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Hall A Collaboration Meeting S. Nanda, June 23, 2005 Hall A Compton Polarimeter For Hall A Collaboration Meeting June 23 rd 2005 Sirish Nanda Thomas Jefferson.

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Presentation on theme: "Hall A Collaboration Meeting S. Nanda, June 23, 2005 Hall A Compton Polarimeter For Hall A Collaboration Meeting June 23 rd 2005 Sirish Nanda Thomas Jefferson."— Presentation transcript:

1 Hall A Collaboration Meeting S. Nanda, June 23, 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

2 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Optical cavity Photon detector Electron detector Dipoles Hall A Compton Polarimeter 15 m Non-intrusive measurement High current capability - 30 cm deflection chicane - Detection of backscattered photons and recoil electrons

3 Hall A Collaboration Meeting S. Nanda, June 23, 2005 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 Hall A Collaboration Meeting S. Nanda, June 23, 2005 SRC Expt

5 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Counting vs. Integrating

6 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Lightwave 1064nm Laser Laser Head Controller/PS (in intensive care!)

7 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Cavity Lock @half power

8 Hall A Collaboration Meeting S. Nanda, June 23, 2005

9 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Compton Upgrade: Scope 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 (Cost 250k$)

10 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Green Optics Test Setup

11 Hall A Collaboration Meeting S. Nanda, June 23, 2005 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

12 Hall A Collaboration Meeting S. Nanda, June 23, 2005

13 Hall A Collaboration Meeting S. Nanda, June 23, 2005 EEL Green Optics lab (Temporary)

14 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Laser: Power Response

15 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Laser: SHG Temp Response

16 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Green: Near field Beam spot

17 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Green Laser: beam profiling

18 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Green Laser Beam focus

19 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Turnkey Polarimeter (Thorlabs)

20 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Prometheus lasers beam pol

21 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Polarization after FOI/45

22 Hall A Collaboration Meeting S. Nanda, June 23, 2005 …After QWP

23 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Circular Polarization for cavity injection

24 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Deepas Prototype cavity

25 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Cavity Mirror Mount

26 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Beam Injection to Cavity

27 Hall A Collaboration Meeting S. Nanda, June 23, 2005 Green beam!

28 Hall A Collaboration Meeting S. Nanda, June 23, 2005 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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