We present the first results of the Fermilab National Accelerator Laboratory (FNAL) Muon g-2 Experiment for the positive muon magnetic anomaly a_{μ}≡(g_{μ}-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 ω_{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 ωover ˜_{p}^{'} in a spherical water sample at 34.7 °C. The ratio ω_{a}/ωover ˜_{p}^{'}, together with known fundamental constants, determines a_{μ}(FNAL)=116 592 040(54)×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 μ^{+} and μ^{-}, the new experimental average of a_{μ}(Exp)=116 592 061(41)×10^{-11} (0.35 ppm) increases the tension between experiment and theory to 4.2 standard deviations.
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Background Almost 50% of patients referred for implantable left ventricular assist device (LVAD) have significant tricuspid regurgitation (TR). Preoperative TR is associated with negative outcomes ...but the clinical benefit of concomitant tricuspid valve procedures has not been extensively studied. Methods One hundred fifteen patients, undergoing implantable LVADs, were identified as having significant TR by echocardiography prior to their surgical procedure. Patients underwent either LVAD alone (n = 81) versus LVAD plus concomitant tricuspid procedures (n = 34) (29 annuloplasty ring repairs and 5 bioprosthetic replacements.) Preoperative characteristics and hemodynamics, as well as TR severity and clinical outcomes were retrospectively determined from chart and database review and compared for the two groups. Results Preoperative characteristics and hemodynamics were similar for the two groups. Postoperative TR was markedly reduced for the group undergoing concomitant procedures versus LVAD alone. A temporary right ventricular assist device was required for only one of the 34 cases in which concomitant tricuspid procedures were performed; for patients undergoing LVAD alone, 8 of 81 required right ventricular assist devices. Mean duration of postoperative inotrope utilization was increased for the LVAD alone group versus the group with concomitant tricuspid procedures (10.0 vs 8.0 days, respectively, p = 0.04). The incidence of postoperative renal dysfunction was increased for the LVAD alone group (39%) versus concomitant procedures (21%) ( p = 0.05). The LVAD alone group also had a greater mean postimplant length of hospitalization versus the concomitant procedures group (26.0 vs 19.0 days, p = 0.02). Finally, there was a trend toward improved survival for the group with concomitant tricuspid procedures versus LVAD alone. Conclusions For patients with significant TR undergoing implantable LVAD procedures, concomitant tricuspid procedures are associated with improved early clinical outcomes.
The Muon g − 2 Experiment at Fermi National Accelerator Laboratory (FNAL) has measured the muon anomalous precession frequency ωam to an uncertainty of 434 parts per billion (ppb), statistical, and ...56 ppb, systematic, with data collected in four storage ring configurations during its first physics run in 2018. When combined with a precision measurement of the magnetic field of the experiment's muon storage ring, the precession frequency measurement determines a muon magnetic anomaly of aμ ( FNAL ) = 116 592 040 ( 54 ) × 10−11 (0.46 ppm). This article describes the multiple techniques employed in the reconstruction, analysis, and fitting of the data to measure the precession frequency. It also presents the averaging of the results from the 11 separate determinations of ωam, and the systematic uncertainties on the result.
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The Muon g-2 Experiment at Fermilab (E989) will measure the muon magnetic anomaly with unprecedented precision (0.14 ppm), which yields a factor of 4 improvement with respect to the previous ...measurements at Brookhaven National Laboratory (BNL) (E821). To achieve this goal, the relative response of each calorimeter channel must be calibrated and monitored at a level better than <inline-formula> <tex-math notation="LaTeX">10^{-3} </tex-math></inline-formula> in the time window of the muon fill. The calibration system uses a laser source and photodetectors. The data acquisition (DAQ) of the system is designed around two field-programmable gate array (FPGA)-based boards and a custom crate bus. The front-end board manages the photodetector operation and signal processing and performs a first-level data concentration task. Up to 12 FPGA boards can be housed in a 6U crate. A readout master controls the boards, implements event-building functionalities, manages the monitoring interface, and facilitates calibration and debugging tasks. A gigabit-ethernet interface is used to transfer data to the on-line farm for storage and further processing. Presently, the system is working at Fermi National Accelerator Laboratory (FNAL). In this article, we present the DAQ system design, run control user interface, and system evaluation.
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, ωover ˜_{p}^{'}, and of the anomalous precession frequency corrected for beam dynamics effects, ω_{a}. From the ratio ω_{a}/ωover ˜_{p}^{'}, together with precisely determined external parameters, we determine a_{μ}=116 592 057(25)×10^{-11} (0.21 ppm). Combining this result with our previous result from the 2018 data, we obtain a_{μ}(FNAL)=116 592 055(24)×10^{-11} (0.20 ppm). The new experimental world average is a_{μ}(exp)=116 592 059(22)×10^{-11} (0.19 ppm), which represents a factor of 2 improvement in precision.
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In high energy physics experiments, calorimeters are calibrated to produce precise and accurate results. Laser light can be used for calibration when the detectors are sensitive to photons in that ...particular energy range, which is often the case. Moreover, it is not unusual that detection systems consist of hundreds of channels that have to be calibrated independently, which produce stringent requirements on the light distribution system in terms of temporal and spatial stability, energy distribution and timing. Furthermore, the economic factor and the ease of production have to be taken into account. We present a prototype light distribution system, based on a series of optical beamsplitters, developed for the Muon g-2 experiment at Fermilab.
Background The progression of tricuspid valve regurgitation (TR) and the impact of preoperative TR on postoperative outcomes in patients having left ventricular assist device (LVAD) implantation has ...not been studied. Methods One hundred seventy-six consecutive implantable LVAD procedures were retrospectively reviewed. A total of 137 patients comprised the final study group with complete preimplant characteristics, before and after echocardiogram assessment of TR, and outcomes data. Patients were divided into two groups: insignificant TR (iTR) consisting of those with preimplant TR grades of none, trace, and mild; and significant TR (sTR) consisting of those with moderate and severe TR grades. Results Relative to patients with iTR, patients with sTR were younger (53.6 ± 12.8 versus 58.4 ± 10.0 years, p = 0.02) and more commonly had nonischemic cardiomyopathies (69% versus 38%, p < 0.001). The preimplant incidence of iTR and sTR was 51% and 49%. Immediately after the LVAD implant procedure, TR did not significantly change. At late follow-up (156 ± 272 days), 32% had moderate or severe TR. Also, 41% of the original sTR group persisted with moderate or severe TR. Relative to patients with iTR, patients with sTR required longer postimplant intravenous inotropic support (8.5 versus 5.0 days, p = 0.02), more commonly required a temporary right ventricular assist device, and had a longer postimplant length of hospital stay (27.0 versus 20.0 days, p = 0.03). There was also a trend toward decreased survival for sTR versus iTR (log rank = 0.05). Conclusions Tricuspid regurgitation is not reduced immediately after LVAD implantation. Significant TR is associated with longer postimplant inotropic support and length of hospital stay.
The Muon g−2 Experiment at Fermilab is expected to start data taking in 2017. It will measure the muon anomalous magnetic moment, aμ=(gμ−2)/2 to an unprecedented precision: the goal is 0.14 parts per ...million (ppm). The new experiment will require upgrades of detectors, electronics and data acquisition equipment to handle the much higher data volumes and slightly higher instantaneous rates. In particular, it will require a continuous monitoring and state-of-art calibration of the detectors, whose response may vary on both the millisecond and hour long timescale. The calibration system is composed of six laser sources and a light distribution system will provide short light pulses directly into each crystal (54) of the 24 calorimeters which measure energy and arrival time of the decay positrons. A Laser Control board will manage the interface between the experiment and the laser source, allowing the generation of light pulses according to specific needs including detector calibration, study of detector performance in running conditions, evaluation of DAQ performance. Here we present and discuss the main features of the Laser Control board.
Objective Patients referred for implantable continuous-flow left ventricular assist devices (cfLVAD) frequently have preoperative right heart failure and tricuspid regurgitation (TR). The objective ...of this report is to examine early clinical benefits of concomitant tricuspid surgery for these patients. Methods Sixty-one of 200 consecutive cfLVAD patients at our institution displayed preimplant right heart dysfunction and significant TR. Thirty-three underwent cfLVAD plus a tricuspid valve procedure (TVP), and 28 had cfLVAD alone. Preimplant characteristics and clinical outcomes were retrospectively studied. As previously described, post-LVAD right ventricular failure was defined as need for right ventricular assist device (RVAD) support or greater than 14 days of intravenous inotropic support. Results Preimplant characteristics were similar between the 2 groups. Cardiopulmonary bypass time was increased for the group that received concomitant TVPs. The most common TVP consisted of an undersizing ring annuloplasty. The cfLVAD-alone group had greater TR after implant relative to the cfLVAD+TVP group. The cfLVAD-alone group experienced greater postprocedure right ventricular failure relative to cfLVAD+TVP (46.4% vs 18.2%; P < .05). Furthermore, prolonged hospitalization was increased for the cfLVAD-alone group versus the cfLVAD+TVP. Survival was similar between the 2 groups. Conclusions Concomitant TVP appears to reduce postprocedure right ventricular failure for patients with significant TR undergoing cfLVAD implantation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The anomalous muon dipole magnetic moment can be measured (and calculated) with great precision thus providing insight on the Standard Model and new physics. Currently an experiment is under ...construction at Fermilab (U.S.A.) which is expected to measure the anomalous muon dipole magnetic moment with unprecedented precision. One of the improvements with respect to the previous experiments is expected to come from the laser calibration system which has been designed and constructed by the Italian part of the collaboration (INFN). An emphasis of this paper will be on the calibration system that is in the final stages of construction as well as the experiment which is expected to start data taking this year.
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