# Presentation: 855524

## AN ANOMALOUS CURVATURE EXPERIMENT

- Carol Y. Scarlett
- Brookhaven National Laboratory
- Apr. 27th, 2006

## Collaborators

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

## Experiments 

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

## BNL E840

- 1989 Search for Axions at BNL E840 saw a rotation of polarized light of order 10-8 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:
- 			  5.8 · 10-12 rad

## PVLAS

- 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 ~ 10-7 rad giving: ma ~ 1meV
- PVLAS plans for regeneration experiment

## Axion Detection Exp.

- Ellipticity changes: BNL E840 & PVLAS

## Optical Effects

- Ellipticity:

## Optical Effects

- Dichroism:

## Photon-EM Interaction

- In the presence of an externally applied Magnetic field:
-        1                    A
-   L= —— (E2+B2) + —— [(E2 - B2)2 + 7 (  E · B  )2]
-          8                   4 π
- Vacuum becomes birefringent

## Photon-EM Interactions

- A photon propagating through an external field will acquire an ellipticity:
-    	n||  = 1 + 7 A B2ext  sin2
- 		n = 1 + 4 A B2ext  sin2
-            L                      π L
-  =  —— (n|| -  n ) = —— 3 A B2ext
-                                   

## Photon-EM Interaction

- 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
- Peccei & Quinn proposed axion field
- QCD Ground State reinterpreted as
-    a dynamical variable
-              a(x) / fa

## Axion Field Equation

- If we include the axion field in the Lagrangian for photon-EM interactions
- L = (1/4) F F + (1/2) (a a –
-                                          ~
- 		m2aa2) + (1/4M)  F  F a +
- 		(2/90m4e) [ (F F )2 +
-                          ~
- 		(7/4) (F  F )2 ]

## Axion Mass Range

## Experimental Setup

- Current experiment uses a RHIC Quad

## Experimental Parameters

- Vacuum 10-9 Torr
- Gradient 95 T/m
- Quadrupole Field (Superconducting Quad)
- HeNe laser at 543 nm
- Beam Diameter ~ 1.5 mm
- Field Modulation: 80 mHz & 225 mHz

## Experimental Calibration

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

## Current Status

- Run 1 completed as of 10/30/2005: ~6950 min of data taken
- Run 2 completed as of 03/20/2006:
-    ~2088 min of useful data
- Data analysis underway
- 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...
- 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...
- 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:
- 			Shunt Measurement
- 			No Light Measurement
- 			Probing Alternative Positions
- 				in the Field
- 			Measure the stray field

## Wk 2: Data 

- Peak observed at 80 mHz
- The amplitude of the peak:  6.4310-5 ± 1.0110-5 (stat)

## Wk 2: Data

## Possible Backgrounds

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

## External Magnetic Field

- Work Bench:
- 0.7-0.8 Gauss

- Magnet Center:
-  0.4-0.9 Gauss

- Bellows: 0.8-1.0 Gauss

- PR1:
- 0.0-5.9 Gauss

## Observation: No Light

- No peak seen
- Amplitude at 80 mHz:  3.5810-5 ± 3.4010-5 (stat)

## Observations: Shunt

- Peak seen at 80 mHz
- The extracted amplitude:  2.6410-5 ± 6.8210-6 (stat)

## Shunt: Phase Shift

## DATA AT 225 – SUM 

- Peak observed at 225 mHz
- The amplitude of the peak:  3.7610-5 ± 1.0310-5 (stat)

## DATA AT 225

- Data rotated up to Pi/2
- Amp Vary:  (2.90 to 4.74)10-5 ± (0.91 to 1.09)10-5 (stat)

## SHUNT AT 225 - SUM

- NO PEAK observed at 225 mHz in the shunt meas
- The amplitude of 225mHz:  1.4810-5 ± 1.4910-5 (stat)

## SHUNT AT 225

- Data rotated up to Pi/2
- Amp Vary:  (1.32 to 1.48)10-5 ± (1.47 to 1.49)10-5 (stat)

## Horizontal Movement

- 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...

## E-Loop Scaling

- E-Loop peaks observed
- A(Shunt):  2.0510-4 ± 5.8710-6 (stat)
- A(NL): 2.5810-4 ± 4.5710-6 (stat)

## E-Loop Scaling

- E-Loop Data A(Shunt):  9.0410-5 ± 1.9010-5 (stat)
- Rescaling No Light gives peak ~ 20 times that in Shunt

## Future 

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

## References

- 1.	Peccei & Quinn, PRL 38 (1977), 1440
- 2.	Wilczek, PRL 40 (1978), 279
- 3.	A Simple Solution to the Strong CP Problem with a Harmless Axion, Dine, Fischler and Srednicki, Phy. Lett. 104B, 199
- 4.	CAST: A search for solar axions at CERN hep-ex/0304024
- 5.	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: 153-158, 2002
- 8.	Anomalous axion interactions and topological currents in dense matter, M. Metlitski & A Zhitnitsky, Phy. Rev. D 72, 045011 (2005)
- 9.	MINOWA Group, Solar axion search experiment with a superconducting magnet,
- 	www-icepp.s.u-tokyo.ac.jp/~minowa/Minowa_Group.files/s...

## Axion Mass

- 10-10

- 10-5

- 1 eV

- 105

- ma

- Lab Exp

- RG (DFSZ)

- RG
- (Hadronic)

- SN 87A

- Relic Decays

- a (Davis) > ]

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