Search results for "Nuclear system"
showing 4 items of 4 documents
Photons and Lepton Pairs — The Deep Probes of Quark-Gluon Plasma
1993
Photons and lepton pairs are close to the ideal probes to study the dynamics of the dense system of strongly interacting quanta expected to be produced in ultrarelativistic nucleus-nucleus collisions1,2. Electromagnetic interactions are strong enough to lead to a detectable signal from the secondary collisions of final state particles, yet, they are weak enough to let the emitted photons and leptons to escape from the finite nuclear system without further interactions. Thus, the spectra of photons and dileptons from the dense phase of the collision can provide information on the properties of the constituents and on their momentum distributions.
Resonance State inH7
2007
The existence of the $^{7}\mathrm{H}$ nuclear system was investigated via a one-proton transfer reaction with a $^{8}\mathrm{He}$ beam at $15.4\mathrm{A}\text{ }\text{ }\mathrm{MeV}$ and a $^{12}\mathrm{C}$ gas target. The experimental setup was based on the active-target MAYA which allowed a complete reconstruction of the reaction kinematics. The existence of the $^{7}\mathrm{H}$ was confirmed with the identification of seven events where the system was formed with a resonance energy of ${0.57}_{\ensuremath{-}0.21}^{+0.42}\text{ }\text{ }\mathrm{MeV}$ above the $^{3}\mathrm{H}+4n$ threshold and a resonance width of ${0.09}_{\ensuremath{-}0.06}^{+0.94}\text{ }\text{ }\mathrm{MeV}$. This stu…
On the interdependence between ground and one-phonon RPA states
1998
Working within a schematic model and in a boson formalism, we provide a descrip tion of the ground and first-excited states of a nuclear system in terms of two independent phonon operators. The description reveals itself quite effective in reproducing the energies of the states. A comparison between these two phonon operators allows us to localize a region where a correct description of these states is compatible with the Random Phase Approximation (RPA) requirement of a single phonon. This region is found to coincide approximately with that spanned by the standard RPA. Outside this region, the two phonons start differing rapidly therefore making the application of the RPA scheme impossible…
An analytical model of heat transfer and fluid dynamic performances of an unconventional NTR engine for manned interplanetary missions
2009
Abstract An analytical model of fluid flow and heat transfer of a Nuclear Thermal Rocket (NTR) engine concept is presented. The engine is based on the direct conversion of the kinetic energy of the fission fragments (FFs) into the propellant enthalpy. The FFs can escape from an extremely thin layer of fissionable material: a sufficiently large surface coated with few micrometers of Americium 242m, confined by a neutron moderator–reflector, may become a critical reactor. Three dimensional coupled CFD-Monte Carlo simulations have already been presented in Di Piazza and Mulas (2006) . In this paper, an analytical integral 1-D model of fluid dynamics and heat transfer is built in order to fores…