Prototype Calibration System for Forward Hadron Calorimeter L. Almeida, M. Baarmand, L. Caraway, M. Hohlmann, T. Qureshi, I. Vodopianov FLORIDA TECH 10 m jacketed light fiber 1 ->4 light splitter 1 1 ->9 light splitter w/ pulsed LEDs, input for UV laser pulses, and PIN diode light monitoring Electronic pulser for ~100 ns LED pulses w/ single-shot and external trigger capability
HF Calibration Optical Fiber Path Test Beam 2002 Counting Room N 2 Laser 200 J 337 nm 300 QQ 75 m 1 4 9 PMT Boxes 300 QQ 9 m 9 PMT Boxes Bottom Rack Calib Box 2 9 PMT Boxes 9 600 QP 18 m 9 PMT Boxes
Calibration Box - 1 x 9 splitter PIN Diode 4 mm 300 QQ ADC LED 1 MIXER 50 mm 15 mm PIN 1 PIN 2 PIN 3 Polystyrene LED 2 Pulser 600 QP Blue Scintilator 4 mm 8 mm 9 8 mm To PMT Box 3
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PMT BOX SHIELDING Empty PMT TUBE (CLI) 600 QP Calibration Tube 40 cm Light Guide 120 Non-reflective coating 600 QP PMT 5 Light Guide 5
Calibration Light Injector (CLI) Plate 3 Plate 2 Calibration Tube Fiber Ferrule SMA Connector SMA-SMA connector Holographic Diffuser 9 cm Jacket Fiber 600 QP SMA Connectors Collimation Assembly 6 Aspheric Lens 11 mm Focal Length
1 2 One-PE Response: 3 Plot#1 Plot#2 Plot#3 111 or 117 ADC counts 106 ADC counts 104 ADC counts => stable 7 laser pulse
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PMT 154 (315 E 22) behavior PMT relative gains for ROBOX 3 measured in Iowa: PMT N 148 149 150 151 152 153 154 155 156 157 158 159 160 161… Gain % 48 74 74 76 76 76 77 78 96 97 98 100 102 104… High output, narrow peak 9 Usual pedestal …
10 PMT (PE) / (Laser / Laser 100%)
LED Data 1 LED at threshold V 2 LED at 10 V 11
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Comparison of PMT response to laser and LED at similar light intensity 13
2 LED at 10 V (close intensity) Laser 48% 14
ADCC = (ADC-Pedestal) / Gain 15
16 ADCC
1 x 4 splitter 75 mm 17 300 QQ SMA Connectors 300 QQ 1000 QQ (Silica) Fiber to Fiber ratio = (1/0. 3)2 11 Average in/out measurement 22
Splitter study PMT 154 “best” 1 4 splitter attenuation: no fiber 1 3 18 2 4 1 50 2 49 3 42 4 43 red light 43 42 36 37 25 22 22 18
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100% laser intensity corresponds to 360 Ge. V electron 22
100% laser int. corresponds to 933 Ge. V p for E-PMT 1467 Ge. V p for H-PMT 23
Questions • Are fibers in calibration and PMT bundles polished? • How many calibration fibers are used for PMT 154 (315)? What is different in calibration lightpipe for this PMT? • Which PMTs have bad light guides? 24
Concerns • Insufficient laser intensity (attenuation factor 12 in 150 m fiber) place UV laser closer to detector or use blue laser • Build (or buy) low attenuation splitter 25
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