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HF Laser/LED Calibration Studies

HF Laser/LED Calibration Studies. L. Almeida, M. Baarmand , L. Caraway, M. Hohlmann, T. Qureshi, I. Vodopianov FLORIDA TECH. 10 m jacketed optical fiber. Electronic pulser for ~100 ns LED pulses w/ single-shot and external trigger capability. 1->4 light splitter.

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HF Laser/LED Calibration Studies

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

  2. HF Calibration Optical Path Test Beam 2002 Counting Room N2 Laser 200 mJ 337 nm 300 QQ 75m 1  4 300 QQ 9m CLI ROBox 3 9 CALIB Box 600 QP 18m

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

  4. PMT BOX SHIELDING Empty PMT TUBE 40cm 600 QP Calibration Light Injector (CLI) 120 Light Guide Non-reflective coating 600 QP 5 PMT Light Guide Light Guide • Some PMTs have more or fewer than 5 fibers !!!

  5. Calibration • Light Injector • (CLI)

  6. Calibration Light Injector in R O Box 3 Plate 3 Plate 2 Calibration Tube Fiber Ferrule Holographic Diffuser SMA Connector 9cm • ±4% • Non • uniformity SMA-SMA connector Jacket Fiber 600 QP SMA Connectors Aspheric Lens 11mm Focal Length Collimation Assembly

  7. HF Laser/LED Calibration IssuesTest Beam 2002 • Insufficient light intensity • low laser output power • laser used at test beam misaligned or badly focused? • attenuation of UV in fibers • move laser downstairs / use DYE (blue) laser • small efficiency in 14 splitter, CALIB Box, CLI • improvements under investigation – see below • low LED light • use brighter LEDs and drive at higher bias voltage? • Non-uniformity as seen by PMTs (~20%) • mostly due to light guides and calibration fibers downstream of CLI

  8. R O Box 3 • PMT 154 • 8-10 fibers!!!

  9. Attenuation of UV in 300m QQ • Atten. Length = 60m Counting Room • without splitter attenuation N2 Laser 300 mJ 337 nm 75m/150m/20m 300 QQ 1  4/8 0m/20m/20m 300 QQ CALIB Box

  10. Splitter 1 × 4 (1 × 8) efficiency 75 mm 1000m QQ (Silica) 300m QQ 300m QQ SMA connectors cross section ratio  11 (9%)

  11. Present Calibration Box • laser • Mixer50  15  15 mm3 • PIN ) 22° ε = 10% Scintillator 8  4  8 mm3 • 10 × 600m • fiber bundle • Ø3mm (7mm2) • 10 × 600m • fiber bundle • Ø3mm (7mm2) • Light collection: • 0.1% bybundle, 0.004% byeachfiber Total efficiency = 410-6 per output fiber

  12. Calibration Box with smaller mixer to be tested • 20  7  4 mm3 • LED PIN laser • ~10 times better • efficiency ~ 410-5 • 10 × 600m • fiber bundle • Ø3mm (7mm2) • Max light collected within 22° = 3.6%  max efficiency for this mixer+bundle = 1.410-5per output fiber

  13. Present C L I →Calibration Bundle Lens (F=11mm Ø=6mm) Holographic Diffuser • Light guide CALIB Bundle 120 × 600m SMA Connector 5 fibers e = 0.12% with non-uniformity of 4% lens e = 16% Efficiency = 1.9 × 10-4 per PMT

  14. Modified Calibration Light Injector (to be tested) current Lens Ø = 16mm F = 20mm 60°diffuser Estimated efficiency ≈1.7 × 10-3per PMT ~ 10 times better ! SMA fiber 10°diffusers

  15. Results from 2002 test beam • Estimated total efficiency = 2.210-10 • attenuation of UV in fibers = 3.5 • CALIB Box efficiency = 410-6 • CLI → bundle efficiency = 1.910-4 • Attenuation (bundle → PMT) ≈ 2* • Hamamatsu: QE(PMT) = 27% • Test beam: (laser → PMT) = 74 PE (wish 750 PE!) • 2.51012 laser photons • 200mJ is 3.31014 photons (~100 times higher!) * Obtained by combining LEDs power output and test beam measurements – in agreement with measured light guideattenuation

  16. Outlook (laser calibration) • Improvements: • UV laser downstairs or DYE laser   1.8 • Better CALIB Box efficiency   10 • Better CLI efficiency   10 • Efficiency of 18 splitter = 1.3% overall efficiency increased by ~ 2 • Possible laser power recovered up to ~10 times (to be confirmed with measurements)

  17. Outlook(LED calibration) • LED subsystem is independent of splitter efficiency and UV attenuation • Improvements: • use more powerful LEDs • assume this to be compensated by gate 100ns → 25ns • improve CALIB Box and CLI as above overall efficiency increased by ~ 100

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