Long term test of LED Long term test of LED pulsing pulsing Long - - PowerPoint PPT Presentation

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Long term test of LED Long term test of LED pulsing pulsing Long - - PowerPoint PPT Presentation

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Long term test of LED Long term test of LED pulsing pulsing Long time LED system stability measurement Aging of part of optical system Future plans Jaroslav Zalesak, Jan Smolik Institute of Physics ASCR, Prague Sep 13, 2007 CALICE

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SLIDE 1

Sep 13, 2007 CALICE Collaboration Meeting Prague 1

Long term test of LED Long term test of LED pulsing pulsing

Long time LED system stability measurement Aging of part of optical system Future plans

Jaroslav Zalesak, Jan Smolik Institute of Physics ASCR, Prague

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SLIDE 2

Sep 13, 2007 CALICE Collaboration Meeting Prague 2

Setup: in Setup: in-

  • box view

box view

CMB - LED driver + PIN ampl + temp sensors VME DAQ controlled with PC APD + electronics black box

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SLIDE 3

Sep 13, 2007 CALICE Collaboration Meeting Prague 3

Setup: CMB Setup: CMB – – LED + PIN LED + PIN

UV LED PIN CAN bus V-calib +T-calib signals High LED light intensity LED driver pulsing @ 1kHz

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SLIDE 4

Sep 13, 2007 CALICE Collaboration Meeting Prague 4

Fiber +APD detector Fiber +APD detector

Scintillator tile w/ quarter circle groove

  • air gap to attenuate height
  • f signal amplitude to APD

APD Ubias = 270V very low gain (~3) ↔ pin diode

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SLIDE 5

Sep 13, 2007 CALICE Collaboration Meeting Prague 5

Measurement: temperature Measurement: temperature

  • Long time period: 1 month

→ >2 billion pulses

  • Large variations in temperature within 7 K
  • 3 sensors (2 @ CMB, 1 nearby APD)
  • same time history
  • full correlated
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SLIDE 6

Sep 13, 2007 CALICE Collaboration Meeting Prague 6

ADP + PIN response ADP + PIN response

APD PIN

  • good correlation ADP-PIN

response

  • very similar time response
  • PIN more noisy due to low signal ampl
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SLIDE 7

Sep 13, 2007 CALICE Collaboration Meeting Prague 7

Relative response Relative response

  • normalized at average
  • ver whole time scale
  • variation in response

at level ± 10%

  • visible time slope fall

in PD responses

  • light intensity decrease

in time

APD PIN Temp inverse

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SLIDE 8

Sep 13, 2007 CALICE Collaboration Meeting Prague 8

Time stability Time stability

  • PIN / APD – Temperature correlation
  • unexpected result -> time instability
  • light intensity decrease in time – PIN & APD response decreasing
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SLIDE 9

Sep 13, 2007 CALICE Collaboration Meeting Prague 9

APD APD – – PIN correction PIN correction

  • PIN correction (dividing responses) to APD signal

as used in LED calibration procedure

  • almost flat result < 2%
  • difference from uniformity ↔

not same PIN / low gain APD temperature dependence

  • small jumps in time = (probably PIN) electronics instability
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SLIDE 10

Sep 13, 2007 CALICE Collaboration Meeting Prague 10

Summary Summary

Long time stability of LED-PIN-APD electronic-optical

system was measured over one month Large temperature variation cause big variations in response of optical system -> PIN – low gain APD and/or temperature dependence PIN-APD system can correct on long time instability of whole system Probably visible aging effects of optical fibers

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SLIDE 11

Sep 13, 2007 CALICE Collaboration Meeting Prague 11

Future plans Future plans

Test for two fibers with different lengths to study

aging of fibers, avoiding possible aging of LED Setup prepared for future (EUDET) CMB with new LED driver Study of ‘party’ side-emitting fiber leading along many scintillator tiles with old/new LED driver