A. C. Hayes

Shell-model calculations of neutrino scattering from {sup 12}C

Neutrino reaction cross sections ({nu}{sub {mu}},{mu}{sup -}), ({nu}{sub e},e{sup -}) and {mu}-capture and photoabsorption rates on {sup 12}C are computed within a large-basis shell-model framework, which included excitations up to 4((Planck constant)/2{pi}){omega}. When ground-state correlations are included with an open p shell the predictions of the calculations are in reasonable agreement with most of the experimental results for these reactions. Woods-Saxon radial wave functions are used, with their asymptotic forms matched to the experimental separation energies for bound states, and matched to a binding energy of 0.01 MeV for unbound states. We obtain, for the neutrino-absorption inclusive cross sections (but excluding the {sup 12}N ground-state contribution) {sigma}(bar sign)=13.2x10{sup -40} cm{sup 2} for the ({nu}{sub {mu}},{mu}{sup -}) decay-in-flight flux in agreement with the LSND datum of (11.7{+-}1.8)x10{sup -40} cm{sup 2} and {sigma}(bar sign)=4.1x10{sup -42} cm{sup 2} for the ({nu}{sub e},e{sup -}) decay-at-rest flux, less than the experimental result of (5.4{+-}0.8)x10{sup -42} cm{sup 2}. (c) 2000 The American Physical Society.

Nuclear electric dipole moment of 3He

A permanent electric dipole moment (EDM) of a physical system would require time-reversal (T) violation, which is equivalent to charge-conjugation-parity (CP) violation by CPT invariance. Experimental programs are currently pushing the limits on EDMs in atoms, nuclei, and the neutron to regimes of fundamental theoretical interest. Nuclear EDMs can be studied at ion storage rings with sensitivities that may be competitive with atomic and neutron measurements. Here we calculate the magnitude of the CP-violating EDM of {sup 3}He and the expected sensitivity of such a measurement to the underlying CP-violating interactions. Assuming that the coupling constants are of comparable magnitude for {pi}-, {rho}-, and {omega}-exchanges, we find that the pion-exchange contribution dominates. Finally, our results suggest that a measurement of the {sup 3}He EDM is complementary to the planned neutron and deuteron experiments, and could provide a powerful constraint for the theoretical models of the pion-nucleon P,T-violating interaction.

Possible origins and implications of the shoulder in reactor neutrino spectra

We analyze within a nuclear database framework the shoulder observed in the antineutrino spectra in current reactor experiments. We find that the ENDF/B-VII.1 database predicts that the antineutrino shoulder arises from an analogous shoulder in the aggregate fission beta spectra. In contrast, the JEFF-3.1.1 database does not predict a shoulder for two out of three of the modern reactor neutrino experiments, and the shoulder that is predicted by JEFF-3.1.1 arises from

Prompt radiochemistry at the National Ignition Facility (invited).

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Splitting sensitivity of the ground and 7.6 eV isomeric states of {sup 229}Th

U. We consider several possible origins of the shoulder, and find possible explanations. For example, there could be a problem with the measured aggregate beta spectra, or the harder neutron spectrum at a light-water power reactor could affect the distribution of beta-decaying isotopes. In addition to the fissile actinides, we find that

PROMPT BETA SPECTROSCOPY AS A DIAGNOSTIC FOR MIX IN IGNITED NIF CAPSULES

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Determining Reactor Flux from Xenon-136 and Cesium-135 in Spent Fuel

U could also play a significant role in distorting the total antineutrino spectrum. Distinguishing these and quantifying whether there is an anomaly associated with measured reactor neutrino signals will require new short-baseline experiments, both at thermal reactors and at reactors with a sizable epithermal neutron component.

Analysis of the Daya Bay Reactor Antineutrino Flux Changes with Fuel Burnup

Understanding mix in inertial confinement fusion (ICF) experiments at the National Ignition Facility requires the diagnosis of charged-particle reactions within an imploded target. Radiochemical diagnostics of these reactions are currently under study by scientists at Los Alamos and Lawrence Livermore National Laboratories. Measurement of these reactions requires assay of activated debris and tracer gases from the target. Presented below is an overview of the prompt radiochemistry diagnostic development efforts, including a discussion of the reactions of interest as well as the progress being made to collect and count activated material.

Reaction-in-flight neutrons as a test of stopping power in degenerate plasmas

The lowest-known excited state in nuclei is the 7.6 eV isomer of {sup 229}Th. This energy is within the range of laser-based investigations that could allow accurate measurements of possible temporal variation of this energy splitting. This in turn could probe temporal variation of the fine-structure constant or other parameters in the nuclear Hamiltonian. We investigate the sensitivity of this transition energy to these quantities. We find that the two states are predicted to have identical deformations and thus the same Coulomb energies within the accuracy of the model (viz., within roughly 30 keV). We therefore find no enhanced sensitivity to variation of the fine-structure constant. In the case of the strong interaction the energy splitting is found to have a complicated dependence on several parameters of the interaction, which makes an accurate prediction of sensitivity to temporal changes of fundamental constants problematical. Neither the strong- nor Coulomb-interaction contributions to the energy splitting of this doublet can be constrained within an accuracy better than a few tens of keV, so that only upper limits can be set on the possible sensitivity to temporal variations of the fundamental constants.

Measurement of reaction-in-flight neutrons using thulium activation at the National Ignition Facility

The National Ignition Facility (NIF) technology is designed to drive deuterium–tritium (DT) internal confinement fusion (ICF) targets to ignition using indirect radiation from laser beam energy captured in a hohlraum. Hydrodynamical instabilities at interfaces in the ICF capsule leading to mix between the DT fuel and the ablator shell material are of fundamental physical interest and can affect the performance characteristics of the capsule. Here we describe new radiochemical diagnostics for mix processes in ICF capsules with plastic or Be(0.9% Cu) ablator shells. Reactions of high-energy tritons with shell material produce high-energy β-emitters. We show that mix between the DT fuel and the shell material enhances high-energy prompt beta emission from these reactions by more than an order of magnitude over that expected in the absence of mix. We further show how a mix signal could be detectable in an ignition failure regime corresponding to yields greater than about 2 kJ.