arXiv subjects

K. Lang

Publications and source records attributed to K. Lang.

At least 73 records · Page 4Linked to original sources

arXiv2017

Calorimeter development for the SuperNEMO double beta decay experiment

SuperNEMO is a double-$β$ decay experiment, which will employ the successful tracker-calorimeter technique used in the recently completed NEMO-3 experiment. SuperNEMO will implement 100 kg of double-$β$ decay isotope, reaching a sensitivity to the neutrinoless double-$β$ decay ($0νββ$) half-life of the order of $10^{26}$ yr, corresponding to a Majorana neutrino mass of 50-100 meV. One of the main goals and challenges of the SuperNEMO detector development programme has been to reach a calorimeter energy resolution, $Δ$E/E, around 3%/$sqrt(E)$(MeV) $σ$, or 7%/$sqrt(E)$(MeV) FWHM (full width at half maximum), using a calorimeter composed of large volume plastic scintillator blocks coupled to photomultiplier tubes. We describe the R\&D programme and the final design of the SuperNEMO calorimeter that has met this challenging goal.

physics.ins-det↗

arXiv2017

The BiPo-3 detector for the measurement of ultra low natural radioactivities of thin materials

The BiPo-3 detector, running in the Canfranc Underground Laboratory (Laboratorio Subterráneo de Canfranc, LSC, Spain) since 2013, is a low-radioactivity detector dedicated to measuring ultra low natural radionuclide contaminations of $^{208}$Tl ($^{232}$Th chain) and $^{214}$Bi ($^{238}$U chain) in thin materials. The total sensitive surface area of the detector is 3.6 m$^2$. The detector has been developed to measure radiopurity of the selenium double $β$-decay source foils of the SuperNEMO experiment. In this paper the design and performance of the detector, and results of the background measurements in $^{208}$Tl and $^{214}$Bi, are presented, and validation of the BiPo-3 measurement with a calibrated aluminium foil is discussed. Results of the $^{208}$Tl and $^{214}$Bi activity measurements of the first enriched $^{82}$Se foils of the double $β$-decay SuperNEMO experiment are reported. The sensitivity of the BiPo-3 detector for the measurement of the SuperNEMO $^{82}$Se foils is $\mathcal{A}$($^{208}$Tl) $<2$ $μ$Bq/kg (90\% C.L.) and $\mathcal{A}$($^{214}$Bi) $<140$ $μ$Bq/kg (90\% C.L.) after 6 months of measurement.

physics.ins-det↗

arXiv2017

Constraints on Oscillation Parameters from $ν_e$ Appearance and $ν_μ$ Disappearance in NOvA

Results are reported from an improved measurement of $ν_μ\rightarrow ν_e$ transitions by the NOvA experiment. Using an exposure equivalent to $6.05\times10^{20}$ protons-on-target 33 $ν_e$ candidates were observed with a background of $8.2\pm0.8$ (syst.). Combined with the latest NOvA $ν_μ$ disappearance data and external constraints from reactor experiments on $\sin^22θ_{13}$, the hypothesis of inverted mass hierarchy with $θ_{23}$ in the lower octant is disfavored at greater than $93\%$ C.L. for all values of $δ_{CP}$.

hep-ex↗

arXiv2017

Search for neutrinoless quadruple-$β$ decay of $^{150}$Nd with the NEMO-3 detector

We report the results of a first experimental search for lepton number violation by four units in the neutrinoless quadruple-$β$ decay of $^{150}$Nd using a total exposure of $0.19$ kg$\cdot$y recorded with the NEMO-3 detector at the Modane Underground Laboratory (LSM). We find no evidence of this decay and set lower limits on the half-life in the range $T_{1/2}>(1.1-3.2)\times10^{21}$ y at the $90\%$ CL, depending on the model used for the kinematic distributions of the emitted electrons.

hep-ex↗

arXiv2017

Measurement of $ν_μ$ and $\barν_μ$ Neutral Current $π^{0} \rightarrow γγ$ Production in the ArgoNeuT Detector

The ArgoNeuT collaboration reports the first measurement of neutral current $π^{0}$ production in $ν_μ$-argon and $\barν_μ$-argon scattering. This measurement was performed using the ArgoNeuT liquid argon time projection chamber deployed at Fermilab's NuMI neutrino beam with an exposure corresponding to 1.2$\times 10^{20}$ protons-on-target from the Fermilab Main Injector and a mean energy for $ν_μ$ of 9.6~GeV and for $\barν_μ$ of 3.6~GeV. We compare the measured cross section and kinematic distributions to predictions from the GENIE and NuWro neutrino interaction event generators.

hep-ex↗

arXiv2017

Measurement of the neutrino mixing angle $θ_{23}$ in NOvA

This Letter reports new results on muon neutrino disappearance from NOvA, using a 14 kton detector equivalent exposure of $6.05\times10^{20}$ protons-on-target from the NuMI beam at the Fermi National Accelerator Laboratory. The measurement probes the muon-tau symmetry hypothesis that requires maximal mixing ($θ_{23} = π/4$). Assuming the normal mass hierarchy, we find $Δm^2 = (2.67 \pm 0.11)\times 10^{-3}$ eV$^2$ and $\sin^2 θ_{23}$ at the two statistically degenerate values $0.404^{+0.030}_{-0.022}$ and $0.624^{+0.022}_{-0.030}$, both at the 68% confidence level. Our data disfavor the maximal mixing scenario with 2.6 $σ$ significance.

hep-ex↗

arXiv2017

First Observation of Low Energy Electron Neutrinos in a Liquid Argon Time Projection Chamber

The capabilities of liquid argon time projection chambers (LArTPCs) to reconstruct the spatial and calorimetric information of neutrino events have made them the detectors of choice in a number of experiments, specifically those looking to observe electron neutrino ($ν_e$) appearance. The LArTPC promises excellent background rejection capabilities, especially in this "golden" channel for both short and long baseline neutrino oscillation experiments. We present the first experimental observation of electron neutrinos and anti-neutrinos in the ArgoNeut LArTPC, in the energy range relevant to DUNE and the Fermilab Short Baseline Neutrino Program. We have selected 37 electron candidate events and 274 gamma candidate events, and measured an 80\% purity of electrons based on a topological selection. Additionally, we present a of separation of electrons from gammas using calorimetric energy deposition, demonstrating further separation of electrons from background gammas.

hep-ex↗

arXiv2017

Constraints on Large Extra Dimensions from the MINOS Experiment

We report new constraints on the size of large extra dimensions from data collected by the MINOS experiment between 2005 and 2012. Our analysis employs a model in which sterile neutrinos arise as Kaluza-Klein states in large extra dimensions and thus modify the neutrino oscillation probabilities due to mixing between active and sterile neutrino states. Using Fermilab's NuMI beam exposure of $10.56 \times 10^{20}$ protons-on-target, we combine muon neutrino charged current and neutral current data sets from the Near and Far Detectors and observe no evidence for deviations from standard three-flavor neutrino oscillations. The ratios of reconstructed energy spectra in the two detectors constrain the size of large extra dimensions to be smaller than $0.45\,μ\text{m}$ at 90% C.L. in the limit of a vanishing lightest active neutrino mass. Stronger limits are obtained for non-vanishing masses.

hep-ex↗

arXiv2016

Measurement of the $2νββ$ Decay Half-Life and Search for the $0νββ$ Decay of $^{116}$Cd with the NEMO-3 Detector

The NEMO-3 experiment measured the half-life of the $2νββ$ decay and searched for the $0νββ$ decay of $^{116}$Cd. Using $410$ g of $^{116}$Cd installed in the detector with an exposure of $5.26$ y, ($4968\pm74$) events corresponding to the $2νββ$ decay of $^{116}$Cd to the ground state of $^{116}$Sn have been observed with a signal to background ratio of about $12$. The half-life of the $2νββ$ decay has been measured to be $ T_{1/2}^{2ν}=[2.74\pm0.04\mbox{(stat.)}\pm0.18\mbox{(syst.)}]\times10^{19}$ y. No events have been observed above the expected background while searching for $0νββ$ decay. The corresponding limit on the half-life is determined to be $T_{1/2}^{0ν} \ge 1.0 \times 10^{23}$ y at the $90$ % C.L. which corresponds to an upper limit on the effective Majorana neutrino mass of $\langle m_ν \rangle \le 1.4-2.5$ eV depending on the nuclear matrix elements considered. Limits on other mechanisms generating $0νββ$ decay such as the exchange of R-parity violating supersymmetric particles, right-handed currents and majoron emission are also obtained.

hep-ex↗

arXiv2016

A search for flavor-changing non-standard neutrino interactions using $ν_{e}$ appearance in MINOS

We report new constraints on flavor-changing non-standard neutrino interactions from the MINOS long-baseline experiment using $ν_{e}$ and $\barν_{e}$ appearance candidate events from predominantly $ν_μ$ and $\barν_μ$ beams. We used a statistical selection algorithm to separate $ν_{e}$ candidates from background events, enabling an analysis of the combined MINOS neutrino and antineutrino data. We observe no deviations from standard neutrino mixing, and thus place constraints on the non-standard interaction matter effect, $|\varepsilon_{eτ}|$, and phase, $(δ_{CP}+δ_{eτ})$, using a thirty-bin likelihood fit.

hep-ex↗

arXiv2016

Search for time-independent Lorentz violation using muon neutrino to muon antineutrino transitions in MINOS

Data from the MINOS experiment has been used to search for mixing between muon neutrinos and muon antineutrinos using a time-independent Lorentz-violating formalism derived from the Standard-Model Extension (SME). MINOS is uniquely capable of searching for muon neutrino-antineutrino mixing given its long baseline and ability to distinguish between neutrinos and antineutrinos on an event-by-event basis. Neutrino and antineutrino interactions were observed in the MINOS Near and Far Detectors from an exposure of 10.56$\times10^{20}$ protons-on-target from the NuMI neutrino-optimized beam. No evidence was found for such transitions and new, highly stringent limits were placed on the SME coefficients governing them. We place the first limits on the SME parameters $(c_{L})^{TT}_{μμ} $ and $(c_{L})^{TT}_{ττ}$ at $-8.4\times10^{-23} < (c_{L})^{TT}_{μμ} < 8.0\times10^{-23}$ and $-8.0\times10^{-23} < (c_{L})^{TT}_{ττ} < 8.4\times10^{-23}$, and the world's best limits on the $\tilde{g}^{ZT}_{μ\overlineμ}$ and $\tilde{g}^{ZT}_{τ\overlineτ}$ parameters at $|\tilde{g}^{ZT}_{μ\overlineμ}| < 3.3\times 10^{-23}$ and $|\tilde{g}^{ZT}_{τ\overlineτ}| < 3.3\times 10^{-23}$, all limits quoted at $3σ$.

hep-ex↗

arXiv2016

Measurement of the 2$νββ$ decay half-life of $^{150}$Nd and a search for 0$νββ$ decay processes with the full exposure from the NEMO-3 detector

We present results from a search for neutrinoless double-$β$ ($0νββ$) decay using 36.6 g of the isotope $^{150}$Nd with data corresponding to a live time of 5.25 y recorded with the NEMO-3 detector. We construct a complete background model for this isotope, including a measurement of the two-neutrino double-$β$ decay half-life of $T^{2ν}_{1/2}=$[9.34 $\pm$ 0.22 (stat.) $^{+0.62}_{-0.60}$ (syst.)]$\times 10^{18}$ y for the ground state transition, which represents the most precise result to date for this isotope. We perform a multivariate analysis to search for \zeronu decays in order to improve the sensitivity and, in the case of observation, disentangle the possible underlying decay mechanisms. As no evidence for \zeronu decay is observed, we derive lower limits on half-lives for several mechanisms involving physics beyond the Standard Model. The observed lower limit, assuming light Majorana neutrino exchange mediates the decay, is $T^{0ν}_{1/2} >$ 2.0 $\times 10^{22}$ y at the 90% C.L., corresponding to an upper limit on the effective neutrino mass of $\langle m_ν \rangle$ $<$ 1.6 - 5.3 eV..

hep-ex↗

arXiv2016

Measurement of single $π^0$ production by coherent neutral-current $ν$ Fe interactions in the MINOS Near Detector

Forward single $π^0$ production by coherent neutral-current interactions, $ν\mathcal{A} \to ν\mathcal{A} π^0$, is investigated using a 2.8$\times 10^{20}$ protons-on-target exposure of the MINOS Near Detector. For single-shower topologies, the event distribution in production angle exhibits a clear excess above the estimated background at very forward angles for visible energy in the range~1-8 GeV. Cross sections are obtained for the detector medium comprised of 80% iron and 20% carbon nuclei with $\langle \mathcal{A} \rangle = 48$, the highest-$\langle \mathcal{A} \rangle$ target used to date in the study of this coherent reaction. The total cross section for coherent neutral-current single-$π^0$ production initiated by the $ν_μ$ flux of the NuMI low-energy beam with mean (mode) $E_ν$ of 4.9 GeV (3.0 GeV), is $77.6\pm5.0\,(\text{stat}) ^{+15.0}_{-16.8}\,(\text{syst})\times10^{-40}\,\text{cm}^2~\text{per nucleus}$. The results are in good agreement with predictions of the Berger-Sehgal model.

hep-ex↗

arXiv2016

Search for Sterile Neutrinos Mixing with Muon Neutrinos in MINOS

We report results of a search for oscillations involving a light sterile neutrino over distances of 1.04 and $735\,\mathrm{km}$ in a $ν_μ$-dominated beam with a peak energy of $3\,\mathrm{GeV}$. The data, from an exposure of $10.56\times 10^{20}\,\textrm{protons on target}$, are analyzed using a phenomenological model with one sterile neutrino. We constrain the mixing parameters $θ_{24}$ and $Δm^{2}_{41}$ and set limits on parameters of the four-dimensional Pontecorvo-Maki-Nakagawa-Sakata matrix, $|U_{μ4}|^{2}$ and $|U_{τ4}|^{2}$, under the assumption that mixing between $ν_{e}$ and $ν_{s}$ is negligible ($|U_{e4}|^{2}=0$). No evidence for $ν_μ \to ν_{s}$ transitions is found and we set a world-leading limit on $θ_{24}$ for values of $Δm^{2}_{41} \lesssim 1\,\mathrm{eV}^{2}$.

hep-ex↗

arXiv2016

Background Studies for the MINER Coherent Neutrino Scattering Reactor Experiment

The proposed Mitchell Institute Neutrino Experiment at Reactor (MINER) experiment at the Nuclear Science Center at Texas A&M University will search for coherent elastic neutrino-nucleus scattering within close proximity (about 2 meters) of a 1 MW TRIGA nuclear reactor core using low threshold, cryogenic germanium and silicon detectors. Given the Standard Model cross section of the scattering process and the proposed experimental proximity to the reactor, as many as 5 to 20 events/kg/day are expected. We discuss the status of preliminary measurements to characterize the main backgrounds for the proposed experiment. Both in situ measurements at the experimental site and simulations using the MCNP and GEANT4 codes are described. A strategy for monitoring backgrounds during data taking is briefly discussed.

physics.ins-det↗

arXiv2016

Measurement of the double-beta decay half-life and search for the neutrinoless double-beta decay of $^{48}{\rm Ca}$ with the NEMO-3 detector

The NEMO-3 experiment at the Modane Underground Laboratory has investigated the double-$β$ decay of $^{48}{\rm Ca}$. Using $5.25$ yr of data recorded with a $6.99\,{\rm g}$ sample of $^{48}{\rm Ca}$, approximately $150$ double-$β$ decay candidate events have been selected with a signal-to-background ratio greater than $3$. The half-life for the two-neutrino double-$β$ decay of $^{48}{\rm Ca}$ has been measured to be $T^{2ν}_{1/2}\,=\,[6.4\, ^{+0.7}_{-0.6}{\rm (stat.)} \, ^{+1.2}_{-0.9}{\rm (syst.)}] \times 10^{19}\,{\rm yr}$. A search for neutrinoless double-$β$ decay of $^{48}{\rm Ca}$ yields a null result and a corresponding lower limit on the half-life is found to be $T^{0ν}_{1/2} > 2.0 \times 10^{22}\,{\rm yr}$ at $90\%$ confidence level, translating into an upper limit on the effective Majorana neutrino mass of $< m_{ββ} > < 6.0 - 26$ ${\rm eV}$, with the range reflecting different nuclear matrix element calculations. Limits are also set on models involving Majoron emission and right-handed currents.

hep-ex↗

arXiv2016

Measurement of the Multiple-Muon Charge Ratio in the MINOS Far Detector

The charge ratio, $R_μ= N_{μ^+}/N_{μ^-}$, for cosmogenic multiple-muon events observed at an under- ground depth of 2070 mwe has been measured using the magnetized MINOS Far Detector. The multiple-muon events, recorded nearly continuously from August 2003 until April 2012, comprise two independent data sets imaged with opposite magnetic field polarities, the comparison of which allows the systematic uncertainties of the measurement to be minimized. The multiple-muon charge ratio is determined to be $R_μ= 1.104 \pm 0.006 {\rm \,(stat.)} ^{+0.009}_{-0.010} {\rm \,(syst.)} $. This measurement complements previous determinations of single-muon and multiple-muon charge ratios at underground sites and serves to constrain models of cosmic ray interactions at TeV energies.

hep-ex↗

arXiv2015

Result of the search for neutrinoless double-$β$ decay in $^{100}$Mo with the NEMO-3 experiment

The NEMO-3 detector, which had been operating in the Modane Underground Laboratory from 2003 to 2010, was designed to search for neutrinoless double $β$ ($0νββ$) decay. We report final results of a search for $0νββ$ decays with $6.914$ kg of $^{100}$Mo using the entire NEMO-3 data set with a detector live time of $4.96$ yr, which corresponds to an exposure of 34.3 kg$\cdot$yr. We perform a detailed study of the expected background in the $0νββ$ signal region and find no evidence of $0νββ$ decays in the data. The level of observed background in the $0νββ$ signal region $[2.8-3.2]$ MeV is $0.44 \pm 0.13$ counts/yr/kg, and no events are observed in the interval $[3.2-10]$ MeV. We therefore derive a lower limit on the half-life of $0νββ$ decays in $^{100}$Mo of $T_{1/2}(0νββ)> 1.1 \times 10^{24}$ yr at the $90\%$ Confidence Level, under the hypothesis of light Majorana neutrino exchange. Depending on the model used for calculating nuclear matrix elements, the limit for the effective Majorana neutrino mass lies in the range $\langle m_ν \rangle < 0.33$--$0.62$ eV. We also report constraints on other lepton-number violating mechanisms for $0νββ$ decays.

hep-ex↗