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At least 415 records · Page 23

Study of the Neutrino Magnetic Moment with the NOvA Near Detector

The NuMI Off-Axis νe Appearance (NOvA) Experiment is a long baseline neutrino experiment consisting of two detectors, a Near Detector (ND) at Fermilab in Batavia, IL, and a Far Detector (FD) in Ash River, MN. The ND observes the unoscillated neutrino beam while the FD is able to observe neutrinos which have oscillated. Because the ND does not observe oscillated neutrinos, it works in tandem with the FD to provide control measurements. However, the ND has independent physics goals, such as observing processes which lead to physics beyond the Standard Model (BSM). One such process is the existence of a neutrino magnetic moment. At leading order, neutrinos do not interact electromagnetically, but, by considering higher order perturbative effects, it becomes possible for neutrinos to have an effective coupling with a photon and a non-zero neutrino magnetic moment emerges. Measurement of the neutrino magnetic moment can aid in the process of determining if neutrinos are Dirac or Majorana fermions, as well as provide insights into BSM physics. In this talk, we discuss the NOvA ND’s capabilities for making a direct measurement of the neutrino magnetic moment.

Choate, Sarah [Iowa U.]↗

Study of the Neutrino Magnetic Moment with the NOvA Near Detector

The NuMI Off-Axis νe Appearance (NOvA) Experiment is a long baseline neutrino experiment consisting of two detectors, a Near Detector (ND) at Fermilab in Batavia, IL, and a Far Detector (FD) in Ash River, MN. The ND observes the unoscillated neutrino beam while the FD is able to observe neutrinos which have oscillated. Because the ND does not observe oscillated neutrinos, it works in tandem with the FD to provide control measurements. However, the ND has independent physics goals, such as observing processes which lead to physics beyond the Standard Model (BSM). One such process is the existence of a neutrino magnetic moment. At leading order, neutrinos do not interact electromagnetically, but, by considering higher order perturbative effects, it becomes possible for neutrinos to have an effective coupling with a photon and a non-zero neutrino magnetic moment emerges. Measurement of the neutrino magnetic moment can aid in the process of determining if neutrinos are Dirac or Majorana fermions, as well as provide insights into BSM physics. For this poster, we present the NOvA ND's capabilities for making a direct measurement of the neutrino magnetic moment as well as the work currently being done to accomplish this.

Choate, Sarah [Iowa U.]↗

Intrinsic Fano factor of nuclear recoils for dark matter searches

Nuclear recoils in germanium and silicon are shown to have much larger variance in electron-hole production than their electron recoil counterparts for recoil energies between 10 and 200 keV. This effect—owing primarily to deviations in the amount of energy given to the crystal lattice in response to a nuclear recoil of a given energy—has been predicted by the Lindhard model. Here, we parametrize the variance in terms of an intrinsic nuclear recoil Fano factor that is 24.3 ± 0.2 and 26 ± 8 at around 25 keV for silicon and germanium, respectively. The variance has important effects on the expected signal shapes for experiments utilizing low-energy nuclear recoils such as direct dark matter searches and coherent neutrino-nucleus scattering measurements.

79 ASTRONOMY AND ASTROPHYSICS↗

Measurement of 3-Flavour Neutrino Oscillation Parameters in the NOvA Experiment

NOvA is a long-baseline neutrino oscillation experiment consisting of two functionally identical tracking calorimeters, a Near and Far Detector, that measure neutrino interactions induced by the Fermi National Accelerator Laboratory’s NuMI beam at baselines of 1 km and 810 km, respectively. The NuMI beam can be configured to produce either a primary ν µ neutrino or $\bar{ν}$ µ anti-neutrino beam. Neutrino oscillations are observed and measured by the analysis of ν µ + $\bar{ν}$ µ disappearance and νe + $\bar{ν}$ e appearance in the beam, comparing the neutrino energy spectra in the Near and Far detectors means that neutrino oscillation parameters sin 2 θ 23 , |Δ$m^2_{32}$|, and δ CP can be constrained. This thesis presents the 2018 NOvA ν µ +$\bar{ν}$ µ disappearance, ν e +$\bar{ν}$ e appearance, and combined analyses using both neutrino and anti-neutrino data, where oscillation fits have been performed, where possible, on an event-by-event basis rather than on a bin-by-bin basis as has conventionally been used in NOvA oscillation analyses. This allows for better precision in applying both neutrino oscillation probabilities and systematic uncertainties. Furthermore, oscillation analyses for the disappearance, appearance, and combined channels are presented using an unbinned likelihood fit and compared with the equivalent binned χ 2 likelihood fit used in the standard analysis. The 14 ktonne detector equivalent beam exposures used for this thesis are 8.85 × 10 20 and 6.91 × 10 20 protons on target for neutrino and antineutrino data respectively, corresponding to 5 years of NOvA data taking. A combined ν µ + $\bar{ν}$ µ disappearance and ν e + $\bar{ν}$ e appearance fit to the Far Detector data, assuming normal mass ordering and using the event-by-event oscillation and unbinned fitting methodologies, produces oscillation parameter constraints of Δ$m^2_{32}$ = (2.50$^{+0.08}_{-0.06}$) × 10 -3 eV 2 , sin 2 θ 23 = 0.59$^{+0.02}_{-0.04}$, and δ CP = 0.72$^{+0.5}_{-0.9}$π.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

First Double-Differential Cross Section Measurement of Neutral-Current 𝜋 0 Production in Neutrino-Argon Scattering in the MicroBooNE Detector

We report the first double-differential cross section measurement of neutral-current neutral pion (NC⁢𝜋 0 ) production in neutrino-argon scattering, as well as single-differential measurements of the same channel in terms of final states with and without protons. The kinematic variables of interest for these measurements are the 𝜋 0 momentum and the 𝜋 0 scattering angle with respect to the neutrino beam. A total of 4971 candidate NC⁢𝜋 0 events fully contained within the MicroBooNE detector are selected using data collected at a mean neutrino energy of ∼0.8 GeV from 6.4 ×10 20 protons on target from the Booster Neutrino Beam at the Fermi National Accelerator Laboratory. After extensive data-driven model validation to ensure unbiased unfolding, the Wiener-singular-value-decomposition method is used to extract nominal flux-averaged cross sections. The results are compared to predictions from commonly used neutrino event generators, which tend to overpredict the measured NC⁢𝜋 0 cross section, especially in the 0.2–0.5 GeV/c 𝜋 0 momentum range and at forward scattering angles. Events with at least one proton present in the final state are also underestimated. This data will help improve the modeling of NC⁢𝜋 0 production, which represents a major background in measurements of charge-parity violation in the neutrino sector and in searches for new physics beyond the standard model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Neutron tagging following atmospheric neutrino events in a water Cherenkov detector

We present the development of neutron-tagging techniques in Super-Kamiokande IV using a neural network analysis. The detection efficiency of neutron capture on hydrogen is estimated to be 26%, with a mis-tag rate of 0.016 per neutrino event. The uncertainty of the tagging efficiency is estimated to be 9.0%. Measurement of the tagging efficiency with data from an Americium-Beryllium calibration agrees with this value within 10%. The tagging procedure was performed on 3,244.4 days of SK-IV atmospheric neutrino data, identifying 18,091 neutrons in 26,473 neutrino events. The fitted neutron capture lifetime was measured as 218±9 μs.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DUNE Photon Detection System

The Deep Underground Neutrino Experiment (DUNE) aims to provide a broad physics program primarily addressed to probing CP violation in the neutrino sector and identifying the neutrino mass hierarchy. The search for proton decay, the observation of supernova neutrino bursts, and the investigation of solar neutrinos represent other additional goals of DUNE experiment, which can be enhanced by the use and the high performances of the Photon Detection System (PDS). Using the technology based on liquid argon Time Projection Chamber (LArTPC), the experiment plans to observe neutrino interactions inside detectors located 1300 km away from the Long Baseline Neutrino Facility (LBNF) at Fermi National Accelerator Laboratory (FNAL), where the neutrinos are produced. The experiment consists of two main parts, respectively the far and near detectors. The far site will comprise four detector modules. The first module is constituted by a vertical drift single-phase LArTPC, while the second module provides a horizontal drift single-phase LArTPC. The configurations of the other modules are still under definition. Neutrino detection in LArTPCs is achieved by identifying the charge and light generated from its interactions with liquid argon. The wire planes of the instrumented anode and the PDS detect these signals, respectively. The PDS in the first two modules, detailed in the present document, uses a modified version of the so-called ARAPUCA technology, named X-ARAPUCA. This system consisting of a highly reflecting box with an entrance window made by dichroic filters and wavelength shifters, creates a trap to detect the VUV (128 nm) scintillation photons. The X-ARAPUCA of the first module is called Supercell, and it has dimensions of 488×100 mm 2 , while Megacell is the second module version, with an active area of 60×60 cm 2 . This latter configuration also represents a significant technological advancement. Since half of the modules are placed on the cathode at high voltage, they are powered and read out using innovative power-over-fiber (PoF) and signal-over-fiber (SoF) technologies. Meanwhile, the other half are installed in a membrane behind the field cage, with a total transparency of around 70%.

Neutrino detectors↗

Muon flux measurement at China Jinping Underground Laboratory

China Jinping Underground Laboratory (CJPL) is ideal for studying solar, geo-, and supernova neutrinos. A precise measurement of the cosmic-ray background is essential in proceeding with R&D research for these MeV-scale neutrino experiments. Using a 1-ton prototype detector for the Jinping Neutrino Experiment (JNE), we detected 264 high-energy muon events from a 645.2-day dataset from the first phase of CJPL (CJPL-I), reconstructed their directions, and measured the cosmic-ray muon flux to be $(3.53\pm0.22_{\rm{stat.}}\pm0.07_{\rm{sys.}})\times10^{-10}$ cm $^{-2}$s $^{-1}$. The observed angular distributions indicate the leakage of cosmic-ray muon background and agree with simulation data accounting for Jinping mountain's terrain. A survey of muon fluxes at different laboratory locations, considering both those situated under mountains and those down mine shafts, indicates that the flux at the former is generally a factor of $(4\pm2)$ larger than at the latter, with the same vertical overburden. In conclusion, this study provides a convenient back-of-the-envelope estimation for the muon flux of an underground experiment.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Viterbi decoding of CRES signals in Project 8

Abstract Cyclotron radiation emission spectroscopy (CRES) is a modern approach for determining charged particle energies via high-precision frequency measurements of the emitted cyclotron radiation. For CRES experiments with gas within the fiducial volume, signal and noise dynamics can be modelled by a hidden Markov model. We introduce a novel application of the Viterbi algorithm in order to derive informational limits on the optimal detection of cyclotron radiation signals in this class of gas-filled CRES experiments, thereby providing concrete limits from which future reconstruction algorithms, as well as detector designs, can be constrained. The validity of the resultant decision rules is confirmed using both Monte Carlo and Project 8 data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Novel application of neutrinos to evaluate U.S. nuclear weapons performance

There is a growing realization that neutrinos can be used as a diagnostic tool to better understand the inner workings of a nuclear weapon. Robust estimates demonstrate that an Inverse Beta Decay (IBD) neutrino scintillation detector built at the Nevada Test Site with a 1000-ton active target mass at a standoff distance of 500 m would detect thousands of antineutrino events per nuclear test. This would provide less than 4% statistical error on the measured antineutrino rate and 5% error on antineutrino energy. Extrapolating this to an error on the test device explosive yield requires knowledge from evaluated nuclear databases, non-equilibrium fission rates, and assumptions on internal neutron fluxes. Initial calculations demonstrate that the total number of neutrinos emitted per fission in the first 10 3 s after a short pulse of 239 Pu fission is about a factor of two less than that from Pu fissioning under steady state conditions. Furthermore, there are significant energy spectral differences as a function of time after the pulse that must be considered. These and other model dependencies will be discussed in the paper. In the absence of nuclear weapons testing, many of the technical and theoretical challenges of a full nuclear test could be mitigated with a low cost smaller scale 20 ton fiducial mass IBD demonstration detector placed near a pulsed reactor. Potential reactors include the Texas A&M University TRIGA 1 GW–10 ms pulsed facility or the Sandia Annular Core Research Reactor. The short duty cycle and repeatability of pulses would provide critical real environment testing and measurements, which would be valuable for planning a possible real test shot in the future. Furthermore, the antineutrino rate as a function of time data would provide unique constraints on fission databases and model assumptions. Finally, there are impactful science drivers such as sensitive searches for ∼1 eV 2 sterile neutrinos and ∼MeV scale axions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Reconstruction of interactions in the ProtoDUNE-SP detector with Pandora

The Pandora Software Development Kit and algorithm libraries provide pattern-recognition logic essential to the reconstruction of particle interactions in liquid argon time projection chamber detectors. Pandora is the primary event reconstruction software used at ProtoDUNE-SP, a prototype for the Deep Underground Neutrino Experiment far detector. ProtoDUNE-SP, located at CERN, is exposed to a charged-particle test beam. This paper gives an overview of the Pandora reconstruction algorithms and how they have been tailored for use at ProtoDUNE-SP. In complex events with numerous cosmic-ray and beam background particles, the simulated reconstruction and identification efficiency for triggered test-beam particles is above 80% for the majority of particle type and beam momentum combinations. Specifically, simulated 1 GeV/c charged pions and protons are correctly reconstructed and identified with efficiencies of 86.1$\pm 0.6$% and 84.1$\pm 0.6$%, respectively. The efficiencies measured for test-beam data are shown to be within 5% of those predicted by the simulation.

43 PARTICLE ACCELERATORS↗

Latest Constraints on Three-Flavor Neutrino Oscillation Parameters from the NOvA Experiment.

NOvA, is a two-detector, long-baseline neutrino oscillation experiment located at Fermilab, Batavia, IL, USA. The NOvA experiment was designed primarily to constrain neutrino oscillation parameters by analyzing $\nu_\mu (\bar{\nu}_\mu)$ disappearance and $\nu_e (\bar{\nu}_e)$ appearance data observed at the far detector. The Neutrinos at Main Injector (NuMI) beamline at Fermilab provides a high purity beam of neutrinos and anti-neutrinos to the experiment. The NOvA experiment consists of two functionally identical, finely granulated liquid tracking calorimeters, both situated 14.6 mrad off-axis to the beam direction. The NOvA near detector, situated 100 meters underground and 1 kilometer from the beam source, detects the non-oscillated $\nu_\mu (\bar{\nu}_\mu)$ and beam $\nu_e (\bar{\nu}_e)$ events. The far detector, located in Ash River, MN, USA, 810 kilometers from the beam source, records the non-oscillated $\nu_\mu (\bar{\nu}_\mu)$ and the oscillated $\nu_\mu (\bar{\nu}_\mu) \to \nu_e (\bar{\nu}_e)$ events. The most recent measurements of three flavor neutrino oscillation parameters based on an analysis of the data collected from neutrino-beam exposure of $26.60 \times 10^{20}$ POT and anti-neutrino beam exposure of $12.50\times 10^{20}$ POT including an additional low energy $\nu_e$ sample, will be presented in this talk.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Acceptance tests of Hamamatsu R7081 photomultiplier tubes

Photomultiplier tubes (PMTs) are traditionally an integral part of large underground experiments as they measure the light emission from particle interactions within the enclosed detection media. The BUTTON experiment will utilise around 100 PMTs to measure the response of different media suitable for rare event searches. A subset of low-radioactivity 10-inch Hamamatsu R7081 PMTs were tested, characterised, and compared to manufacture certification. This manuscript describes the laboratory tests and analysis of gain, peak-to-valley ratio and dark rate of the PMTs to give an understanding of the charge response, signal-to-noise ratio and dark noise background as an acceptance test of the suitability of these PMTs for water-based detectors. Following the evaluation of these tests, the PMT performance agreed with the manufacturer specifications. These results are imperative for modeling the PMT response in detector simulations and providing confidence in the performance of the devices once installed in the detector underground.

neutrino detectors↗

Production and validation of scintillating structural components from low-background Poly(ethylene naphthalate)

Poly Ethylene Naphthalate (PEN) is an industrial polymer plastic which is investigated as a low background, transparent, scintillating and wavelength shifting structural material. PEN scintillates in the blue region and has excellent mechanical properties both at room and cryogenic temperatures. Thus, it is an ideal candidate for active structural components in experiments for the search of rare events like neutrinoless double-beta decay or dark matter recoils. Such optically active structures improve the identification and rejection efficiency of backgrounds events, like this improving the sensitivity of experiments. This paper reports on the production of radiopure and transparent PEN plates These structures can be used to mount germanium detectors operating in cryogenic liquids (LAr, LN). Thus, as first application PEN holders will be used to mount the Ge detectors in the LEGEND-200 experiment. The whole process from cleaning the raw material to testing the PEN active components under final operational conditions is reported.

47 OTHER INSTRUMENTATION↗

Methods for Precision Studies of Neutrino Interactions

Accelerator neutrino oscillation experiments provide a sensitive way to investigatea number of major open questions in neutrino physics. To achieve precision neutrinooscillation measurements, we need a good understanding of key aspects of the experiments,such as the detection technologies used and neutrino interactions at few-GeV energies.The MicroBooNE experiment has advanced the development of technologies for LArTPCs.An ultra-violet laser system was introduced to MicroBooNE in order to measure theelectric field in situ, which plays a central role in the formation of charge and lightsignals in LArTPCs. This thesis describes the setup and operation of the laser system. Ideveloped a general methodology to measure the electric field and the consequent spatialdistortion in LArTPCs, which supports precision measurements in accelerator neutrinooscillation experiments. In MicroBooNE, the measured electric field distortions are upto 15 ± 3 % with respect to the nominal value, and the measured spatial distortions areup to 15 ± 3 cm. The result of the electric field measurement is applied to the detectorsimulation and the event reconstruction, which leads to a better detector characterizationfor neutrino analyses. A significant concern for measurements of neutrino interactions ismodel dependence, as the currently available models are not sufficient for describing thepicture of neutrino interacting at few-GeV energies. In this thesis, I developed a detailedstrategy for a model-independent cross-section measurement at low energy transfers,where the available model predictions do not agree with the inclusive measurementsfrom multiple experiments. A likelihood fit technique for cross-section extraction isrealized in an accelerator neutrino experiment using a LArTPC for the first time. Thetreatment of systematic uncertainties developed in this thesis is generally applicable foranalyses using similar fitting techniques. This neutrino interaction study at low energytransfers provides a probe to the poorly understood region of neutrino cross sections. Themeasurement scheme developed here aims to guide future model-independent cross-sectionmeasurements, particularly for neutrino experiments using LArTPCs.

Chen, Yifan↗

Reactor rate modulation oscillation analysis with two detectors in Double Chooz

A θ 13 oscillation analysis based on the observed antineutrino rates at the Double Chooz far and near detectors for different reactor power conditions is presented. This approach provides a so far unique simultaneous determination of θ 13 and the total background rates without relying on any assumptions on the specific background contributions. The analysis comprises 865 days of data collected in both detectors with at least one reactor in operation. The oscillation results are enhanced by the use of 24.06 days (12.74 days) of reactor-off data in the far (near) detector. The analysis considers the ${\overline{\nu}}_e$ interactions up to a visible energy of 8.5 MeV, using the events at higher energies to build a cosmogenic background model considering fast-neutrons interactions and 9 Li decays. The background-model-independent determination of the mixing angle yields sin 2 (2 θ 13 ) = 0.094 ± 0.017, being the best-fit total background rates fully consistent with the cosmogenic background model. A second oscillation analysis is also performed constraining the total background rates to the cosmogenic background estimates. While the central value is not significantly modified due to the consistency between the reactor-off data and the background estimates, the addition of the background model reduces the uncertainty on θ 13 to 0.015. Along with the oscillation results, the normalization of the anti-neutrino rate is measured with a precision of 0.86%, reducing the 1.43% uncertainty associated to the expectation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗