WACH4 26/11/2002 Julien Cogan CERN/EP/C MA -1- THERMAL STEPS ANALYSIS • Goals & Means : – apply a “step function” on the cooling water – look at : • APD response with laser runs • APD+crystal response with beam runs – get : • APD gain variation with temperature • crystal change in scintillation with temperature • characteristic time of the system • Outline : – method used – steps performed – analysis • Laser (step #3) • Beam (step #1 & 2)
21
Embed
WACH4 26/11/2002Julien Cogan CERN/EP/CMA-1- THERMAL STEPS ANALYSIS Goals & Means : –apply a “step…
WACH4 26/11/2002Julien Cogan CERN/EP/CMA-3- DURING BEAM PERIOD : STEP #1 Step UP : 18 C 19 C (04/08/02 05/08/02) –change room temperature ambient & regulation circuit simultaneously –beam on crystal #1230 –fixed gain mode on FPPA –laser intensity too high SATURATION At equilibrium (after ~12 h) –scan over 64 crystals (around #1230) –reduce laser intensity ( 30%) Step DOWN : 19 C 18 C (05/08/02 06/08/02) –change room temperature ambient & regulation circuit simultaneously –beam on crystal #1142 At equilibrium (after ~12 h) –scan over 24 crystals (around #1230)
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-1-
THERMAL STEPS ANALYSIS• Goals & Means :
– apply a “step function” on the cooling water – look at :
• APD response with laser runs• APD+crystal response with beam runs
– get :• APD gain variation with temperature• crystal change in scintillation with temperature• characteristic time of the system
– cut on beam chambers (3 mm radius around beam center)– reconstruct pulse maximum with method #2 (analytic function)– for each run, get mean value of maximum (resolution ~ 1.2%, ~150 events)
• Laser runs :– APD : reconstruct pulse maximum with method #2– PN : reconstruct pulse maximum with 3rd deg. poly.– For each run, get mean value of APD/PN (resolution ~ 1%, 1000 events)
WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-3-
DURING BEAM PERIOD : STEP #1• Step UP : 18C 19C (04/08/02 05/08/02)
– change room temperature ambient & regulation circuit simultaneously– beam on crystal #1230– fixed gain mode on FPPA– laser intensity too high SATURATION
• At equilibrium (after ~12 h)– scan over 64 crystals (around #1230)– reduce laser intensity ( 30%)
• Step DOWN : 19C 18C (05/08/02 06/08/02) – change room temperature ambient & regulation circuit simultaneously– beam on crystal #1142
• At equilibrium (after ~12 h)– scan over 24 crystals (around #1230)
WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-4-
DURING BEAM PERIOD : STEP #2• New scan with reduced laser intensity (30 %) to avoid saturation
• Beam on the same crystal during step UP & DOWN
• Step UP : 18C 19C (14/08/02 15/08/02) – beam on crystal #1142
• At equilibrium (after ~12 h)– scan over 25 crystals (around #1142)
• Step DOWN : 19C 18C (15/08/02 16/08/02) – beam on crystal #1142
• At equilibrium (after ~12 h)– scan over 25 crystals (around #1142)
WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-5-
STEPS #1 & 2 : REMARKS• From previous analysis (see M0 meeting 15/10/02 ECAL WEEK) :
– fluctuations of the laser pulse width induce an effect on ADP/PN – systematic change of the laser intensity when temperature is changed– not understood fluctuations on APD/PN (crude timing correction attempted)– observed sensitivity to temperature : ~ 3% / C ???
20%PN
APD/PN
PN
APD/PN3% 3 %
30%
STEP #1 DOWN STEP #26h2h
WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-6-
AFTER BEAM PERIOD : STEP #3• After change of laser lamp & laser tuning
• New temperature steps :– try to quantify the temperature effect on laser intensity – temperature sensor installed on laser table– get cleaner data for APD gain -VS- temperature studies