Fermilab T-1007:Optical Cavity Test Bench in the MP8 beamline

Aaron S. Chou

Wilson Fellow, FNAL

All Experimenters Meeting

January 10, 2011

Enables tests of long-baseline optical beams

Axions HolographicInformation bound

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• asdf

10-3 eV: Neutrino oscillations.dark energy via SDSS, DES, laser search, etc

103 GeV: Tevatron, LHC,dark matter direct detection

105 GeV: cosmic ray showers

1011 GeV:axion-photon oscillations

1019 GeV: holographic noise

Laser experiments to probe the highest energy scales

1 eV-1 GeV: Chemistry, nuclear physics, strong interactions

10-33 eV: Hubble scale

Every photon in a laser beam is in the same state, so coherence effects can amplify ultraweak phenomena

The new MP8 laser lab is now the largest laser lab on-site.(~50m long x 7.5’ wide)

Currently installing a vacuum-enclosed 40m optical beamline.

Thanks to AD Tevatron vacuum group! (McCormick, Dymond, Lambert, Williams, et.al.)

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Laser shutter interlock system + kill switch for safe operation of class 4 lasers.(Thanks AD interlock group, ES&H laser safety group)

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End station vacuum vessels hold custom optical cavity mirrors and eventually beamsplitters

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Portable clean rooms (class <100?) mounted on ceiling rails

Allows dust-free access to vacuum enclosed optics.

Requirements on optics cleanliness:

Axions: <5 ppm scattering lossHolometer: <50 ppm scattering loss

Thanks to PPD mechanical group:Korienek, Lindenmeyer, Nebel, Taccki

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Current optical device R&D in Linac Laser Lab. The MP8 lab will relieve some of this congestion!Tests of full-scale 40m optical cavities planned for early 2011.

Frequency reference cavity

Mode-cleaning cavity

2 kHz PZT-actuated 2” mirror mount

Laser auto-correlation test

25 MHz RF control system

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Application 1: Search for couplings to photons of new axion-like particles by photon-photon scattering

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Tevatron

Use optical cavities to improve world-leading GammeV coupling sensitivity by 4 orders of magnitude. (Increase event rate by 1010.)

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Application 2: The Fermilab Holometer:Interferometer probe of the quantum structure of space-time at the Planck scale 1019 GeV

• Fermilab: A. S. Chou (co-PI, acting project manager), H. Glass, C. Hogan, E.

Ramberg, J. Steffen, C. Stoughton, R. Tomlin, J. Volk, W. Wester. • MIT LIGO:

S. Waldman, R. Weiss • U.Chicago

S. Meyer (co-PI)• U. Michigan LIGO

D. Gustafson • Caltech LIGO

S.Whitcomb

Large overlap in both scientific staff and R&D topics with the FNAL axion group.

The large cavity-recycled photon flux (up to 1024 photons/s) can be used either for searches for rare events or to make precise position measurements.

Tentative Schedule:2011-2013(?): Holometer2013-? : Axions

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The Holographic Principle implies a maximum information density in the universe

R. Bousso

Black hole entropy S = Mpl2 Area / 4

Our apparently 3D world is actually 2D and has a bandwidth limit ?!?!

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How can we tell if we are living in the

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Look closely at beamsplitter position to detect the fuzziness of space-time.

Detect via the resulting phase noise in the interference fringe.

(Hogan)

The proposed 40m Fermilab Holometer will search for correlations in the noise between 2 neighboring interferometers

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Cross-correlate the photocurrents from the two devices.

Need only a few hours integration time for correlated noise to beat random uncorrelated noise.

Diagnostic knob:The holographic correlation signal can be turned off by spatially separating the two devices so the beamsplitters cannot be causally connected.

Concrete vacuum pipe support bases installed outside MP8 in preparation for a 40m interferometer test in Summer, 2011.

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100 MHz data acquisition and RF cavity/interferometer control electronics

Funded by U.Chicago SCI grant (Meyer, Chou, Stoughton) Digital feedback control to piezo actuators on the laser and mirror mounts Currently being tested at FNAL MP8 laser lab

Expected holographic cross-correlation signal between two photodiodes plotted vs delay time between the two data streams.

Actual cross-correlation data taken with the digital DAQ.

Delay time (us)

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