The Experts below are selected from a list of 48351 Experts worldwide ranked by ideXlab platform

E. Friedman - One of the best experts on this subject based on the ideXlab platform.

  • Unified approach to nuclear densities from exotic atoms
    Hyperfine Interactions, 2009
    Co-Authors: E. Friedman
    Abstract:

    Parameters of nuclear density Distributions are derived from least-squares fits to strong interaction observables in exotic atoms. Global analyses of antiprotonic and pionic atoms show reasonably good agreement between the two types of probes regarding the average behaviour of root-mean-square radii of the Neutron Distributions. Apparent conflict regarding the shape of the Neutron Distribution is attributed to different radial sensitivities of these two probes.

  • Unified approach to nuclear densities from exotic atoms
    Hyperfine Interactions, 2009
    Co-Authors: E. Friedman
    Abstract:

    Parameters of nuclear density Distributions are derived from least-squares fits to strong interaction observables in exotic atoms. Global analyses of antiprotonic and pionic atoms show reasonably good agreement between the two types of probes regarding the average behaviour of root-mean-square radii of the Neutron Distributions. Apparent conflict regarding the shape of the Neutron Distribution is attributed to different radial sensitivities of these two probes.Comment: 5 pages, 3 figures, to appear in proceedings of leap08 conference. V2 a few details adde

M.c. Welliver - One of the best experts on this subject based on the ideXlab platform.

  • On improving the determination of the Neutron Distribution in a heavy spin-0 nucleus
    Journal of Physics G, 2003
    Co-Authors: M.c. Welliver, Steven J. Pollock
    Abstract:

    As a theorists' guide to future experiments, we investigate the possibility of improving the determination of the rms Neutron radius in a heavy spin-0 nucleus by combining measurements of the left-right asymmetry in parity violating electron scattering at two different momentum transfers. We estimate the level of constraint on Rn ≡ r21/2n for spin-0 nuclei in a nuclear model independent analysis in both plane wave and Coulomb distorted calculations. We find that experiments at two different kinematics reduce the need to make theoretical arguments about present uncertainties in the shape of the spatial Neutron Distribution compared to a single experiment with the same total beam time. We estimate that the rms Neutron radius in 208Pb can be constrained at about the 1% level, without requiring significant theoretical nuclear model assumptions.

  • Effects of spatial Neutron Distributions on low-energy parity-violating observables
    Journal of Physics G, 2001
    Co-Authors: Steven J. Pollock, M.c. Welliver
    Abstract:

    We investigate the optimal kinematic conditions for extracting information about the spatial Distribution of Neutrons in heavy spin-0 nuclei from a hypothetical parity-violating electron scattering (PVES) experiment. We further investigate the extent to which present uncertainties in the shape of the Neutron Distribution affect the extraction of the rms Neutron radius (the first moment of the Distribution Rn). We conclude that present theoretical uncertainties in the shape of the Neutron Distribution will not preclude a PVES measurement of Rn at the 1% level in lead. We also calculate the additional constraints provided by measurements at two different values of the momentum transfer. Finally, we examine the connection to atomic parity non-conservation (PNC) observables and find that a single optimally designed PVES experiment could eliminate nuclear structure uncertainties in future precision tests of the standard model at the sub-1% level.

Steven J. Pollock - One of the best experts on this subject based on the ideXlab platform.

  • On improving the determination of the Neutron Distribution in a heavy spin-0 nucleus
    Journal of Physics G, 2003
    Co-Authors: M.c. Welliver, Steven J. Pollock
    Abstract:

    As a theorists' guide to future experiments, we investigate the possibility of improving the determination of the rms Neutron radius in a heavy spin-0 nucleus by combining measurements of the left-right asymmetry in parity violating electron scattering at two different momentum transfers. We estimate the level of constraint on Rn ≡ r21/2n for spin-0 nuclei in a nuclear model independent analysis in both plane wave and Coulomb distorted calculations. We find that experiments at two different kinematics reduce the need to make theoretical arguments about present uncertainties in the shape of the spatial Neutron Distribution compared to a single experiment with the same total beam time. We estimate that the rms Neutron radius in 208Pb can be constrained at about the 1% level, without requiring significant theoretical nuclear model assumptions.

  • Effects of spatial Neutron Distributions on low-energy parity-violating observables
    Journal of Physics G, 2001
    Co-Authors: Steven J. Pollock, M.c. Welliver
    Abstract:

    We investigate the optimal kinematic conditions for extracting information about the spatial Distribution of Neutrons in heavy spin-0 nuclei from a hypothetical parity-violating electron scattering (PVES) experiment. We further investigate the extent to which present uncertainties in the shape of the Neutron Distribution affect the extraction of the rms Neutron radius (the first moment of the Distribution Rn). We conclude that present theoretical uncertainties in the shape of the Neutron Distribution will not preclude a PVES measurement of Rn at the 1% level in lead. We also calculate the additional constraints provided by measurements at two different values of the momentum transfer. Finally, we examine the connection to atomic parity non-conservation (PNC) observables and find that a single optimally designed PVES experiment could eliminate nuclear structure uncertainties in future precision tests of the standard model at the sub-1% level.

D. S. Selengut - One of the best experts on this subject based on the ideXlab platform.

  • THERMAL Neutron FLUX IN A CELL WITH TEMPERATURE DISCONTINUITIES
    Nuclear Science and Engineering, 2017
    Co-Authors: D. S. Selengut
    Abstract:

    In calculations of thermal Neutron flux, the interpretation of lattice measurements, in which the part of the lattice being studied is held at elevated temperature, is complicated by uncertainties as to the width of the transition region caused by the temperature discontinuity. As an altemative to a straightforward multigroup approach to the solution of the problem, a method wae developed which employs the formalism of few-group theory while retaining the qualitative features of Neutron Distribution in space and energy. The basic procedure is to approximate the actual Neutron Distribution by a superposition of overlapping thermal groups, one in eqtilibrium with each region of uniform temperature in the system. Neutrons in the nonequilibrium groups will then make transitions into the local equilibrium group at a rate that can be easily calculated. (M.C.G.)

Koji Ono - One of the best experts on this subject based on the ideXlab platform.

  • Development of two dimensional thermal Neutron flux monitor using multi-wire proportional counter for boron Neutron capture therapy
    2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS MIC), 2012
    Co-Authors: Hiroki Tanaka, Yoshinori Sakurai, Minoru Suzuki, Shin-ichiro Masunaga, Masahiro Hino, Yuko Kinashi, Koji Ono, Akira Maruhashi
    Abstract:

    At Kyoto University Research Reactor Institute, clinical studies of around 400 of Boron Neutron Capture Therapy (BNCT) have been performed using research reactor. On the other hand, we have developed cyclotron based epithermal Neutron source. To improve the quality of treatment, it is necessary to perform the detection of two dimensional thermal Neutron Distribution before and during treatment as quality control. Generally, the method of activation using gold foiVwire and germanium semiconductor detector is applied to detection of thermal Neutron flux at several positions. However, the activation method using semiconductor detector takes some time to decide the thermal Neutron flux. Therefore, we propose the method using multi-wire proportional counter for detection of two dimensional thermal Neutron Distribution. We constructed the system consisting of multi-wire detection head, multi-channel preamplifier, multi-channel discriminator, centroid calculation circuit, and data acquisition system. Detection efficiency for BNCT irradiation field was evaluated using Am-Be Neutron source with moderator for producing thermal Neutrons. Furthermore, two dimensional thermal Neutron Distribution was demonstrably obtained.

  • Development of thermal Neutron flux monitor using small scintillator array coupled with quartz fibers for Boron Neutron Capture Therapy
    2011 IEEE Nuclear Science Symposium Conference Record, 2011
    Co-Authors: Hiroki Tanaka, Yoshinori Sakurai, Minoru Suzuki, Shin-ichiro Masunaga, Yuko Kinashi, Natsuko Kondo, Yuji Kawabata, Takahiro Yagi, Tsuyoshi Misawa, Koji Ono
    Abstract:

    At Kyoto University Research Reactor Institute, over three hundred clinical trials of Boron Neutron Capture Therapy (BNCT) have been performed using research reactor. On the other hand, we have developed cyclotron based epithermal Neutron source. To improve the quality of treatment, it is necessary to perform the detection of two dimensional thermal Neutron Distribution before treatment as quality control. Generally, the method of activation using gold foil/wire and germanium semiconductor detector is applied to detection of thermal Neutron flux at several positions. However, the activation method using semiconductor detector takes some time to decide the thermal Neutron flux. Therefore, we propose the method using small scintillator arrays coupled with quartz fibers for easy detection of two dimensional thermal Neutron Distribution with low radiation damage. To reduce the number of electric circuit and scintillators, we proposed the scanning method using one dimensional scintillation array. To evaluate this method, the irradiation test was performed using Kyoto University Research Reactor(KUR). Two dimensional thermal Neutron Distribution was easily obtained with the spatial resolution of 5mm.