437 research outputs found
TriSol: a major upgrade of the TwinSol RNB facility
We report here on the recent upgrade of the TwinSol radioactive nuclear beam
(RNB) facility at the University of Notre Dame. The new TriSol system includes
a magnetic dipole to provide a second beamline and a third solenoid which acts
to reduce the size of the radioactive beam on target.Comment: submitted to Nuclear Instruments and Methods
Structure Effects on Coulomb Dissociation of B
Coulomb Dissociation provides an alternative method for determining the
radiative capture cross sections at astrophysically relevant low relative
energies. For the breakup of B on Ni, we calculate the total Coulomb
Dissociation cross section and the angular distribution for E1, E2 and M1. Our
calculations are performed first within the standard first order semiclassical
theory of Coulomb Excitation, including the correct three body kinematics, and
later including the projectile-target nuclear interactions.Comment: 6 pages, proceedings from International Workshop on RNB, Puri, India,
January 1998 - to be published in J. Phys.
Alpha particle production by molecular single-particle effect in reactions of Be just above the Coulomb barrier
The -particle production in the dissociation of Be on
Bi and Zn at energies just above the Coulomb barrier is studied
within the two-center shell model approach. The dissociation of Be on
Bi is caused by a molecular single-particle effect (Landau-Zener
mechanism) before the nuclei reach the Coulomb barrier. Molecular
single-particle effects do not occur at that stage of the collision for
Be+Zn, and this explains the absence of fusion suppression
observed for this system. The polarisation of the energy level of the last
neutron of Be and, therefore the existence of avoided crossings with that
level, depends on the structure of the target.Comment: 5 pages, 4 figure
The risks may be too high
The proposed revisions to the diagnosis of personality disorders in ICDâ11 move the diagnosis of personality disorders from the categorical to the dimensional. Although there may be a number of good reasons to consider changes in the manner in which we diagnose personality disorders, the method proposed here goes too far in the degree of changes that it proposes. It ignores the fact that at least for some of the personality disorders, there is data that supports them as distinct diagnostic entities separate from other axis I and axis II disorders. Eliminating the diagnostic categories that have been part of the established psychiatric nomenclature for the last 30âyears threatens to undermine the significant research and clinical advances that have been made using categorical diagnoses. Copyright © 2011 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87112/1/pmh187.pd
Transfer/Breakup Modes in the 6He+209Bi Reaction Near and Below the Coulomb Barrier
Reaction products from the interaction of 6He with 209Bi have been measured
at energies near the Coulomb barrier. A 4He group of remarkable intensity,
which dominates the total reaction cross section, has been observed. The
angular distribution of the group suggests that it results primarily from a
direct nuclear process. It is likely that this transfer/breakup channel is the
doorway state that accounts for the previously observed large sub-barrier
fusion enhancement in this system.Comment: 4 pages; 3 figure
Fusion of radioactive Sn with Ni
Evaporation residue and fission cross sections of radioactive Sn on
Ni were measured near the Coulomb barrier. A large sub-barrier fusion
enhancement was observed. Coupled-channel calculations including inelastic
excitation of the projectile and target, and neutron transfer are in good
agreement with the measured fusion excitation function. When the change in
nuclear size and shift in barrier height are accounted for, there is no extra
fusion enhancement in Sn+Ni with respect to stable Sn+Ni.
A systematic comparison of evaporation residue cross sections for the fusion of
even Sn and Sn with Ni is presented.Comment: 9 pages, 11 figure
Simultaneous Optical Model Analyses of Elastic Scattering, Breakup, and Fusion Cross Section Data for the He + Bi System at Near-Coulomb-Barrier Energies
Based on an approach recently proposed by us, simultaneous
-analyses are performed for elastic scattering, direct reaction (DR)
and fusion cross sections data for the He+Bi system at
near-Coulomb-barrier energies to determine the parameters of the polarization
potential consisting of DR and fusion parts. We show that the data are well
reproduced by the resultant potential, which also satisfies the proper
dispersion relation. A discussion is given of the nature of the threshold
anomaly seen in the potential
Protein dynamics with off-lattice Monte Carlo moves
A Monte Carlo method for dynamics simulation of all-atom protein models is
introduced, to reach long times not accessible to conventional molecular
dynamics. The considered degrees of freedom are the dihedrals at
C-atoms. Two Monte Carlo moves are used: single rotations about
torsion axes, and cooperative rotations in windows of amide planes, changing
the conformation globally and locally, respectively. For local moves Jacobians
are used to obtain an unbiased distribution of dihedrals. A molecular dynamics
energy function adapted to the protein model is employed. A polypeptide is
folded into native-like structures by local but not by global moves.Comment: 10 pages, 4 Postscript figures, uses epsf.sty and a4.sty; scheduled
tentatively for Phys.Rev.E issue of 1 March 199
E2 properties of nuclei far from stability and the proton-halo problem of 8B
E2 properties of A=6--10 nuclei, including those of nuclei far from
stability, are studied by a shell-model calculation which
includes E2 core-polarization effects explicitly. The quadrupole moments and
the E2 transition strengths in A=6--10 nuclei are described quite well by the
present calculation. This result indicates that the relatively large value of
the quadrupole moment of B can be understood without introducing the
proton-halo in B. An interesting effect of the
core-polarization is found for effective charges used in the
shell model; although isoscalar effective-charges are almost constant as a
function of nucleus, appreciable variations are needed for isovector
effective-charges which play important roles in nuclei with high
isospin-values.Comment: (LaTeX, 23 pages
- âŠ