E07-007 & E08-025 s tatus report
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E07-007 & E08-025 status report
E07-007 & E08-025 status report
1GoalsMeasure DVCS and p0 electroproduction cross sections at different Q off proton and neutron.
Two beam energies:- Separate DVCS.BH and |DVCS| terms.- Separate L/T of p0 cross sections.
t=(p-p)GPDg*g, p0Q2ppxBQ (GeV)Energie faisceau(GeV)0.361.5(3.355 ; 5.55)0.361.75(4.455 ; 5.55)0.362(4.455 ; 5.55)2Experimental SetupData taken from October to December 2010.
208 PbF2 blocks3Data analysisBeam line- Polarimetry (Compton + Moller) data (FINISHED), E. Fuchey- Beam charge monitors (BCM) calibration (FINISHED), J. Roche
HRS- Optics and mispointing checks (FINISHED), P. Bertin- Drift chambers time offsets (FINISHED), C. Munoz- Trigger/ detectors efficiency (FINISHED), M. Defurne, C. Hyde, M. Mazouz- Normalization : DIS cross section (IN PROGRESS), M. Defurne
Calorimeter-Calibrations (FINISHED), A. Marti, C. Desnault, M. Ben Ali- Waveform analysis of PMT pulses (FINISHED), A. Marti- Timing corrections (FINISHED), M. Mazouz
MC simulation- GEANT4 written from scratch based on previous GEANT3 and their comparison, (FINISHED) R. Paremuzyan, M. Defurne
Physics analysis (IN PROGRESS)- DVCS off proton, A. Marti- DVCS off neutron, C. Desnault , M. Ben Ali- p0 electroproduction cross section, M. Defurne4
G4 countsG4/G3 countsR. Paremuzyan
G3-G4 in relatively good agreement
G4 Simulation package 5Calorimeter calibrationFirst step: block calibration coefficients are determined using elastic runs (proton in HRS, electron in the calo). (A. Marti)
Second step: gain variations can be monitored and corrected day-by-day using e N -> e N p0 (C. Desnault M. Ben Ali)
Missing mass eN->e p0 X and invariant mass of the two photons in the calorimeter (GeV)6C. Desnault
* Before calibration* After calibrationCalorimeter calibrationMissing and invariant mass much more stable after calibration!!7NormalizationNormalization studies through Deep Inelastic Scattering cross section extraction.
-> Quality control, run-by-run
-> Quality of the normalization (corrections, charge calculation,)
Upstream BCMDownstream BCM2%8
Pion rejector spectrum of single and multitrack eventsEnergy (GeV)Multitrack events in HRS9Multitrack eventscontribution9
Multitrack events in HRSBetween 5 and 10% of multitrack events Failure of the tracking -> remove them and apply a correction
BUT they are not all electron events: down to a 3% correction (max)E2 GeV in 2 tracks: Electrons10HRS acceptanceFirst kinematics was run without collimator.
5 other kinematics were run with the collimator.
Collimator at the wrong position ?R-function> 0.005. Monte Carlo. Experimental dataIN PROGRESS1112
M. DefurneBCM problemCerenkov ThresholdIN PROGRESS
1 weekBCM problemNext Adapt the R-function and/or find a suitable set of cuts to compute the HRS acceptance.
Compare DIS results with theoretical value (F2 parametrization).
First DVCS cross sections off proton for late Fall 2013.(A. Marti)
First DVCS off neutron (C. Desnault M. Ben Ali) and p0 electroproduction cross sections (M. Defurne) for 2014.14