Selection and performance of PMT
candidates for TREND ground array
Hou Yueyun1, Feng Zhaoyang1, Liu Cheng1，
Liu Maoyuan1
1, IHEP 2, Tibet University
2014.1.8
Extended array of Tibet Asγ Exp.
To improve the sensitivity of Tibet MD+AS at 100 TeV energy region
Prototype detector
Prototype detector
PMT, base and sleeve
TREND ground array VS Extended ASγ
Energy
spacing
Area
Angular Res.．
Dynamic range：
Time res. ．
TREND
Extended ASγ
1016-1018eV
1013-1015eV
300m(X)/600m(Y)
15m
4000m*800m
270m*270m
1-3 degree(? )
0.4o@10TeV
0.2o@100TeV
1-30(?) MIPs/m2
1-1000MIPs/m2
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：～107
5 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 parameters( @1PE):
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(1.4-3.0)
Example: R7725
2.8e+07@1750V
Gain VS HV
Dynamic range of Anode
R7725
R7725
_CA0130
R7725
_CA0130
Gain:1E+07
HV:1540V
FWHM:25
TTS:1.55ns
R7725
_CA0130
Gain:1.9E+07
HV:1650V
FWHM:23
TTS:1.42ns
R7725
_CA0134
Gain:2.9E+07
HV:1750V
FWHM:24
TTS:1.48ns
Gain:1.1E+07
HV:1480V
FWHM:18
TTS:1.11ns
ET9814B_11007
ET9829B_28033
Gain:0.9E+07
HV:1850
FWHM:23
TTS:1.42ns
GXBS_GDB
61_z0070
Gain:1E+07
HV:1700V
FWHM:15
TTS:0.93ns
GXBS_GDB
61_z0081
Gain:0.92E+07
HV:2100V
FWHM:14
TTS:0.87ns
Gain:0.97E+07
HV:1800V
FWHM:12
TTS:0.74ns
Magnetic field effect
R7725 A0130
ET9814B
ET9829B
GXBSz81
Example: R7725 A0130 Cathode response
uniformity
13
Summary of the testing result
TTs
1.55ns
1.11ns
1.42ns
0.93ns
0.87ns
0.74ns
Reference
1.3ns
1.3ns
2.2ns
2.2ns
--
--
 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
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!)
R7725
Tapered
15
Dynamic range with optimized base of R7725
Anode Non-Linearity ±5%: 0~100mA
Dynode Non-Linearity ±5%: 0~18mA
Summary:
◆PMT linearity ±5% : 0~1375mA@ 1750V
anode dynamic range of R7725
HV: 1750V
Before improvement：
Anode linearity(±5%):
1~70mA
After improvement：
Anode linearity(±5%):
1~100mA
gain: 2.8E+07
gain: 1.5E+07
Transit time uniformity
Mean 50.39
RMS 0.2404
▶Non-uniformity: < 1 ns。
R7725_CA0130 dynamic range at different gain
Anode output
linearity(±5%)：
1400V：0~70mA
1600V：0~90mA
1750V：0~100mA
1800V：0~100mA
2000V：0~120mA
the influence of the magnetic field
光纤
光源
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
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
End, Thanks!