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AN ANOMALOUS CURVATURE EXPERIMENT

AN ANOMALOUS CURVATURE EXPERIMENT. Carol Y. Scarlett Brookhaven National Laboratory Apr. 27 th , 2006. Collaborators. Russ Burns Don Lazarus Carol Scarlett Yannis Semertzidis Mike Sivertz. Experiments. Experiments with Polarized Laser Light inside a dipole magnetic field:

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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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