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AN ANOMALOUS CURVATURE EXPERIMENT

The experiment conducted at Brookhaven National Laboratory investigates the interaction of polarized laser light within dipole magnetic fields. Collaborators including Carol Y. Scarlett and Yannis Semertzidis studied anomalies such as the observed rotation of polarized light in the search for axions, surpassing the predictions of Quantum Electrodynamics (QED) background noise. The experimental setup involved advanced optical cavities and magnetic configurations, with systematic data analysis revealing significant findings including ellipticity shifts and possible photon-photon scattering effects related to axion theories.

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AN ANOMALOUS CURVATURE EXPERIMENT

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

  2. Collaborators • Russ Burns • Don Lazarus • Carol Scarlett • Yannis Semertzidis • Mike Sivertz

  3. 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.

  4. 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

  5. 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

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

  7. Optical Effects • Ellipticity:

  8. Optical Effects • Dichroism:

  9. 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

  10. 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 πL  =  —— (n|| - n ) = —— 3 A B2ext  

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

  12. 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

  13. 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 ]

  14. Axion Mass Range

  15. Experimental Setup • Current experiment uses a RHIC Quad

  16. 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

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

  18. 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

  19. Wk 1 Data

  20. 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…

  21. FFT Change in Position

  22. FFT Total Energy (Sum)

  23. FFT Change in Sum

  24. Observations: 80 mHz

  25. Observation: 225 mHz

  26. 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…

  27. Adjusting Phase

  28. 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

  29. Wk 2: Data • Peak observed at 80 mHz • The amplitude of the peak: 6.4310-5± 1.0110-5 (stat)

  30. Wk 2: Data

  31. 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

  32. External Magnetic Field Magnet Center: 0.4-0.9 Gauss PR1: 0.0-5.9 Gauss Work Bench: 0.7-0.8 Gauss Bellows: 0.8-1.0 Gauss

  33. Observation: No Light • No peak seen • Amplitude at 80 mHz: 3.5810-5± 3.4010-5 (stat)

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

  35. Shunt: Phase Shift

  36. DATA AT 225 – SUM • Peak observed at 225 mHz • The amplitude of the peak: 3.7610-5± 1.0310-5 (stat)

  37. 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)

  38. 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)

  39. 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)

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

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

  42. 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)

  43. 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

  44. 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

  45. 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…

  46. Axion Mass ma 10-10 10-5 1 eV 105 Lab Exp RG (DFSZ) RG (Hadronic) SN 87A a > ] Relic Decays a (Davis) > ]

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