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Ghosh, A.

Publications and source records attributed to Ghosh, A..

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Measurement of $K^{+}$ production in charged-current $\nu_{\mu}$ interactions

Production of K+ mesons in charged-current νμ interactions on plastic scintillator (CH) is measured using MINERvA exposed to the low-energy NuMI beam at Fermilab. Timing information is used to isolate a sample of 885 charged-current events containing a stopping K+ which decays at rest. The differential cross section in K+ kinetic energy, dσ/dTK, is observed to be relatively flat between 0 and 500 MeV. Its shape is in good agreement with the prediction by the genie neutrino event generator when final-state interactions are included, however the data rate is lower than the prediction by 15%.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Measurement of neutrino flux from neutrino-electron elastic scattering

Muon-neutrino elastic scattering on electrons is an observable neutrino process whose cross section is precisely known. Consequently, a measurement of this process in an accelerator-based ν μ beam can improve the knowledge of the absolute neutrino flux impinging upon the detector; typically this knowledge is limited to ~10% due to uncertainties in hadron production and focusing. We also isolated a sample of 135±17 neutrino-electron elastic scattering candidates in the segmented scintillator detector of MINERvA, after subtracting backgrounds and correcting for efficiency. We show how this sample can be used to reduce the total uncertainty on the NuMI ν μ flux from 9% to 6%. Finally, our measurement provides a flux constraint that is useful to other experiments using the NuMI beam, and this technique is applicable to future neutrino beams operating at multi-GeV energies.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Dimensional changes of Nb 3 Sn Rutherford cables during heat treatment

In high field magnet applications, Nb 3 Sn coils undergo a heat treatment step after winding. During this stage, coils radially expand and longitudinally contract due to the Nb 3 Sn phase change. In order to prevent residual strain from altering superconducting performances, the tooling must provide the adequate space for these dimensional changes. The aim of this paper is to understand the behavior of cable dimensions during heat treatment and to provide estimates of the space to be accommodated in the tooling for coil expansion and contraction. In addition, this paper summarizes measurements of dimensional changes on strands, single Rutherford cables, cable stacks, and coils performed between 2013 and 2015. These samples and coils have been performed within a collaboration between CERN and the U.S. LHC Accelerator Research Program to develop Nb 3 Sn quadrupole magnets for the HiLumi LHC. The results are also compared with other high field magnet projects.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Characteristic length scale dependence on conductivity for La{sub 2-x}Er{sub x}Mo{sub 2}O{sub 9} (0.05 ≤ x ≤ 0.3) oxide ion conductors

Structural property of polycrystalline La{sub 2-x}Er{sub x}Mo{sub 2}O{sub 9} has been investigated. Rietveld refinements at room temperature of the materials suggest a single phase nature with cubic symmetry (space group P2{sub 1}3). The electron density contour plot confirms the nature of different cation-oxygen bonds. Time dependent mean square displacement (√ ) and the spatial extent of the sub-diffusive motion (√ ) are evaluated using the linear response theory. The localized hop at O{sub 2} and O{sub 3} sites is found to be favorable for oxygen ion migration for these systems.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Test results of the LARP Nb$_3$Sn quadrupole HQ03a

The US LHC Accelerator Research Program (LARP) has been developing $Nb_3Sn$ quadrupoles of progressively increasing performance for the high luminosity upgrade of the Large Hadron Collider. The 120 mm aperture High-field Quadrupole (HQ) models are the last step in the R&D phase supporting the development of the new IR Quadrupoles (MQXF). Three series of HQ coils were fabricated and assembled in a shell-based support structure, progressively optimizing the design and fabrication process. The final set of coils consistently applied the optimized design solutions, and was assembled in the HQ03a model. Furthermore, this paper reports a summary of the HQ03a test results, including training, mechanical performance, field quality and quench studies.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Measurement of electron neutrino quasielastic and quasielasticlike scattering on hydrocarbon at $\langle E_{\nu} \rangle $ = 3.6 GeV

The first direct measurement of electron neutrino quasielastic and quasielasticlike scattering on hydrocarbon in the few-GeV region of incident neutrino energy has been carried out using the MINERvA detector in the NuMI beam at Fermilab. The flux-integrated differential cross sections in the electron production angle, electron energy, and Q 2 are presented. The ratio of the quasielastic, flux-integrated differential cross section in Q 2 for ν e with that of similarly selected ν μ -induced events from the same exposure is used to probe assumptions that underpin conventional treatments of charged-current νe interactions used by long-baseline neutrino oscillation experiments. Furthermore, the data are found to be consistent with lepton universality and are well described by the predictions of the neutrino event generator GENIE.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Second-generation coil design of the Nb 3 Sn low-β quadrupole for the high luminosity LHC

As part of the Large Hadron Collider Luminosity upgrade (HiLumi-LHC) program, the US LARP collaboration and CERN are working together to design and build a 150 mm aperture Nb 3 Sn quadrupole for the LHC interaction regions. A first series of 1.5 m long coils were fabricated and assembled in a first short model. A detailed visual inspection of the coils was carried out to investigate cable dimensional changes during heat treatment and the position of the windings in the coil straight section and in the end region. The analyses allow identifying a set of design changes which, combined with a fine tune of the cable geometry and a field quality optimization, were implemented in a new, second-generation, coil design. In this study, we review the main characteristics of the first generation coils, describe the modification in coil lay-out, and discuss their impact on parts design and magnet analysis.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Development of MQXF: The Nb 3 Sn low-β quadrupole for the HiLumi LHC

The High Luminosity (HiLumi) Large Hadron Collider (LHC) project has, as the main objective, to increase the LHC peak luminosity by a factor five and the integrated luminosity by a factor ten. This goal will be achieved mainly with a new interaction region layout, which will allow a stronger focusing of the colliding beams. The target will be to reduce the beam size in the interaction points by a factor of two, which requires doubling the aperture of the low-β (or inner triplet) quadrupole magnets. The use of Nb3Sn superconducting material and, as a result, the possibility of operating at magnetic field levels in the windings higher than 11 T will limit the increase in length of these quadrupoles, called MQXF, to acceptable levels. After the initial design phase, where the key parameters were chosen and the magnet's conceptual design finalized, the MQXF project, a joint effort between the U.S. LHC Accelerator Research Program and the Conseil Europeen pour la Recherche Nucleaire (CERN), has now entered the construction and test phase of the short models. Concurrently, the preparation for the development of the full-length prototypes has been initiated. Lastly, this paper will provide an overview of the project status, describing and reporting on the performance of the superconducting material, the lessons learnt during the fabrication of superconducting coils and support structure, and the fine tuning of the magnet design in view of the start of the prototyping phase.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Occurrence of magnetoelectric effect correlated to the Dy order in Dy{sub 2}NiMnO{sub 6} double perovskite

Magnetic, dielectric, and ac conductivity as well as room temperature structural and Raman studies are performed on double perovskite Dy{sub 2}NiMnO{sub 6}. The crystal structure of the compound adopts monoclinic P2{sub 1}/n space group, where alternate Mn and Ni distorted octahedral are arranged in anti-phase a{sup −} a{sup −} b{sup +} order in Glazer notation. Magnetization studies show two magnetic transitions around 100 K and 20 K which are related to the ordering of transition and rare earth cations moment, respectively. Temperature dependent dielectric permittivity shows Havriliak-Negami type thermally activated dielectric relaxation. The ac conductivity at different temperature is found to follow Jonscher power law behavior. Time-temperature scaling of the conductivity spectra reveals that the charge transport dynamics is independent of temperature. Intriguingly, an anomaly in the dielectric constant is observed close to the order of Dy moment which indicates intrinsic magnetoelectric coupling. The hybridization between Dy and Ni/Mn is suggested to be correlated with the magnetoelectric coupling.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Enhancement of thermal shock resistance of reaction sintered mullite–zirconia composites in the presence of lanthanum oxide

Mullite–zirconia composites containing 20 wt.% zirconia were prepared by reaction sintering of zircon flour, sillimanite beach sand and calcined alumina. 0 to 8 mol% of La{sub 2}O{sub 3} with respect to zirconia was used as sintering aid. The effect of additive on the various physical, microstructures, mechanical and thermo-mechanical properties was studied. Quantitative phase analysis shows the change in tetragonal zirconia content with incorporation of lanthanum oxide. La{sub 2}O{sub 3} addition has significantly improved the thermal shock resistance of the samples. Samples without additive retained only 20% of initial flexural strength after 5 cycles, whereas samples containing 5 mol% La{sub 2}O{sub 3} retained almost 78% of its initial flexural strength even after 15 thermal shock cycles. - Highlights: • Mullite–zirconia composites were prepared by reaction sintering route utilizing zircon and sillimanite beach sand. • Lanthanum oxide was used as sintering aid. • The presence of lanthanum oxide decreased the densification temperature. • Lanthanum oxide significantly improved the thermal shock resistance of the composites.

36 MATERIALS SCIENCE↗