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• Measure the anomalous magnetic moment of the muon to 140 parts per billion (ppb) • Measure the difference between cyclotron and spin precession frequencies of muons in a highly uniform magnetic field • Will shed light on 3.5 sigma standard deviation between Standard Model calculations and previous experiment
We describe the installation, commissioning, and characterization of the injection kicker system for the E-989 experiment at Fermilab for a precision measurement of the muon anomalous magnetic moment. Control and monitoring systems have been implemented to acquire and record the waveforms of each kicker pulse, and measurements of various kicker system observables were recorded in the presence of the 1.45 T g-2 storage ring magnetic field. These monitoring systems are necessary to understand the systematic contribution to the measurement of the precession frequency. We examine the dependence of muon capture to kicker field predictions.
The hit response of silicon vertex and tracking detectors to muon collider beam background and results of a study of hit reducing techniques are presented. The background caused by decays of the 750 GeV/c m+ and m- beams was simulated using the MARS15 program, which included the infrastructure of the beam line elements near the detector and the 10 degree nozzles that shield the detector from this background. The ILCRoot framework, along with the Geant4 program, was used to simulate the hit response of the silicon vertex and tracker detectors to the muon decay background remaining after the shielding nozzles. The background hit reducing techniques include timing, energy deposition, and hit location correlation in the double layer geometry.
Simulations for the 125-GeV Higgs Factory (HF) Muon Collider (MC) have shown large background particle loads on the collider detector. To verify level, source and composition of background calculations were performed using FLUKA and MARS codes for two shielding configurations. After comprehensive tuning of muon beam parameters, geometry setups and scoring procedures, background particle distributions at the detector entrance were simulated and compared. The spatial distributions and energy spectra of background particles obtained by two codes are rather similar. Average numbers of background particles simulated using MARS and FLUKA agree within a factor of two.
We consider semi-infinite electrostatic deflectors with plates of different thickness, including plates with rounded edges, and we calculate their electrostatic potential and field using conformal mappings. To validate the calculations, we compare the fringe fields of these electrostatic deflectors with fringe fields of finite electrostatic capacitors, and we extend the study to fringe fields of adjacent electrostatic deflectors with consideration of electrostatic induction, where field falloffs of semi-infinite electrostatic deflectors are slower than exponential and thus behave differently from most magnetic fringe fields. Building on the success with electrostatic deflectors, we develop a highly accurate and fully Maxwellian conformal mappings method for calculation of main fields of electrostatic particle optical elements. A remarkable advantage of this method is the possibility of rapid recalculations with geometric asymmetries and mispowered plates. We use this conformal mappings method to calculate the multipole terms of the high voltage quadrupole used in the storage ring of the Muon g-2 Experiment (FNALE- 0989). Completing the methodological framework, we present a method for extracting multipole strength falloffs of a particle optical element from a set of Fourier mode falloffs. We calculate the quadrupole strength falloff and its effective field boundary (EFB) for the Muon g-2 quadrupole, which has explained the experimentally measured tunes, while simple estimates based on a linear model exhibited discrepancies up to 2%.
The target station of the Muon g-2 Experiment is one of the central pieces for the production of secondary pions which eventually will decay to the desired muons. In this paper, we report adjustments made to optimize its perfor-mance. For instance, in the simulation we vary the size of the primary incoming beam and examine its impact on the downstream production. We then compare this with the ac-tual measured beam size upstream of the target. In addition, we examine the sensitivity in performance with the strength of the lithium lens and the distance between lens and target. We compare measured data with simulation results.
• Measure the magnetic anomaly of the muon to 140 parts per billion • Probe the difference between cyclotron and spin precession frequencies of positive muons in a highly uniform 1.45 T magnetic field • Will shed light on current ~3.7 standard deviation discrepancy between Standard Model calculations and best measurement to date (BNL E821)
The NOvA experiment consists of two finely segmented, liquid scintillator detectors operating 14.6 mrad off-axis from the NuMI muon-neutrino beam. The Near Detector (ND) is located in the Fermilab campus, 1 km from the NuMI target, while the Far Detector (FD) is located at Ash River, MN, 810 km from the NuMI target. The NOvA experiment is primarily designed to measure electron-neutrino appearance at the FD using the ND to control systematic uncertainties. However, the ND is well suited to search for anomalous short-baseline (SBL) oscillations. The standard three-flavor neutrino oscillations have well explained by a wide range of neutrino experiments. The anomalous results, such as electron-antineutrino excess seen by LSND and MiniBooNE do not fit the three-flavor paradigm. This can be explained by an additional fourth flavor sterile neutrino at a larger mass scale than the existing three flavor neutrinos. This thesis presents a novel method for selecting tau neutrino interact ions with high purity at the ND using a convolutional neural network (CNN). Using this method, the preliminary sensitivities of anomalous SBL muon-neutrino disappearance and tau-neutrino appearance due to sterile neutrino oscillations in NOvA are shown.
The muon anomaly, a µ = $\frac{g-2}{2}$, is a low energy observable that can be both measured and computed with high precision. Therefore it provides an important test of the Standard Model (SM) and it is a sensitive probe for new physics. The a µ value has been measured to a precision of 0.54 ppm by the E821 experiment at the Brookhaven National Laboratory (BNL). This result shows a difference greater than 3 σ compared to the SM prediction. In an effort to clarify this discrepancy between experimental measurement and theoretical calculation, the Muon g-2(E989) experiment at Fermilab aims to reduce the experimental error on a µ by a factor of four. E989 collected a dataset with the same statistical power of the BNL experiment during the Run 1 data taking (2018). The analysis of data is ongoing and the first result should become available in early 2020. In this paper, I will discuss the experimental setup and report on the status of the Run1 analysis.
Development of energy-efficient fast cycling accelerator magnets is critical for the next generation of proton rapid cycling synchrotrons (RCS) for neutrino research and booster accelerators of future muon colliders. We see a unique opportunity for having such magnets to be built on base of High Temperature Superconductors (HTS). Besides being superconducting at relatively high temperatures, rare-earth HTS tapes have shown very small AC losses compared to low-temperature NbTi superconductor cables. Recent tests of the HTS-based 0.5 m long two-bore superconducting accelerator magnet have shown record high dB/dt ramping rates of about 300 T/s at 10 Hz repetition rate and 0.5 T B-field span. No temperature rise in 6 K cooling He was observed within the 0.003 K error setting the upper limit on the cryogenic power loss in the magnet conductor coil to be less than 0.2 W/m. Based on this result we outline a possible upgrade of this test magnet design to 2 T B-field in the 10 mm beam gap with the dB/dt ramping rates up to 1000 T/s. The power test results of this short sample magnet will be used to project both cryogenic and electrical power losses as a function of the magnet B-field and the dB/dt ramping rates. Then these projections will be scaled to the range of expected accelerator magnet beam gaps and B-fields for the proton and muon RCS accelerators. We invite collaborators to join these studies and call for support of the R&D program aimed at comprehensive demonstration of this approach that includes design, construction, and power tests of a long prototype of the HTS-based fast-cycling accelerator magnet by 2028.
We report on the first example of quantum coherence between the spins of muons and quadrupolar nuclei. We observe this effect in vanadium intermetallic compounds which adopt the A15 crystal structure, and whose members include all technologically dominant superconductors. The entangled states are extremely sensitive to the local structural and electronic environments through the electric field gradient at the quadrupolar nuclei. This case-study demonstrates that positive muons can be used as a quantum sensing tool to probe also structural and charge related phenomena in materials, even in the absence of magnetic order.
We describe a search for νµ disappearance using the MicroBooNE Deep Learning analysis 1µ1p selection. Presently, the unexplained MiniBooNE and LSND anomalies could be explained by a sterile neutrino impacting neutrino oscillations. Our analysis searches for the allowed parameter space that could describe such a sterile neutrino. We determine the allowed and excluded region of a 3+1 sterile-based muon neutrino disappearance model in MicroBooNE at 90% confidence. Our allowed region includes both the null model, and current global best fit model. Context for the underlying Deep Learning analysis is provided and several validation studies surrounding both the disappearance search, and originating 1µ1p selection are performed to strengthen confidence in the result. In addition, a next-generation deep learning tool for cosmic-ray-muon event discrimination is proposed and evaluated, demonstrating a removal of 70% of the remaining event background when added to current methods, under the cut criteria used.
We describe a search for νµ disappearance using the MicroBooNE Deep Learning analysis 1µ1p selection. Presently, the unexplained MiniBooNE and LSND anomalies could be explained by a sterile neutrino impacting neutrino oscillations. Our analysis searches for the allowed parameter space that could describe such a sterile neutrino. We determine the allowed and excluded region of a 3+1 sterile-based muon neutrino disappearance model in MicroBooNE at 90% confidence. Our allowed region includes both the null model, and current global best fit model. Context for the underlying Deep Learning analysis is provided and several validation studies surrounding both the disappearance search, and originating 1µ1p selection are performed to strengthen confidence in the result. In addition, a next-generation deep learning tool for cosmic-ray-muon event discrimination is proposed and evaluated, demonstrating a removal of 70% of the remaining event background when added to current methods, under the cut criteria used.
The next generation of lepton flavour violation experiments will use high intensity and high quality muon beams. Such beams can be produced by sending a short proton pulse to the pion production target, capturing pions and performing RF phase rotation on the resulting muon beam in an FFAG ring, which was proposed for the PRISM project. A PRISM task force was created to address the accelerator and detector issues that need to be solved in order to realise the PRISM experiment. The parameters of the initial proton beam required and the PRISM experiment are reviewed. Alternative designs of the PRISM FFAG ring are presented and compared with the reference design. The ring injection/extraction system, matching with the solenoid channel and progress on the ring’s main hardware systems like RF and kicker magnet are discussed. The progress and future directions of the study are presented in this paper.
The value of the anomalous magnetic moment of the muon measured at Brookhaven National Lab disagrees with that predicted by the Standard Model by more than three standard deviations. This raises the prospects of discovering physics beyond the Standard Model if this discrepancy can be substantially verified. The uncertainty on the Standard Model result is dominated by hadronic corrections. The leading correction is currently estimated by a dispersive analysis of experimental measurements, but recent results have demonstrated that a fully theoretical and nonperturbative determination of this contribution can be obtained using the methods of lattice QCD. I will review the latest lattice calculations and discuss the prospects for a precise determination of the leading QCD correction to the muon g-2.
The PIP-II proton accelerator will provide the intensity sufficient to power a new generation of high energy facilities at Fermilab. Extension of that linac to higher energy with following acceleration and bunching rings could provide the intensity needed to feed a muon production target for a high-energy $\mu^{+} - \mu^{-}$ collider. Scenarios using a rapid-cycling synchrotron or an $\sim$8 GeV Linac are presented and discussed. Some near-term opportunities at Fermilab for muon collider R\&D are introduced.
The production of high-intensity muon beams is crucial for advancing particle and accelerator physics, both now and in the future. Achieving these high-intensity goals requires overcoming significant challenges in high-power targetry. Here, we will outline the key challenges and explore the selection of target materials, focusing on muon production and susceptibility to radiation damage -- key factors for optimal target designs.
Charged-lepton flavor violation (cLFV) is one of the most powerful probes for New Physics (NP). Since lepton flavor conservation is an accidental symmetry in the Standard Model (SM), it is naturally violated in many NP models, with contributions at the level of the current experimental sensitivities. Moreover, the negligible SM contributions would make the observation of cLFV unambiguous evidence of NP. It makes these searches extremely sensitive and, at the same time, extremely pure. Thanks to the intense muon beams currently available, their intriguing upgrade programs, and the progress in the detection techniques, cLFV muon processes are the golden channels in this field. Experimental programs to search for $\mu^+ \to e^+ \gamma$, $\mu^+ \to e^+ e^+ e^-$ and the $\mu \to e$ conversion in the nuclear field are currently ongoing. We review the current status and the strategic plans for future searches. This document is an update of the prior cLFV submission to the 2018 European Strategy for Particle Physics (ESPP); the earlier submission should be consulted for more experimental details.