Developments in hemispherical tubes for underwater Neutrinos detection. Bruno Combettes PHOTONIS Group Product Manager PHOTONIS-Brive, France CPPM Meeting March 2007

HEP projects followed by PHOTONIS Km3 (CPPM, INFN…) BAIKAL lake (INR) Super-NEMO (Modane, Bordeaux) Auger North (IPNO) Double-CHOOZ (Aachen)

PHOTONIS PMTs Traditional PMTs sizes : 0.5“ - 3/4“ - 1“ - 1“1/8 - 1“1/2 2“ - 3“- 4“- 5“ Hemispherical PMTs 5“- 8“- 9“-10“-10.6“-12“

References of hemispherical tubes from Photonis 5’’ tube : XP1803 8’’ tube : XP1806 9’’ tube : XP1805 (Auger Tube) 10’’ tube : XP1804 (NEMO) 12’’ tube : XP1807

PHOTONIS large tube range Two types of traditional tubes available : –9’’ tube equiped with a first ‘’foil’’ dynode ( XP1805 AUGER tube ). –5’’, 8’’, 10’’ and 12’’ equiped with a linear focused dynode (10.6’’ developped for ANTARES experiment )

Advantages / disavantages of each solution Multiplier with a first dynode ’’foil’’ (XP1805) : –Good collection uniformity +++ –Good Photocathode – D1 isochronism ++ –Very low level of after pulses +++ –Poor P/V ( avg 1.4 max at 1.8 ) --

Advantages / disavantages of each solution Multiplier with a first dynode ’’linear focused’’ : –Good P/V typ = 2.3 with a min spec at – Good collection uniformity + –Good isochronism + – high After pulses rate --

XP1804 : 10’’ tube for NEMO

● dimension inch ● Spectral response nm ● Wavelength of maximum response420 nm ● Quantum efficiency at maximum25% ● Photocathode materialbialkali ● Window materialborosilicate glass ● Dark counts < 5000 khz (1/3 p.e.) ● Gain 5*10exp7 for supply voltage < 1800 Volts ● Pulse risetime <10 ns ● Peak/valley ratio >2 ● Pulse transit-time spread <3 ns (FWHM) ● Afterpulse 1 < 1.0% ● Afterpulse 2 <5 % ● Delayed pulse <5 % ● Pre pulse <1% PMT Specifications

After Pulses type 2 : in the range of micro-second

After Pulses type 2 : measurements

Where do After Pulses come from? Collision electrons – gazous between D1 and D2 Positive ions feedback

XP1804 : 10’’ tube for NEMO Ion shield : prevent after pulses by traping unexpected positive ions

R&D in photocathodes

Glass radioactivity study and improvement: There is a need for very low radioactive glass for some specific scientific experiments (Super-NEMO in Frejus Tunnel) (Collaboration with Prime Verre, Montpellier) Sample Bq/kg P (g) T (h) 40 K 137 Cs 238 U 226 R a 228 Ra 228 Th Standard low noise Schott glass <0,02912,62,32,6 Special Optic Schott glass (very low noise) 60236,11,5<0,005<0,20,14<0,0 4 <0,02 Low noise glass for general applications at Photonis ,59,7<0,0080,90,840,450,51 Specific VERY low noise glass used by Photonis 30,589,443,9< 0,015<0,333,60,220,04

Pixeled tube PHOTONIS is the leader to produce large volume of QUAD tube for PET machines. There could be a possibility to use this type of multiplier ( foil as a first dynode ) to develop a tube equiped with 4 ’’sectors’’ to make some directionnality detection. Light guide to segmented PC Collaboration INFN Genova.

R x Standard 10” PMT: no info about light direction Photocathode divided in 4 quadrants: incoming light hits different quadrants (PM with 4 anodes) Mirrors in gel divide photocathode into 4 quadrants by directing light onto single quadrants (total collected light unchanged) A Possible “quadrant” approach from M. Taiuti (INFN Genova) From VLVnT2, Catania, Nov’05

Quads for PET scan

Various collaborations european wide France : IN2P3 –Orsay : measures of after pulses, timing resolution –Marseille : measures of segmentation Italy : INFN –Genova : light guide and segmentation –Catania : NEMO Netherland : NIKHEF –High QE photocathode CERN : sphérical hybrid tubes Russia : INR Greece : Pylos

Bruno COMBETTES Photonis Group product management Grazie a tutti per l’attenzione