159 research outputs found
Structure of isobaric analog states in 91Nb populated by the 90Zr(a,t) reaction
Decay via proton emission of isobaric analog states (IAS's) in
was studied using the reaction at =180 MeV.
This study provides information about the damping mechanism of these states.
Decay to the ground state and low-lying phonon states in was
observed. The experimental data are compared with theoretical predictions
wherein the IAS `single-particle' proton escape widths are calculated in a
continuum RPA approach. The branching ratios for decay to the phonon states are
explained using a simple model.Comment: 3 figures. submitted to Phys. Lett.
Transverse Dynamics and Energy Tuning of Fast Electrons Generated in Sub-Relativistic Intensity Laser Pulse Interaction with Plasmas
The regimes of quasi-mono-energetic electron beam generation were
experimentally studied in the sub-relativistic intensity laser plasma
interaction. The observed electron acceleration regime is unfolded with
two-dimensional-particle-in-cell simulations of laser-wakefield generation in
the self-modulation regime.Comment: 10 pages, 5 figure
Structure of Excited States of 10Be studied with Antisymmetrized Molecular Dynamics
We study structure of excited states of 10Be with the method of variation
after spin parity projection in the framework of antisymmetrized molecular
dynamics. Present calculations describe many excited states and reproduce the
experimental data of E2 and E1 transitions and the new data of the
transition strength successfully. We make systematic discussions on the
molecule-like structures of light unstable nuclei and the important role of the
valence neutrons based on the results obtained with the framework which is free
from such model assumptions as the existence of inert cores and clusters.Comment: 15 pages, RevTex, seven postscript figures (using epsf.sty
Measurement of the Gamow-Teller Strength Distribution in 58Co via the 58Ni(t,3He) reaction at 115 MeV/nucleon
Electron capture and beta decay play important roles in the evolution of
pre-supernovae stars and their eventual core collapse. These rates are normally
predicted through shell-model calculations. Experimentally determined strength
distributions from charge-exchange reactions are needed to test modern
shell-model calculations. We report on the measurement of the Gamow-Teller
strength distribution in 58Co from the 58Ni(t,3He) reaction with a secondary
triton beam of an intensity of ~10^6 pps at 115 MeV/nucleon and a resolution of
\~250 keV. Previous measurements with the 58Ni(n,p) and the 58Ni(d,2He)
reactions were inconsistent with each other. Our results support the latter. We
also compare the results to predictions of large-scale shell model calculations
using the KB3G and GXPF1 interactions and investigate the impact of differences
between the various experiments and theories in terms of the weak rates in the
stellar environment. Finally, the systematic uncertainties in the normalization
of the strength distribution extracted from 58Ni(3He,t) are described and turn
out to be non-negligible due to large interferences between the dL=0, dS=1
Gamow-Teller amplitude and the dL=2, dS=1 amplitude.Comment: 14 pages, 8 figure
Structure of excited states of Be-11 studied with Antisymmetrized Molecular Dynamics
The structures of the ground and excited states of Be-11 were studied with a
microscopic method of antisymmetrized molecular dynamics. The theoretical
results reproduce the abnormal parity of the ground state and predict various
kinds of excited states. We suggest a new negative-parity band with a
well-developed clustering structure which reaches high-spin states. Focusing on
a clustering structure, we investigated structure of the ground and
excited states. We point out that molecular orbits play important roles for the
intruder ground state and the low-lying states. The features of
the breaking of clusters were also studied with the help of data for
Gamow-Teller transitions.Comment: 24 pages, 7 figures, to be submitted to Phys.Rev.
Simulation Study on Computer Tomography Imaging of Nuclear Distribution by Quasi Monoenergetic Gamma Rays with Nuclear Resonance Fluorescence: case study for ELI-NP application
CoE on Sustainable Energy System (Thai-Japan), Faculty of Engineering, Rajamangala University of Technology Thanyaburi (RMUTT), ThailandNon-destructive inspection carried out by using nuclear resonances excited by an MeV energy region gamma ray is a promising method. The high penetrability of MeV gamma ray of nuclear resonant energy makes possible the detection of nuclides surrounded by massive materials. As an application of this method, computed tomography imaging of nuclear distribution inside objects can be reconstructed from transmission factor of gamma rays. We have studied the image reconstruction of the nuclear distribution using Monte-Carlo simulations to estimate the gamma-ray transmission factor assuming the ELI-NP facility where about 3 order higher intensity of quasi-monoenergetic gamma rays will be available
Soft X-ray harmonic comb from relativistic electron spikes
We demonstrate a new high-order harmonic generation mechanism reaching the
`water window' spectral region in experiments with multi-terawatt femtosecond
lasers irradiating gas jets. A few hundred harmonic orders are resolved, giving
uJ/sr pulses. Harmonics are collectively emitted by an oscillating electron
spike formed at the joint of the boundaries of a cavity and bow wave created by
a relativistically self-focusing laser in underdense plasma. The spike
sharpness and stability are explained by catastrophe theory. The mechanism is
corroborated by particle-in-cell simulations
Association between mycobacterial genotypes and disease progression in Mycobacterium avium pulmonary infection
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