The High Dynamics Readout of PMT for BGO Calorimeter Calo2010. May10-14. Beijing The High Dynamics Readout of PMT for BGO Calorimeter Center for Particle Physics and Technology University of Science and Technology of China Yunlong Zhang Calo2010. May10-14. Beijing CPPT USTC

Overview Motivation Experiment Setup Results ● LED Test Calo2010. May10-14. Beijing Overview Motivation Experiment Setup Results ● LED Test ● Cosmic Ray Test Outlook Calo2010. May10-14. Beijing CPPT USTC

Calo2010. May10-14. Beijing Motivation Why would we need to design high dynamic range readout for calorimeter ？ For one cell of BGO-EM energy deposition of electron/gamma with energy above TeV is between 0.5 MIPs and 105 MIPs, the readout system need to cover this high dynamic range. e- 300GeV Calo2010. May10-14. Beijing CPPT USTC

Experiment Setup Pulse generator LED optical fiber PMT Calo2010. May10-14. Beijing CPPT USTC

It was coupled with R5611 PMT that in the crystal bottom Experiment Setup BGO crystal It was coupled with R5611 PMT that in the crystal bottom optical fiber XP2262B Calo2010. May10-14. Beijing CPPT USTC

Experiment Setup The block diagram for the calibration measurement. The LED was driven by a pulse generator. The photon intensity was controlled by the voltage of the generator. The VA32 is a charged preamplifier and it’s charge range is from -4pc to 12pc. Calo2010. May10-14. Beijing CPPT USTC

The Response Function of PMT Q1=Q0 n=0 σ1 = σ0 E.H. Bellamy. Et al., Nucl. Instr. And Method., A339(1994) 468-476 μ is the mean photoelectrons number detected by PMT. σ1 is the single photoelectron’s sigma Q1 is the channel of single photoelectron Q0 is the pedestal position σ0is the pedestal sigma The response of a multiplicative dynode system to a single photoelectron can be discribed by a gaussian distribution The number of detected photoelectrons in PMT cathode follow a poisson distribution. Calo2010. May10-14. Beijing CPPT USTC

Test PMT —— XP2262B channel channel Calculate gain(*106) of PMT: μ= 1.6 1 ph.e μ= 2.6 Q1= 339.5±9.2 2 ph.e Q1= 325.0+8.7 3 ph.e channel channel Calculate gain(*106) of PMT: μ= 10.0 Q1= 328.1±7.3 μ= 1.6 : 2.42±0.065 μ= 2.6 : 2.32±0.062 μ= 10.0: 2.34±0.052 channel Calo2010. May10-14. Beijing CPPT USTC

Test PMT — R5611 Calo2010. May10-14. Beijing CPPT USTC

Test PMT — R5611 μ= 4.4 Q1 = 24.4 The gain of R5611 at high voltage 800V is (1.7±0.3)e+5. Calo2010. May10-14. Beijing CPPT USTC

Relationship Between Dynodes Fit function: a+b*x As the light intensity increase gradually, the signal of dynode 7 and 4 increase too. we can see the signal of dy7 is about 20 times that of dy4. Fit function:a+b*x+c*x2 Calo2010. May10-14. Beijing CPPT USTC

The Output of Anode vs Dynode From the experiment, we got the single photoelectron’s ADC channel of Anode is 24. We measured the relationship between anode and dynode7, finding the single photoelectron position of dy7 is 0.54 channel. According to relationship between dy7 and dy4, we noticed dy4’s single photoelectron position is 0.027 channel. Calo2010. May10-14. Beijing CPPT USTC

The Output of Dynode vs LED Intensity The intensity of LED light (ph.e) and ADC channel measured by each dynode. Calo2010. May10-14. Beijing CPPT USTC

Cosmic Ray Test The block diagram for cosmic test Calo2010. May10-14. Beijing CPPT USTC

Cosmic Ray Test Signal of Dy7: ~3000 Signal of Dy4: ~150 Calo2010. May10-14. Beijing CPPT USTC

Cosmic Ray Test Dy7 Dy4 Dy1 Min(MIPs) 0.5 100 2000? Max(MIPs) 250 2500 Because of the Dy7 could only response over about 20 ph.e (or 40 channels test by LED) So we can put an absorber between BGO and PMT to attenuate photons, ensuring the response of Dy7 to 1 MIPs is about 80 channels. So the dynamic range of Dy7 is 0.5 MIPs to 125 MIPs. According the correlation between Dynodes, we can set: Dy7 Dy4 Dy1 Min(MIPs) 0.5 100 2000? Max(MIPs) 250 2500 50000? Calo2010. May10-14. Beijing CPPT USTC

Outlook complete dynode readout studies Dynode 1… continue “absorber” test try PD or APD readout Calo2010. May10-14. Beijing CPPT USTC

Thanks Calo2010. May10-14. Beijing CPPT USTC