K. Jungmann

Measurement of the negative muon anomalous magnetic moment to 0.7 ppm

The anomalous magnetic moment of the negative muon has been measured to a precision of 0.7 ppm (ppm) at the Brookhaven Alternating Gradient Synchrotron. This result is based on data collected in 2001, and is over an order of magnitude more precise than the previous measurement for the negative muon. The result a(mu(-))=11 659 214(8)(3) x 10(-10) (0.7 ppm), where the first uncertainty is statistical and the second is systematic, is consistent with previous measurements of the anomaly for the positive and the negative muon. The average of the measurements of the muon anomaly is a(mu)(exp)=11 659 208(6) x 10(-10) (0.5 ppm).

Precise Measurement of the Positive Muon Anomalous Magnetic Moment

A precise measurement of the anomalous g value, a(mu) = (g-2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron. The result a(mu+) = 11 659 202(14) (6) x 10(-10) (1.3 ppm) is in good agreement with previous measurements and has an error one third that of the combined previous data. The current theoretical value from the standard model is a(mu)(SM) = 11 659 159.6(6.7) x 10(-10) (0.57 ppm) and a(mu)(exp) - a(mu)(SM) = 43(16) x 10(-10) in which a(mu)(exp) is the world average experimental value.

Improved limit on the muon electric dipole moment

G.W. Bennett, B. Bousquet, H.N. Brown, G. Bunce, R.M. Carey, P. Cushman, G.T. Danby, P.T. Debevec, M. Deile, H. Deng, W. Deninger, S.K. Dhawan, V.P. Druzhinin, L. Duong, E. Efstathiadis, F.J.M. Farley, G.V. Fedotovich, S. Giron, F.E. Gray, D. Grigoriev, M. Grosse-Perdekamp, A. Grossmann, M.F. Hare, D.W. Hertzog, X. Huang, V.W. Hughes, M. Iwasaki, K. Jungmann, D. Kawall, M. Kawamura, B.I. Khazin, J. Kindem, F. Krienen, I. Kronkvist, A. Lam, R. Larsen, Y.Y. Lee, I. Logashenko, R. McNabb, W. Meng, J. Mi, J.P. Miller, Y. Mizumachi, W.M. Morse, D. Nikas, C.J.G. Onderwater, Y. Orlov, C.S. Özben, J.M. Paley, Q. Peng, C.C. Polly, J. Pretz, R. Prigl, G. zu Putlitz, T. Qian, S.I. Redin, O. Rind, B.L. Roberts, N. Ryskulov, S. Sedykh, Y.K. Semertzidis, P. Shagin, Yu.M. Shatunov, E.P. Sichtermann, E. Solodov, M. Sossong, A. Steinmetz, L.R. Sulak, C. Timmermans, A. Trofimov, D. Urner, P. von Walter, D. Warburton, D. Winn, A. Yamamoto and D. Zimmerman (Muon (g − 2) Collaboration) Department of Physics, Boston University, Boston, MA 02215 Brookhaven National Laboratory, Upton, NY 11973 Budker Institute of Nuclear Physics, 630090 Novosibirsk, Russia LEPP, Cornell University, Ithaca, NY 14853 Fairfield University, Fairfield, CT 06430 6 Kernfysisch Versneller Instituut, University of Groningen, NL-9747 AA, Groningen, The Netherlands 7 Physikalisches Institut der Universität Heidelberg, 69120 Heidelberg, Germany 8 Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801 9 KEK, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan Department of Physics, University. of Minnesota., Minneapolis, MN 55455 11 Science University of Tokyo, Tokyo, 153-8902, Japan 12 Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551, Japan 13 Department of Physics, Yale University, New Haven, CT 06520 † Deceased

A high precision magnetometer based on pulsed NMR

Abstract A magnetometer based on pulsed proton magnetic resonance has been developed and constructed. The system will be employed for an accurate measurement of the absolute magnetic field in the region of 1.45 T in a precision experiment on the muons anomalous magnetic moment at the Brookhaven National Laboratory (BNL, USA), where a knowledge of the magnetic field is required with 1 × 10−7 relative accuracy. The performance of the magnetometer has been tested in a large bore superconducting magnet and a precision of one part in 108 was achieved.

A MEASUREMENT OF THE 1S-2S TRANSITION FREQUENCY IN MUONIUM

Doppler-free two-photon laser spectroscopy has been employed to measure the 12S12−22S12 transition in the muonium atom (μ+e−). A value of 2 455 529 002(33) (46) MHz has been obtained, which agrees with QED calculations within two standard deviations. The Lamb shift contributions are tested to the level 8×10−3. The corresponding measurements in hydrogen and deuterium using the same apparatus and laser system provide a test of the applied systematic corrections and have verified the systematic error of 46 MHz quoted. The mass of the positive muon has been derived from the isotope shift in this transition and yields a value of 105.65880(29)(43) MeVc2.

The superconducting inflector for the BNL g-2 experiment

The muon g-2 experiment at Brookhaven National Laboratory (BNL) has the goal of determining the muon anomalous magnetic moment, a(mu) (= (g-2)/2), to the very high precision of 0.35 parts per million and thus requires a storage ring magnet with great stability and homogeneity. A super-ferric storage ring has been constructed in which the field is to be known to 0.1 ppm. In addition, a new type of air core superconducting inflector has been developed and constructed, which successfully serves as the injection magnet. The injection magnet cancels the storage ring field, 1.5 T, seen by the entering muon beam very close to the storage ring aperture. At the same time, it gives negligible influence to the knowledge of the uniform main magnetic field in the muon storage region located at just 23 rum away from the beam channel. This was accomplished using a new double cosine theta design for the magnetic field which traps most of the return field, and then surrounding the magnet with a special superconducting sheet which traps the remaining return field. The magnet is operated using a warm-to-cold cryogenic cycle which avoids affecting the precision field of the storage ring. This article describes the design, research development, fabrication process, and final performance of this new type of superconducting magnet

MEASUREMENT OF THE POLARIZATION OF THERMAL MUONIUM IN VACUUM

We report the first measurement of the polarization of thermal muonium in vacuum. A 20 MeV/c beam of μ+ was stopped in a layer of SiO2 powder which emitted (17±1)% of the stopped μ+ into vacuum as thermal muonium. The muonium Larmor precession was observed in a transverse magnetic field of 1.4 G, and the measured amplitude of the precession signal indicates that the μ+ polarization in the muonium is (39±9)%.

Light-shift calculation in the ns-states of hydrogenic systems

We present the results of the light-shift calculations in the ns-states of hydrogenicsystems in the presence of a weak laser field. This is done by means of analytical calculations of the scalar dynamic polarizabilities (DP) of the corresponding levels. In contrast to the usual technique, 1.e. by solving certain inhomogeneous differential equation. As a result, we obtained for the DP a closed analytical expression valid for all principal quantum numbers, n. Within a framework of such an approach we succeeded both in retrieving the well known results and finding several new ones, as well.Our interest is focused mainly on the states with low n, n=1,2, since they are of particular importance.Various analytical properties of the DP of such levels are discussed in full details. Numerical values of light-shifts are computed for those energies and intensities of the laser field that are used in the 1S-2S experimental investigation of the muonium atom.

Radial magnetic field measurements with a Hall probe device in the muon (g-2) storage ring magnet at BNL

A Hall probe device has been built to measure the radial component of the magnetic field in the muon (g-2) storage ring at Brookhaven National Laboratory. The ultraprecise (g-2) magnet provides a dominantly vertical magnetic field of about 1:45 T. In order to limit the vertical shift of the muon orbit, the average radial field component should be no more than 5 � 10 � 5 of the vertical field. Our measurements with the Hall probe device achieved an accuracy of 1 � 10 � 5 , which is one of the most precise measurements with Hall probes. This provides adequate accuracy for shimming and control of the radial field. # 2001 Elsevier Science B.V. All rights reserved.

Test results of the g-2 superconducting solenoid magnet system

The g-2 experiment dipole consists of a single 48 turn, 15.1 meter diameter outer solenoid and a pair of 24 turn inner solenoids, 13.4 meters in diameter. The inner solenoids are hooked in series and are run at a polarity that is opposite that of the outer solenoid, thus creating a dipole field in the space between the inner and outer solenoids. The dipole flux is returned by a C shaped continuous iron yoke. The superconducting solenoid coils are closely coupled to the solenoid mandrels and as such are subject to quench back. This report presents the results of various tests on the g-2 magnet system operating within its iron return yoke. These tests include quench back time constant measurements for the inner and outer solenoids and measurements of the response of the two-phase forced cooled helium cryogenic system to magnet quenches. The overall effectiveness of the g-2 magnet quench protection system was measured.