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Complete Separation of Deeply Virtual Photon and p 0 Electroproduction Observables on Unpolarized Protons E07-007. Alexandre Camsonne Jefferson Laboratory Hall A Collaboration meeting June 21 st 2007. Overview. New DVCS experiment What we learnt from E00-110 and E03-106 DVCS 2

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Complete Separation of Deeply Virtual Photon and p0Electroproduction Observables on Unpolarized ProtonsE07-007

Alexandre Camsonne

Jefferson Laboratory

Hall A Collaboration meeting

June 21st 2007

overview
Overview
  • New DVCS experiment
    • What we learnt from E00-110 and E03-106
    • DVCS2
    • p0 production
  • Detector upgrade
    • Calorimeter
      • Radiation hardness test
      • Calorimeter upgrade
    • Electronics upgrade
      • Sampling system upgrade
      • Calorimeter trigger upgrade
  • Man power
  • Timeline
  • Conclusion

Hall A Collaboration meeting

November 19, 2014

e00 110 and e03 106
E00-110 and E03-106
  • First dedicated experiment proposed for the study of the Deeply Virtual Compton Scattering ( E00-110 )
  • 4 years of developments, ran in 2004
  • A unique approach from what was done previously and now
    • High resolution on a limited kinematic range
      • Study of scaling with fixed xbj and variation in Q2
    • High resolution calorimeter
    • Focus on cross section measurement
    • Ensure exclusivity
    • High luminosity

1037 cm-2.s-1

Hall A Collaboration meeting

November 19, 2014

experimental setup
Experimental setup

Hall A Collaboration meeting

November 19, 2014

what we learnt from e00 110 and e03 106
What we learnt from E00-110 and E03-106
  • The good
    • Experiment is possible
    • New dedicated electronics worked ( elastic cross section )
    • Resolution is sufficient to work in double arm
  • The “less” good
    • Triple coincidence cross sections are difficult ( on going effort to understand efficiency of proton array )
    • Radiation damage very random
    • Calibration of the calorimeter is very important because of radiation damages
    • p0 were cut by threshold on calorimeter trigger
    • Dead time can be large with high spectrometer rates
    • Better study of background effects needed to be taken into account in simulation ( more random runs )

Hall A Collaboration meeting

November 19, 2014

what we learnt about physics
What we learnt about physics
  • Early scaling
  • Contribution of the DVCS2 amplitude is not negligible at JLab kinematics
  • p0 production very interesting to study
  • Calibration is possible using p0 and p-

Hall A Collaboration meeting

November 19, 2014

e07 007 motivations
E07-007 motivations
  • Improvements compared to previous experiment
    • Use of 2 beam energies
      • Study p0 production with a LT separation
      • Study of the importance of the DVCS2
    • Calorimeter work
      • Increase size for larger acceptance
      • Blocks selection
      • Curing of radiation damage
    • Improvement in p0 detection
      • Better kinematical range ( lower threshold cut)
      • Improved p0 subtraction

Hall A Collaboration meeting

November 19, 2014

e07 007 motivations1

For the future experiments

3.6 - 3.7 %

E07-007 motivations

Expected errors :

  • At this day (Jun 21 2007):
  • 3% HRS+PbF2 acceptance +luminosity + target
  • 3% H(e,e’g)Xg p0 background
  • 2% Inclusive H(e,e’g)Np

2% Radiative Corrections only on the cross section difference

  • 2% Beam polarization measurement

2%X

1% X

1%X

Total (quadratic sum)= 5.1% (5.6%)

Hall A Collaboration meeting

November 19, 2014

new experimental setup
New experimental setup
  • Double arm experiment : proton array not needed
  • Calorimeter
    • Increased size of the calorimeter from 132 to 208 blocks for larger acceptance in t
  • Electronics
    • Improved trigger for optimal pi0 detection
    • Speed improvement to accommodate lower threshold

Hall A Collaboration meeting

November 19, 2014

experimental setup1
Experimental setup

New beamline design

Hall A Collaboration meeting

November 19, 2014

e07 007 new issues
E07-007 new issues
  • No proton array means higher luminosity but also higher irradiation damages
  • p0 detection imply lower thresholds
    • New trigger scheme
    • Improve rate capability of system

Hall A Collaboration meeting

November 19, 2014

calorimeter curing
Calorimeter curing
  • Systematic irradiation of blocks to reject the bad ones
  • Ohio State University
    • Test transmission

summer student

Sylvain Gregoire

    • FEL block irradiation test: recreate dose from experiment
    • Blue light curing process similar to process used at Mainz on PVA4

Hall A Collaboration meeting

November 19, 2014

data acquisition
Data acquisition
  • Redesign for new calorimeter geometry
  • New trigger
    • Triggering on total sum
      • Digital
      • Analog sum
    • Multiple level trigger

Effectively reduce threshold on many clusters event to detect p0

Hall A Collaboration meeting

November 19, 2014

data acquisition1
Data acquisition
  • Sampling system
    • Different alternative
      • Simple one increase bandwidth by using larger number of crates
      • Upgrade ARS motherboard to new technologies using same form factor
        • VME64 ( 80 Mbytes/s )
        • 2eVME ( 160 Mbytes/s )
        • VME320SST ( 320 Mbytes/s)
      • Switch serial VXS ( 1 Gbyte/s)
  • Technical choice to be decided soon since we have 2 years to develop
  • Depends on man power available

Hall A Collaboration meeting

November 19, 2014

man power
Man power
  • Ohio
  • Clermont Ferrand
  • ODU
  • Jefferson Laboratory
    • More collaborators welcomed !
      • Calorimeter design
      • Mechanical design
      • electronics
      • Analysis
  • Collaboration meeting in September

Hall A Collaboration meeting

November 19, 2014

timeline
Timeline
  • MRI submitted for financing calorimeter upgrade by ODU/OU
    • Result by the end of June
    • Procurement of PMTs and PbF2 blocks
  • Electronics
  • FEL irradiation tests
    • Fall 2007
  • Start fiscal year 2008 : mechanical design
    • might be scheduled as soon as second half of 2009

Hall A Collaboration meeting

November 19, 2014

conclusion
Conclusion
  • Capitalizing on what was learnt from the previous experiments by improving the method
    • LT separation for the p0
    • Evaluation of the importance of the DVCS amplitude
    • 6 GeV experiment in could run in 2009
  • Research and development on PbF2 calorimeter curing
  • Development of new trigger scheme and investigating electronics speed improvement.

Hall A Collaboration meeting

November 19, 2014