Νμ Beam Research Articles

Understanding and Calibrating the Calorimeter for the T2K Near Detector

T2K (Tokai-to-Kamioka) is a long-baseline neutrino experiment with the primary purpose of measuring the mixing angle θ13, using a νμ beam which is produced at J-PARC and aimed towards Super-Kamiokande (SK). A near detector located 280m from the neutrino production target, the ND280, is used to measure the neutrino energy spectrum, flavour content and interaction rates of the un-oscillated beam and to predict the neutrino interactions at SK. The downstream module of the ND280 electromagnetic calorimeter system, the DsECal, is in situ and taking data. Prior to installation in ND280, calibration data was collected whilst the DsECAL was commissioned in a beam test at CERN in 2009.

OPERA: Electronic Detectors

The OPERA detector aims to see ντ appearance in the CNGS νμ beam as a result of neutrino oscillations. It is a hybrid detector consisting of both nuclear emulsions and electronic detectors that are discribed in this poster.

T2K: Electron Neutrino Analysis At Near Detector ND280

Starting with a νμ beam T2K will search for νe appearance in the Far Detector (Super-Kamiokande) and aims to produce the first measurement of the neutrino mixing angle θ13. Beam contamination of νe will be one of the main background components. The Near Detector, ND280, is optimized for measuring the νe contamination through the reconstruction of νe interactions. The reconstruction of electron neutrinos at Near Detector and the method to estimate the νe beam contamination at Super-Kamiokande will be reviewed.

T2K: New physics results

The T2K experiment is designed to probe the θ13 neutrino mixing parameter by looking for the appearance of νe in a pure νμ beam and to precisely measure atmospheric Δm2 and θ23 parameters. A neutrino beam produced at J-PARC, Japan, is aimed at 2.5° off-axis angle to the Super-Kamiokande far neutrino detector, 295km away. The narrow energy neutrino beam peaked at about 600 MeV is optimized to maximize the probability of oscillation at the atmospheric Δm2 scale. The neutrino beam is monitored by a complex of neutrino near detectors at 280m from the production target. T2K has successfully operated since January 2010. Data-taking has been presently paused due to the recent earthquake in Japan. Results on measurements of νe appearance and νμ disappearance are reported.

Reactor experiment reveals neutrino oscillation’s third mixing angle

A nonzero value for this elusive parameter offers a possible explanation for the cosmic shortage of antimatter.

ND280 TPC contribution to recent T2K results

The T2K (Tokai to Kamioka) experiment is a long baseline neutrino oscillation experiment designed to measure the θ13 neutrino mixing parameter by looking for the appearance of νe in an almost pure νμ beam. The concurrent measurement of νμ disappearance allows refined measurements of the atmospheric Δm2 and of the θ23 mixing parameters.A neutrino beam is produced at the Japan Proton Accelerator Research Complex (J-PARC) in Tokai, Japan, and aimed at 2.5° off the direction of the Super-Kamiokande (SK) detector, 295 km away. The resulting narrow energy band neutrino beam at the SK location, peaked at about 600 MeV, is optimized to maximize the probability of oscillation at the atmospheric Δm2 scale, minimizing at the same time the backgrounds for νe searches. The neutrino beam is monitored before the oscillation by a Near Detector, ND280 located at J-PARC at 280 m from the target. A key element of the T2K Near Detector is composed of three large TPCs instrumented with MicroMEGAS detectors used to measure the neutrino spectrum and flavor composition before the oscillation. The charge and momentum of the charged particles crossing the TPCs are reconstructed, as well as the ionization energy loss in the TPCs allowing to distinguish electrons from muons.T2K has successfully operated since January 2010, and it has presently been paused due to the recent earthquake in Japan. Results on the search for νe appearance and of νμ disappearance have been presented in this talk, particularly stressing the inputs to these measurements from the TPCs.

New limits on radiative sterile neutrino decays from a search for single photons in neutrino interactions

It has been recently shown that excess events observed by the LSND and MiniBooNE neutrino experiments could be interpreted as a signal from the radiative decay of a heavy sterile neutrino νh produced in νμ neutral-current-like neutrino interactions. If the νh exist, it would be also produced by the νμ beam from the CERN SPS in the neutrino beam line shielding. The νhʼs would penetrate the shielding and be observed through the νh→γν decay followed by the photon conversion into e+e− pair in the active target of the NOMAD detector. The νhʼs could be also produced in the iron of the magnetic spectrometer of the CHORUS detector, located just in front of NOMAD. Considering these two sources of νhʼs we set new constraints on νh properties and exclude part of the LSND/MiniBooNE νh parameter space using bounds on single photons production in neutrino reactions recently reported by the NOMAD Collaboration. We find that broad bands in the parameter space are still open for more sensitive searches for the νh in future neutrino experiments.

OPERA experimental results

The aim of the OPERA experiment is to search for the appearance of the tau neutrino in the quasi pure muon neutrino beam produced at CERN (CNGS). The detector, installed in the Gran Sasso underground laboratory 730 km away from CERN, consists of a lead/emulsion target complemented with electronic detectors. Runs with CNGS neutrinos were successfully carried out in 2008, 2009, and 2010. After a brief description of the beam and the experimental setup, we report on event analysis of a sample of events corresponding to 1.89×1019 p.o.t. in the CERN CNGS νμ beam that yielded the observation of a first candidate ντ CC interaction. The topology and kinematics of this candidate event are described in detail. The background sources are explained and the significance of the candidate is assessed.

Summary of the OPERA analysis

The OPERA experiment is located in the Gran Sasso underground laboratory and designed to directly detect the appearance of ντ in a pure νμ beam by observing the decay of charged τ leptons produced in ντ charged current interactions. The OPERA detector is a hybrid detector, containing electronic detectors (ED) and high resolution nuclear emulsions. A short introduction to the detector is presented. The analysis procedures will be described, including the analysis flow chain and the vertex decay search procedure. First results will be presented, including the main kinematic measurements obtained until now and the cross checks made on the background expectation.

Improved Search for Muon-Neutrino to Electron-Neutrino Oscillations in MINOS

We report the results of a search for ν(e) appearance in a ν(μ) beam in the MINOS long-baseline neutrino experiment. With an improved analysis and an increased exposure of 8.2 × 10(20) protons on the NuMI target at Fermilab, we find that 2 sin(2) (θ(23))sin(2)(2θ(13))<0.12(0.20) at 90% confidence level for δ = 0 and the normal (inverted) neutrino mass hierarchy, with a best-fit of 2sin(2) (θ(23))sin(2)(2θ(13)) = 0.041(-0.031)(+0.047) (0.079(-0.053) (+0.071)). The θ(13) = 0 hypothesis is disfavored by the MINOS data at the 89% confidence level.

The Photographic Emulsion Technology of the OPERA Experiment on its Way to Find the [formula omitted] Oscillation

The OPERA experiment (Oscillation Project with Emulsion tRacking Apparatus) is a long baseline appearance search for νμ→ντ oscillation. A pure νμ beam from CERN is sent to the 730 km far away LNGS underground laboratory in Italy where the OPERA detector is located. The charged current ντ interaction will produce a tau lepton which then can be identified according to its decay topology. The detection of the tau requires a high resolution of the active detection material because of the short lifetime of the tau. Nuclear emulsion films are the most suitable detector material capable of fulfilling this requirement. This article is going to review the status of the experiment, the detector and the way to find the νμ→ντ oscillation by observing the tau lepton. Special emphasis is put on the emulsion detection technique.

SEARCH FOR νμ→νe OSCILLATIONS IN THE MINOS EXPERIMENT

The MINOS experiment uses the NuMI νμ beam to make precise measurements of neutrino flavor oscillations in the "atmospheric" neutrino sector. MINOS can also probe the yet-unknown neutrino mixing angle θ13 by searching for a νe appearance signal in the νμ beam. This paper reviews the techniques developed for the first νe appearance analysis in MINOS.

A BRIEF REVIEW OF MINOS NEUTRINO OSCILLATION RESULTS

The MINOS long-baseline experiment is using the NuMI neutrino beam to make precise measurements of neutrino flavor oscillations in the "atmospheric" neutrino sector. MINOS observes the νμ disappearance oscillations seen in atmospheric neutrinos, tests possible disappearance to sterile ν by measuring the neutral current flux, and extends our reach towards the so far unseen θ13 by looking for νe appearance in this νμ beam. The magnetized MINOS detectors also allow tests of CPT conservation by discriminating between neutrinos and anti-neutrinos on an event-by-event basis. The intense, well-understood NuMI neutrino beam created at Fermilab is observed 735 km away at the Soudan Mine in Northeast Minnesota. High-statistics studies of the neutrino interactions themselves and the cosmic rays seen by the MINOS detectors have also been made. MINOS started taking beam data in May 2005 and is now nearing the end of its five-year run. This paper reviews results published based on the first several years of data.

Current MINOS neutrino oscillation results

The MINOS experiment is now making precise measurements of the νμ disappearance oscillations seen in atmospheric neutrinos, tests possible disappearance to sterile ν by measuring the neutral current flux, and has extended our reach towards the so far unseen θ13 by looking for νe appearance in the νμ beam. It does so by using the intense, well-understood NuMI neutrino beam created at Fermilab and observing it 735km away at the Soudan Mine in Northeast Minnesota. High-statistics studies of the neutrino interactions themselves and the cosmic rays seen by the MINOS detectors have also been made. Results from MINOS' first three years of operations will be presented.

Neutrinos from CERN to Gran Sasso: The CNGS project

The CNGS project (CERN Neutrinos to Gran Sasso) has been approved to make an unambiguous and direct observation of νμ − ντ oscillations. An intense and relatively pure νμ beam is generated at CERN and directed towards LNGS (Laboratori Nazionali del Gran Sasso) in Italy. Two experiments, OPERA already started in 2007 and ICARUS T600, will try to detect tau neutrinos using large and complex detectors. These "appearance" experiments will use the τ decay topology as signature of the presence of ντ in the initial neutrino beam. An overview of the CNGS beam facility is given. Results from the first observed OPERA events and performances are presented. Few elements are given concerning the ICARUS T600 starting.

Contemporary status of the OPERA experiment for detecting νμ → ντ oscillations in a νμ beam

The first results of the physical stage of the OPERA experiment in 2007, when observation of oscillations of gvμ into gvτ started, are discussed. Thirty eight events related to neutrino interactions in emulsion blocks (bricks) are found. The underground muon spectrum and the μ+/μ− ratio are obtained. The results of using detachable emulsion packs (changeable sheets) and accuracy of predictions of neutrino interaction vertices in emulsion layers are discussed. The results of the hardware and software upgrade of the automatic emulsion scanning system PAVIKOM are reported.

The OPERA experiment in the CERN to Gran Sasso neutrino beam

The OPERA neutrino oscillation experiment has been designed to prove the appearance of ντ in a nearly pure νμ beam (CNGS) produced at CERN and detected in the underground Hall C of the Gran Sasso Laboratory, 730 km away from the source. In OPERA, τ leptons resulting from the interaction of ντ are produced in target units called bricks made of nuclear emulsion films interleaved with lead plates. The OPERA target contains 150000 of such bricks, for a total mass of 1.25 kton, arranged into walls interleaved with plastic scintillator strips. The detector is split into two identical supermodules, each supermodule containing a target section followed by a magnetic spectrometer for momentum and charge measurement of penetrating particles. Real time information from the scintillators and the spectrometers provide the identification of the bricks where the neutrino interactions occurred. The candidate bricks are extracted from the walls and, after X-ray marking and an exposure to cosmic rays for alignment, their emulsion films are developed and sent to the emulsion scanning laboratories to perform the accurate scan of the event. In this paper, we review the design and construction of the detector and of its related infrastructures, and report on some technical performances of the various components. The construction of the detector started in 2003 and it was completed in Summer 2008. The experiment is presently in the data taking phase. The whole sequence of operations has proven to be successful, from triggering to brick selection, development, scanning and event analysis.

LIQUID ARGON DETECTORS FOR NEUTRINO PHYSICS

In this paper we give a short review of liquid argon detectors for neutrino physics. We will first introduce noble liquid detectors with particular emphasis on liquid argon and detectors of the time projection chamber variety, and we will explain why liquid argon detectors are good for neutrino physics, in particular the measurement of the mixing angle θ13, CP-violating phase δ CP and determination of the mass hierarchy through νe appearance on a νμ beam. We will stress what we consider the main achievements and the main challenges facing liquid argon detectors for neutrino physics.

MiniBooNE oscillation results and implications

The MiniBooNE Collaboration has reported first results of a search for νe appearance in a νμ beam. With two largely independent analyses, no significant excess was observed of events above background for reconstructed neutrino energies above 475 MeV and the data are consistent with no oscillations within a two neutrino appearance-only oscillation model. An excess of events (186 ± 27 ± 33 events) is observed below the 475 MeV oscillation search cut. This low-energy excess cannot be explained by a two-neutrino oscillation model. This report presents an overview of the MiniBooNE first result and decribes some initial cross checks and investigations associated with the low energy excess.

The OPERA experiment and the first events from the CNGS neutrino beam

The aim of the OPERA experiment is to provide unambiguous evidence for the νμ↔ντ oscillation by looking at the appearance of ντ in a pure νμ beam. The detector is located on the high-energy, long-baseline CERN to LNGS beam (CNGS) 730 km away from the neutrino source. The apparatus consists of a target made of lead/emulsion-films bricks complemented by electronic detectors. The neutrino interaction inside the bricks is tagged using the electronic trackers. In August 2006, a short CNGS run was successfully performed and a first sample of neutrino events was collected. Experiment description and results from the first CNGS run are reported in details.