AN ANOMALOUS CURVATURE EXPERIMENT Carol Y. Scarlett Brookhaven National Laboratory Apr. 27 th, 2006

Collaborators Russ Burns Russ Burns Don Lazarus Don Lazarus Carol Scarlett Carol Scarlett Yannis Semertzidis Yannis Semertzidis Mike Sivertz Mike Sivertz

Experiments Experiments with Polarized Laser Light inside a dipole magnetic field: Experiments with Polarized Laser Light inside a dipole magnetic field: E840 at BNL PVLAS Italy Have seen an effect above the predicted QED background. Have seen an effect above the predicted QED background.

BNL E Search for Axions at BNL E840 saw a rotation of polarized light of order rad 1989 Search for Axions at BNL E840 saw a rotation of polarized light of order rad Experiment used two CBA Dipole magnets with B  5.0 T and an optical cavity giving a length of  10 km… QED predicted rotation: Experiment used two CBA Dipole magnets with B  5.0 T and an optical cavity giving a length of  10 km… QED predicted rotation:   5.8 · rad

PVLAS PVLAS has performed a similar experiment to E840 with: B  5.5 T and an effective length  52 km PVLAS has performed a similar experiment to E840 with: B  5.5 T and an effective length  52 km PVLAS Results (2005): both an observed dichroism and ellipticity ~ rad giving: m a ~ 1meV PVLAS Results (2005): both an observed dichroism and ellipticity ~ rad giving: m a ~ 1meV PVLAS plans for regeneration experiment PVLAS plans for regeneration experiment

Axion Detection Exp. Ellipticity changes: BNL E840 & PVLAS Ellipticity changes: BNL E840 & PVLAS

Optical Effects Ellipticity: Ellipticity:

Optical Effects Dichroism: Dichroism:

Photon-EM Interaction In the presence of an externally applied Magnetic field: In the presence of an externally applied Magnetic field: 1 A 1 A L= —— (E 2 +B 2 ) + —— [(E 2 - B 2 ) ( E · B ) 2 ] L= —— (E 2 +B 2 ) + —— [(E 2 - B 2 ) ( E · B ) 2 ] 8 4 π 8 4 π Vacuum becomes birefringent Vacuum becomes birefringent

Photon-EM Interactions A photon propagating through an external field will acquire an ellipticity: A photon propagating through an external field will acquire an ellipticity: n || = A B 2 ext sin 2  n || = A B 2 ext sin 2  n  = A B 2 ext sin 2  L π L L π L  =  —— (n || - n  ) = —— 3 A B 2 ext

Photon-EM Interaction Another type of ‘photon-photon’ scattering: axion intermediate state Another type of ‘photon-photon’ scattering: axion intermediate state

Theory of Axions QCD Lagrangian contains CP violating term, however strong interactions conserve the CP symmetry QCD Lagrangian contains CP violating term, however strong interactions conserve the CP symmetry Peccei & Quinn proposed axion field Peccei & Quinn proposed axion field QCD Ground State reinterpreted as QCD Ground State reinterpreted as a dynamical variable a dynamical variable   a(x) / f a   a(x) / f a

Axion Field Equation If we include the axion field in the Lagrangian for photon-EM interactions If we include the axion field in the Lagrangian for photon-EM interactions L = (1/4) F  F  + (1/2) (   a   a – ~ m 2 a a 2 ) + (1/4M) F  F  a + (  2 /90m 4 e ) [ (F  F  ) 2 + ~ (7/4) (F  F  ) 2 ]

Axion Mass Range

Experimental Setup Current experiment uses a RHIC Quad Current experiment uses a RHIC Quad

Experimental Parameters Vacuum Torr Vacuum Torr Gradient 95 T/m Gradient 95 T/m Quadrupole Field (Superconducting Quad) Quadrupole Field (Superconducting Quad) HeNe laser at 543 nm HeNe laser at 543 nm Beam Diameter ~ 1.5 mm Beam Diameter ~ 1.5 mm Field Modulation: 80 mHz & 225 mHz Field Modulation: 80 mHz & 225 mHz

Experimental Calibration Minimal calibration needed Minimal calibration needed No cavity mirror alignment No cavity mirror alignment No movement of mirrors in fringe fields No movement of mirrors in fringe fields No residual gas due to cooling of magnet No residual gas due to cooling of magnet

Current Status Run 1 completed as of 10/30/2005: ~6950 min of data taken Run 1 completed as of 10/30/2005: ~6950 min of data taken Run 2 completed as of 03/20/2006: Run 2 completed as of 03/20/2006: ~2088 min of useful data ~2088 min of useful data Data analysis underway Data analysis underway Shunt measurement taken for Run 2 only Shunt measurement taken for Run 2 only

Wk 1 Data

Small Signal Analysis In place of performing an FFT on the normalized values of position ( i.e. position/total energy) can perform an FFT on these variables separately… In place of performing an FFT on the normalized values of position ( i.e. position/total energy) can perform an FFT on these variables separately… Can also use the FFT to look for small signals in the derivative ( point-to- point change in a value) of the available variables… Can also use the FFT to look for small signals in the derivative ( point-to- point change in a value) of the available variables…

FFT Change in Position

FFT Total Energy (Sum)

FFT Change in Sum

Observations: 80 mHz

Observation: 225 mHz

Why Signal Drops? When taking an FFT of the change in a variable, where a small signal is present, the phase of the signal determines its amplitude and sign… When taking an FFT of the change in a variable, where a small signal is present, the phase of the signal determines its amplitude and sign… Since the phase of the signal is unavailable, the initial phase is set by triggering on when the phase of the current is zero… Since the phase of the signal is unavailable, the initial phase is set by triggering on when the phase of the current is zero…

Adjusting Phase

Wk 2 Data: Goal for second run period was to perform systematic studies: Goal for second run period was to perform systematic studies: Shunt Measurement No Light Measurement Probing Alternative Positions in the Field Measure the stray field

Wk 2: Data Peak observed at 80 mHz Peak observed at 80 mHz The amplitude of the peak: 6.43  ± 1.01  (stat) The amplitude of the peak: 6.43  ± 1.01  (stat)

Wk 2: Data

Possible Backgrounds Movement due to eddy currents Movement due to eddy currents Electronic loops Electronic loops Magnet Vibrations: test bench uses airbags to isolate magnet Magnet Vibrations: test bench uses airbags to isolate magnet Temperature changes in test area Temperature changes in test area Movement along surface of optical elements Movement along surface of optical elements

External Magnetic Field Work Bench: Gauss Magnet Center: Gauss Bellows: Gauss PR1: Gauss

Observation: No Light No peak seen No peak seen Amplitude at 80 mHz: 3.58  ± 3.40  (stat) Amplitude at 80 mHz: 3.58  ± 3.40  (stat)

Observations: Shunt Peak seen at 80 mHz Peak seen at 80 mHz The extracted amplitude: 2.64  ± 6.82  (stat) The extracted amplitude: 2.64  ± 6.82  (stat)

Shunt: Phase Shift

DATA AT 225 – SUM Peak observed at 225 mHz Peak observed at 225 mHz The amplitude of the peak: 3.76  ± 1.03  (stat) The amplitude of the peak: 3.76  ± 1.03  (stat)

DATA AT 225 Data rotated up to Pi/2 Data rotated up to Pi/2 Amp Vary: (2.90 to 4.74)  ± (0.91 to 1.09)  (stat) Amp Vary: (2.90 to 4.74)  ± (0.91 to 1.09)  (stat)

SHUNT AT SUM NO PEAK observed at 225 mHz in the shunt meas NO PEAK observed at 225 mHz in the shunt meas The amplitude of 225mHz: 1.48  ± 1.49  (stat) The amplitude of 225mHz: 1.48  ± 1.49  (stat)

SHUNT AT 225 Data rotated up to Pi/2 Data rotated up to Pi/2 Amp Vary: (1.32 to 1.48)  ± (1.47 to 1.49)  (stat) Amp Vary: (1.32 to 1.48)  ± (1.47 to 1.49)  (stat)

Horizontal Movement No peak evident in either the FFT of the horizontal position nor the FFT of its change… No peak evident in either the FFT of the horizontal position nor the FFT of its change…

Vertical Movement No peak evident in either the FFT of the vertical position nor the FFT of its change… No peak evident in either the FFT of the vertical position nor the FFT of its change…

E-Loop Scaling E-Loop peaks observed E-Loop peaks observed A(Shunt): 2.05  ± 5.87  (stat) A(Shunt): 2.05  ± 5.87  (stat) A(NL): 2.58  ± 4.57  (stat) A(NL): 2.58  ± 4.57  (stat)

E-Loop Scaling E-Loop Data A(Shunt): 9.04  ± 1.90  (stat) E-Loop Data A(Shunt): 9.04  ± 1.90  (stat) Rescaling No Light gives peak ~ 20 times that in Shunt Rescaling No Light gives peak ~ 20 times that in Shunt

Future Repeat measurement with beam splitter to simultaneously observe laser output… Repeat measurement with beam splitter to simultaneously observe laser output… Take longer data run periods to improve statistics… Take longer data run periods to improve statistics… Develop a mirror cavity to search for agreement with E840/PVLAS Develop a mirror cavity to search for agreement with E840/PVLAS

References 1.Peccei & Quinn, PRL 38 (1977), Wilczek, PRL 40 (1978), A Simple Solution to the Strong CP Problem with a Harmless Axion, Dine, Fischler and Srednicki, Phy. Lett. 104B, CAST: A search for solar axions at CERN hep-ex/ PVLAS Results INFN-LNL (REP) 206/05 6.‘An Experiment to Search for Axions’ www-phys.llnl.gov/N_Div/Axion/axion.html 7.Axions, G. Raffelt, Space Science Reviews 100: , Anomalous axion interactions and topological currents in dense matter, M. Metlitski & A Zhitnitsky, Phy. Rev. D 72, (2005) 9.MINOWA Group, Solar axion search experiment with a superconducting magnet, www-icepp.s.u-tokyo.ac.jp/~minowa/Minowa_Group.files/s…

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