5,775 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
The Effect of Noise on the Dust Temperature - Spectral Index Correlation
We investigate how uncertainties in flux measurements affect the results from
modified blackbody SED fits. We show that an inverse correlation between the
dust temperature T and spectral index (beta) naturally arises from least
squares fits due to the uncertainties, even for sources with a single T and
beta. Fitting SEDs to noisy fluxes solely in the Rayleigh-Jeans regime produces
unreliable T and beta estimates. Thus, for long wavelength observations (lambda
>~ 200 micron), or for warm sources (T >~ 60 K), it becomes difficult to
distinguish sources with different temperatures. We assess the role of noise in
recent observational results that indicate an inverse and continuously varying
T - beta relation. Though an inverse and continuous T - beta correlation may be
a physical property of dust in the ISM, we find that the observed inverse
correlation may be primarily due to noise.Comment: 14 pages, including 5 Figures; Accepted for publication in Ap
Image findings of cranial nerve pathology on [18F]-2- deoxy-D-glucose (FDG) positron emission tomography with computerized tomography (PET/CT): a pictorial essay.
This article aims to increase awareness about the utility of (18)F -FDG-PET/CT in the evaluation of cranial nerve (CN) pathology. We discuss the clinical implication of detecting perineural tumor spread, emphasize the primary and secondary (18)F -FDG-PET/CT findings of CN pathology, and illustrate the individual (18)F -FDG-PET/CT CN anatomy and pathology of 11 of the 12 CNs
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.
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