1. Green Compton Polarimeter Upgrade For Hall A Collaboration Meeting December 16 th 2004 Deepa Graduate Student @ Old Dominion University Graduate Student Research Associate Thomas Jefferson National Accelerator Facility 12000 Jefferson Ave, Newport News, Virginia 25606 deepa@jlab.org

2. Preview of presentation Compton Upgrade –Review –Status –Future plan Present Compton –Review –Status Electron Beam D1D4 D3D2 Cavity γ Photon Detector Electron Detector Optical Table Pneumatic Isolators 15.35m Electron Beam To Target Review of Compton

3. FP Cavity 1064nm 1200Watts D3 D4 Photon Calorimeter PbWO4 5x5 array of 20x20x230mm Electron Beam Electron Detector 4 Planes 48 micro strips/plane 5mm To Target

4. Status of present Compton Cavity locking problems during HAPPEX - Problem Fixed EPICS transferred to Accelerator Division Minor software related problems else smooth operation Laser standard operating procedure (LSOP) updated Operations Manual updated Compton Operators trained Liquid Crystal Variable Retarder (LCVR) under Evaluation – Credit to Lingyan Zhu

5. Green Compton Upgrade PresentUpgrade Wavelength (nm)1064532 Intra-cavity power (W)15003000 Cavity Q1.0x10 11 1.8x10 11 Luminosity @50μA(μ b.s) -1 0.26 FOM (σ.A 2 ) @0.85GeV0.572.2 Energy Range (GeV)2- 60.8 – 6 δP e /p e @0.85GeV-1% Doubling Frequency Four-fold enhancement of F.O.M Improvements to Electron Detector, Photon Calorimeter, Photon Integrating method 1% absolute accuracy of beam polarization measurements at 0.85GeV Comparison of Compton Parameters

6. Optical Layout

7. Cavity Specifications Specifications Prometheus Green Laser Output beam Wavelength532 nm~ CW power100 mW~ Spatial modeTEM 00 (M 2 < 1,1)~ Amplitude noise (10hz to 10Mhz) < 0.1% rms~ Warm-up time<1 min Linewidth, over 1 msc.1 kHz(/ms)~ Coherence length, calculated > 1 km~ Frequency drift, at constant temperature2 Mhz/min~ Thermal tuning range, continuous Thermal Response Bandwidth Thermal tuning coefficient 10 GHz 1Hz -6 GHz Thermal tuning range, total60 GHz~ Thermal tuning rate10 GHz/sec Piezzo tuning range + 15 V (PZT tuning coefficient (MHz/V)) (PZT tuning Range(MHz)) 30 MHz (>2)~ +200~ Piezzo response bandwidth, small signal100 kHz~ polarization, linear > 300 : 1, vertical Waist diameter, 1/e 2, vertical0.35 mm Waist diameter, 1/e 2, horizontal0.46 mm Beam divergence, full angle, vertical3.9 mRad Beam divergence, full angle, horizontal3.0 mRad Input and ambient requirements DC voltage/Current max load+5 V/6 A, - 5 V/4 A Operating ambient temperature10 to 45 C° Relative humidity, non-condensing10 to 90 % Size and weight Laser head, w, h, d14.9,11.1,32.0 cm~ Mass 3.5 kg~ Standard electronics size, w, h, d35, 14, 34 cm~ Standard electronics weight10 kg~ Power supply Voltage AC 85 V to 265 V, 50 Hz to 400 Hz Electrical power consumption 20 W typical, 50 W maximum ParametersValuesSymbol Finesse49000F Power Gain14990G Q-Factor1.8x10 11 Q Length0.98mL Free Spectral Range 153MHz Δυ FSR Cavity Bandwidth 3.12kHzδυ Cav Beam Waist Size60μmσ

8. Laser Specifications ParametersValuesUnits Wavelength532nm Output power200mW ModeTEM00 Beam roundness<1.1 Beam Diameter0.38mm Beam Divergence2.8mrad Polarization> 100:1 Thermal Tuning Coefficient-6GHz/K Thermal tuning range60GHz Thermal response bandwidth1Hz PZT tuning coefficient2MHz/V PZT tuning range+200MHz PZT response bandwidth100kHz Spectral line width1kHz/100ms Coherence length>1km Frequency drift2MHz/min Relative Intensity Noise (RIN)>-90dB/Hz Noise eater option RIN>-140db/Hz

9. Mirror Specifications Specifications Prometheus Green Laser Output beam Wavelength532 nm~ CW power100 mW~ Spatial modeTEM 00 (M 2 < 1,1)~ Amplitude noise (10hz to 10Mhz) < 0.1% rms~ Warm-up time<1 min Linewidth, over 1 msc.1 kHz(/ms)~ Coherence length, calculated > 1 km~ Frequency drift, at constant temperature2 Mhz/min~ Thermal tuning range, continuous Thermal Response Bandwidth Thermal tuning coefficient 10 GHz 1Hz -6 GHz Thermal tuning range, total60 GHz~ Thermal tuning rate10 GHz/sec Piezzo tuning range + 15 V (PZT tuning coefficient (MHz/V)) (PZT tuning Range(MHz)) 30 MHz (>2)~ +200~ Piezzo response bandwidth, small signal100 kHz~ polarization, linear > 300 : 1, vertical Waist diameter, 1/e 2, vertical0.35 mm Waist diameter, 1/e 2, horizontal0.46 mm Beam divergence, full angle, vertical3.9 mRad Beam divergence, full angle, horizontal3.0 mRad Input and ambient requirements DC voltage/Current max load+5 V/6 A, - 5 V/4 A Operating ambient temperature10 to 45 C° Relative humidity, non-condensing10 to 90 % Size and weight Laser head, w, h, d14.9,11.1,32.0 cm~ Mass 3.5 kg~ Standard electronics size, w, h, d35, 14, 34 cm~ Standard electronics weight10 kg~ Power supply Voltage AC 85 V to 265 V, 50 Hz to 400 Hz Electrical power consumption 20 W typical, 50 W maximum ParametersValuesSymbol TypePlano-concave SubstrateBK7 Radius of curvature0.5mρ Diameter7.75mmd Thickness4mmt CoatingHR @ 532nm, 0° concave face AR for planar face Reflectivity99.9936%R Loss<5ppmA Damage Threshold10kW/mm ², CW Axis edging<0.015o

10. Status of Upgrade 1.Laser Delivered LSOP under development Test area in He3 target lab (scheduled from January 2005) 2. Mirrors Ordered - Research Electro Optics (REO) Status – in Fabrication Confirmed delivery date – two weeks from now 3. Cavity Adapt basic design from SACLAY Study improvements to mirror mounts -FEM analysis with IDEAS 4. Servo electronics Adaptation of the PVLAS design Built by SACLAY New set of locking electronics shipped from SACLAY 5. Transport optics Standard elements Being ordered Estimated delivery date end of January

11. Optical Studies Specifications Prometheus Green Laser Output beam Wavelength532 nm~ CW power100 mW~ Spatial modeTEM 00 (M 2 < 1,1)~ Amplitude noise (10hz to 10Mhz) < 0.1% rms~ Warm-up time<1 min Linewidth, over 1 msc.1 kHz(/ms)~ Coherence length, calculated > 1 km~ Frequency drift, at constant temperature2 Mhz/min~ Thermal tuning range, continuous Thermal Response Bandwidth Thermal tuning coefficient 10 GHz 1Hz -6 GHz Thermal tuning range, total60 GHz~ Thermal tuning rate10 GHz/sec Piezzo tuning range + 15 V (PZT tuning coefficient (MHz/V)) (PZT tuning Range(MHz)) 30 MHz (>2)~ +200~ Piezzo response bandwidth, small signal100 kHz~ polarization, linear > 300 : 1, vertical Waist diameter, 1/e 2, vertical0.35 mm Waist diameter, 1/e 2, horizontal0.46 mm Beam divergence, full angle, vertical3.9 mRad Beam divergence, full angle, horizontal3.0 mRad Input and ambient requirements DC voltage/Current max load+5 V/6 A, - 5 V/4 A Operating ambient temperature10 to 45 C° Relative humidity, non-condensing10 to 90 % Size and weight Laser head, w, h, d14.9,11.1,32.0 cm~ Mass 3.5 kg~ Standard electronics size, w, h, d35, 14, 34 cm~ Standard electronics weight10 kg~ Power supply Voltage AC 85 V to 265 V, 50 Hz to 400 Hz Electrical power consumption 20 W typical, 50 W maximum Integrating Sphere Green Laser Head Diaphragm Faraday Isolator Half-wave plate Liquid crystal Variable Retarder Mirror Quarter-wave Plate Wollaston Prism Integrating Sphere Phase 1 – Laser Characterization Phase 2 – Cavity Characterization Integrating Sphere Green Laser Head Diaphragm Faraday Isolator Half-wave plate Liquid crystal Variable Retarder Mirror Quarter-wave Plate Wollaston Prism Integrating Sphere Mirror Fabry- Perot Cavity Phase 3 – PDH Characterization

12. Future Plans Laser Studies Cavity Prototype Mirror Finesse Measurement Cavity locking - PDH Polarization Studies Installation in Hall A Q1 - 2005 Q2 - 2005 Q3 - 2005 Q4 - 2005 – Q2 2006 Q3 - 2006 Q4 – 2006 Green Compton growth 2005 - 2006 Polarization of present cavity

13. End of Presentation Thank you