147 research outputs found
The measurement of the anomalous magnetic moment of the muon at fermilab
The anomalous magnetic moment of the muon is one of the most precisely measured quantities in experimental particle physics. Its latest measurement at Brookhaven National Laboratory deviates from the Standard Model expectation by approximately 3.5 standard deviations. The goal of the new experiment, E989, now under construction at Fermilab, is a fourfold improvement in precision. Here, we discuss the details of the future measurement and its current status
Data acquisition system for the MuLan muon lifetime experiment
We describe the data acquisition system for the MuLan muon lifetime
experiment at Paul Scherrer Institute. The system was designed to record muon
decays at rates up to 1 MHz and acquire data at rates up to 60 MB/sec. The
system employed a parallel network of dual-processor machines and repeating
acquisition cycles of deadtime-free time segments in order to reach the design
goals. The system incorporated a versatile scheme for control and diagnostics
and a custom web interface for monitoring experimental conditions.Comment: 19 pages, 8 figures, submitted to Nuclear Instruments and Methods
New results on the hadronic vacuum polarization to the muon g-2
Results on the lowest-order hadronic vacuum polarization contribution to the
muon magnetic anomaly are presented. They are based on the latest published
experimental data used as input to the dispersion integral. Thus recent results
on tau to nutau pi pi0 decays from Belle and on e+ e- annihilation to pi+ pi-
from BABAR and KLOE are included. The new data, together with improved
isospin-breaking corrections for tau decays, result into a much better
consistency among the different results. A discrepancy between the Standard
Model prediction and the direct g-2 measurement is found at the level of 3
sigma.Comment: proceedings of the PhiPsi09 conference, Oct. 13-16, 2009, Beijing,
Chin
Measurement of the Positive Muon Lifetime and Determination of the Fermi Constant to Part-per-Million Precision
We report a measurement of the positive muon lifetime to a precision of 1.0
parts per million (ppm); it is the most precise particle lifetime ever
measured. The experiment used a time-structured, low-energy muon beam and a
segmented plastic scintillator array to record more than 2 x 10^{12} decays.
Two different stopping target configurations were employed in independent
data-taking periods. The combined results give tau_{mu^+}(MuLan) =
2196980.3(2.2) ps, more than 15 times as precise as any previous experiment.
The muon lifetime gives the most precise value for the Fermi constant:
G_F(MuLan) = 1.1663788 (7) x 10^-5 GeV^-2 (0.6 ppm). It is also used to extract
the mu^-p singlet capture rate, which determines the proton's weak induced
pseudoscalar coupling g_P.Comment: Accepted for publication in Phys. Rev. Let
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 parts per million (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 of the negative
muon. The result a_mu= 11 659 214(8)(3) \times 10^{-10} (0.7 ppm), where the
first uncertainty is statistical and the second is sytematic, is consistend
with previous measurements of the anomaly for the positive and negative muon.
The average for the muon anomaly a_{mu}(exp) = 11 659 208(6) \times 10^{-10}
(0.5ppm).Comment: 4 pages, 4 figures, submitted to Physical Review Letters, revised to
reflect referee comments. Text further revised to reflect additional referee
comments and a corrected Fig. 3 replaces the older versio
Implementation of chamber misalignments and deformations in the ATLAS muon spectrometer simulation
"The implementation of run-time dependent corrections for alignment and distortions in the detector description of the ATLAS Muon Spectrometer is discussed, along with the strategies for studying such effects in dedicated simulations."http://deepblue.lib.umich.edu/bitstream/2027.42/64214/1/jpconf8_119_032010.pd
Measurement of the Pion Form Factor in the Energy Range 1.04-1.38 GeV with the CMD-2 Detector
The cross section for the process is measured in the
c.m. energy range 1.04-1.38 GeV from 995 000 selected collinear events
including 860000 events, 82000 events, and 33000
events. The systematic and statistical errors of measuring the
pion form factor are equal to 1.2-4.2 and 5-13%, respectively.Comment: 5 pages, 2 figure
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