Hall A Compton Polarimeter For Hall A Collaboration
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 Hall A Collaboration Meeting S. Nanda, June 23, 2005
Hall A Compton Polarimeter ector t e d n Non-intrusive measurement High current capability al Optic Photo cavity or tect e d n tro Elec es Dipol 15 m - 30 cm deflection chicane - Detection of backscattered photons and recoil electrons 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. Hall A Collaboration Meeting S. Nanda, June 23, 2005
SRC Expt Hall A Collaboration Meeting S. Nanda, June 23, 2005
Counting vs. Integrating Hall A Collaboration Meeting S. Nanda, June 23, 2005
Lightwave 1064 nm Laser Controller/PS (in intensive care!) Laser Head Hall A Collaboration Meeting S. Nanda, June 23, 2005
Cavity Lock @half power Hall A Collaboration Meeting S. Nanda, June 23, 2005
Hall A Collaboration Meeting S. Nanda, June 23, 2005
Compton Upgrade: Scope (Cost 250 k$) • 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 Hall A Collaboration Meeting S. Nanda, June 23, 2005
Green Optics Test Setup 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 Hall A Collaboration Meeting S. Nanda, June 23, 2005
Hall A Collaboration Meeting S. Nanda, June 23, 2005
EEL Green Optics lab (Temporary) Hall A Collaboration Meeting S. Nanda, June 23, 2005
Laser: Power Response Hall A Collaboration Meeting S. Nanda, June 23, 2005
Laser: SHG Temp Response Hall A Collaboration Meeting S. Nanda, June 23, 2005
Green: Near field Beam spot Hall A Collaboration Meeting S. Nanda, June 23, 2005
Green Laser: beam profiling Hall A Collaboration Meeting S. Nanda, June 23, 2005
Green Laser Beam focus Hall A Collaboration Meeting S. Nanda, June 23, 2005
Turnkey Polarimeter (Thorlabs) Hall A Collaboration Meeting S. Nanda, June 23, 2005
Prometheus laser’s beam pol Hall A Collaboration Meeting S. Nanda, June 23, 2005
Polarization after FOI/45 Hall A Collaboration Meeting S. Nanda, June 23, 2005
…After QWP Hall A Collaboration Meeting S. Nanda, June 23, 2005
Circular Polarization for cavity injection Hall A Collaboration Meeting S. Nanda, June 23, 2005
Deepa’s Prototype cavity Hall A Collaboration Meeting S. Nanda, June 23, 2005
Cavity Mirror Mount Hall A Collaboration Meeting S. Nanda, June 23, 2005
Beam Injection to Cavity Hall A Collaboration Meeting S. Nanda, June 23, 2005
Green beam! 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. Hall A Collaboration Meeting S. Nanda, June 23, 2005
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