338 research outputs found
New mechanism for the production of the extremely fast light particles in heavy-ion collisions in the Fermi energy domain
Employing a four-body classical model, various mechanisms responsible for the
production of fast light particles in heavy ion collisions at low and
intermediate energies have been studied. It has been shown that at energies
lower than 50 A MeV, light particles of velocities of more than two times
higher than the projectile velocities are produced due to the acceleration of
the target light-particles by the mean field of the incident nucleus. It has
also been shown that precision experimental reaction research in normal and
inverse kinematics is likely to provide vital information about which mechanism
is dominant in the production of fast light particles.Comment: 4 pages, 3 figures, LaTeX, to be published in Proceedings of VII
International School-Seminar on Heavy Ion Physics, May 27 - June 1, 2002,
Dubna, Russi
Production of -particle condensate states in heavy-ion collisions
The fragmentation of quasi-projectiles from the nuclear reaction +
at 25 MeV/nucleon was used to produce excited states candidates to
-particle condensation. The experiment was performed at LNS-Catania
using the CHIMERA multidetector. Accepting the emission simultaneity and
equality among the -particle kinetic energies as experimental criteria
for deciding in favor of the condensate nature of an excited state, we analyze
the and states of C and the state of O. A
sub-class of events corresponding to the direct 3- decay of the Hoyle
state is isolated.Comment: contribution to the 2nd Workshop on "State of the Art in Nuclear
Cluster Physics" (SOTANCP2), Universite Libre de Bruxelles (Belgium), May
25-28, 2010, to be published in the International Journal of Modern Physics
Nanoscale Distribution of Nuclear Sites by Super-Resolved Image Cross-Correlation Spectroscopy
Deciphering the spatiotemporal coordination between nuclear functions is important to understand its role in the maintenance of human genome. In this context, super-resolution microscopy has gained considerable interest because it can be used to probe the spatial organization of functional sites in intact single-cell nuclei in the 20\u2013250 nm range. Among the methods that quantify colocalization from multicolor images, image cross-correlation spectroscopy (ICCS) offers several advantages, namely it does not require a presegmentation of the image into objects and can be used to detect dynamic interactions. However, the combination of ICCS with super-resolution microscopy has not been explored yet. Here, we combine dual-color stimulated emission depletion (STED) nanoscopy with ICCS (STED-ICCS) to quantify the nanoscale distribution of functional nuclear sites. We show that super-resolved ICCS provides not only a value of the colocalized fraction but also the characteristic distances associated to correlated nuclear sites. As a validation, we quantify the nanoscale spatial distribution of three different pairs of functional nuclear sites in MCF10A cells. As expected, transcription foci and a transcriptionally repressive histone marker (H3K9me3) are not correlated. Conversely, nascent DNA replication foci and the proliferating cell nuclear antigen(PCNA) protein have a high level of proximity and are correlated at a nanometer distance scale that is close to the limit of our experimental approach. Finally, transcription foci are found at a distance of 130 nm from replication foci, indicating a spatial segregation at the nanoscale. Overall, our data demonstrate that STED-ICCS can be a powerful tool for the analysis of the nanoscale distribution of functional sites in the nucleus
Critical influence of target-to-substrate distance on conductive properties of LaGaO3/SrTiO3 interfaces deposited at 10-1 mbar oxygen pressure
We investigate pulsed laser deposition of LaGaO3/SrTiO3 at 10-1 mbar oxygen
background pressure, demonstrating the critical effect of the
target-to-substrate distance, dTS, on the interface sheet resistance, Rs. The
interface turns from insulating to metallic by progressively decreasing dTS.
The analysis of the LaGaO3 plume evidences the important role of the plume
propagation dynamics on the interface properties. These results demonstrate the
growth of conducting interfaces at an oxygen pressure of 10-1 mbar, an
experimental condition where a well-oxygenated heterostructures with a reduced
content of oxygen defects is expected.Comment: 16 pages, 3 figure
Status and perspectives of the 4 pi charged particles multidetector CHIMERA
The construction of the multidetector CHIMERA designed to detect
and identify charged particles and fragments emitted in heavy ion reactions
at intermediate energy is in progress and is coming to an end. The
construction of this multidetector is presented in this paper as well as the
status of the project
Effect of the intermediate velocity emissions on the quasi-projectile properties for the Ar+Ni system at 95 A.MeV
The quasi-projectile (QP) properties are investigated in the Ar+Ni collisions
at 95 A.MeV taking into account the intermediate velocity emission. Indeed, in
this reaction, between 52 and 95 A.MeV bombarding energies, the number of
particles emitted in the intermediate velocity region is related to the overlap
volume between projectile and target. Mean transverse energies of these
particles are found particularly high. In this context, the mass of the QP
decreases linearly with the impact parameter from peripheral to central
collisions whereas its excitation energy increases up to 8 A.MeV. These results
are compared to previous analyses assuming a pure binary scenario
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