A new photon recoil experiment: towards a determination of the fine structure constant

We report on progress towards a measurement of the fine structure constant to an accuracy of $5\times 10^{-10}$ or better by measuring the ratio of the Planck constant to the mass of the cesium atom. Compared to similar experiments, ours is improved in three significant ways: (i) simultaneous conjugate interferometers, (ii) multi-photon Bragg diffraction between same internal states, and (iii) an about 1000 fold reduction of laser phase noise to -138 dBc/Hz. Combining that with a new method to simultaneously stabilize the phases of four frequencies, we achieve 0.2 mrad effective phase noise at the location of the atoms. In addition, we use active stabilization to suppress systematic effects due to beam misalignment.Comment: 12 pages, 9 figure

Effects of Large CP violating phases on g_{\m}-2 in MSSM

Effects of CP violation on the supersymmetric electro-weak correction to the anomalous magnetic moment of the muon are investigated with the most general allowed set of CP violating phases in MSSM. The analysis includes contributions from the chargino and the neutralino exchanges to the muon anomaly. The supersymmetric contributions depend only on specific combinations of CP phases. The independent set of such phases is classified. We analyse the effects of the phases under the EDM constraints and show that large CP violating phases can drastically affect the magnitude of the supersymmetric electro-weak contribution to $a_{\mu}$ and may even affect its overall sign.Comment: 26 pages Latex file including 4 figure

News from the Muon (g-2) Experiment at BNL

The magnetic moment anomaly a_mu = (g_mu - 2) / 2 of the positive muon has been measured at the Brookhaven Alternating Gradient Synchrotron with an uncertainty of 0.7 ppm. The new result, based on data taken in 2000, agrees well with previous measurements. Standard Model evaluations currently differ from the experimental result by 1.6 to 3.0 standard deviations.Comment: Talk presented at RADCOR - Loops and Legs 2002, Kloster Banz, Germany, September 8-13 2002, to be published in Nuclear Physics B (Proc. Suppl.); 5 pages, 3 figure

Electron beam test of key elements of the laser-based calibration system for the muon g - 2 experiment

We report the test of many of the key elements of the laser-based calibration system for muon g - 2 experiment E989 at Fermilab. The test was performed at the Laboratori Nazionali di Frascati's Beam Test Facility using a 450 MeV electron beam impinging on a small subset of the final g - 2 lead-fluoride crystal calorimeter system. The calibration system was configured as planned for the E989 experiment and uses the same type of laser and most of the final optical elements. We show results regarding the calorimeter's response calibration, the maximum equivalent electron energy which can be provided by the laser and the stability of the calibration system components

Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm

We present the first results of the Fermilab Muon g-2 Experiment for the positive muon magnetic anomaly $a_\mu \equiv (g_\mu-2)/2$. The anomaly is determined from the precision measurements of two angular frequencies. Intensity variation of high-energy positrons from muon decays directly encodes the difference frequency $\omega_a$ between the spin-precession and cyclotron frequencies for polarized muons in a magnetic storage ring. The storage ring magnetic field is measured using nuclear magnetic resonance probes calibrated in terms of the equivalent proton spin precession frequency ${\tilde{\omega}'^{}_p}$ in a spherical water sample at 34.7$^{\circ}$C. The ratio $\omega_a / {\tilde{\omega}'^{}_p}$, together with known fundamental constants, determines $a_\mu({\rm FNAL}) = 116\,592\,040(54)\times 10^{-11}$ (0.46\,ppm). The result is 3.3 standard deviations greater than the standard model prediction and is in excellent agreement with the previous Brookhaven National Laboratory (BNL) E821 measurement. After combination with previous measurements of both $\mu^+$ and $\mu^-$, the new experimental average of $a_\mu({\rm Exp}) = 116\,592\,061(41)\times 10^{-11}$ (0.35\,ppm) increases the tension between experiment and theory to 4.2 standard deviationsComment: 10 pages; 4 figure

The calibration system of the new g-2 experiment at Fermilab

The muon anomaly ( g 12 2 ) \u3bc / 2 has been measured to 0.54 parts per million by E821 experiment at Brookhaven National Laboratory, and at present there is a 3\u20134 standard-deviation difference between the Standard Model prediction and the experimental value. A new muon g 122 experiment, E989, is being prepared at Fermilab that will improve the experimental error by a factor of four to clarify this difference. A central component to reach this fourfold improvement in accuracy is the high-precision laser calibration system which should monitor the gain fluctuations of the calorimeter photodetectors at 0.04% accuracy