Alexandre Camsonne Jefferson Laboratory Hall A Collaboration meeting June 21 st 2007

1. Complete Separation of Deeply Virtual Photon and p0Electroproduction Observables on Unpolarized ProtonsE07-007 Alexandre Camsonne Jefferson Laboratory Hall A Collaboration meeting June 21st 2007

2. 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

3. 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

4. Experimental setup Hall A Collaboration meeting November 19, 2014

5. 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

6. 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

7. 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

8. 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

9. 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

10. Experimental setup New beamline design Hall A Collaboration meeting November 19, 2014

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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