4,095 research outputs found
Symmetry Energy in the Equation of State of Asymmetric Nuclear Matte
The symmetry energy is an important quantity in the equation of state of
isospin asymmetric nuclear matter. This currently unknown quantity is key to
understanding the structure of systems as diverse as the neutron-rich nuclei
and neutron stars. At TAMU, we have carried out studies, aimed at understanding
the symmetry energy, in a variety of reactions such as, the multifragmentation
of Ar, Ca + Fe, Ni and Ni, Fe +
Ni, Fe reactions at 25 - 53 AMeV, and deep-inelastic reactions of
Kr + Sn, Ni (25 AMeV), Ni + Ni,
Sn, Th, Pb (25 AMeV) and Xe + Ni,
Sn, Th, Au (20 AMeV). Here we present an overview
of some of the results obtained from these studies. The results are analyzed
within the framework of statistical and dynamical models, and have important
implications for future experiments using beams of neutron-rich nuclei.Comment: 10 pages, 4 figures, talk presented at VI Latin American Symposium on
Nuclear Physics and Application
Effective nucleon mass and the nuclear caloric curve
Assuming a schematic form of the nucleon effective mass as a function of
nuclear excitation energy and mass, we provide a simple explanation for
understanding the experimentally observed mass dependence of the nuclear
caloric curve. It is observed that the excitation energy at which the caloric
curve enters into a plateau region, could be sensitive to the nuclear mass
evolution of the effective nucleon mass.Comment: 5 pages, 5 figures, Accepted for publication in Phys. Rev. C. Minor
changes mad
Tracing the evolution of the symmetry energy of hot nuclear fragments from the compound nucleus towards multifragmentation
The evolution of the symmetry energy coefficient of the binding energy of hot
fragments with increasing excitation is explored in multifragmentation
processes following heavy-ion collisions below the Fermi energy. In this work,
high-resolution mass spectrometric data on isotopic distributions of
projectile-like fragments from collisions of 25 MeV/nucleon 86Kr and 64Ni beams
on heavy neutron-rich targets are systematically compared to calculations
involving the Statistical Multifragmentation Model. The study reveals a gradual
decrease of the symmetry energy coefficient from 25 MeV at the compound nucleus
regime (E*/A < 2 MeV) towards 15 MeV in the bulk multifragmentation regime
(E*/A > 4 MeV). The ensuing isotopic distributions of the hot fragments are
found to be very wide and extend towards the neutron drip-line. These findings
may have important implications to the composition and evolution of hot
astrophysical environments, such as core-collapse supernova.Comment: 5 pages, 4 figures, submitted to Phys. Rev.
The decay time scale for highly excited nuclei as seen from asymmetrical emission of particles
A novel method was developed for the extraction of short emission times of
light particles from the projectile-like fragments in peripheral deep-inelastic
collisions in the Fermi energy domain. We have taken an advantage of the fact
that in the external Coulomb field particles are evaporated asymmetrically. It
was possible to determine the emission times in the interval 50-500 fm/c using
the backward emission anisotropy of alpha-particles relative to the largest
residue, in the reaction 28Si + 112Sn at 50 MeV/nucleon. The extracted times
are consistent with predictions based on the evaporation decay widths
calculated with the statistical evaporation model generalized for the case of
the Coulomb interaction with the target.Comment: 13 pages, 5 figures, submitted to Phys. Lett.
EVALUATION OF THRUST FORCE IN DRILLING OF BD-CFRP COMPOSITE USING TAGUCHI ANALYSIS, RESPONSE SURFACE METHODOLOGY AND NEURAL NETWORK
Drilling is the most frequently used machining operation in carbon fiber reinforced polymer (CFRP) composite materials. The quality of the drilled holes is significantly affected by the thrust force generated during drilling of CFRP composite materials. In the present work, an attempt has been made to study the effects of process parameters such as feed rate, spindle speed, drill diameter and point angle on thrust force in drilling of bi-directional carbon fiber reinforced polymer (BD-CFRP) composite laminate using Taguchi design of experiments (DOE), the response surface methodology (RSM) and the genetic algorithm optimized radial basis function neural network (GA-RBFNN). The analysis of variance (ANOVA) is also performed for investigating the influence of process parameters on machining process using high speed steel (HSS) drills. The results reveal that the drill diameter is the most significant design factor influencing the thrust force followed by the spindle speed. It is evident from the investigation that the experimental results of the thrust force in drilling of BD-CFRP composite laminate are in good agreement with the predicted results as per RSM and GA-RBFNN
Symmetry energy and the isospin dependent equation of state
The isoscaling parameter , from the fragments produced in the
multifragmentation of Ni + Ni, Fe + Ni and
Fe + Fe reactions at 30, 40 and 47 MeV/nucleon, was compared with
that predicted by the antisymmetrized molecular dynamic (AMD) calculation based
on two different nucleon-nucleon effective forces, namely the Gogny and
Gogny-AS interaction. The results show that the data agrees better with the
choice of Gogny-AS effective interaction, resulting in a symmetry energy of
18-20 MeV. The observed value indicate that the fragments are formed at
a reduced density of 0.08 fm.Comment: 5 pages, 5 figures, Accepted for publication in Phys. Rev. C (Rapid
Communication
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