43 research outputs found
Reconstruction of neutrino induced neutral current neutral pion events with the T2K ND280 Tracker and ECAL
T2K is a long baseline neutrino oscillation experiment in Japan. One of
the goals is to search for electron neutrino appearance at the far detector
(Super Kamiokande) in a muon neutrino beam produced 295 km away, to
make a measurement of the unknown neutrino oscillation angle [Symbol appears here. To view, please open pdf attachment]13. A
major background to this appearance search is neutral pions (Ï€0) produced
in neutral current (NC) neutrino interactions. The π0s decay to photons,
which can in cases mimic the electron appearance signal.
The near detector of the experiment (ND280) has the capability of measuring
the rates of NCÏ€0 production processes. NCÏ€0 interactions in the
Tracker of the detector (plastic scintillator targets, and time projection
chambers for tracking charged particles) can be detected through photon
conversions in the electromagnetic calorimeter that surrounds the Tracker.
For these types of events, the photon reconstruction in the calorimeter has
to have good energy and angular resolutions.
This thesis describes the T2K experiment, the ND280 detector and its
offline software, and gives details on the ECal reconstruction of photons.
The performance of the reconstruction in relation to the π0 decay photons,
their energy and angular resolutions, is studied.
An analysis is presented for the reconstruction of NC π0s produced in
the trackers, with both photons converting in the downstream calorimeter, developed purely with Monte Carlo (with GENIE as the interaction generator),
and then applied to the first-year data from ND280. The Monte Carlo
expectation is 17.7 ± 1.1(stat) ± 4.9(syst) events, with 37 ± 4% NCπ0 purity;
21 events are seen in the first year data. The MC is consistent with data at
the 0.5σ level.
As a crosscheck, the same analysis is applied to a different Monte Carlo
production (using NEUT as the generator). The expectation from this
production is 16.8 ± 1.0(stat) ± 4.7(syst) events, with 30 ± 4% purity. This
is consistent with data at the 0.7σ level
A Combined Limit on the Neutrino Mass from Neutrinoless Double-Beta Decay and Constraints on Sterile Majorana Neutrinos
We present a framework to combine data from the latest neutrinoless
double-beta decay experiments for multiple isotopes and derive a limit on the
effective neutrino mass using the experimental energy distributions. The
combined limits on the effective mass range between 130-310 meV, where the
spread is due to different model calculations of nuclear matrix elements
(NMEs). The statistical consistency (p values) between this result and the
signal observation claimed by the Heidelberg-Moscow experiment is derived. The
limits on the effective mass are also evaluated in a (3+1) sterile neutrino
model, assuming all neutrinos are Majorana particles.Comment: 8 pages, 8 figures. Version accepted by Phys Rev D, including latest
CUORE-0 result
A Combined View of Sterile-Neutrino Constraints from CMB and Neutrino Oscillation Measurements
We perform a comparative analysis of constraints on sterile neutrinos from
the Planck experiment and from current and future neutrino oscillation
experiments (MINOS, IceCube, SBN). For the first time, we express the Planck
constraints on and from the Cosmic
Microwave Background in the parameter space used by oscillation experiments
using both mass-squared differences and mixing angles. In a model with a single
sterile neutrino species and using standard assumptions, we find that the
Planck data and the oscillation experiments measuring muon-neutrino
disappearance have similar sensitivity.Comment: 6 pages, 3 figures, Version accepted by Physics Letters B, minor
changes to text, results unchange
Direct comparison of sterile neutrino constraints from cosmological data, disappearance data and appearance data in a model
We present a quantitative, direct comparison of constraints on sterile
neutrinos derived from neutrino oscillation experiments and from Planck data,
interpreted assuming standard cosmological evolution. We extend a model,
which is used to compare exclusions contours at the 95% CL derived from Planck
data to those from -disappearance measurements, to a model. This
allows us to compare the Planck constraints with those obtained through
appearance searches, which are sensitive to more
than one active-sterile mixing angle. We find that the cosmological data fully
exclude the allowed regions published by the LSND, MiniBooNE and Neutrino-4
collaborations, and those from the gallium and rector anomalies, at the 95% CL.
Compared to the exclusion regions from the Daya Bay -disappearance
search, the Planck data are more strongly excluding above and
, with the Daya Bay
exclusion being stronger below these values. Compared to the combined Daya
Bay/Bugey/MINOS exclusion region on appearance,
the Planck data is more strongly excluding above , with the exclusion strengths of the Planck
data and the Daya Bay/Bugey/MINOS combination becoming comparable below this
value.Comment: 9 pages, 4 figures, accepted by Eur. Phys. J.
Direct comparison of sterile neutrino constraints from cosmological data, ν e disappearance data and ν μ → ν e appearance data in a 3 + 1 model
From Springer Nature via Jisc Publications RouterHistory: received 2020-02-22, registration 2020-07-03, accepted 2020-07-03, pub-print 2020-08, pub-electronic 2020-08-19, online 2020-08-19Publication status: PublishedFunder: H2020 Marie Sklodowska-Curie Actions; doi: http://dx.doi.org/10.13039/100010665; Grant(s): 752309Abstract: We present a quantitative, direct comparison of constraints on sterile neutrinos derived from neutrino oscillation experiments and from Planck data, interpreted assuming standard cosmological evolution. We extend a 1+1 model, which is used to compare exclusion contours at the 95% Cl derived from Planck data to those from νe-disappearance measurements, to a 3+1 model. This allows us to compare the Planck constraints with those obtained through νμ→νe appearance searches, which are sensitive to more than one active-sterile mixing angle. We find that the cosmological data fully exclude the allowed regions published by the LSND, MiniBooNE and Neutrino-4 collaborations, and those from the gallium and rector anomalies, at the 95% Cl. Compared to the exclusion region from the Daya Bay νe-disappearance search, the Planck data are more strongly excluding above |Δm412|≈0.1eV2 and meffsterile≈0.2eV, with the Daya Bay exclusion being stronger below these values. Compared to the combined Daya Bay/Bugey/MINOS exclusion region on νμ→νe appearance, the Planck data is more strongly excluding above Δm412≈5×10-2eV2, with the exclusion strengths of the Planck data and the Daya Bay/Bugey/MINOS combination becoming comparable below this value
Search for heavy neutral leptons decaying into muon-pion pairs in the MicroBooNE detector
This document was prepared by the MicroBooNE
Collaboration using the resources of the Fermi National
Accelerator Laboratory (Fermilab), a U.S. Department of
Energy, Office of Science, HEP User Facility. Fermilab is
managed by Fermi Research Alliance, LLC (FRA), acting
under Contract No. DE-AC02-07CH11359. MicroBooNE
is supported by the following: the U.S. Department
of Energy, Office of Science, Offices of High Energy
Physics and Nuclear Physics; the U.S. National Science
Foundation; the Swiss National Science Foundation; the
Science and Technology Facilities Council (STFC), part of
the United Kingdom Research and Innovation; and The
Royal Society (United Kingdom). Additional support for
the laser calibration system and cosmic ray tagger was
provided by the Albert Einstein Center for Fundamental
Physics, Bern, Switzerland.We present upper limits on the production of heavy neutral leptons (HNLs) decaying to μπ pairs using data collected with the MicroBooNE liquid-argon time projection chamber (TPC) operating at Fermilab. This search is the first of its kind performed in a liquid-argon TPC. We use data collected in 2017 and 2018 corresponding to an exposure of 2.0×1020 protons on target from the Fermilab Booster Neutrino Beam, which produces mainly muon neutrinos with an average energy of ≈800  MeV. HNLs with higher mass are expected to have a longer time of flight to the liquid-argon TPC than Standard Model neutrinos. The data are therefore recorded with a dedicated trigger configured to detect HNL decays that occur after the neutrino spill reaches the detector. We set upper limits at the 90% confidence level on the element |Uμ4|2 of the extended PMNS mixing matrix in the range |Uμ4|2<(6.6–0.9)×10−7 for Dirac HNLs and |Uμ4|2<(4.7–0.7)×10−7 for Majorana HNLs, assuming HNL masses between 260 and 385 MeV and |Ue4|2=|Uτ4|2=0.Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract No. DE-AC02-07CH1135