18,415 research outputs found
Evaporation of alpha particles from P nucleus
The energy spectra of alpha particles have been measured in coincidence with
the evaporation residues for the decay of the compound nucleus P produced
in the reaction F (96 MeV) + C. The data have been compared with the
predictions of the statistical model code CASCADE. It has been observed that
significant deformation effect in the compound nucleus need to be considered in
order to explain the shape of the evaporated alpha particle energy spectra.Comment: 4 pages, 3 figures, revtex, epsf styl
Scanning probe imaging of coexistent ferromagnetism and ferroelectricity at room temperature
Room temperature coexistence of ferromagnetism and ferroelectricity in a thin
film of a novel material of nominal composition PbTi0.5Fe0.5O3-d is probed by
standard ferroelectric and ferromagnetic hysteresis loop measurements and by
scanning probe microscopy of various kinds. Both magnetic domains and
ferroelectric domains are observed in the same spatial region of the material,
implying phase coexistence in this system. For both order parameters, sample
morphology strongly affects roughness of the domain walls.Comment: 15 pages, 5 figure
Study of Dissipative Collisions of Ne (7-11 MeV/nucleon) + Al
The inclusive energy distributions of complex fragments (3 Z 9)
emitted in the reactions Ne (145, 158, 200, 218 MeV) + Al have
been measured in the angular range 10 - 50. The fusion-fission and
the deep-inelastic components of the fragment yield have been extracted using
multiple Gaussian functions from the experimental fragment energy spectra. The
elemental yields of the fusion-fission component have been found to be fairly
well exlained in the framework of standard statistical model. It is found that
there is strong competition between the fusion-fission and the deep-inelastic
processes at these energies. The time scale of the deep-inelastic process was
estimated to be typically in the range of 10 - 10 sec.,
and it was found to decrease with increasing fragment mass. The angular
momentum dissipations in fully energy damped deep-inelastic process have been
estimated from the average energies of the deep-inelastic components of the
fragment energy spectra. It has been found that, the estimated angular momentum
dissipations, for lighter fragments in particular, are more than those
predicted by the empirical sticking limit.Comment: 16 pages, 9 figure
Giant Dipole Resonance Width in near-Sn Nuclei at Low Temperature and High Angular Momentum
High energy gamma-rays in coincidence with low energy yrast gamma-rays have
been measured from 113Sb, at excitation energies of 109 and 122 MeV, formed by
bombarding 20Ne on 93Nb at projectile energies of 145 and 160 MeV respectively
to study the role of angular momentum (J) and temperature (T) over Giant Dipole
Resonance (GDR) width. The maximum populated angular momenta for fusion were
67hbar and 73hbar respectively for the above-mentioned beam energies. The high
energy photons were detected using a Large Area Modular BaF2 Detector Array
(LAMBDA) along with a 24-element multiplicity filter. After pre-equilibrium
corrections, the excitation energy E* was averaged over the decay steps of the
compound nucleus (CN). The average values of temperature, angular momentum, CN
mass etc. have been calculated by the statistical model code CASCADE. Using
those average values, results show the systematic increase of GDR width with T
which is consistent with Kusnezov parametrization and the Thermal Shape
Fluctuation Model. The rise of GDR width with temperature also supports the
assumptions of adiabatic coupling in the Thermal Shape Fluctuation Model. But
the GDR widths and corresponding reduced plots with J are not consistent with
the theoretical model at high spins.Comment: 19 pages, 10 figures, Submitted to Physics Review
Search for Excited Quarks in at the LHC
If quarks are composite particles, then excited states are expected to play a
r\^ole in the Large Hadron Collider phenomena. Concentrating on virtual
effects, and using a large part of the CMS detection criteria, we present here
a realistic examination of their effect in diphoton production at the LHC. For
various luminosities, we present the 99 % confidence limit (CL) achievable in
parameter space where is the compositeness scale and
M_{q^*} the mass of the state. For a q^* of mass 0.5 TeV, can be excluded at 99% CL with 30 (200) integrated
luminosity.Comment: 11 pages, 11 figure
Dissipation of angular momentum in light heavy ion collision
The inclusive energy distributions of fragments (4Z7) emitted in
the reactions O (116 MeV) + Al, Si, Ne (145 MeV) +
Al, Co have been measured in the angular range =
10 - 65. Fusion-fission and deep inelastic components of the
fragment emission have been extracted from the experimental data. The angular
mometum dissipations in fully damped deep inelastic collisions have been
estimated assming exit channel configuration similar to those for
fusion-fission process. It has been found that, the angular momentum
dissipations are more than those predicted by the empirical sticking limit in
all cases. The deviation is found to increase with increasing charge transfer
(lighter fragments). Qualitatively, this may be due to stronger friction in the
exit channel. Moreover, for the heavier system Ne + Co, the
overall magnitude of deviation is less as compared to those for the lighter
systems, {\it i.e.}, O + Al, Si, Ne + Al.
This may be due to lesser overlap in time scales of fusion and deep inelastic
time scales for heavier systems.Comment: 15 pages, 9 figures, accepted for publication in Phys. Rev.
On Some properties of Di-hadronic states
The binding energies of di- hadronic states have been calculated assuming a
'molecular' interaction provided by the asymptotic expression of the residual
confined gluon exchange potential between the component hadrons in the system.
Meson- meson and meson- baryon states have been studied in detail and a mass
formula has been used to calculate total mass of the 'molecules'.Comment: 11 page
- …