Installation! of! E (g 2p ) & E (G Ep /G Mp )! in Hall A! during the 6MSD!!"#$%&'(#

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1 Installation! of! E (g 2p ) & E (G Ep /G Mp )! in Hall A! during the 6MSD!!"#$%&'(#

2 E (g 2p )!! Measure the inelastic spin structure function g 2 of the proton in the low invariant momentum transfer (Q 2 ) region [(0.02 </= Q 2 (GeV/c) 2 </= 0.3]!! g 2 has a component sensitive to low-q 2 effects (e.g. non-perturbative QCD). Knowledge of g 2,! " allows to check if the Burkhardt-Cottingham sum rule is fulfilled for the proton - no singularities in g 2! " aids in the development of chiral perturbation theories (calculable approximations to QCD at low energies)! " helps improve the computational accuracy of the ground-state hyperfine splitting of hydrogen (exp < 1:10 12, calc ~ few:10 6 )!! Requires target polarized transversely to incident beam polarization. Uses! CLAS EG4 data for g 1.!

3 E Part II Projected uncertainties (w/ 70 deg target) Μ P G E G M Q 2 GeV 2

4 But Also... PSI Lamb shift in Sick Bernauer et al. This work CODATA Pohl et al. muonic Hydrogen. Inconsistent with other measurements. Hot Topic... E08007-II will help resolve it Proton charge radius [fm]

5 Key Experimental Points!! UVA polarized target (NH 3 ) 5 Tesla field normal to beam direction. Parallel to beam direction at one energy (3.3) " Need beam chicane to change vertical angle of incident beam so that the target field brings it back to horizontal at the target center chicane changes with beam energy (1.1, 1.6, 2.2, 3.3 GeV)!! Local dump for un-scattered beam (deflected downwards by target field)!! Beam current of nanoa - needs Tungsten ( silver ) calorimeter for absolute current measurement & increased sensitivity of Beam Position Monitors and Beam Current Monitors (cavity)!! Slow raster required - area at target of 25 mm X 25 mm. Need large aperture BPMs & raster pattern affects BPM measurement.!! Beam current needed for polarimetry:! # Moller polarimeter ~ 200 nanoa (needs testing)! # Compton polarimeter (?)!! Experimental setup (two phases):! I. Target ~ 87 cm upstream of nominal pivot & septum magnet deflects particles scattered at 6-degrees into the two HRS at 12.5 degrees.! II. Target at nominal pivot, septum magnet removed, HRSs are used to detect particles scattered at 12.5 and 15 degrees.!

6 Timelines & Main Tasks! Timeline! Engineering/Design/Manufacture " "5/2011! " " " most engineering/design done by 2/2011! Installation " " " " "5/ /2011! Commissioning" " " " "11/2011! Data taking " " " " "11/2011-3/2012! Remove septa and move target location "1/2012! Beamline: Tim Michalski (Project Lead) / Butch Dillon-Townes (Engineering Group)! Support from various groups (/Installation, Alignment, Vacuum, )! Target: Chris Keith (Target group)/hall A personnel/users (UVA)! Hall infrastructure/septum/dump: Hall A personnel! Others (Spectrometer, detector, DAQ, polarimeters ): Hall A personnel/users/acc SW!

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11 Where are we?! Beam Transport (weekly meetings). Making good progress - see! G2P_Weekly_Beam_Transport_Meeting_Minutes_16Nov_2010.pdf! for a status summary as of 11/16/10. Some long-lead items have already been ordered.! Hall Infrastructure (previous sketches). Presently working on,! dump design (well along, checking beam position monitoring scheme)! thin upstream window design and check of failure modes! Target large roughing pumps and components have been ordered by the target group. Magnet refurbishing ongoing at Oxford (magnet expected to be here early next year).! Refurbishing and fitting third set of coils to room-temperature septum magnet is proceeding in the Experimental Staging Building (ESB)!

12 ID Task Name 1 2 G2P installation 3 4 RadCon Hold 5 post beam checklist 6 7 beam line prep work LCW work ***From here to line 116 is eng installation and electronics group*** 25 ***recourses for this work needs to be assigned by*** 26 ***Neil Wilson, John Heckman, and electronics group*** remove EP install slow raster install calorimeter remove dual quads & install corrector remove girder install FZ magnets target / septa prep work cryo work Detector work remove target 168 This schedule is managed by Ed Folts Ph # 7857 Thu 11/11/10 Mar 20, '11 Apr 17, '11 May 15, '11 Jun 12, '11 Jul 10, '11 Aug 7, '11 Sep 4, '11 Oct 2, '11 Oct 30, '11 No T M F T S W S T M F T S W S T M F T S W S T M RadCon Hold post beam checklist Page 1 RADCON Hall A Techs 5/16 5/16 5/16 5/16

13 ID Task Name 169 remove Big Bite install septum and target Moeller end stuff stuff to do Mar 20, '11 Apr 17, '11 May 15, '11 Jun 12, '11 Jul 10, '11 Aug 7, '11 Sep 4, '11 Oct 2, '11 Oct 30, '11 No T M F T S W S T M F T S W S T M F T S W S T M This schedule is managed by Ed Folts Ph # 7857 Thu 11/11/10 Page 2