arXiv subjects
Publications and source records attributed to B. Viren.
We report new constraints on flavor-changing non-standard neutrino interactions (NSI) using data from the MINOS experiment. We analyzed a combined set of beam neutrino and antineutrino data, and found no evidence for deviations from standard neutrino mixing. The observed energy spectra constrain the NSI parameter to the range $-0.20 < \varepsilon_{μτ} < 0.07\;\text{(90% C.L.)}$
With the discovery of a modest size for the mixing angle $θ_{13} \sim 9^\circ$ by the Daya Bay collaboration at $>$5 sigma (\cite{dayabay}) the science of neutrino oscillations has shifted to explicit demonstration of CP violation and precision determination of the CP phase in the 3-flavor framework. Any additional contributions from new physics to the oscillation channel $ν_μ\to ν_e$ could be uncovered by multiple constraints in the ($θ_{13}, δ_{CP}$) parameter space. In long-baseline experiments such constraints will require examination of the oscillation strength at higher $L/E$ where the effects of CP violation will be large. For the fixed baseline of 1300 km for the Long-Baseline Neutrino Experiment (LBNE, Fermilab to Homestake), it will be important to examine oscillations at low energies ($<1.5$ GeV) with good statistics, low backgrounds, and excellent energy resolution. The accelerator upgrades in the Project-X era have the potential to offer the beams of the needed intensity and quality for this advanced science program. In this paper we examine the event rates for high intensity, low energy running of Project-X and the Fermilab Main Injector complex, and the precision in the ($θ_{13}, δ_{CP}$) space. In this paper we have examined the baseline distance of 1300 km in detail, however we point out that much longer distances such as 2500 km should also be exmained with a beam from FNAL in light of the new understanding of the neutrino mixing.
We report the first observation of off-axis neutrino interactions in the MiniBooNE detector from the NuMI beamline at Fermilab. The MiniBooNE detector is located 745 m from the NuMI production target, at 110 mrad angle ($6.3^{\circ}$) with respect to the NuMI beam axis. Samples of charged current quasi-elastic $ν_μ$ and $ν_e$ interactions are analyzed and found to be in agreement with expectation. This provides a direct verification of the expected pion and kaon contributions to the neutrino flux and validates the modeling of the NuMI off-axis beam.
Experiment E949 at Brookhaven National Laboratory has observed three new events consistent with the decay K+ => pi+,nu,nubar in the pion momentum region 140 < P_pi < 199 MeV/c in an exposure of 1.71e12 stopped kaons with an estimated total background of 0.93+-0.17(stat.)+0.32-0.24(syst.) events. This brings the total number of observed K+ => pi+,nu,nubar events to seven. Combining this observation with previous results, assuming the pion spectrum predicted by the standard model, results in a branching ratio of (1.73+1.15-1.05)e-10. An interpretation of the results for alternative models of the decay K^ => pi+,nothing is also presented.
This report provides the results of an extensive and important study of the potential for a U.S. scientific program that will extend our knowledge of neutrino oscillations well beyond what can be anticipated from ongoing and planned experiments worldwide. The program examined here has the potential to provide the U.S. particle physics community with world leading experimental capability in this intensely interesting and active field of fundamental research. Furthermore, this capability could be unique compared to anywhere else in the world because of the available beam intensity and baseline distances. The present study was initially commissioned in April 2006 by top research officers of Brookhaven National Laboratory and Fermi National Accelerator Laboratory and, as the study evolved, it also provided responses to questions formulated and addressed to the study group by the Neutrino Scientific Advisory Committee (NuSAG) of the U.S. DOE and NSF. The participants in the study, its Charge and history, plus the study results and conclusions are provided in this report and its appendices. A summary of the conclusions is provided in the Executive Summary.
We carry out a state-of-the-art assessment of long baseline neutrino oscillation experiments with wide band beams. We describe the feasibility of an experimental program using existing high energy accelerator facilities, a new intense wide band neutrino beam (0-6 GeV) and a proposed large detector in a deep underground laboratory. We find that a decade-long program with 1 MW operation in the neutrino mode and 2 MW operation in the antineutrino mode, a baseline as long as the distance between Fermilab and the Homestake mine (1300 km) or the Henderson mine (1500 km), and a water Cherenkov detector with fiducial mass of about 300 kT has optimum sensitivity to θ_{13}, the mass hierarchy and to neutrino CP violation at the 3σC.L. for \sin^22θ_{13}>0.008. This program is capable of breaking the eight-fold degeneracy down to the octant degeneracy without additional external input.
The Neutrinos at the Main Injector (NuMI) facility is a conventional horn-focused neutrino beam which produces muon neutrinos from a beam of mesons directed into a long evacuated decay volume. The relative alignment of the primary proton beam, target, and focusing horns affects the neutrino energy spectrum delivered to experiments. This paper describes a check of the alignment of these components using the proton beam.
Neutrino interaction rates for experiments placed off axis in the NuMI beam are calculated. Primary proton beam energy is 120 GeV and four locations at 810 km from target and 6, 12, 30 and 40 km off axis are considered. This report is part of the Joint FNAL/BNL Future Long Baseline Neutrino Oscillation Experiment Study.
The Neutrinos at the Main Injector (NuMI) facility is a conventional neutrino beam which produces muon neutrinos by focusing a beam of mesons into a long evacuated decay volume. We have built four arrays of ionization chambers to monitor the position and intensity of the hadron and muon beams associated with neutrino production at locations downstream of the decay volume. This article describes the chambers' construction, calibration, and commissioning in the beam.
The Neutrinos at the Main Injector (NuMI) beamline will deliver an intense muon neutrino beam by focusing a beam of mesons into a long evacuated decay volume. We have built 4 arrays of ionization chambers to monitor the neutrino beam direction and quality. The arrays are located at 4 stations downstream of the decay volume, and measure the remnant hadron beam and tertiary muons produced along with neutrinos in meson decays.
The Neutrinos at the Main Injector (NuMI) beamline will deliver an intense muon neutrino beam by focusing a beam of mesons into a long evacuated decay volume. The beam must be steered with 1 mRad angular accuracy toward the Soudan Underground Laboratory in northern Minnesota. We have built 4 arrays of ionization chambers to monitor the neutrino beam direction and quality. The arrays are located at 4 stations downstream of the decay volume, and measure the remnant hadron beam and tertiary muons produced along with neutrinos in meson decays. We review how the monitors will be used to make beam quality measurements, and as well we review chamber construction details, radiation damage testing, calibration, and test beam results.
This is a preliminary version of a formal proposal by the 3M collaboration to construct a megaton, modular, multipurpose (3M) neutrino detector for a program of experiments in neutrino physics. The detector components will be located in chambers approximately 7000 ft below the Earth's surface in the Homestake Mine at Lead, South Dakota, to carry out experiments on neutrino oscillations directed toward the principal experimental goal of the program, viz., the issue of CP-invariance violation in the lepton sector of elementary particles, an issue that has been the subject of study in the quark sector for several decades. The principal physics goal of this program also requires a moderately intense neutrino beam from an accelerator located a long distance from the detector array, such as the 2540 km distance of BNL from Homestake. The construction plan for that neutrino beam is at http://nwg.phy.bnl.gov/. Other experimental searches that do not require the accelerator-generated beam can be carried out with the 3M detector independently of and at the same time as the neutrino oscillation and CP-invariance violation measurements are in progress. They are searches for Proton Decay, UHE Neutrinos, and Supernovae Neutrinos.
We analyze the prospects of a feasible, Brookhaven National Laboratory based, very long baseline (BVLB) neutrino oscillation experiment consisting of a conventional horn produced low energy wide band beam and a detector of 500 kT fiducial mass with modest requirements on event recognition and resolution. Such an experiment is intended primarily to determine CP violating effects in the neutrino sector for 3-generation mixing. We analyze the sensitivity of such an experiment. We conclude that this experiment will allow determination of the CP phase $δ_{CP}$ and the currently unknown mixing parameter $θ_{13}$, if $\sin ^2 2 θ_{13} \geq 0.01$, a value $\sim 15$ times lower than the present experimental upper limit. In addition to $θ_{13}$ and $δ_{CP}$, the experiment has great potential for precise measurements of most other parameters in the neutrino mixing matrix including $Δm^2_{32}$, $\sin^2 2θ_{23}$, $Δm^2_{21}\times \sin 2 θ_{12}$, and the mass ordering of neutrinos through the observation of the matter effect in the $ν_μ\to ν_e$ appearance channel.
Radiation-hard ionization chambers were tested using an intense electron beam from the accelerator test facility (ATF) at the Brookhaven National Laboratory (BNL). The detectors were designed to be used as the basic element for monitoring muons in the Main Injector Neutrino beamline (NuMI) at the Fermi National Accelerator Laboratory (FNAL). Measurements of linearity of response, voltage dependence, and the onset of ionization saturation as a function of gap voltage were performed.