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

Links

Meeting Main Page-    Meeting Agenda    -    All Meetings Reports    -   BT F2F in Washington -   BT EVO Meetings

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?