E07-007 & E08-025 s tatus report

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E07-007 & E08-025 status report Maxime DEFURNE CEA-Saclay/Irfu/SPhN 1
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E07-007 & E08-025 s tatus report. Maxime DEFURNE CEA-Saclay/ Irfu / SPhN. Goals. Measure DVCS and p 0 electroproduction cross sections at different Q² off proton and neutron . Two beam energies: - Separate DVCS.BH and |DVCS|² terms. - Separate σ L / σ T of p 0 cross sections. - PowerPoint PPT Presentation

Transcript of E07-007 & E08-025 s tatus report

E07-007 & E08-025 status report

E07-007 & E08-025 status report

Maxime DEFURNECEA-Saclay/Irfu/SPhN

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.

Calorimeter

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

G3 counts

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

13

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