K. Slifer, UNH

1. E08-027 g2p & the LT Spin Polarizability K. Slifer, UNH for the E08-027 Collaboration June 9, 2011

2. Inclusive Scattering When we add spin degrees of freedom to the target and beam, 2 Additonal SF needed. ° * Inclusive Polarized Cross Section SFs parameterize everything we don’t know about proton structure

3. Unpolarized SF are very well known Proton g1 also well known

4. Proton World Data g2 g1 not quite as good... really well determined 0.015 < Q2 < 30 Q2 = 1.3 and 5

5. Proton World Data g2 g1 not quite as good... really well determined 0.015 < Q2 < 30 Q2 = 1.3 and 5

6. E08-027 : Proton g2 Structure Function Fundamental spin observable has never been measured at low or moderate Q2 Camsonne, Crabb, Chen, Slifer(contact) • BC Sum Rule : violation suggested for proton at large Q2,but found satisfied for the neutron & 3He. • Spin Polarizability: Major failure (>8s) of PT for neutron dLT. Need g2 isospinseparation to solve. • Hydrogen HyperFine Splitting : Lack of knowledge of g2 at low Q2 is one of the leading uncertainties. • Proton Charge Radius : also one of the leading uncertainties in extraction of <Rp> from m-H Lamb shift. g2 data strongly anticipated by theorists BC Sum Rule Spin Polarizability LT

7. Experimental Technique Inclusive Polarized Cross Section differences We Need: Polarized proton target(Principals: C. Keith, D. Crabb) upstream chicane (Project Lead: T. Michalski) downstream local dump (Design: A. Gavalya) Low current polarized beam Upgrades to existing Beam Diagnostics to work at 85 nA (T. Michalski) Lowest possible Q2 in the resonance region Septa Magnets to detect forward scattering (A. Gavalya, E. Folts)

9. Polarized Ammonia Target 5 Tesla Transverse Field Current = 85 nA

10. Moller Polarimeter Third arm luminosity monitor for cross-check(not shown). Compton will not be used.

11. New Beam Diagnostics for low current Slow raster for target

12. Up Stream Chicane 2 Dipoles to compensate for target field Magnets on loan from Hall C

13. Low Power Local Dump Mag field of target -> beam will not make it to hall dump

14. Room Temperature Septum Magnets -Used in Prex, modified with new coils. -bend 5.6o to 12.5o -allow access to lowest possible Q2

15. Systematic Error Budget Statistical error to be equal or better at all kins

16. Experimental Goal/Considerations • Goal is to measure g2p in the low Q2 region with a precision ~ 5-7% • by measuring transversely polarized cross section difference = A x s • Measure both asymmetries and cross sections to 4-5% • In addition to statistics, we need to control total systematics to 3-5%, i. e., each system • to be below that (1-3%). • Main systematics for asymmetries: • Target polarization (3-4%) • Beam polarization (2-3%) • Dilution factor/packing factor (some cancellation) • Main systematics for cross sections • Acceptance/optics (~3%) • Dilution factor/packing factor (some cancellation) • Density (2-3%) • Beam charge (1-2%) • Position and angle determination (0.1-0.2 mm, 0.03-0.05 degree) • Detector efficiencies (~< 1%) • Background (pions, …) (1%) • Radiative corrections (including radiative tails) (1-4%) • … slide courtesy of JP Chen

17. Readiness Review May 6, 2011 Full Report available at: http://hallaweb.jlab.org/experiment/g2p/review/

18. Physics Manpower Faculty and Staff (near fulltime effort) Alexandre Camsonne (JLab): Beam line, DAQ, … Jian-Ping Chen (JLab) : Project manager, overall coordination. Don Crabb (UVA) : Target Expert. Karl Slifer : Contact Person onsite fulltime summer, fall, and ½ of spring. *For these slides, I’m not counting E08-007 manpower Guy Ron, Doug Higinbotham, Ron Gilman, Donal Day, John Arrington, Adam Sarty......

19. E08-027 Grad Students Min Huang Duke Ryan Zielinski UNH Chao Gu UVa Toby Badman UNH Pengjia Zhu USTC Melissa Cummings W & M + Temple student?

20. E08-027 Post-Docs James Maxwell UNH Target, Spin Structure Kalyan Allada JLab Beamline, 3rd Arm Jixie Zhang JLab Geant 4, Optics + Post-Docs (Part-time effort) Hovhannes Baghdasaryan (UVa) Narbe Kalantarians(UVa) Sarah Phillips (UNH) Xiaohui Zhan (Argonne)

21. People Power and Tasks • Overall coordination: • Project manager (Jian-ping Chen, Hall A) • Project coordinator for beamline (Tim Michalski, engineering division) • Collaboration contacts: Karl Slifer (g2p), Guy Ron (GEp) • Beamline • Engineering Division/Accelerator Division (Tim Michalski coordinator) • Engineer/design (Butch Dillon-Townes) • Installation (Neil Wilson) • Instrumentation/magnets/vacuum/alignment/software/radcon groups, • as identified in 6-month-down schedule/planning • Users (Alexandre Camsonne and Pengjia Zhu) on BCM/BPM/Slow raster… • Target • Target Group (Chirs Keith) • UVA(Don Crabb, Donal Day, psotdocs and students) • New Hampshire (Karl Slifer, James Maxwell) • Other postdocs/students • Hall A engineering/design: Septa/LC Dump/Pivot Layout … • Hall A engineering/design team (Robin Wines, Al, Gavalya) • With input from the collaboration • Hall A installation • Hall A installation team (Ed Folts) • Simulation/optics/HRS/detectors/DAQ/3rd Arm • Users(Physicists/postdocs/students) slide courtesy of JP Chen

22. Schedule and Milestones • Main Items, each has it’s schedule and milestones (separate talks) • Beamline • Target • Hall infrastructure, beam dump, septa • Installation • May, 2011, Main design complete. • End of May, 2011 Target magnet cool-down in EEL • July, 2011, Parts manufactured and arrived • Aug 3, 2011, Beamline region 1 installation complete • Aug 16, 2011, Beamline region 2 installation complete • Mid-late Aug, 2011, Target test in EEL • Sept 1, 2011, Septa, LC beam dump, scattering chamber installed. • Sept 1, 2011, Target move to Hall A for installation • Sept 15, 2011, Beamline region 3 installation complete • Oct 1, 2011, Dump/target/magnet/chamber alignment complete • Oct 10, 2011, Beamline alignment complete • Nov 14, 2011, Target cool-down/polarize • Nov 19, 2011, Experiment Commission Starts • Jan 23 – March16, 2012, Remove Septa, Move Target back to Pivot • May 2012, End of experiment data taking slide courtesy of JP Chen

23. Budget and User Contributions • FY11 addition funding from DOE has been confirmed on the way. • User groups contribution to procurement/machining : • UVa (Don/Donal): target magnet repair, material irradiation • Temple (Zein-Eddine): procurement • Rutgers (Ron): machining + procurement • UVa (Nilanga): machining • HUJI (Guy): machining + procurement • UNH (Karl): procurement • Nice to have these contributions slide courtesy of JP Chen

24. slide courtesy of C. Keith

25. Target Status (C. Keith and Target group) 1st test: Mid May Located and repaired leak in the indium seal during initial LN2 cooldown. 2nd test: Late May Performed successful (but limited) cooldown of Magnet May 30 cooled magnet to liquid Helium temperature ramped to full field (5T) and held in persistent mode for 20 mins and ramped down No Quench Next day did not have enough Helium to continue. Loss rate greater than expected. Bottom Line : Magnet seems healthy, some concern over leaks. Target group wants to thoroughly leak-test before next full cooldown. Plan to do another full cooldown when leaks are better understood.

26. Proposal Kinematics EG4: g1p E08-027 : g2p 0.02 < Q2 < 0.5 GeV2 Resonance Region

27. Changes from Proposal Room temp septa magnets instead of cryo septa for co-existence with QWeak. leads to a small gap in coverage at large Q2, but the min Q2 is unchanged. requires transition time to remove the septa.

28. Changes from Proposal Room temp septa magnets instead of cryo septa for co-existence with QWeak. leads to a small gap in coverage at large Q2, but the min Q2 is unchanged. requires transition time to remove the septa. Target field distorts the scattering plane much more than initial estimates. If ignored this would push the Q2 coverage to 0.08 GeV2 instead of 0.02 GeV2

29. Changes from Proposal Room temp septa magnets instead of cryo septa for co-existence with QWeak. leads to a small gap in coverage at large Q2, but the min Q2 is unchanged. requires transition time to remove the septa. Target field distorts the scattering plane much more than initial estimates. If ignored this would push the Q2 coverage to 0.08 GeV2 instead of 0.02 GeV2 We’ve addressed this by: a) Running at 2.5 T for the lowest incident energies. b) Manipulating incident angle of the electron beam.

30. Bottom Line All the physics proposal goals are still attainable. JLab support in dealing with this issue has been phenomenal ! Beamline/Accelerator/Design/Installation/Target

31. Solution run the two lowest energies with only 2.5 T target field & Manipulate the incident beam angle reach Q2 = 0.03 GeV2 but 2.5T => PT = 40%

32. This is the most recent “Least-painful” choice of settings run the two lowest energies with only 2.5 T target field & Manipulate the incident beam angle reach Q2 = 0.03 GeV2 Large W kinematics are typically the most time consuming so they’ve been trimmed. but 2.5T => PT = 40% can regain some stat by changing from 0.5 cm target to 3 cm.

34. Rates / Schedule

35. Runplan SEPTA IN SEPTA OUT

36. Runplan run at ½ field and nonzero incident angle for lowest energies

37. Runplan Beam Allocation is 87 days + 21 commissioning, Increasing DAQ rate from 4-8 kHz can save us about 7 calendar days.

38. Draft Schedule

39. Summary Recently passed JLab Readiness review Some issues to address, but mostly positive evaluation Target Magnet is onsite and appears to be in good shape Another full cooldown will be done prob in next few weeks. RunPlan and kinematic configuration request has been submitted to the scheduling committee 1.1 GeV and 1.7 GeV will have to be negotiated with other halls Installation is under way in the hall Lots of work to finish before the Fall Collaborators welcome!