CREX Magnet Considerations

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1 CREX Magnet Considerations Seamus Riordan University of Massachusetts, Amherst April 12, 2014 Seamus Riordan CREX Magnet 1/12

2 Optimize Kinematics Compete against falling rates with higher asymmetry as Q 2 grows Need to optimize to sensitivity of A to marginal changes in radius C-REX: Sensitivity to 1% change in Neutron Radius 9 da/a for a 1% change in Rn 8 da/a (%) C-REX: Absolute Error in Neutron Radius dr (fm) θ (scattering angle) For 2.2 GeV standard-energy beam, θ θ (scattering angle) δr n 0.02 fm with 35 days beamtime and anticipated systematics Seamus Riordan CREX Magnet 2/12

Septum Magnet Septum Magnet Requirements HRS only go to 12.5, require septum to reach 4 4.

3 Septum Magnet Septum Magnet Requirements HRS only go to 12.5, require septum to reach Sufficient hardware resolution must be maintained, need pure dipole Need to reach 1350 A/cm 2 with 2-coil configuration (factor 2.2 Bdl from PREX) Require new power supply, LCW pumps Target must be moved back 30 cm for 4 acceptance Seamus Riordan CREX Magnet 3/12

4 Septum Magnet - g p 2 Seamus Riordan CREX Magnet 4/12

5 HRS and Quartz Detectors HRS has hardware resolution 10 3, use to separate inelastic states 0.2 Y (m) X-Y of Tracks in HRS Focal Plane Cut defining "in the detector" First excited state 3.84 MeV Elastic events X (m) dispersive direction Place quartz Cerenkov detectors to minimize inelastics Several states, but kept to < 0.5%. Asymmetries calculable to some level and are expected to be benign Seamus Riordan CREX Magnet 5/12

6 CREX Configuration Need 30 cm back for 4.3 (45 cm for 4 ) Scattering chamber radius is 50 cm Rolling pin target 90 cm Seamus Riordan CREX Magnet 6/12

7 HRSMC HRSMC developed by Jixie for g p 2, G p E Has LeRose transport functions built in as well as support for septum See earlier talk by Jixie Seamus Riordan CREX Magnet 7/12

8 HRSMC - Optics Magnetic transport through the septum can be used to Look at entrance/exit window event energy degredation Determine quality of optics transport Seamus Riordan CREX Magnet 8/12

9 HRSMC - Assuming LeRose transport Using only standard LeRose transport, background constributions look good Seamus Riordan CREX Magnet 9/12

10 HRSMC - Using Geant4+LeRose From Bob and Jixie: Final optics in HRSMC don t seem to show dispersion we would expect Need to look very closely at transport through septum Seamus Riordan CREX Magnet 10/12

11 APEX Magnet From Bogdan: APEX magnet could provide alternative option to PREX magnet They need 2.2 GeV at 5 Already funded by APEX collaboration/hall A? Need to weigh experimental advantages against practical Seamus Riordan CREX Magnet 11/12

12 Work To Do Projects: Settle on simulation framework to evaluate optics - HRSMC is likely choice If we need a new tune, we should add collaborators who are experts or grow in-house Finalize expectations for acceptance and resolution at ideal (maybe not optmized ) kinematics Look at field maps for both existing magnet and APEX option - needs to be higher priority as this determines scheduling Seamus Riordan CREX Magnet 12/12

13 BACKUP Seamus Riordan CREX Magnet 12/12

14 Beam Request and Proposed Data Energy 2.2 GeV Current 150 µa Polarization Full, 85% Production Commissioning Pol, calib., A T 150 µa available with 50 µa for remaining halls 35 days 5 days 5 days Require full longitudinal and (vertically) transverse beam Measured Asymmetry (p e A) 2 ppm Scattering Angle 4 Detected Rate (each HRS) 140 MHz Statistical Uncertainty of A PV 2.1% Systematic Uncertainty of A PV 1.2% Statistical Uncertainty of A T 0.4 ppm Seamus Riordan CREX Magnet 12/12

15 Systematic Uncertainties Charge Normalization 0.1% Beam Asymmetries 0.3% Detector Non-linearity 0.3% Transverse 0.1% Polarization 0.8% Inelastic Contribution 0.2% Effective Q 2 0.8% Total 1.2% Statistics dominate total uncertainty CREX more sensitive to Q 2 uncertainty than PREX, angular resolution demonstrated using elastic ep Seamus Riordan CREX Magnet 12/12

Thin Quartz Detector R&D and PMT Linearity Studies

Thin Quartz Detector R&D and PMT Linearity Studies Dustin McNulty Idaho State University mcnulty@jlab.org Thanks to: Carlos Bula, Brady Lowe, Will Gorman April 11, 2014 Still working on Integrating DAQ