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Hall A Compton Polarimeter For Hall A Collaboration Meeting June 23 rd 2005

Hall A Compton Polarimeter For Hall A Collaboration Meeting June 23 rd 2005. Sirish Nanda Thomas Jefferson National Accelerator Facility 12000 Jefferson Ave, Newport News, Virginia 23606. Electron detector. Photon detector. Optical cavity. Dipoles. Hall A Compton Polarimeter.

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Hall A Compton Polarimeter For Hall A Collaboration Meeting June 23 rd 2005

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  1. Hall A Compton Polarimeter For Hall A Collaboration MeetingJune 23rd 2005 Sirish Nanda Thomas Jefferson National Accelerator Facility 12000 Jefferson Ave, Newport News, Virginia 23606

  2. Electron detector Photon detector Optical cavity Dipoles Hall A Compton Polarimeter Non-intrusive measurement High current capability - 30 cm deflection chicane - Detection of backscattered photons and recoil electrons 15 m

  3. Operational Status • SRC Experiment: • High current operation • Beam quality monitoring • Development tests of integrating DAQ. • Trouble begins… • Laser Power supply/controller failed. • Backup power supply incompatible • Unable to contact manufacturer=> PANIC! • Solution • Manual calibration of new controller. • Rework EPICS control algorithm => Problem Solved. We no longer have a spare.

  4. SRC Expt

  5. Counting vs. Integrating

  6. Lightwave 1064nm Laser Controller/PS (in intensive care!) Laser Head

  7. Cavity Lock @half power 

  8. Compton Upgrade: Scope (Cost 250k$) • Green Laser and Cavity (30% completed) • Four-fold increase in figure-of-merit • Larger scattering angles => possible to detect electrons at lower energies • New Electron detector (5% completed) • Finer pitch improves energy resolution • Adjustable distance from beam to improve dynamic range • Integrating Photon DAQ (70% completed) • Provides redundancy to photon counting • Improved systematics

  9. Green Optics Test Setup

  10. Laser Safety Issues • Jab Safety Standards require a dedicated Green laser room • Lab management is in the process of get us dedicated lab space in the ARC building • Until then… • We have set up a low power (class II, “e.g laser pointer”) setup in the EEL Lab • We can study most things at low power • Get to know the green Laser and cavity • Test setup is now operational in EEL

  11. EEL Green Optics lab (Temporary)

  12. Laser: Power Response

  13. Laser: SHG Temp Response

  14. Green: Near field Beam spot

  15. Green Laser: beam profiling

  16. Green Laser Beam focus

  17. Turnkey Polarimeter (Thorlabs)

  18. Prometheus laser’s beam pol

  19. Polarization after FOI/45

  20. …After QWP

  21. Circular Polarization for cavity injection

  22. Deepa’s Prototype cavity

  23. Cavity Mirror Mount

  24. Beam Injection to Cavity

  25. Green beam!

  26. Conclusion • The present IR Compton laser/cavity is operating ok. But needs a functional backup laser, just in case… • The integrating Compton DAQ has made great progress. Needs better understanding of systematic errors • The Green Compton project is moving well. But needs help. • It desperately needs a dedicated Green Laser lab. I hope to complete the Green Compton Project by 2007.

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