Search Results (259)

The MicroBooNE liquid argon time projection chamber experiment is pursuing a broad range of neutrino physics measurements, including some of the first high-statistics results for neutrino–argon scattering cross-sections. At the neutrino energies relevant for MicroBooNE and its companion experiments in the Fermilab Short-Baseline Neutrino program, the dominant event topology involves mesonless final states containing one or more protons. A complete description of these events requires modeling the contributions of quasielastic and two-particle, two-hole neutrino interactions, as well as more inelastic reaction modes in which final state pions are reabsorbed by the residual nucleus. Refinements to the current understanding of these processes, informed by new neutrino cross-section data, will enable a precise and reliable interpretation of future measurements of neutrino oscillations and searches for exotic physics processes involving neutrinos. This proceeding presents the first double-differential cross-section results from MicroBooNE for mesonless charged current scattering of muon neutrinos on argon. Full article

In many modern particle physics experiments, high-rate data handling is one of the most critical challenges due to the increase in particle intensity required to achieve higher statistics. We will tackle the challenge in the COMET experiment by developing the sub-microseconds ultra-fast machine learning (ML) algorithm implemented inside FPGAs to search for the lepton flavour violation process, a $\mu$-e conversion, using the world’s most intense muon beam. Our previous study showed that a trigger algorithm based on a gradient-boosted decision tree will realise the sufficient trigger performance within 3.2 $\mathsf{\mu }$s with a cut-based event classification. In this paper, we further investigated neural network algorithms as event classifications. For the feasibility test, a multi-layer perceptron (MLP) model was implemented inside the FPGA, and the preliminary results are presented. Full article

The observation of lepton flavour violation (LFV) in the charged lepton sector would be an unambiguous sign of physics beyond the Standard Model (BSM), and thus, it is the channel of choice for many BSM searches. LFV searches in muon decays in particular benefit from the fact that muons can be easily produced at high rates. There is a global effort to search for LFV at high-intensity muon sources to which the upcoming Mu3e experiment at the Paul Scherrer Institute (PSI) will contribute. The Mu3e Collaboration aims to perform a background-free search for the LFV decay ${\mu }^{+}\to e^{+}{e}^{-}{e}^{+}$ with an unprecedented sensitivity in the order of 10⁻¹⁵ in the first phase of operation and 10⁻¹⁶ in the final phase—an improvement over the preceding SINDRUM experiment by four orders of magnitude. The high muon stopping rates and low momenta of the decay electrons make high demands on momentum and time resolution and on the data acquisition. The innovative experimental concept is based on a tracking detector built from novel ultra-thin silicon pixel sensors and scintillating fibres and tiles as well as online event reconstruction and filtering in real time. Full article

Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton liquid scintillator-based neutrino experiment, being built in the Guangdong province in Southern China. JUNO will act as a multipurpose observatory for neutrinos produced by artificial and natural sources. The detector calibration is a crucial and challenging tile for the success of the JUNO rich physics programme; its strategy is based on the periodical deployment of radioactive sources within the liquid scintillator. The hardware design consists of several independent and low-background subsystems able to deploy the sources in multiple positions, to optimize the energy resolution and to provide a detailed assessment of the detector energy response. By exploiting this comprehensive calibration program, along with a dual calorimetry technique based on two independent photosensor systems, the JUNO central detector will be able to achieve a better than 1% energy linearity and a 3% effective energy resolution, which are crucial requirements for the neutrino mass ordering determination. In the following, the JUNO calibration strategy and requirements, along with the system hardware design and the simulation results, will be outlined. Full article

Long-baseline neutrino oscillation experiments rely on detailed models of neutrino interactions on nuclei. These models constitute an important source of systematic uncertainty, partially because detectors to date have been unable to detect final state neutrons. A novel three-dimensional projection scintillator tracker will be a component of the upgraded off-axis near detector of the T2K experiment. Due to the good timing resolution and fine granularity, this technology is capable of measuring neutron kinematics in neutrino interactions on an event-by-event basis and will provide valuable data for refining neutrino interaction models. A prototype is exposed to the neutron beamline at Los Alamos National Laboratory with neutron energies between 0 and 800 MeV. In order to demonstrate the capability to measure neutron kinematics, the total neutron–scintillator cross section as a function of the neutron kinetic energy is measured. Full article

The discovery of neutrino oscillations is the first laboratory evidence of New Physics beyond the Standard Model. Oscillating neutrinos necessarily imply that neutrinos are massive and that (neutral) lepton flavour is violated. However, a signal of charged lepton flavour violation (cLFV) has so far eluded experimental discovery. In this proceeding, we review some phenomenological implications of the current experimental bounds (and future sensitivities) on observables related to muons, with particular attention to charged lepton flavour violating processes. In connection to neutrino masses, we also highlight some phenomenological implications of leptonic CP violation on cLFV observables. Full article

We discuss the phenomenology of dark-sector signals coming not only from the conventionally-used neutral meson decays but also from recently-realized charged-meson decays. We argue that charged mesons can be overlooked even though there are efficient sources of dark-sector particles. Two applications are presented: a dark-sector interpretation of the MiniBooNE excess and an anomalous appearance of ${\nu }_{\tau }$ in the near detector of beam-focused neutrino experiments. Full article

The IceCube detector is particularly sensitive to high-energy neutrinos due to its size and photosensor spacing. In this review we present results from the search for dark matter in the sun and earth, including a search for dark matter that annihilates into a metastable mediator that subsequently decays into standard model particles and a search for solar atmospheric neutrinos that present a significant background to solar dark matter searches. We present the results from different searches for dark matter in the sun and the earth in this proceeding paper. Full article

The Jiangmen Underground Neutrino Observatory (JUNO) is a neutrino experiment under construction in an underground laboratory with a 650 m rock overburden near Jiangmen in southern China. The detector’s main component will be 20 kton of liquid scintillator held in a spherical acrylic vessel. The experiment is designed for the determination of neutrino mass ordering, one of the key open questions in neutrino physics. This measurement will be based on observations of the vacuum oscillation pattern of antineutrinos from two nuclear power plants at a baseline of 53 km. The estimated sensitivity is 3$\sigma$ in about six years with 26.6 GW${}_{\mathrm{th}}$ of reactor power. A key ingredient for the success is an excellent and extremely challenging energy resolution of 3% at 1 MeV. The light produced by the scintillator will be seen by 17,612 large twenty-inch PMTs and 25,600 small three-inch PMTs. The OSIRIS detector will monitor the radio purity of the liquid scintillator during the months-long filling process of the main detector. The unoscillated antineutrino spectrum from one reactor core will be measured with unprecedented precision by the Taishan Antineutrino Observatory (TAO), located at a baseline of about 30 m. JUNO is expected to substantially improve the precision of ${sin}^{2}2{\theta }_{12}$, $\Delta m_{21}^2$, and $\Delta m_{31}^2$ neutrino oscillation parameters. Astrophysical measurements of solar, geo-, supernova, DSNB, and atmospheric neutrinos, as well as searching for proton decay and dark matter, are integral parts of the vast JUNO physics program. This contribution reviews the physics goals and current status of the JUNO project. Full article

We performed beam studies with a cycling period of 1.36 s in the main ring synchrotron (MR) of Japan Proton Accelerator Research Complex (J-PARC) after hardware upgrade to enable high repetition operation. After optics tuning, we have successfully controlled the beam with an intensity of $2.7\times {10}^{13}$ protons per bunch, corresponding to a beam power of 740 kW considering the beam survival ratio, during the beam injection period. We have verified the beam optics for the 740 kW FX operation. Split quadrupole families caused three-fold symmetry breaking of the beam optics, resulting in deterioration of the beam survivals. We are planning further beam loss reduction by adding correction quadrupole magnetic fields and recovering the three-fold symmetry. Full article

Monitored neutrino beams are facilities where beam diagnostics enable the counting and identification of charged leptons in the decay tunnel of a narrow band beam. These facilities can monitor neutrino production at the single particle level (flux precision $<1$%) and provide information about the neutrino energy at the 10% level. The ENUBET Collaboration has demonstrated that lepton monitoring might be achieved not only by employing kaon decays but also by identifying muons from the ${\pi }^{+}\to {\mu }^{+}{\nu }_{\mu }$ decays and positrons from the decay-in-flight of muons before the hadron dump. As a consequence, beam monitoring can be performed using the ENUBET technique even when the kaon production yield is kinematically suppressed. This finding opens up a wealth of opportunities for measuring neutrino cross-sections below 1 GeV. In this paper, we investigate this opportunity at the European Spallation Source (ESS), which is an ideal facility to measure ${\nu }_{\mu }$ and ${\nu }_e$ cross-sections in the 0.2–1 GeV range. We also describe the planned activities for the design of this beam at the ESS within the framework of the ESS$\nu$SB+ design study, which was approved by the EU in July 2022. Full article

The Short-Baseline Near Detector (SBND) will be one of three Liquid Argon Time Projection Chamber (LArTPC) neutrino detectors positioned along the axis of the Booster Neutrino Beam (BNB) at Fermilab, as part of the Short-Baseline Neutrino (SBN) Program. The detector is currently in the construction phase and is anticipated to begin operation in 2023. SBND is characterized by superb imaging capabilities and will record over a million neutrino interactions per year. Thanks to its unique combination of measurement resolution and statistics, SBND will carry out a rich program of neutrino interaction measurements and novel searches for physics beyond the Standard Model (BSM). It will enable the potential of the overall SBN sterile neutrino program by performing a precise characterization of the unoscillated event rate, and by constraining BNB flux and neutrino–argon cross-section systematic uncertainties. In this proceedings article, the physics reach, current status, and future prospects of SBND are discussed. Full article

The IsoDAR neutrino source comprises a novel compact cyclotron capable of delivering 10 mA of 60 MeV protons in cw mode and a high-power neutrino production target. It has obtained preliminary approval to run at the new underground facility Yemilab in South Korea. IsoDAR will produce a very pure, isotropic ${\overline{\nu }}_e$ source, with a peak neutrino energy of around 6 MeV and an endpoint around 15 MeV. Paired with a kton-scale detector like the planned Liquid Scintillator Counter (LSC) at Yemilab, IsoDAR can measure ${\overline{\nu }}_e$ disappearance through the inverse beta decay (IBD) channel. We expect about $1.67·{10}^6$ IBD events and 7000 ${\overline{\nu }}_e$ – e${}^{-}$ elastic scatter events in the LSC in five years of running, letting us distinguish many different models for noble (aka sterile) neutrinos and significantly improving existing limits for Non-Standard Interactions (NSIs). Finally, [email protected] is sensitive to new particles produced in the target (such as light X bosons that decay to ${\overline{\nu }}_e$${\nu }_e$). We describe the accelerator developments for IsoDAR that enable us to produce about a mole of neutrinos in five years of running. These include direct injection through a radiofrequency quadrupole, exploiting complex beam dynamics, and applying machine learning in accelerator design and optimization. Full article

The detection and cross-section measurement of Coherent Elastic Neutrino–Nucleus Scattering (CEvNS) are vital for particle physics, astrophysics, and nuclear physics. Therefore, a new CEvNS detection experiment is proposed in China. Undoped CsI crystals, each coupled with two Photon Multiplier Tubes (PMTs), will be cooled down to 77 K and placed at the China Spallation Neutron Source (CSNS) to detect the CEvNS signals produced by neutrinos from stopped pion decays occurring within the Tungsten target of CSNS. Owing to the extremely high light yield of pure CsI at 77 K, even though it only has a neutrino flux 60% weaker than the COHERENT experiment, the detectable signal event rate is still expected to be 0.074/day/kg (0.053/day/kg for COHERENT). Low-radioactivity materials and devices will be used to construct the detector, and strong shielding will be applied to reduce the radioactive and neutron background. Dual-PMT readout should be able to reject PMT dark count background. Using all the strategies mentioned above, we hope to reach a 5.1$\sigma$ signal detection significance within six months of data collection with four 3 kg CsI. This paper will discuss the experiment’s design, as well as the estimation of the signal, various kinds of background, and expected signal sensitivity. Full article

The muon anomalous magnetic moment ($g-2$) measurement at the Fermilab National Accelerator Laboratory (FNAL-E989) is consistent with a previous experiment at the Brookhaven National Laboratory (BNL-E821), and these results show a deviation of 4.2 standard deviations from the prediction of the Standard Model. This deviation may suggest the existence of unknown particles, and a completely different approach from previous experiments is needed for further verification. The J-PARC experiment’s objective is to measure the muon g-2 and the electric dipole moment (EDM) with high precision using a new method with a low-emittance muon beam generated by RF linear acceleration. In this paper, the development of an interdigital H-mode drift tube linac (IH-DTL) for the muon linear accelerator is described. Full article