Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session H5: Precision Experiments and Tests of Fundamental Laws |
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Sponsoring Units: GFC Chair: Harvey Gould, Lawrence Berkeley National Laboratory Room: Hyatt Regency Jacksonville Riverfront Grand 6 |
Sunday, April 15, 2007 8:30AM - 9:06AM |
H5.00001: Science with LIGO Invited Speaker: The LIGO Science Collaboration has entered an extended period of searching for gravitational wave emissions from the near universe. While other talks at this meeting will highlight the current status of LIGO and give results of searches for gravitational waves, I will focus mainly on Advanced LIGO, a second generation ground-based detector. The Advanced LIGO interferometers are designed to detect gravitational waves with a ten-fold sensitivity increase over the current LIGO interferometers and a projected detection rate of 10 - 500 events per year for binary neutron star inspiral events. This enhanced sensitivity will come about from major upgrades to all of the interferometer subsystems, including a significant increase in the input laser power and the use of associated high power handling optics, better low frequency performance through the use of triple and quadruple pendulum suspended mirrors and active seismic isolation, low loss fused silica test masses with engineered optical coatings, the addition of a signal recycling mirror for tuned operation, and homodyne readout of the GW signal. This talk will discuss the current status of Advanced LIGO as well as some of the interesting physical effects and challenges associated with high average power operation of km-class interferometers. [Preview Abstract] |
Sunday, April 15, 2007 9:06AM - 9:42AM |
H5.00002: Ultrasensitive Searches for the Axion Invited Speaker: After thirty years, the axion, a hypothetical elementary particle, still represents the best solution to the Strong-CP problem, i.e. why the neutron has a vanishingly small electric dipole moment. If it exists at all, the axion must be extremely light, not much heavier than a millielectronvolt, but not much lighter than a microelectronvolt. At the lower end of the mass window, the axion also represents an excellent dark matter candidate. Furthermore, in addition to being exceedingly light, the axion possesses extraordinarily feeble couplings to matter and radiation, far below those of the weak interaction. Being a pseudoscalar however, like the neutral pion, the axion can couple to two photons, and as recognized by Pierre Sikivie in 1983, the axion can therefore convert to a single real photon in an external electromagnetic field, an effect historically known in pion physics as the Primakoff interaction. The coherent mixing of axions and photons in strong magnetic fields of large spatial extent has thus become the primary strategy for virtually all searches for the axion, which otherwise lies far beyond reach of any conventional particle physics experiment. This talk will review three major experimental efforts to discover the axion by coherent axion-photon mixing: the microwave cavity search for halo dark matter axions (AMDX); a search for solar axions (CAST); and purely laboratory experiments, looking for magnetically-induced dichroism and birefringence of the vacuum (PVLAS), and photon regeneration. [Preview Abstract] |
Sunday, April 15, 2007 9:42AM - 10:18AM |
H5.00003: Preferred Frame and CP-Violation Tests with Polarized Electrons Invited Speaker: We used a torsion pendulum containing 10$^{23}$ polarized electrons to search for CP-violating interactions between the pendulum's electrons and unpolarized matter in the earth or the sun, to test rotation and boost-dependent preferred-frame effects using the earth's rotation and velocity around the sun, and to search for exotic velocity-dependent potentials between polarized electrons and the sun. Experimental constraints on these spin-dependent couplings will be presented along with a description of the experiments and the means by which the spin density of the pendulum was determined. [Preview Abstract] |
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