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James, C.

Publications and source records attributed to James, C..

At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Detection of back-to-back proton pairs in charged-current neutrino interactions with the ArgoNeuT detector in the NuMI low energy beam line

Short range nucleon-nucleon correlations in nuclei (NN SRC) carry important information on nuclear structure and dynamics. NN SRC have been extensively probed through two-nucleon knock- out reactions in both pion and electron scattering experiments. We report here on the detection of two-nucleon knock-out events from neutrino interactions and discuss their topological features as possibly involving NN SRC content in the target argon nuclei. The ArgoNeuT detector in the Main Injector neutrino beam at Fermilab has recorded a sample of 30 fully reconstructed charged current events where the leading muon is accompanied by a pair of protons at the interaction vertex, 19 of which have both protons above the Fermi momentum of the Ar nucleus. Out of these 19 events, four are found with the two protons in a strictly back-to-back high momenta configuration directly observed in the final state and can be associated to nucleon Resonance pionless mechanisms involving a pre-existing short range correlated np pair in the nucleus. Another fraction (four events) of the remaining 15 events have a reconstructed back-to-back configuration of a np pair in the initial state, a signature compatible with one-body Quasi Elastic interaction on a neutron in a SRC pair. The detection of these two subsamples of the collected (mu- + 2p) events suggests that mechanisms directly involving nucleon-nucleon SRC pairs in the nucleus are active and can be efficiently explored in neutrino-argon interactions with the LAr TPC technology.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Measurements of inclusive muon neutrino and antineutrino charged current differential cross sections on argon in the NuMI antineutrino beam

The ArgoNeuT collaboration presents measurements of inclusive muon neutrino and antineutrino charged current differential cross sections on argon in the Fermilab NuMI beam operating in the low energy antineutrino mode. The results are reported in terms of outgoing muon angle and momentum at a mean neutrino energy of 9.6 GeV (neutrinos) and 3.6 GeV (antineutrinos), in the range 0° < θ µ < 36° and 0 < p µ < 25 GeV/c, for both neutrinos and antineutrinos.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Combined Analysis of ν μ Disappearance and ν μ → ν e Appearance in MINOS Using Accelerator and Atmospheric Neutrinos

We report on a new analysis of neutrino oscillations in MINOS using the complete set of accelerator and atmospheric data. The analysis combines the $\nu_{\mu}$ disappearance and $\nu_{e}$ appearance data using the three-flavor formalism. We measure $|\Delta m^{2}_{32}|=[2.28-2.46]\times10^{-3}\mbox{\,eV}^{2}$ (68% C.L.) and $\sin^{2}\theta_{23}=0.35-0.65$ (90% C.L.) in the normal hierarchy, and $|\Delta m^{2}_{32}|=[2.32-2.53]\times10^{-3}\mbox{\,eV}^{2}$ (68% C.L.) and $\sin^{2}\theta_{23}=0.34-0.67$ (90% C.L.) in the inverted hierarchy. The data also constrain $\delta_{CP}$, the $\theta_{23}$ octant degeneracy and the mass hierarchy; we disfavor 36% (11%) of this three-parameter space at 68% (90%) C.L.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Superconducting Nb thin films on Cu and Cu alloys for applications in SRF accelerators

This article presents the results of Nb thin films deposited on Cu and phosphor bronze via coaxial energetic deposition (CEDTM). CEDTM is a non-equilibrium cathodic arc process that drives medium energy (50 - 150 eV) ions into a few atomic layers beneath the surface to promote the growth of dense, ordered films via sub-plantation physics1. Nb films deposited on crystalline substrates by CEDTM have shown bulk-Nb like (>300-500) RRR values1. Here we describe Nb films of 1-10 ?m deposited on coupons and complex structures made of Cu and phosphor bronze at substrate temperatures of 100 have been achieved on fine grain Cu with little surface preparation. The vortex penetration magnetic field was measured by DC SQUID and these results are presented along with comparisons between bulk Nb and thin film Nb on crystalline substrates. The CEDTM approach has applications in superconducting bellows interconnects as well as to SRF cavities. 1 M. Krishnan, E. Valderrama, B. Bures, K. Wilson-Elliott, X. Zhao, L. Phillips, Anne-Marie Valente-Feliciano, Joshua Spradlin, C. Reece and K. Seo, Superconductor Science and Technology, vol. 24, no. 11, p. 115002, Nov. 2011.

James, C.↗
DOE OSTI2012

Nb3Sn thin films grown using energetic condensation for SRF applications

The traditional method used to coat thin films of Nb3Sn onto SRF cavities has been to start with a Nb cavity and dip it into molten Sn. At high temperatures (>1100 °C), the Sn diffuses into the Nb to create a stoichiometrically correct film1,2 that offers superconducting properties. Here we describe a lower-temperature process that uses two separate plasmas of Nb and Sn to fire 50-150eV ions of Nb and Sn at a substrate that is heated to <400 °C. The non-equilibrium energetic condensation of Nb and Sn ions via subplantation3 creates a high crystal quality film of Nb3Sn. The stoichiometry of this film is controlled by adjusting the currents to the two separate cathodes that in turn controls the ion fluxes to the substrate. EDX, Tc, RRR and other measurements show that this method enables growth of superconducting films even on relatively low temperature substrates. This approach might offer a path to creating higher temperature Cu SRF cavities of the future that might reduce materials and cryogenics costs. 1 G. Arnolds-Mayer, Proc. SRF2, Geneva, Switzerland, pp. 643-666, 1984 2 Sam Posen, Matthias Liepe, Yi Xie, N. Valles, Proceedings of Thin Films Workshop, Padua Italy, October 2010 3 M. Krishnan et al., Superconductor Science and Technology, vol. 24, no. 11, p. 115002, Nov. 2011

James, C.↗
DOE OSTI2012

Analysis of a Large Sample of Neutrino-Induced Muons with the ArgoNeuT Detector

ArgoNeuT, or Argon Neutrino Test, is a 170 liter liquid argon time projection chamber designed to collect neutrino interactions from the NuMI beam at Fermi National Accelerator Laboratory. ArgoNeuT operated in the NuMI low-energy beam line directly upstream of the MINOS Near Detector from September 2009 to February 2010, during which thousands of neutrino and antineutrino events were collected. The MINOS Near Detector was used to measure muons downstream of ArgoNeuT. Though ArgoNeuT is primarily an R&D project, the data collected provide a unique opportunity to measure neutrino cross sections in the 0.1-10 GeV energy range. Fully reconstructing the muon from these interactions is imperative for these measurements. This paper focuses on the complete kinematic reconstruction of neutrino-induced through-going muons tracks. Analysis of this high statistics sample of minimum ionizing tracks demonstrates the reliability of the geometric and calorimetric reconstruction in the ArgoNeuT detector.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1997

Gas Dynamics, Characterization, and Calibration of Fast Flow Flight Cascade Impactor Quartz Crystal Microbalances (QCM) for Aerosol Measurements

During recent high altitude flights, we have tested the aerosol section of the fast flow flight cascade impactor quartz crystal microbalance (QCM) on loan to Howard University from NASA. The aerosol mass collected during these flights was disappointingly small. Increasing the flow through the QCM did not correct the problem. It was clear that the instrument was not being operated under proper conditions for aerosol collect ion primarily because the gas dynamics is not well understood. A laboratory study was therefore undertaken using two different fast flow QCM's in an attempt to establish the gas flow characteristics of the aerosol sections and its effect on particle collection, Some tests were made at low temperatures but most of the work reported here was carried out at room temperature. The QCM is a cascade type impactor originally designed by May (1945) and later modified by Anderson (1966) and Mercer et al (1970) for chemical gas analysis. The QCM has been used extensively for collecting and sizing stratospheric aerosol particles. In this paper all flow rates are given or corrected and referred to in terms of air at STP. All of the flow meters were kept at STP. Although there have been several calibration and evaluation studies of moderate flow cascade impactors of less than or equal to 1 L/rein., there is little experimental information on the gas flow characteristics for fast flow rates greater than 1 L/rein.

Grant, J.R.↗