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Focal Plane Scanner

Focal Plane Scanner. Jeff Martin University of Winnipeg with: Jie Pan, Peiqing Wang, David Harrison. Motivation. Q 2 determination, background studies, all done at 10 nA using tracking system. Region III operable up to 100 nA. Qweak production running 180 A.

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Focal Plane Scanner

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  1. Focal Plane Scanner Jeff Martin University of Winnipeg with: Jie Pan, Peiqing Wang, David Harrison

  2. Motivation • Q2 determination, background studies, all done at 10 nA using tracking system. • Region III operable up to 100 nA. • Qweak production running 180 A. • Need a way to extrapolate over 3 orders of magnitude.

  3. Qweak Focal Plane Scanner • A scanning detector with small active area to sense high-energy electrons, operable at any beam current. • Similar technique used in E158 and HAPPEx. • For E158, it was used to determine optics parameters, confirm Monte Carlo predictions of rates.

  4. Scanner Principle pre-rad quartz radiator Design criteria: • 1 cm2 active area. • 1 MHz max rate allows operation in counting mode with two PMT’s. • operable at both high and low current. Č scattered electrons air-core light pipe PMT

  5. Scanner Concept scattered electrons beam view side view

  6. Implementation in Qweak Č-bar y-axis motion x-axis motion • 2D motion assy scans behind Č-bar • Mount in any one octant at a time • Attach to fixed support structure • Motion assy mounted “inside” Č-bars

  7. Recent Progress on Scanner • 3/06 – Approval from CFI received (detector lab) • 4/06 – Funding from NSERC received (scanner) • Report for today: • Start of prototyping tests related to detector performance. • Simulation of detector performance. • Mechanical design • Mounting and 2D motion assy. • Detector assy.

  8. Prototyping Tests (Pan, Wang, Harrison) • 2” tube lined with “Alzak” sheet (aluminum sheet with PVD aluminum on top, and clear anodized) “Anomet” “MIRO 2”

  9. Prototyping Tests – Cosmics Testing upper trigger test detector lower trigger inside Alzak tube is a small test scint mounted on a plunger

  10. Prototyping Tests • MCA reads out shaped pulse height. • Begun work with small scintillator samples. (Plan to transition to quartz) • Begun work with high reflectivity light pipes. • Electronics to be replaced with CFI funded detector lab.

  11. Simulation • Builds on QweakSim (K. Grimm, M. Gericke) • Currently at stage of benchmarking vs. E158 NIM article.

  12. Simulation – comparisons to E158 NIM Jie Pan E158 • work in progress • q.e. model not right, etc. different prerad

  13. Mechanics • support structure (P. Medeiros, G. Smith) • 2D motion assy. • detector assy. (P. Wang and G. Mollard @ UM)

  14. Mechanics • support structure • early 2006, decision to not use R3 rotator • plan now is to mount to fixed Cherenkov-bar support structure, most of device in towards beamline. • motion octant-to-octant possible by bolting device in place • need drawings! • 2D motion assy. • budgetary quote from Bosch-Rexroth. • no progress other than some discussions with P. Decowski (E158 scanner) on rad hardness.

  15. Mechanics • detector assy. • initial 2D CAD drawings • begun 3D SolidWorks model (P. Wang) • eventually, support from UM shop (G. Mollard) starting on SolidWorks design

  16. Summary and to-do list • Answer prototyping/simulation questions: • radiator design (quartz? scint? size? tilt angle? prerad?) • tube diameter (backgrounds) • two-tube layout (backgrounds and fiducial area) • establish viability of coincidence technique (rates) • Mechanics • support structure – need P. Medeiros’ time. • purchase 2D motion assy. and program it. • design and build a mechanical mock-up of detector assy and then a realistic detector

  17. Additional Usesof a Scanner Detector • Scan over large fiducial region, into inelastic region, over Cherenkov bar light guides, to get additional confidence in backgrounds. • “Light map” can be compared to simulation. • Q2 extrapolation/determination • mini-torus setting during production running? • gas vs. liquid target extrapolation? • at least, complementary to region III.

  18. Implementation in Qweak Č-bar y-axis motion x-axis motion • 2D motion assy scans behind the Č-bar • Mount in one octant, attach to fixed support structure

  19. Implementation in Qweak

  20. Implementation in Qweak

  21. Implementation in Qweak

  22. Implementation in Qweak

  23. Expected rates at 180 A courtesy J. Mammei • Max rate = 1 MHz

  24. Procedure • Measure light distribution with scanner at low beam current acceptable to region III and Cherenkov bar coincidence. • Measure light distribution with scanner at 180 uA. • If they are the same, region III/Cherenkov light distribution believable at 180 uA to high confidence. • Note: scanner light map will not be the same as the region III/Cherenkov bar coincidence map.

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