528 research outputs found
Systematics of intermediate-energy single-nucleon removal cross sections
There is now a large and increasing body of experimental data and theoretical
analyses for reactions that remove a single nucleon from an intermediate-energy
beam of neutron- or proton-rich nuclei. In each such measurement, one obtains
the inclusive cross section for the population of all bound final states of the
mass A-1 reaction residue. These data, from different regions of the nuclear
chart, and that involve weakly- and strongly-bound nucleons, are compared with
theoretical expectations. These calculations include an approximate treatment
of the reaction dynamics and shell-model descriptions of the projectile initial
state, the bound final states of the residues, and the single-particle
strengths computed from their overlap functions. The results are discussed in
the light of recent data, more exclusive tests of the eikonal dynamical
description, and calculations that take input from more microscopic nuclear
structure models.Comment: 4 pages, 1 figure, with reference correcte
Matter radii of light halo nuclei
We re-examine the matter radii of diffuse halo nuclei, as deduced from
reaction cross section measurements at high energy. Careful consideration is
given to the intrinsic few-body structure of these projectiles and the
adiabatic nature of the projectile-target interaction. Using Li,
Be and B as examples we show that data require significantly
larger matter radii than previously reported. The revised value for Li
of 3.55 fm is consistent with three-body models with significant -intruder
state components, which reproduce experimental Li momentum distributions
following Li breakup, but were hitherto thought to be at variance with
cross section data.Comment: 8 pages RevTeX plus 5 Postscript figures. Figures also available at
http://www.ph.surrey.ac.uk/scnp/jakpub/figures.html Scheduled tentatively for
13May96 issue of Phys. Rev. Let
Cooper pair correlations and energetic knock-out reactions
Two-nucleon removal (or knock-out) reactions at intermediate energies are a
developing tool for both nuclear spectroscopy and for the study of certain
nucleon correlations in very exotic and some stable nuclei. We present an
overview of these reactions with specific emphasis on the nature of the
two-nucleon correlations that can be probed. We outline future possibilities
and tests needed to fully establish these sensitivities.Comment: 12 pages, 3 figures: Contribution to the Volume 50 years of Nuclear
BCS edited by World Scientifi
Relating breakup and incomplete fusion of weakly-bound nuclei through a classical trajectory model with stochastic breakup
A classical dynamical model that treats break-up stochastically is presented
for low energy reactions of weakly-bound nuclei. The three-dimensional model
allows a consistent calculation of breakup, incomplete and complete fusion
cross sections. The model is assessed by comparing the breakup observables with
CDCC quantum mechanical predictions, which are found to be in reasonable
agreement. Through the model, it is demonstrated that the breakup probability
of the projectile as a function of its distance from the target is of primary
importance for understanding complete and incomplete fusion at energies near
the Coulomb barrier.Comment: Accepted in Physical Review Letter
Microscopic two-nucleon overlaps and knockout reactions from C
The nuclear structure dependence of direct reactions that remove a pair of
like or unlike nucleons from a fast C projectile beam are considered.
Specifically, we study the differences in the two-nucleon correlations present
and the predicted removal cross sections when using -shell shell-model and
multi- no-core shell-model (NCSM) descriptions of the two-nucleon
overlaps for the transitions to the mass =10 projectile residues. The NCSM
calculations use modern chiral two-nucleon and three-nucleon (NN+3N)
interactions. The -removal cross sections to low-lying =0, B
final states are enhanced when using the NCSM two-nucleon amplitudes. The
calculated absolute and relative partial cross sections to the low energy
B final states show a significant sensitivity to the interactions used,
suggesting that assessments of the overlap functions for these transitions and
confirmations of their structure could be made using final-state-exclusive
measurements of the -removal cross sections and the associated momentum
distributions of the forward travelling projectile-like residues.Comment: 9 pages, 7 figure
Dissipative quantum dynamics in low-energy collisions of complex nuclei
Model calculations that include the effects of irreversible, environmental
couplings on top of a coupled-channels dynamical description of the collision
of two complex nuclei are presented. The Liouville-von Neumann equation for the
time-evolution of the density matrix of a dissipative system is solved
numerically providing a consistent transition from coherent to decoherent (and
dissipative) dynamics during the collision. Quantum decoherence and dissipation
are clearly manifested in the model calculations. Energy dissipation, due to
the irreversible decay of giant-dipole vibrational states of the colliding
nuclei, is shown to result in a hindrance of quantum tunneling and fusion.Comment: Accepted in Physical Review
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