Selection and performance of PMT candidates for TREND ground array Hou Yueyun 1, Feng Zhaoyang 1, Liu Cheng 1 ， Liu Maoyuan 1 1, IHEP 2, Tibet University

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 ASγ Energy eV eV spacing 300m(X)/600m(Y) 15m Area 4000m*800m 270m*270m Angular Res. ． 1-3 degree(? ) Dynamic range ： 1-30(?) MIPs/m MIPs/m2 Time res. ． 10 ns(?) ~1ns The PMT used in Extended ASγ can meet the requirements of TREND ground array

Four 2 inches PMT candidates 1,Hamamatsu R7725 （ 2 ， CA0130 ， CA0134 ） ~4000 RMB 2, ET 9814B (1), ~6500 RMB 3, ET9829B (1), ~4600 RMB 4, GXBS GDB61 （ 2 ， Z81, Z70) ? RMB

Requirements ： 1, size ： ~2 inch 2, good rise time ： ~2-3ns 3, small TTS, 1-2 ns 4, Gain ：～ large dynamic range 6, not bad cathode response uniformity 7, lower noise Test items: 1.Single PE (absolute gain) 2.HV response (relative gain) 3.Dynamic Range 4.pulse Rise Time Falling Time TTS (Transit time spread) 5.Cathode response uniformity 6. Magnetic shielding study 7. Noise rate

SPE and its resolution All th SPE peak can be measured with a good peak/valley ratio( ) Example: R7725

Gain VS HV

Dynamic range of Anode

Gain:1E+07 HV:1540V FWHM:25 TTS:1.55ns Gain:1.9E+07 HV:1650V FWHM:23 TTS:1.42ns R7725 Gain:2.9E+07 HV:1750V FWHM:24 TTS:1.48ns Gain:1.1E+07 HV:1480V FWHM:18 TTS:1.11ns R7725 _CA0130 R7725 _CA0130 R7725 _CA0130 R7725 _CA0130 R7725 _CA0134 R7725 _CA0134

Gain:0.9E+07 HV:1850 FWHM:23 TTS:1.42ns Gain:0.92E+07 HV:2100V FWHM:14 TTS:0.87ns Gain:0.97E+07 HV:1800V FWHM:12 TTS:0.74ns Gain:1E+07 HV:1700V FWHM:15 TTS:0.93ns GXBS_GDB 61_z0070 GXBS_GDB 61_z0081 ET9814B_11007 ET9829B_28033

Magnetic field effect R7725 A0130ET9814B ET9829BGXBSz81

Example: R7725 A0130 Cathode response uniformity 13

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 TTs1.55ns1.11ns1.42ns0.93ns0.87ns0.74ns Reference1.3ns 2.2ns --

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 R

Dynamic range with optimized base of R7725 Anode Non-Linearity ±5%: 0~100mA Dynode Non-Linearity ±5%: 0~18mA Summary: ◆ PMT linearity ±5% : 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 RMS 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 ： 2.6 Energy 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