205 research outputs found
Relation between the phenomenological interactions of the algebraic cluster model and the effective two--nucleon forces
We determine the phenomenological cluster--cluster interactions of the
algebraic model corresponding to the most often used effective two--nucleon
forces for the O + system.Comment: Latex with Revtex, 1 figure available on reques
Deformed Base Antisymmetrized Molecular Dynamics and its Application to ^{20}Ne
A new theoretical framework named as deformed base antisymmetrized molecular
dynamics that uses the localized triaxially deformed Gaussian as the single
particle wave packet is presented. The model space enables us to describe
sufficiently well the deformed mean-field structure as well as the cluster
structure and their mixed structure within the same framework. The improvement
over the original version of the antisymmetrized molecular dynamics which uses
the spherical Gaussian is verified by the application to
nucleus. The almost pure cluster structure of the
= band, the distortion of the cluster structure in the
= band and the dominance of the deformed mean-field structure of
the = band are confirmed and their observed properties are
reproduced. Especially, the intra-band E2 transition probabilities in
= and bands are reproduced without any effective charge.
Since it has been long known that the pure
cluster model underestimates the intra-band transitions in the
= band by about 30%, we consider that this success is due to the
sufficient description of the deformed mean-field structure in addition to the
cluster structure by the present framework. From the successful description of
, we expect that the present framework presents us with a
powerful approach for the study of the coexistence and interplay of the
mean-field structure and the cluster structure
Study of the Fusion-Fission Process in the Reaction
Fusion-fission and fully energy-damped binary processes of the
Cl+Mg reaction were investigated using particle-particle
coincidence techniques at a Cl bombarding energy of E
8 MeV/nucleon. Inclusive data were also taken in order to determine the partial
wave distribution of the fusion process. The fragment-fragment correlation data
show that the majority of events arises from a binary-decay process with a
relatively large multiplicity of secondary light-charged particles emitted by
the two primary excited fragments in the exit channel. No evidence is observed
for ternary-breakup processes, as expected from the systematics recently
established for incident energies below 15 MeV/nucleon and for a large number
of reactions. The binary-process results are compared with predictions of
statistical-model calculations. The calculations were performed using the
Extended Hauser-Feshbach method, based on the available phase space at the
scission point of the compound nucleus. This new method uses
temperature-dependent level densities and its predictions are in good agreement
with the presented experimental data, thus consistent with the fusion-fission
origin of the binary fully-damped yields.Comment: 30 pages standard REVTeX file, 10 eps Figures; to be published at the
European Physical Journal A - Hadrons and Nucle
Extended Hauser-Feshbach Method for Statistical Binary-Decay of Light-Mass Systems
An Extended Hauser-Feshbach Method (EHFM) is developed for light heavy-ion
fusion reactions in order to provide a detailed analysis of all the possible
decay channels by including explicitly the fusion-fission phase-space in the
description of the cascade chain. The mass-asymmetric fission component is
considered as a complex-fragment binary-decay which can be treated in the same
way as the light-particle evaporation from the compound nucleus in
statistical-model calculations. The method of the phase-space integrations for
the binary-decay is an extension of the usual Hauser-Feshbach formalism to be
applied to the mass-symmetric fission part. The EHFM calculations include
ground-state binding energies and discrete levels in the low excitation-energy
regions which are essential for an accurate evaluation of the phase-space
integrations of the complex-fragment emission (fission). In the present
calculations, EHFM is applied to the first-chance binary-decay by assuming that
the second-chance fission decay is negligible. In a similar manner to the
description of the fusion-evaporation process, the usual cascade calculation of
light-particle emission from the highly excited complex fragments is applied.
This complete calculation is then defined as EHFM+CASCADE. Calculated
quantities such as charge-, mass- and kinetic-energy distributions are compared
with inclusive and/or exclusive data for the S+Mg and
Cl+C reactions which have been selected as typical examples.
Finally, the missing charge distributions extracted from exclusive measurements
are also successfully compared with the EHFM+CASCADE predictions.Comment: 34 pages, 6 Figures available upon request, Phys. Rev. C (to be
published
Dissipative collisions in O + Al at E=116 MeV
The inclusive energy distributions of fragments (3Z7) emitted in
the reaction O + Al at 116 MeV have been measured in
the angular range = 15 - 115. A non-linear
optimisation procedure using multiple Gaussian distribution functions has been
proposed to extract the fusion-fission and deep inelastic components of the
fragment emission from the experimental data. The angular distributions of the
fragments, thus obtained, from the deep inelastic component are found to fall
off faster than those from the fusion-fission component, indicating shorter
life times of the emitting di-nuclear systems. The life times of the
intermediate di-nuclear configurations have been estimated using a diffractive
Regge-pole model. The life times thus extracted (
Sec.) are found to decrease with the increase in the fragment charge. Optimum
Q-values are also found to increase with increasing charge transfer i.e. with
the decrease in fragment charge.Comment: 9 pages, 4 figures, 1 tabl
On the role of different Skyrme forces and surface corrections in exotic cluster-decay
We present cluster decay studies of Ni formed in heavy-ion
collisions using different Skyrme forces. Our study reveals that different
Skyrme forces do not alter the transfer structure of fractional yields
significantly. The cluster decay half-lives of different clusters lies within
\pm 10% for PCM and \pm 15% for UFM.Comment: 13 pages,6 figures and 1 table; in press Pramana Journal of Physics
(2010
Fission and cluster decay of Sr nucleus in the ground-state and formed in heavy-ion reactions
Calculations for fission and cluster decay of are presented for
this nucleus to be in its ground-state or formed as an excited compound system
in heavy-ion reactions. The predicted mass distribution, for the dynamical
collective mass transfer process assumed for fission of , is clearly
asymmetric, favouring -nuclei. Cluster decay is studied within a
preformed cluster model, both for ground-state to ground-state decays and from
excited compound system to the ground-state(s) or excited states(s) of the
fragments.Comment: 14 pages LaTeX, 5 Figures available upon request Submitted to Phys.
Rev.
Pulmonary function testing in HTLV-I and HTLV-II infected humans: a cohort study
BACKGROUND: HTLV-I infection has been linked to lung pathology and HTLV-II has been associated with an increased incidence of pneumonia and acute bronchitis. However it is unknown whether HTLV-I or -II infection alters pulmonary function. METHODS: We performed pulmonary function testing on HTLV-I, HTLV-II and HTLV seronegative subjects from the HTLV outcomes study (HOST), including vital capacity (VC), forced expiratory volume in one second (FEV(1)), and diffusing lung capacity for carbon monoxide (DLCO) corrected for hemoglobin and lung volume. Multivariable analysis adjusted for differences in age, gender, race/ethnicity, height and smoking history. RESULTS: Mean (standard deviation) pulmonary function values among the 257 subjects were as follows: FVC = 3.74 (0.89) L, FEV(1 )= 2.93 (0.67) L, DLCO(corr )= 23.82 (5.89) ml/min/mmHg, alveolar ventilation (VA) = 5.25 (1.20) L and DLCO(corr)/VA = 4.54 (0.87) ml/min/mmHg/L. There were no differences in FVC, FEV1 and DLCO(corr)/VA by HTLV status. For DLCO(corr), HTLV-I and HTLV-II subjects had slightly lower values than seronegatives, but neither difference was statistically significant after adjustment for confounding. CONCLUSIONS: There was no difference in measured pulmonary function and diffusing capacity in generally healthy HTLV-I and HTLV-II subjects compared to seronegatives. These results suggest that previously described HTLV-associated abnormalities in bronchoalveolar cells and fluid may not affect pulmonary function
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