This paper presents the beam dynamics systematic corrections and their uncertainties for the Run-1 dataset of the Fermilab Muong−2Experiment. Two corrections to the measured muon precession ...frequencyωamare associated with well-known effects owing to the use of electrostatic quadrupole (ESQ) vertical focusing in the storage ring. An average vertically oriented motional magnetic field is felt by relativistic muons passing transversely through the radial electric field components created by the ESQ system. The correction depends on the stored momentum distribution and the tunes of the ring, which has relatively weak vertical focusing. Vertical betatron motions imply that the muons do not orbit the ring in a plane exactly orthogonal to the vertical magnetic field direction. A correction is necessary to account for an average pitch angle associated with their trajectories. A third small correction is necessary, because muons that escape the ring during the storage time are slightly biased in initial spin phase compared to the parent distribution. Finally, because two high-voltage resistors in the ESQ network had longer than designedRCtime constants, the vertical and horizontal centroids and envelopes of the stored muon beam drifted slightly, but coherently, during each storage ring fill. This led to the discovery of an important phase-acceptance relationship that requires a correction. The sum of the corrections toωamis0.50±0.09ppm; the uncertainty is small compared to the 0.43 ppm statistical precision ofωam.
We present a new measurement of the positive muon magnetic anomaly, $a$$μ$≡($g$$μ$-2)/2, from the Fermilab Muon g-2 Experiment using data collected in 2019 and 2020. We have analyzed more than 4 ...times the number of positrons from muon decay than in our previous result from 2018 data. The systematic error is reduced by more than a factor of 2 due to better running conditions, a more stable beam, and improved knowledge of the magnetic field weighted by the muon distribution $\tilde {ω}$'p, and of the anomalous precession frequency corrected for beam dynamics effects, $ω$$a$. From the ratio $ω$$a$/$\tilde {ω}$'$p$, together with precisely determined external parameters, we determine $a$$μ$ = 116592057(25)×10-11 (0.21 ppm). Combining this result with our previous result from the 2018 data, we obtain aμ(FNAL)=116592055(24)×10-11 (0.20 ppm). The new experimental world average is $a$$μ$(Exp)=116592059(22)×10-11 (0.19 ppm), which represents a factor of 2 improvement in precision.
The electromagnetic calorimeter for the new muon (g−2) experiment at Fermilab will consist of arrays of PbF2 Cherenkov crystals read out by large-area silicon photo-multiplier (SiPM) sensors. We ...report here on measurements and simulations using 2.0–4.5GeV electrons with a 28-element prototype array. All data were obtained using fast waveform digitizers to accurately capture signal pulse shapes vs. energy, impact position, angle, and crystal wrapping. The SiPMs were gain matched using a laser-based calibration system, which also provided a stabilization procedure that allowed gain correction to a level of 10−4 per hour. After accounting for longitudinal fluctuation losses, those crystals wrapped in a white, diffusive wrapping exhibited an energy resolution σ/E of (3.4±0.1)%/E/GeV, while those wrapped in a black, absorptive wrapping had (4.6±0.3)%/E/GeV. The white-wrapped crystals—having nearly twice the total light collection—display a generally wider and impact-position-dependent pulse shape owing to the dynamics of the light propagation, in comparison to the black-wrapped crystals, which have a narrower pulse shape that is insensitive to impact position.
We present a detailed report of the method, setup, analysis, and results of a precision measurement of the positive muon lifetime. The experiment was conducted at the Paul Scherrer Institute using a ...time-structured, nearly 100% polarized surface muon beam and a segmented, fast-timing plastic scintillator array. The measurement employed two target arrangements: a magnetized ferromagnetic target with a ~ 4 kG internal magnetic field and a crystal quartz target in a 130 G external magnetic field. Approximately 1.6 x 10 super(12) positrons were accumulated and together the data yield a muon lifetime of tau sub( mu )(MuLan) = 2196980.3(2.2) ps (1.0 ppm), 30 times more precise than previous generations of lifetime experiments. The lifetime measurement yields the most accurate value of the Fermi constant G sub(F)(MuLan) = 1.1663787(6) x 10 super(-5) GeV super(-2) (0.5 ppm). It also enables new precision studies of weak interactions via lifetime measurements of muonic atoms.
Search for Muon Catalyzed 3Hed Fusion Fotev, V. D.; Ganzha, V. A.; Ivshin, K. A. ...
Physics of particles and nuclei,
06/2024, Letnik:
55, Številka:
3
Journal Article
Recenzirano
—This report presents the results of an experiment aimed at observation of the muon catalyzed
3
He
d
fusion reaction
3
He +
(3.66 MeV) +
p
(14.64 MeV) + μ which might occur after a negative muon stop ...in the D
2
+
3
He gas mixture. The basic element of the experimental setup is a Time Projection Chamber (TPC) which can detect the incoming muons and the products of the fusion reaction. The TPC operated with the D
2
+
3
He (5%) gas mixture at 31 K temperature. About
3
Heμ
d
molecules were produced with only 2 registered candidates for the muon catalyzed
3
He
d
fusion with the expected background
events. This gives an upper limit for the probability of the fusion decay of the
3
Heμ
d
molecule
at 90% C.L. Also presented are the measured formation rate of the
3
Heμ
d
molecule
and the probability of the fast muon transfer from the excited to the ground state of the
atom
. The obtained results are compared with the previously published data.
The MuCap experiment at the Paul Scherrer Institute has measured the rate Λ{sub S} of muon capture from the singlet state of the muonic hydrogen atom to a precision of 1%. A muon beam was stopped in ...a time projection chamber filled with 10-bar, ultrapure hydrogen gas. Cylindrical wire chambers and a segmented scintillator barrel detected electrons from muon decay. Λ{sub S} is determined from the difference between the μ{sup -} disappearance rate in hydrogen and the free muon decay rate. The result is based on the analysis of 1.2×10{sup 10} μ{sup -} decays, from which we extract the capture rate Λ{sub S} =(714.9±5.4{sub stat} ±5.1{sub syst} )s{sup -1} and derive the proton’s pseudoscalar coupling g{sub P} (q{sup 2}{sub 0} =-0.88m{sup 2}{sub μ} )=8.06±0.55 .
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