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First Light in the T-1007 Prototype 40m Optical Cavity for Holometer/Axions

Holographic information bound. Axions. First Light in the T-1007 Prototype 40m Optical Cavity for Holometer/Axions. Aaron S. Chou Wilson Fellow, FNAL All Experimenters Meeting May 2, 2011. The Actors. Fermilab :

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First Light in the T-1007 Prototype 40m Optical Cavity for Holometer/Axions

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  1. Holographic information bound Axions First Light in the T-1007 Prototype 40m Optical Cavity for Holometer/Axions Aaron S. Chou Wilson Fellow, FNAL All Experimenters Meeting May 2, 2011

  2. The Actors A.S. Chou, All Experimenters Meeting, 5/2/11 Fermilab: • Aaron S. Chou, Hank Glass, Gaston Guitierrez, Craig Hogan, Jason Steffen, Chris Stoughton, Ray Tomlin, Jim Volk, William Wester. MIT LIGO: • Sam Waldman, Rai Weiss U.Chicago • Steve Meyer, Bobby Lanza, Lee McCuller U. Michigan LIGO • Dick Gustafson

  3. Application 1: Use lots of photons to search for rare photon-photon scattering processes mediated by axion-like or Higgs-like particles Tevatron Increase photon flux to 1024γ/s, improve axion sensitivity by 4 orders of magnitude. A.S. Chou, All Experimenters Meeting, 5/2/11

  4. Application 2: Use lots of photons to search for holographic noise Each Nd:YAG photon has position resolution 1064 nm. Measuring with N photons gives resolution: Measure intrinsic blurriness of beamsplitter position due to Planck-scale quantization of space-time Use cross-correlation technique and extended integration time to reach the predicted signal at a tiny distance scale 10-20 m/rtHz

  5. 4/18/11: Completed installation of 40m long vacuum system at MP8. Thanks to AD Tevatron vacuum group! (Scott McCormick, Bill Dymond, Dan Lambert, Bob Steinberg, James Williams) North end, looking south South end, looking north

  6. End station vacuum vessels hold custom optical cavity mirrors and eventually beamsplitters A.S. Chou, All Experimenters Meeting, 5/2/11

  7. UHV levels of cleanliness are required to avoid power absorption losses due to accumulation of monolayers of hydrocarbons on mirrors RGA scan after mirror installation A.S. Chou, All Experimenters Meeting, 5/2/11

  8. Beamspot on injection mirror. Due to seismic motion of cavity and laser frequency noise, different modes (with different transverse momentum) drift in and out of resonance. A.S. Chou, All Experimenters Meeting, 5/2/11

  9. Pound Drever Hall Locking Laser beam Measure the length of the cavity by looking at the coherent interference between: A) Light that reflects directly from the (partially transmissive) injection mirror and B) Light that makes a roundtrip in the cavity and leaks back out Lock condition: Zero phase difference when cavity length = integer number of ½ wavelengths. A.S. Chou, All Experimenters Meeting, 5/2/11

  10. Sinusoidal sweep of laser frequency by piezo-electric pressure on laser crystal. Separation of cavity harmonics indicates the laser PZT frequency response is 1.5 MHz/Volt. 3.75 MHz A.S. Chou, All Experimenters Meeting, 5/2/11

  11. Pound-Drever-Hall technique gives a signed error signal for detecting instantaneous mismatches between the laser frequency and the cavity resonance. Width of resonance indicates a power-recycling factor of around 20. (1W builds up to 20 W). Just for fun: Q=280 THz/150 kHz = 2×109 A.S. Chou, All Experimenters Meeting, 5/2/11

  12. Cavity lock achieved in 3 ways Analog loop using benchtop amplifiers, filters Analog loop using custom servo box. Feed back to the laser PZT to force the laser frequency to follow the instantaneous resonant frequency of the cavity. Digital loop using Labview, digital data acquisition, FPGAs A.S. Chou, All Experimenters Meeting, 5/2/11

  13. Cavity locked on Gaussian fundamental mode. A.S. Chou, All Experimenters Meeting, 5/2/11

  14. Working on stability of lock, via negative feedback loop. Feedback signal adjusts the laser wavelength to match small changes in the instantaneous length of the cavity. A.S. Chou, All Experimenters Meeting, 5/2/11

  15. Next steps Refine cavity lock stability Measure seismic noise spectrum using error signals in feedback loop • Compare quantitatively with AD seismometers. Develop digital control system and digital DAQ. Upgrade with higher reflectivity optics to achieve higher power build-up. (1 kW for holometer) Build 40m interferometer A.S. Chou, All Experimenters Meeting, 5/2/11

  16. Credits AD • Alex Chen, Bill Dymond, Dan Lambert, Scott McCormick, Bob Steinberg, James Williams PPD • John Korienek, Carl Lindenmeyer, Todd Nebel, Jerry Taccki • Herman Cease ES&H • John Anderson, Raymond Lewis, Gary Ross, Rich White, Bill Wickenberg, Randy Zifko • Rob Bushek, Eric McHugh, Tim Miller, Angela Sands FESS • Steve Dixon, Carl Holmgren … A.S. Chou, All Experimenters Meeting, 5/2/11

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