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Franc, J.

Publications and source records attributed to Franc, J..

12 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Monte Carlo method for constructing confidence intervals with unconstrained and constrained nuisance parameters in the NOvA experiment

Measuring observables to constrain models using maximum-likelihood estimation is fundamental to many physics experiments. Wilks' theorem provides a simple way to construct confidence intervals on model parameters, but it only applies under certain conditions. These conditions, such as nested hypotheses and unbounded parameters, are often violated in neutrino oscillation measurements and other experimental scenarios. Monte Carlo methods can address these issues, albeit at increased computational cost. In the presence of nuisance parameters, however, the best way to implement a Monte Carlo method is ambiguous. Furthermore, this paper documents the method selected by the NOvA experiment, the profile construction. It presents the toy studies that informed the choice of method, details of its implementation, and tests performed to validate it. It also includes some practical considerations which may be of use to others choosing to use the profile construction.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Search for 𝐢⁒𝑃-Violating Neutrino Nonstandard Interactions with the NOvA Experiment

This Letter reports a search for charge-parity (𝐢⁒𝑃) symmetry violating nonstandard interactions (NSI) of neutrinos with matter using the NOvA Experiment, and examines their effects on the determination of the standard oscillation parameters. Data from 𝜈 πœ‡ ⁑($\bar{𝜈}$ πœ‡ ) β†’ 𝜈 πœ‡ ⁑($\bar{𝜈}$ πœ‡ ) and 𝜈 πœ‡ ⁑($\bar{𝜈}$ πœ‡ ) β†’ 𝜈 𝑒 ⁑( $\bar{𝜈}$ 𝑒 ) oscillation channels are used to measure the effect of the NSI parameters πœ– π‘’β’πœ‡ and πœ– π‘’β’πœ . With 90% CL the magnitudes of the NSI couplings are constrained to be |πœ– π‘’β’πœ‡ | ≲0.3 and |πœ– π‘’β’πœ | ≲ 0.4. A degeneracy at |πœ– π‘’β’πœ | β‰ˆ 1.8 is reported, and we observe that the presence of NSI limits sensitivity to the standard 𝐢⁒𝑃 phase 𝛿 𝐢⁒𝑃 .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Expanding neutrino oscillation parameter measurements in NOvA using a Bayesian approach

NOvA is a long-baseline neutrino oscillation experiment that measures oscillations in charged-current Ξ½ ΞΌ β†’ Ξ½ ΞΌ (disappearance) and Ξ½ ΞΌ β†’ Ξ½ e (appearance) channels, and their antineutrino counterparts, using neutrinos of energies around 2 GeV over a distance of 810 km. In this work we reanalyze the dataset first examined in our previous paper [] using an alternative statistical approach based on Bayesian Markov chain Monte Carlo. We measure oscillation parameters consistent with the previous results. We also extend our inferences to include the first NOvA measurements of the reactor mixing angle ΞΈ 13 , where we find 0.071 ≀ sin 2 2 ΞΈ 13 ≀ 0.107 , and the Jarlskog invariant, where we observe no significant preference for the C P -conserving value J = 0 over values favoring C P violation. We use these results to examine the effects of constraints from short-baseline measurements of ΞΈ 13 using antineutrinos from nuclear reactors when making NOvA measurements of ΞΈ 23 . Our long-baseline measurement of ΞΈ 13 is shown to be consistent with the reactor measurements, supporting the general applicability and robustness of the Pontecorvo-Maki-Nakagawa-Sakata framework for neutrino oscillations. Published by the American Physical Society 2024

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Bandgap engineering of Cd 1 - x Zn x Te 1 - y Se y ( 0 < x < 0 . 27 , 0 < y < 0 . 026 )

CdZnTe (CZT) detectors with more than 10% zinc content did not show a remarkable improvement in the detector performance due to the additional defects introduced by the higher zinc content. However, recent research showed that the formation of defects was suppressed effectively by adding a small amount of selenium (2%) in CZT. On this basis, we attempted to enhance the detector performance through bandgap engineering by increasing the zinc content up to 25 %, while adding 2 % of selenium. Multiple CdZnTeSe (CZTS) ingots with Zn = 10, 12.5, 15, 20 and 25%, while fixing the Se composition at 2%, were grown by the Bridgman method. The bandgap of CZTS for the different Zn and Se contents was analyzed and then equations for predicting the bandgap for other alloy compositions were introduced. Furthermore, the crystallinity of CZTS was evaluated by photoluminescence measurements. The pulse height spectra for Am-241 and Co-57 sources were used to evaluate the detector performance for the CZTS samples.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND β†—
DOE OSTI2021

Search for slow magnetic monopoles with the NOvA detector on the surface

We report a search for a magnetic monopole component of the cosmic-ray flux in a 95-day exposure of the NOvA experiment’s Far Detector, a 14 kt segmented liquid scintillator detector designed primarily to observe GeV-scale electron neutrinos. No events consistent with monopoles were observed, setting an upper limit on the flux of 2 Γ— 10 -14 cm -2 s -1 sr -1 at 90% C.L. for monopole speed 6 Γ— 10 -4 < Ξ² < 5 Γ— 10 -3 and mass greater than 5 Γ— 10 8 GeV. Because of NOvA’s small overburden of 3 meters-water equivalent, this constraint covers a previously unexplored low-mass region.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND β†—
DOE OSTI2020

Supernova neutrino detection in NOvA

The NOvA long-baseline neutrino experiment uses a pair of large, segmented, liquid-scintillator calorimeters to study neutrino oscillations, using GeV-scale neutrinos from the Fermilab NuMI beam. These detectors are also sensitive to the flux of neutrinos which are emitted during a core-collapse supernova through inverse beta decay interactions on carbon at energies of &calO;(10 MeV). This signature provides a means to study the dominant mode of energy release for a core-collapse supernova occurring in our galaxy. We describe the data-driven software trigger system developed and employed by the NOvA experiment to identify and record neutrino data from nearby galactic supernovae. This technique has been used by NOvA to self-trigger on potential core-collapse supernovae in our galaxy, with an estimated sensitivity reaching out to 10 kpc distance while achieving a detection efficiency of 23% to 49% for supernovae from progenitor stars with masses of 9.6 MβŠ™ to 27 MβŠ™, respectively.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND β†—
DOE OSTI2020

Adjusting neutrino interaction models and evaluating uncertainties using NOvA near detector data

The two-detector design of the NOvA neutrino oscillation experiment, in which two functionally identical detectors are exposed to an intense neutrino beam, aids in canceling leading order effects of cross-section uncertainties. However, limited knowledge of neutrino interaction cross sections still gives rise to some of the largest systematic uncertainties in current oscillation measurements. We show contemporary models of neutrino interactions to be discrepant with data from NOvA, consistent with discrepancies seen in other experiments. Adjustments to neutrino interaction models in GENIE are presented, creating an effective model that improves agreement with our data. We also describe systematic uncertainties on these models, including uncertainties on multi-nucleon interactions from a newly developed procedure using NOvA near detector data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗