This page is gathering any piece of information needed for the Beamtest Status presentation due to the Collaboration Meeting in November 2007 in Washington

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Template

first attempt: DRAFT

  • Instrument performances and features
    • what we understand and what we do not
    • e.g.: PSF, energy resolution, absolute energy scale, CAL xtalk, Tkr alignment...
  • MC simulation
    • what we understand and what we do not
    • e.g.: beam line, physics list
  • Angular resolution (Understood)
  • Hadronic physics (Understood)
  • Absolute energy scale (Not Understood)
  • MC EM Shower profile (Not Understood)
  • Potential impact of CU beamtest systematics upon LAT astrophysical measurements
  • How we plan to study this issue

Comment(Elliott): In your talk I generally agree with the points. However, as I mentioned in the meeting on Wednesday, Nov7, the anti-quenching seen for heavy ions in the two GSI beam tests is still a mystery. Also, the comparisons that Ping has been making between dE/dx theory and GEANT (GLEAM) for the mean energy loss (using MC truth) show a sensitivity to the cuts on the muons. There is good agreement for muons between dE/dx theory and GLEAM for the mean energy deposit, but only for no cuts. Just making a mild directional cut on the muon in the CALdirZ paramenter gives a few percent antiquenching like effect of GLEAM MC vs theory. Preliminary results on protons and C using MC (Ping) and data (Yvonne) also show a strong dependence in the mean energy loss on cuts (in this case energy deposit, not loss). These effects seem to be angle dependent. Thus, I believe that we have a lot of work yet to understand these effects that are the basis of our energy calibration method on orbit. I would feel that we are taking a large risk in using the GSI antiquenching results at face value in our calibration proceedures.

List of all analysis topics

Instrument response

  • PSF : from low energy photons to high energy electrons
  • Energy : Absolute scale and Energy resolution
  • Trigger efficiency
  • ACD efficiency : CNO trigger at GSI

Instrumental effects

  • Verify Timing in GSI data (Martin)
  • CAL
    • pedestal drift
    • FHE/FLE study Autorange (ULD) (Tomi)
    • XTalk measurement and correction (Sasha)
    • alignment with the CU/Tracker (Philippe)
  • TKR
    • High rates
    • FIFO analysis (Johan)
    • trigger efficiency
    • hot/dead/masked trips
    • Charge Sharing for ions
    • Alignment for the Data
  • CsI Light Quenching measurement at GSI (Thierry)
  • CsI Scintillation afterglow (Benoit)

MC simulation

  • Tagger : Is MC understood ?
  • G4 settings
    • Range cuts
    • LowEnergy Physics list for EM showers
    • QGSP_BERT Physics list for hadronic cascades
    • Geometry and other tricks
    • GEANT4 vs EGS5 vs Mars15 comparisons (David)
  • ACD
    • Min/Max collection efficiency in MC
    • Improved digitization
  • Bari digitization algorithm
  • CAL cristal segmentation (Philippe)
  • TKR Alignment : bug fixed, are we fine ? (leon)

Others

  • TKR Hits and Clusters
    • For all kind of particles but in particular : EM showers and mips
    • TKR Hit deficit evaluation after data reprocessing (Nicola)
    • There used to be a difference of behaviour between PS and SPS : we know now it was due to using CO2 in the Cerenkov
    • Cluster Size
  • CAL EM Shower
    • Longitudinal and Transverse shower profiles
    • Number of logs hit
    • gaps scan
    • Cerenkov pressure scan and scaled energy (Philippe)
  • Tagger: PSF measurement with smaller error bars ?
  • ACD : backsplash measurement (Luis)
  • Many pion studies (Berrie)
  • Beam spot: Tuning, Gaps and Fiducial cuts
  • Very high level reconstruction variables : Tkr1CoreHC, CalTransRms...

Background study runs

  • Positron annihilation in MMS
  • Gamma-background produced in MMS by protons (Alex)
  • Albedo runs

Other topics/ideas/comments

things we did

  • Selection of beam test-like events from orbits data
  • Agreement Matrix and BtSysTest
  • Material Audit : TKR and CAL, possible improvements

Some comments (luca)

Talk should have a list of

  • understood (i.e. reproduced)
    • angular resolution (tagged+FB+electrons)
    • energy resolution (spread and tails, not average value)
    • backsplash: are we happy with current strong cuts to reproduce that in MC?
    • trigger efficiency (do we have CAL-LE and CAL-HE plots similar to what nicola made for TKR? CNO efficiency? important for effective area)
    • general g4 behaviour and implementation (comparison with other simulators, beam line simulation)
    • CAL calibration (xtalk, non-linearities) - BUT how is SPS cross-calibration compatible with the GSI calibration and how do we calibrate in flight?
    • Material audit (TKR+CAL): how much more X0 do we expect from modifications to CAL geometry?
    • effects of material along beam line, i.e. no coherent improvement on both TKR and CAL discrepancies
    • effects of LE physics list and range cuts
    • optimized (but not perfect) hadronic physics list
  • NOT understood
    • hit deficit in MC (and clusters)
    • log deficit in MC and overall raw energy scale
  • plans to assess
    • effects of discrepancies on background rejection (data-like simulations, we MUST devise and show a plan here, we have been talking about this for too long now)
    • how do we play with shower shape in g4?
  • No labels