andamp; intensive talks are going on with the MEMPHYS collaboration to define a balanced programme Workshop planned in the spring

Questions?: 

Questions?