Complete Separation of Deeply Virtual Photon and p

Complete Separation of Deeply Virtual Photon and p 0 Electroproduction Observables on Unpolarized Protons E 07 -007 Alexandre Camsonne Jefferson Laboratory Hall A Collaboration meeting June 21 st 2007 Hall A Collaboration meeting

Overview • New DVCS experiment – What we learnt from E 00 -110 and E 03 -106 – DVCS 2 – p 0 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 6/10/2021 2

E 00 -110 and E 03 -106 • First dedicated experiment proposed for the study of the Deeply Virtual Compton Scattering ( E 00 -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 Q 2 – High resolution calorimeter – Focus on cross section measurement – Ensure exclusivity – High luminosity 1037 cm-2. s-1 Hall A Collaboration meeting 6/10/2021 3

Experimental setup Hall A Collaboration meeting 6/10/2021 4

What we learnt from E 00 -110 and E 03 -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 – p 0 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 6/10/2021 5

What we learnt about physics • Early scaling • Contribution of the DVCS 2 amplitude is not negligible at JLab kinematics • p 0 production very interesting to study • Calibration is possible using p 0 and p- Hall A Collaboration meeting 6/10/2021 6

E 07 -007 motivations • Improvements compared to previous experiment – Use of 2 beam energies • Study p 0 production with a LT separation • Study of the importance of the DVCS 2 – Calorimeter work • Increase size for larger acceptance • Blocks selection • Curing of radiation damage – Improvement in p 0 detection • Better kinematical range ( lower threshold cut) • Improved p 0 subtraction Hall A Collaboration meeting 6/10/2021 7

E 07 -007 motivations Expected errors : At this day (Jun 21 2007): For the future experiments 2% X 3% HRS+Pb. F 2 acceptance +luminosity + target 1% 3% X H(e, e’g)Xg p 0 background 2% Inclusive H(e, e’g)Np 2% 1% X 2% Radiative Corrections only on the cross section difference Beam polarization measurement Total (quadratic sum)= 5. 1% (5. 6%) Hall A Collaboration meeting 6/10/2021 3. 6 - 3. 7 % 8

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 pi 0 detection – Speed improvement to accommodate lower threshold Hall A Collaboration meeting 6/10/2021 9

Experimental setup New beamline design Hall A Collaboration meeting 6/10/2021 10

E 07 -007 new issues • No proton array means higher luminosity but also higher irradiation damages • p 0 detection imply lower thresholds – New trigger scheme – Improve rate capability of system Hall A Collaboration meeting 6/10/2021 11

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 PVA 4 Hall A Collaboration meeting 6/10/2021 12

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 p 0 Hall A Collaboration meeting 6/10/2021 13

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 – VME 64 ( 80 Mbytes/s ) – 2 e. VME ( 160 Mbytes/s ) – VME 320 SST ( 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 6/10/2021 14

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 6/10/2021 15

Timeline • MRI submitted for financing calorimeter upgrade by ODU/OU • Result by the end of June • Procurement of PMTs and Pb. F 2 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 6/10/2021 16

Conclusion • Capitalizing on what was learnt from the previous experiments by improving the method – LT separation for the p 0 – Evaluation of the importance of the DVCS amplitude – 6 Ge. V experiment in could run in 2009 • Research and development on Pb. F 2 calorimeter curing • Development of new trigger scheme and investigating electronics speed improvement. Hall A Collaboration meeting 6/10/2021 17