Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Hall A Compton Polarimeter For Hall A Collaboration Meeting

June 23rd 2005

Hall A Compton Polarimeter For Hall A Collaboration Meeting

June 23rd 2005

Sirish NandaThomas Jefferson National Accelerator Facility

12000 Jefferson Ave,Newport News, Virginia 23606

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Optical cavity

Photon detectorElectron detector

Dipoles

Hall A Compton Polarimeter

15 m

Non-intrusive measurementHigh current capability

- 30 cm deflection chicane- Detection of backscattered photons and recoil electrons

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. 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.

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

SRC Expt

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Counting vs. Integrating

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Lightwave 1064nm Laser

Laser Head

Controller/PS (in intensive care!)

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Cavity Lock @half power

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. 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$)

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Green Optics Test Setup

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. 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

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

EEL Green Optics lab (Temporary)

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Laser: Power Response

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Laser: SHG Temp Response

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Green: Near field Beam spot

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Green Laser: beam profiling

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Green Laser Beam focus

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Turnkey Polarimeter (Thorlabs)

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Prometheus laser’s beam pol

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Polarization after FOI/45

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

…After QWP

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Circular Polarization for cavity injection

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Deepa’s Prototype cavity

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Cavity Mirror Mount

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Beam Injection to Cavity

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. Nanda, June 23, 2005

Green beam!

Thomas Jefferson National Accelerator Facility

Hall A Collaboration MeetingS. 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.