Selection and performance of PMT candidates for TREND ground array

Hou Yueyun1, Feng Zhaoyang1, Liu Cheng1 ，Liu Maoyuan1

1, IHEP 2, Tibet University2014.1.8

Extended array of Tibet Asγ Exp.

To improve the sensitivity of Tibet MD+AS at 100 TeV energy region

Prototype detector

PMT, base and sleeve Prototype detector

TREND ground array VS Extended ASγ

　　　　　　　　　　 TREND Extended ASγEnergy 　　　　　　 1016-1018eV 　 1013-1015eVspacing 　　　　 300m(X)/600m(Y) 15mArea 　　　　　　　　 4000m*800m 270m*270mAngular Res. ． 1-3 degree(? ) 0.4o@10TeV 0.2o@100TeVDynamic range ：　 1-30(?) MIPs/m2 1-1000MIPs/m2Time res. ．　　　　　　 10 ns(?) ~1ns

The PMT used in Extended ASγ can meet the requirements of TREND ground array

Four 2 inches PMT candidates1,Hamamatsu R7725 （ 2 ， CA0130 ， CA0134 ） ~4000 RMB2, ET 9814B (1), ~6500 RMB3, ET9829B (1), ~4600 RMB4, GXBS GDB61 （ 2 ， Z81, Z70) ? RMB

Requirements ：1, size ： ~2 inch2, good rise time ： ~2-3ns3, small TTS, 1-2 ns4, Gain ：～ 107

5 large dynamic range6, not bad cathode response

uniformity7, lower noise

Test items:1.Single PE (absolute gain)2.HV response (relative gain) 3.Dynamic Range 4.pulse parameters( @1PE): Rise Time Falling Time TTS (Transit time spread)5.Cathode response uniformity6. Magnetic shielding study7. Noise rate

SPE and its resolution

2.8e+07@1750V

All th SPE peak can be measured with a good peak/valley ratio(1.4-3.0)

Example: R7725

Gain VS HV

Dynamic range of Anode

Gain:1E+07 HV:1540VFWHM:25TTS:1.55ns

Gain:1.9E+07 HV:1650VFWHM:23TTS:1.42ns

R7725

Gain:2.9E+07 HV:1750VFWHM:24TTS:1.48ns

Gain:1.1E+07HV:1480VFWHM:18TTS:1.11ns

R7725_CA0130

R7725_CA0130

R7725_CA0130

R7725_CA0134

Gain:0.9E+07HV:1850FWHM:23TTS:1.42ns

Gain:0.92E+07 HV:2100VFWHM:14TTS:0.87ns

Gain:0.97E+07HV:1800VFWHM:12TTS:0.74ns

Gain:1E+07HV:1700VFWHM:15TTS:0.93ns

GXBS_GDB61_z0070

GXBS_GDB61_z0081

ET9814B_11007 ET9829B_28033

Magnetic field effectR7725 A0130 ET9814B

ET9829B GXBSz81

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Example: R7725 A0130 Cathode response uniformity

Summary of the testing result

Considering the performance and price, Hamamatsu R7725 is selected to be used in extended Asγ array

Then we optimized the base to enlarge the dynamic range

TTs 1.55ns 1.11ns 1.42ns 0.93ns 0.87ns 0.74ns

Reference 1.3ns 1.3ns 2.2ns 2.2ns -- --

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Optimization of the R7725 base

The voltage divider distribution:1,4 : 1 : 2 : 1 : 1 : 1 : 1 : 1 : 1 : 1 : 1 : 2 : 1 (default)2,4.7 : 1 : 2.2 : 1 : 1 : 1.5 : 2.2 : 3 : 3 : 3 : 3 : 4.7 : 2.2 (optimized!)

Tapered

R7725

Dynamic range with optimized base of R7725

Anode Non-Linearity ±5%: 0~100mADynode Non-Linearity ±5%: 0~18mA

Summary:◆PMT linearity ±5% : 0~1375mA@ 1750V

anode dynamic range of R7725

HV: 1750V

gain: 2.8E+07

gain: 1.5E+07

Before improvement：Anode linearity(±5%): 1~70mA

After improvement：Anode linearity(±5%):1~100mA

▶Non-uniformity: < 1 ns 。Mean 50.39RMS 0.2404

Transit time uniformity

R7725_CA0130 dynamic range at different gain

1400V ： 0~70mA

1600V ： 0~90mA

1750V ： 0~100mA

1800V ： 0~100mA

2000V ： 0~120mA

Anode output linearity(±5%)：

the influence of the magnetic field

光源

光纤

Statistic test results of 30 R7725 PMTs

SPE

HV:1750V

The ratio of peak/valley ： 2.6Energy resolution ： 31%Gain ： 1.1~4.8+07

High Voltage Response

TTS

Average TTS ： 1.966ns

More test result would come

Summary

End, Thanks!

Four candidates are tested and Hamamatsu R7725 is selected to be used in extended ASγ array

The base of R7725 is optimized to enlarge the

dynamic range

The preliminary test results of 30 R7725 PMT is obtained