arXiv subjects

M. Yeh

Publications and source records attributed to M. Yeh.

At least 91 records · Page 5Linked to original sources

arXiv2016

Status Report (22th J-PARC PAC): Searching for a Sterile Neutrino at J-PARC MLF (E56, JSNS2)

The JSNS$^2$ (J-PARC E56) experiment aims to search for a sterile neutrino at the J-PARC Materials and Life Sciences Experimental Facility (MLF). After the submission of a proposal to the J-PARC PAC, Stage-1 approval was granted to the JSNS$^2$ experiment on April 2015.This approval followed a series of background measurements which were performed in 2014. Recently, funding (the grant-in-aid for scientific research (S)) in Japan for building one 25~ton fiducial volume detector module was approved for the experiment. Therefore, we aim to start the experiment with one detector in JFY2018-2019. We are now working to produce precise cost estimates and schedule for construction, noting that most of the detector components can be produced within one year from the date of order. This will be reported at the next PAC meeting. In parallel to the detector construction schedule, JSNS$^2$ will submit a Technical Design report (TDR) to obtain the Stage-2 approval from the J-PARC PAC.The recent progress of the R$\&$D efforts towards this TDR are shown in this report. In particular, the R$\&$D status of the liquid scintillator, cosmic ray veto system, and software are shown. We have performed a test-experiment using 1.6~L of liquid scintillator at the 3rd floor of the MLF building in order to determine the identities of non-neutrino background particles coming to this detector location during the proton bunch. This is the so-called "MLF 2015AU0001" experiment. We briefly show preliminary results from this test-experiment.

physics.ins-det↗

arXiv2016

Measurement of $α$-particle quenching in LAB based scintillator in independent small-scale experiments

The $α$-particle light response of liquid scintillators based on linear alkylbenzene (LAB) has been measured with three different experimental approaches. In the first approach, $α$-particles were produced in the scintillator via $^{12}$C($n$,$α$)$^9$Be reactions. In the second approach, the scintillator was loaded with 2% of $^{\mathrm{nat}}$Sm providing an $α$-emitter, $^{147}$Sm, as an internal source. In the third approach, a scintillator flask was deployed into the water-filled SNO+ detector and the radioactive contaminants $^{222}$Rn, $^{218}$Po and $^{214}$Po provided the $α$-particle signal. The behavior of the observed $α$-particle light outputs are in agreement with each case successfully described by Birks' law. The resulting Birks parameter $kB$ ranges from $(0.0066\pm0.0016)$ cm/MeV to $(0.0076\pm0.0003)$ cm/MeV. In the first approach, the $α$-particle light response was measured simultaneously with the light response of recoil protons produced via neutron-proton elastic scattering. This enabled a first time a direct comparison of $kB$ describing the proton and the $α$-particle response of LAB based scintillator. The observed $kB$ values describing the two light response functions deviate by more than $5σ$. The presented results are valuable for all current and future detectors, using LAB based scintillator as target, since they depend on an accurate knowledge of the scintillator response to different particles.

physics.ins-det↗

arXiv2016

Status Report for the 21th J-PARC PAC : Searching for a Sterile Neutrino at J-PARC MLF (J-PARC E56, JSNS2)

The JSNS2 (J-PARC E56) experiment aims to search for sterile neutrinos at the J-PARC Materials and Life Sciences Experimental Facility (MLF).After the submission of a proposal to the J-PARC PAC, stage-1 approval was granted to the JSNS2 experiment. The approval followed a series of background measurements which were performed in 2014. Subsequent for stage-1 approval, the JSNS2 collaboration has made continuous efforts to write a Technical Design Report (TDR).This TDR will include two major items as discussed in the previous status report for the 20th J-PARC PAC: (1) A realistic detector location (2) Well understood and realistic detector performance using simulation studies, primarily in consideration of fast neutron rejection. Since August we have been in discussions with MLF staff regarding an appropriate detector location. We are also in the process of setting up a Monte Carlo (MC) simulation framework in order to study detector's performance in realistic conditions. In addition, we have pursued hardware R&D work for the liquid scintillator (LS) and to improve the dynamic range of the 10" photomultiplier tubes (PMTs). The LS R&D works includes Cherenkov studies inside the LS, and a Pulse Shape Discrimination (PSD) study with a test-beam, performed at Tohoku University. We also estimate the PSD performance of a full-sized detector using a detailed MC simulation. In this status report, we describe progress on this work.

physics.ins-det↗

arXiv2015

The PROSPECT Physics Program

The Precision Reactor Oscillation and Spectrum Experiment, PROSPECT, is designed to make a precise measurement of the antineutrino spectrum from a highly-enriched uranium reactor and probe eV-scale sterile neutrinos by searching for neutrino oscillations over meter-long distances. PROSPECT is conceived as a 2-phase experiment utilizing segmented $^6$Li-doped liquid scintillator detectors for both efficient detection of reactor antineutrinos through the inverse beta decay reaction and excellent background discrimination. PROSPECT Phase I consists of a movable 3-ton antineutrino detector at distances of 7 - 12 m from the reactor core. It will probe the best-fit point of the $ν_e$ disappearance experiments at 4$σ$ in 1 year and the favored region of the sterile neutrino parameter space at $>$3$σ$ in 3 years. With a second antineutrino detector at 15 - 19 m from the reactor, Phase II of PROSPECT can probe the entire allowed parameter space below 10 eV$^{2}$ at 5$σ$ in 3 additional years. The measurement of the reactor antineutrino spectrum and the search for short-baseline oscillations with PROSPECT will test the origin of the spectral deviations observed in recent $θ_{13}$ experiments, search for sterile neutrinos, and conclusively address the hypothesis of sterile neutrinos as an explanation of the reactor anomaly.

physics.ins-det↗

arXiv2015

Background Radiation Measurements at High Power Research Reactors

Research reactors host a wide range of activities that make use of the intense neutron fluxes generated at these facilities. Recent interest in performing measurements with relatively low event rates, e.g. reactor antineutrino detection, at these facilities necessitates a detailed understanding of background radiation fields. Both reactor-correlated and naturally occurring background sources are potentially important, even at levels well below those of importance for typical activities. Here we describe a comprehensive series of background assessments at three high-power research reactors, including $γ$-ray, neutron, and muon measurements. For each facility we describe the characteristics and identify the sources of the background fields encountered. The general understanding gained of background production mechanisms and their relationship to facility features will prove valuable for the planning of any sensitive measurement conducted therein.

physics.ins-det↗

arXiv2015

Light Collection and Pulse-Shape Discrimination in Elongated Scintillator Cells for the PROSPECT Reactor Antineutrino Experiment

A meter-long, 23-liter EJ-309 liquid scintillator detector has been constructed to study the light collection and pulse-shape discrimination performance of elongated scintillator cells for the PROSPECT reactor antineutrino experiment. The magnitude and uniformity of light collection and neutron/gamma discrimination power in the energy range of antineutrino inverse beta decay products have been studied using gamma and spontaneous fission calibration sources deployed along the cell long axis. We also study neutron-gamma discrimination and light collection abilities for differing PMT and reflector configurations. Key design features for optimizing MeV-scale response and background rejection capabilities are identified.

physics.ins-det↗

arXiv2015

Status Report for the 20th J-PARC PAC : A Search for Sterile Neutrino at J-PARC MLF (J-PARC E56, JSNS2)

On April 2015, the J-PARC E56 (JSNS2: J-PARC Sterile Neutrino Search using neutrinos from J-PARC Spallation Neutron Source) experiment officially obtained stage-1 approval from J-PARC. We have since started to perform liquid scintillator R&D for improving energy resolution and fast neutron rejection. Also, we are studying Avalanche Photo-Diodes (SiPM) inside the liquid scintillator. In addition to the R&D work, a background measurement for the proton beam bunch timing using a small liquid scintillator volume was planned, and the safety discussions for the measurement have been done. This report describes the status of the R&D work and the background measurements, in addition to the milestones required before stage-2 approval.

physics.ins-det↗

arXiv2015

Letter of Intent: The Accelerator Neutrino Neutron Interaction Experiment (ANNIE)

Neutron tagging in Gadolinium-doped water may play a significant role in reducing backgrounds from atmospheric neutrinos in next generation proton-decay searches using megaton-scale Water Cherenkov detectors. Similar techniques might also be useful in the detection of supernova neutrinos. Accurate determination of neutron tagging efficiencies will require a detailed understanding of the number of neutrons produced by neutrino interactions in water as a function of momentum transferred. We propose the Atmospheric Neutrino Neutron Interaction Experiment (ANNIE), designed to measure the neutron yield of atmospheric neutrino interactions in gadolinium-doped water. An innovative aspect of the ANNIE design is the use of precision timing to localize interaction vertices in the small fiducial volume of the detector. We propose to achieve this by using early production of LAPPDs (Large Area Picosecond Photodetectors). This experiment will be a first application of these devices demonstrating their feasibility for Water Cherenkov neutrino detectors.

physics.ins-det↗

arXiv2015

Status Report (BKG measurement): A Search for Sterile Neutrino at J-PARC MLF

At the 17th J-PARC PAC, which was held on September 2013, we proposed the sterile neutrino search at J-PARC MLF. After reviewing the proposal, PAC recommended to have a background measurement at the detector's candidate site location in their report to investigate whether the background rates can be manageable for the real experiment or not. Therefore, we have performed the background measurements (MLF; 2013BU1301 test experiment) during the summer of 2014, also following the 18th J-PARC PAC recommendations, and the measurements results are described here.

physics.ins-det↗

arXiv2015

The Physics and Nuclear Nonproliferation Goals of WATCHMAN: A WAter CHerenkov Monitor for ANtineutrinos

This article describes the physics and nonproliferation goals of WATCHMAN, the WAter Cherenkov Monitor for ANtineutrinos. The baseline WATCHMAN design is a kiloton scale gadolinium-doped (Gd) light water Cherenkov detector, placed 13 kilometers from a civil nuclear reactor in the United States. In its first deployment phase, WATCHMAN will be used to remotely detect a change in the operational status of the reactor, providing a first- ever demonstration of the potential of large Gd-doped water detectors for remote reactor monitoring for future international nuclear nonproliferation applications. During its first phase, the detector will provide a critical large-scale test of the ability to tag neutrons and thus distinguish low energy electron neutrinos and antineutrinos. This would make WATCHMAN the only detector capable of providing both direction and flavor identification of supernova neutrinos. It would also be the third largest supernova detector, and the largest underground in the western hemisphere. In a follow-on phase incorporating the IsoDAR neutrino beam, the detector would have world-class sensitivity to sterile neutrino signatures and to non-standard electroweak interactions (NSI). WATCHMAN will also be a major, U.S. based integration platform for a host of technologies relevant for the Long-Baseline Neutrino Facility (LBNF) and other future large detectors. This white paper describes the WATCHMAN conceptual design,and presents the results of detailed simulations of sensitivity for the project's nonproliferation and physics goals. It also describes the advanced technologies to be used in WATCHMAN, including high quantum efficiency photomultipliers, Water-Based Liquid Scintillator (WbLS), picosecond light sensors such as the Large Area Picosecond Photo Detector (LAPPD), and advanced pattern recognition and particle identification methods.

physics.ins-det↗

arXiv2015

PROSPECT - A Precision Reactor Oscillation and Spectrum Experiment at Short Baselines

Current models of antineutrino production in nuclear reactors predict detection rates and spectra at odds with the existing body of direct reactor antineutrino measurements. High-resolution antineutrino detectors operated close to compact research reactor cores can produce new precision measurements useful in testing explanations for these observed discrepancies involving underlying nuclear or new physics. Absolute measurement of the 235U-produced antineutrino spectrum can provide additional constraints for evaluating the accuracy of current and future reactor models, while relative measurements of spectral distortion between differing baselines can be used to search for oscillations arising from the existence of eV-scale sterile neutrinos. Such a measurement can be performed in the United States at several highly-enriched uranium fueled research reactors using near-surface segmented liquid scintillator detectors. We describe here the conceptual design and physics potential of the PROSPECT experiment, a U.S.-based, multi-phase experiment with reactor-detector baselines of 7-20 meters capable of addressing these and other physics and detector development goals. Current R&D status and future plans for PROSPECT detector deployment and data-taking at the High Flux Isotope Reactor at Oak Ridge National Laboratory will be discussed.

physics.ins-det↗

arXiv2014

Advanced Scintillator Detector Concept (ASDC): A Concept Paper on the Physics Potential of Water-Based Liquid Scintillator

The recent development of Water-based Liquid Scintillator (WbLS), and the concurrent development of high-efficiency and high-precision-timing light sensors, has opened up the possibility for a new kind of large-scale detector capable of a very broad program of physics. The program would include determination of the neutrino mass hierarchy and observation of CP violation with long-baseline neutrinos, searches for proton decay, ultra-precise solar neutrino measurements, geo- and supernova neutrinos including diffuse supernova antineutrinos, and neutrinoless double beta decay. We outline here the basic requirements of the Advanced Scintillation Detector Concept (ASDC), which combines the use of WbLS, doping with a number of potential isotopes for a range of physics goals, high efficiency and ultra-fast timing photosensors, and a deep underground location. We are considering such a detector at the Long Baseline Neutrino Facility (LBNF) far site, where the ASDC could operate in conjunction with the liquid argon tracking detector proposed by the LBNE collaboration. The goal is the deployment of a 30-100 kiloton-scale detector, the basic elements of which are being developed now in experiments such as WATCHMAN, ANNIE, SNO+, and EGADS.

physics.ins-det↗

arXiv2014

The Water Purification System for the Daya Bay Reactor Neutrino Experiment

We describe the design, installation, and operation of a purification system that is able to provide large volumes of high purity ASTM (D1193-91) Type-I water to a high energy physics experiment. The water environment is underground in a lightly sealed system, and this provides significant challenges to maintaining high purity in the storage pools, each of which contains several thousand cubic meters. High purity is dictated by the need for large optical absorption length, which is critical for the operation of the experiment. The system is largely successful, and the water clarity criteria are met. We also include a discussion of lessons learned.

physics.ins-det↗

arXiv2014

Expression of Interest: The Atmospheric Neutrino Neutron Interaction Experiment (ANNIE)

physics.ins-det↗

arXiv2013

The OscSNS White Paper

There exists a need to address and resolve the growing evidence for short-baseline neutrino oscillations and the possible existence of sterile neutrinos. Such non-standard particles require a mass of $\sim 1$ eV/c$^2$, far above the mass scale associated with active neutrinos, and were first invoked to explain the LSND $\bar ν_μ\rightarrow \bar ν_e$ appearance signal. More recently, the MiniBooNE experiment has reported a $2.8 σ$ excess of events in antineutrino mode consistent with neutrino oscillations and with the LSND antineutrino appearance signal. MiniBooNE also observed a $3.4 σ$ excess of events in their neutrino mode data. Lower than expected neutrino-induced event rates using calibrated radioactive sources and nuclear reactors can also be explained by the existence of sterile neutrinos. Fits to the world's neutrino and antineutrino data are consistent with sterile neutrinos at this $\sim 1$ eV/c$^2$ mass scale, although there is some tension between measurements from disappearance and appearance experiments. In addition to resolving this potential major extension of the Standard Model, the existence of sterile neutrinos will impact design and planning for all future neutrino experiments. It should be an extremely high priority to conclusively establish if such unexpected light sterile neutrinos exist. The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, built to usher in a new era in neutron research, provides a unique opportunity for US science to perform a definitive world-class search for sterile neutrinos.

physics.ins-det↗

arXiv2013

Proposal: A Search for Sterile Neutrino at J-PARC Materials and Life Science Experimental Facility

We propose a definite search for sterile neutrinos at the J-PARC Materials and Life Science Experimental Facility (MLF). With the 3 GeV Rapid Cycling Synchrotron (RCS) and spallation neutron target, an intense neutrino beam from muon decay at rest (DAR) is available. Neutrinos come from μ+ decay, and the oscillation to be searched for is (anti νμ-> anti νe) which is detected by the inverse βdecay interaction (anti νe + p -> e+ + n), followed by a gamma from neutron capture. The unique features of the proposed experiment, compared with the LSND and experiments using horn focused beams, are; (1) The pulsed beam with about 600 ns spill width from J-PARC RCS and muon long lifetime allow us to select neutrinos from μDAR only. (2) Due to nuclear absorption of π- and μ-, neutrinos from μ- decay are suppressed to about the $10^{-3}$ level. (3) Neutrino cross sections are well known. The inverse βdecay cross section is known to be a few percent accuracy. (4) The neutrino energy can be calculated from positron energy by adding ~1.8 MeV. (5) The anti νμand νe fluxes have different and well defined spectra. This allows us to separate oscillated signals from those due to μ- decay contamination. We propose to proceed with the oscillation search in steps since the region of Δm^2 to be searched can be anywhere between sub-eV^2 to several tens of eV^2. We start to examine the large Δm^2 region, which can be done with short baseline at first. At close distance to the MLF target gives a high neutrino flux, and allows us to use relatively small detector. If no definitive positive signal is found, a future option exists to cover small Δm^2 region. This needs a relatively long baseline and requires a large detector to compensate for the reduced neutrino flux.

physics.ins-det↗

arXiv2013

Neutrino mass hierarchy determination and other physics potential of medium-baseline reactor neutrino oscillation experiments

Medium-baseline reactor neutrino oscillation experiments (MBRO) have been proposed to determine the neutrino mass hierarchy (MH) and to make precise measurements of the neutrino oscillation parameters. With sufficient statistics, better than ~3%/\sqrt{E} energy resolution and well understood energy non-linearity, MH can be determined by analyzing oscillation signals driven by the atmospheric mass-squared difference in the survival spectrum of reactor antineutrinos. With such high performance MBRO detectors, oscillation parameters, such as \sin^22θ_{12}, Δm^2_{21}, and Δm^2_{32}, can be measured to sub-percent level, which enables a future test of the PMNS matrix unitarity to ~1% level and helps the forthcoming neutrinoless double beta decay experiments to constrain the allowed values. Combined with results from the next generation long-baseline beam neutrino and atmospheric neutrino oscillation experiments, the MH determination sensitivity can reach higher levels. In addition to the neutrino oscillation physics, MBRO detectors can also be utilized to study geoneutrinos, astrophysical neutrinos and proton decay. We propose to start a U.S. R&D program to identify, quantify and fulfill the key challenges essential for the success of MBRO experiments.

hep-ex↗

arXiv2013

Light-weight Flexible Magnetic Shields For Large-Aperture Photomultiplier Tubes

Thin flexible sheets of high-permeability FINEMET foils encased in thin plastic layers have been used to shield various types of 20-cm-diameter photomultiplier tubes from ambient magnetic fields. In the presence of the Earth's magnetic field this type of shielding is shown to increase the collection efficiency of photoelectrons and can improve the uniformity of response of these photomultiplier tubes.

physics.ins-det↗