1. 1 Prototype Calibration System for Forward Hadron Calorimeter L. Almeida, M. Baarmand, L. Caraway, M. Hohlmann, T. Qureshi, I. Vodopianov FLORIDA TECH 1->9 light splitter w/ pulsed LEDs, input for UV laser pulses, and PIN diode light monitoring 1->4 light splitter Electronic pulser for ~100 ns LED pulses w/ single-shot and external trigger capability 10 m jacketed light fiber

2. 2 N 2 Laser 300  QQ 75m 9 PMT Boxes Calib Box 1  4 Counting Room HF Calibration Optical Fiber Path Test Beam 2002 200  J 337 nm Bottom Rack9 600  QP 18m 300  QQ 9m

3. 3 LED 2 MIXER 50mm  15mm  15mm Polystyrene PIN3 ADC 9 600  QP 300  QQ Blue Scintilator 8mm  4mm  8mm Calibration Box  1 x 9 splitter To PMT Box PIN Diode 4mm  4mm Pulser PIN1 PIN2 LED 1

4. 4

5. 5 Calibration Tube Empty PMT TUBE (CLI) Light Guide Non-reflective coating Light Guide 600  QP PMT BOX 5 120 SHIELDING 600  QP 40cm Light Guide PMT

6. 6 SMA Connector Fiber 600  QP Jacket SMA Connectors Holographic Diffuser Plate 2Plate 3 SMA-SMA connector Fiber Ferrule Calibration Light Injector (CLI) Calibration Tube 9cm Aspheric Lens 11mm Focal Length Collimation Assembly

7. 7 One-PE Response: Plot#1111 or 117 ADC counts Plot#2106 ADC counts Plot#3104 ADC counts => stable laser pulse 12 3

8. 8

9. 9 PMT 154 (315 E22) 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 peakUsual pedestal …

10. 10 PMT (PE) / (Laser / Laser100%)

11. 11 1 LED at threshold V 2 LED at 10 V LED Data

12. 12

13. 13 Comparison of PMT response to laser and LED at similar light intensity

14. 14 2 LED at 10 V (close intensity) Laser 48%

15. 15 ADC C = (ADC-Pedestal) / Gain

16. 16 ADC C

17. 17 300  QQ 1000  QQ (Silica) 300  QQ SMA Connectors 1 x 4 splitter 75 mm Fiber to Fiber ratio = (1/0.3) 2  11 Average in/out measurement  22

18. 18 Splitter study PMT 154 “best” 12 34 1  4 splitter attenuation: no red fiber light 1 50 43 25 2 49 42 22 3 42 36 22 4 43 37 18

19. 19

20. 20

21. 21

22. 22 100% laser intensity corresponds to 360 GeV electron

23. 23 100% laser int. corresponds to 933 GeV  for E-PMT 1467 GeV  for H-PMT

24. 24 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?

25. 25 Concerns Insufficient laser intensity (attenuation factor 12 in 150m fiber)  place UV laser closer to detector or use blue laser Build (or buy) low attenuation splitter