78 research outputs found
Novel NN interaction and the spectroscopy of light nuclei
Nucleon-nucleon (NN) phase shifts and the spectroscopy of nuclei
are successfully described by an inverse scattering potential that is separable
with oscillator form factors.Comment: 4 pages, 1 figure, 13 table
Mass Dependence of M3Y-Type Interactions and the Effects of Tensor Correlations
The mass dependence of the M3Y-type effective interactions and the effects of
tensor correlations are examined. Two-body nuclear matrix elements are obtained
by the lowest order constrained variational (LOCV) technique with and without
tensor correlations. We have found that the tensor correlations are important
especially in the triplet-even (TE) and tensor-even (TNE) channels in order to
reproduce the G-matrix elements obtained previously. Then M3Y-type potentials
for inelastic scattering are obtained by fitting our two-body matrix elements
to those of a sum of Yukawa functions for the mass numbers A=24, A=40 and A=90.Comment: 13 pages, 6 table
Nuclear Spin-Isospin Correlations, Parity Violation, and the Problem
The strong interaction effects of isospin- and spin-dependent nucleon-nucleon
correlations observed in many-body calculations are interpreted in terms of a
one-pion exchange mechanism. Including such effects in computations of nuclear
parity violating effects leads to enhancements of about 10%. A larger effect
arises from the one-boson exchange nature of the parity non-conserving nucleon-
nucleon interaction, which depends on both weak and strong meson-nucleon
coupling constants. Using values of the latter that are constrained by
nucleon-nucleon phase shifts leads to enhancements of parity violation by
factors close to two. Thus much of previously noticed discrepancies between
weak coupling constants extracted from different experiments can be removed.Comment: 8 pages 2 figures there should have been two figures in v
Cage of covariance in calibration modeling: Regressing multiple and strongly correlated response variables onto a low rank subspace of explanatory variables
Modern topics in theoretical nuclear physics
Over the past five years there have been profound advances in nuclear physics
based on effective field theory and the renormalization group. In this brief,
we summarize these advances and discuss how they impact our understanding of
nuclear systems and experiments that seek to unravel their unknowns. We discuss
future opportunities and focus on modern topics in low-energy nuclear physics,
with special attention to the strong connections to many-body atomic and
condensed matter physics, as well as to astrophysics. This makes it an exciting
era for nuclear physics.Comment: 8 pages, 1 figure, prepared for the Nuclear Physics Town Hall Meeting
at TRIUMF, Sept. 9-10, 2005, comments welcome, references adde
Neutron spectroscopic factors in9Li from2H( 8Li, p)9Li
We have studied the 2H(8Li, p)9Li reaction to obtain information on the spins, parities, and single-neutron spectroscopic factors for states in 9Li, using a radioactive 8Li beam. The deduced properties of the lowest three states are compared to the predictions of a number of calculations for the structure of 9Li. The results of ab initio quantum Monte Carlo calculations are in good agreement with the observed properties
Anthropogenic Space Weather
Anthropogenic effects on the space environment started in the late 19th
century and reached their peak in the 1960s when high-altitude nuclear
explosions were carried out by the USA and the Soviet Union. These explosions
created artificial radiation belts near Earth that resulted in major damages to
several satellites. Another, unexpected impact of the high-altitude nuclear
tests was the electromagnetic pulse (EMP) that can have devastating effects
over a large geographic area (as large as the continental United States). Other
anthropogenic impacts on the space environment include chemical release ex-
periments, high-frequency wave heating of the ionosphere and the interaction of
VLF waves with the radiation belts. This paper reviews the fundamental physical
process behind these phenomena and discusses the observations of their impacts.Comment: 71 pages, 35 figure
Search for excited states in He7 with the (d,p) reaction
We have studied the properties of low-lying levels in He7 using the H2(He6,p)He7 reaction at 11.5 MeV/u. This reaction probes the He6g.s.+n character of states in He7. The ground state was populated with a spectroscopic factor comparable to that obtained from ab initio calculations, supporting the tentative spin-parity assignment of 3/2- in the literature. In addition to the ground state, a broad structure is observed between EX=2-3 MeV, the excitation-energy range expected for the 1/2- state in He7. No evidence was found for a lower-lying, first-excited state reported recently
Precise electromagnetic tests of ab initio calculations of light nuclei: States in Be10
In order to test ab initio calculations of light nuclei, we have remeasured lifetimes in Be10 using the Doppler shift attenuation method (DSAM) following the Li7(Li7,α)Be10 reaction at 8 and 10 MeV. The new experiments significantly reduce systematic uncertainties in the DSAM technique. The Jπ=21+ state at 3.37 MeV has τ=205±(5)stat±(7)sysfs corresponding to a B(E2) of 9.2(3)e2fm4 in broad agreement with many calculations. The Jπ=22+ state at 5.96 MeV was found to have a B(E2) of 0.11(2)e2fm4 and provides a more discriminating test of nuclear models. New Green's function Monte Carlo calculations for these states and transitions with a number of Hamiltonians are also reported and compared to experiment
Lifetime of the 21+ state in 10C
The lifetime of the Jπ=21+ state in 10C was measured using the Doppler shift attenuation method following the inverse kinematics p(10B ,n)10C reaction at 95 MeV. The 21+ state, at 3354 keV, has τ=219±(7)stat±(10)sys fs, corresponding to a B(E2)" of 8.8(3) e2 fm4. This measurement, combined with that recently determined for 10Be [9.2(3) e2 fm4], provides a unique challenge to ab initio calculations, testing the structure of these states, including the isospin symmetry of the wave functions. Quantum Monte Carlo calculations using realistic two- and three-nucleon Hamiltonians that reproduce the 10Be B(E2) value generally predict a larger 10C B(E2) probability but with considerable sensitivity to the admixture of different spatial symmetry components in the wave functions and to the three-nucleon potential used
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