ATLAS ALFA - TESTBEAM OCTOBER 06

Remaining tests in the lab

• Understand and verify channel mapping MAPMT --> offline
• Measure S-curves for all PMFs/MAPMTs (HV=850V)
• Equalize gains
• Evaluate cross-talk (use of single fibre)
• Measure 'dark' counts
• if there is time, repeat above for different voltages

Very desirable, but not absolutely necessary:

• With det. 10_2_16 reconstruct image of Sr-90 source
• With det. 2_2_64 reconstruct image of Sr-90 source
• With det. Overlap Detectors reconstruct image of Sr-90 source (software not yet in 100% ready)

Installation & Start-up in TB zone

• Test HV modules / cables
• Verify beam trigger scintillators with Sr-90 source
• Arrange and align pixel telescope (z positions)
• Test Si telescope (bias & leakage current sensors, voltage & current of readout electronics)
• With beam: verify beam trigger, threshold, coincidence window
• With beam: test Si telescope + reconstruction

• Check light tightness of box
• Test full chain with pulsed LED
  • timing
  • MAPMT alignment on connector
  • pedestal run (HV off) ?
  • HV scan (800 - 900 V)
  • 1 p.e. runs (LED)
  • connectivity
  • reconstruction
  • check cross talk
• Mount detector 10_2_16
• Verify (coarse) alignment with Si telescope

First Tests of ALFA with beam

• Mount 10_2_16
• Load thresh + gains as optimized in lab (hopefully!)
• Verify timing ALFA w.r.t. Trigger
  • HV scan (800 - 900 V)
  • thresh scans
• We should see the image of the ALFA active area (diamond of 7.5 x 7.5 mm2)
• Agree on standard HV & threshold setting

First Tests of ALFA and Si Telescope

• Verify timing ALFA / Telescope / Trigger
• Verify correlation ALFA - Telescope
• Software align ALFA - Telescope

"NORMAL MEASUREMENTS"

Before measurements: Tune beam to have a well defined spot (< 1cm2). Analyze beam spot size and divergence with Si telescope.

1. Hit multiplicity / Efficiency

• Detector 10_2_16
• Runs at standard setting +/- 5%
• Software should be able to provide number of hits per trigger for every fibre

2. Cross Talk

Use above runs and analyze

• number of non-ajacent hits per layer -> cross talk at connector / MAPMT / electronics
• number of adjacent hits per layer -> cross talk in detector / connector
• Question: is software able to provide number of hits per layer ?

3. Spatial resolution

• Detector 10_2_16
• Runs at standard setting +/- 5%
• optimize detector alignment rel. to beam (systematic angular scans)
• cuts on Silicon theta, phi if necessary
• move ALFA to expose central and edge region
• take very high statistic runs at optimum settings

4. Edge sensitivity & resolution

• Detector 10_2_16
• standard settings
• mount small scint. counter (S330) below detector (long sice aligned with beam)
• take runs with S330 in trigger
• take runs without S330
• very high statistics !

5. Determination of active surface

• Detector 10_2_16
• Use large trigger counter 30x30 mm2 (S3030)
• Large uniform beam spot
• very high statistics !

OVERLAP DETECTORS

• Mount OD1 and OD2
• Mount trigger counter (ideally 25 x 8 mm, to be made)
• Verify connectivity & reconstruction by moving OD1/OD2 infront of Telescope
• Take runs by moving OD1 w.r.t. OD2 (steps of 1, 0.1, 0.01 mm)
• take runs with beam in the light guide region (background from Cherenkov light ?)
• Evaluate trigger efficiency in various regions. How ? Would need a VME register to store scintillator hits ?

OTHER MEASUREMENTS

• Detector 2_2_64
• efficiency & multiplicity
• move Si telescope in center and at edge of 2_2_64

-- ChristianJoram - 28 Sep 2006