Neutron yield from a thick target irradiated by 90MeV protons

In the context or the design of an intense source of low and intermediate energy, neutrons, the angular and energy distributions of neutrons produced in the interaction of 90 MeV protons in a C-12 target, in which the protons are stopped, have been measured by time-of-flight and activation techniques, As compared to C-12 the yield is less than a factor two higher, while it is somewhat less than for a Be-9 target. (c) 2005 Elsevier B.V. All rights reserved.

High intensity neutrino oscillation facilities in Europe

The EUROnu project has studied three possible options for future, high intensity neutrino oscillation facilities in Europe. The first is a Super Beam, in which the neutrinos come from the decay of pions created by bombarding targets with a 4 MW proton beam from the CERN High Power Superconducting Proton Linac. The far detector for this facility is the 500 kt MEMPHYS water Cherenkov, located in the Frejus tunnel. The second facility is the Neutrino Factory, in which the neutrinos come from the decay of mu(+) and mu(-) beams in a storage ring. The far detector in this case is a 100 kt magnetized iron neutrino detector at a baseline of 2000 km. The third option is a Beta Beam, in which the neu…

Clustering effects in 48Cr composite nucleus produced via the reaction 24Mg + 24Mg at the excitation energy of 60 MeV

The reaction 24Mg + 24Mg was used to produce the composite nucleus 48Cr at 60 MeV of excitation energy where a narrow resonance (170 KeV) has been found by measuring the elastic and inelastic channels. To determine the occurrence of deformation of this compound nucleus and its possible connection with the resonances and the hypothetical cluster structure, evaporative Light Charged Particles (LCP) were measured and compared to Statistical Model (SM) predictions. The experiment was performed at LNL using the 8πLP apparatus. The comparison of the evaporation residue-LCP coincidence angular distributions and LCP energy spectra with SM calculations supports the presence of a very large deformati…

Early-design improvement of human reliability in an experimental facility: A combined approach and application on SPES

Abstract SPES (Selective Production of Exotic Species) is a second-generation Isotope Separation On-Line (ISOL) facility for advanced nuclear physics applications, currently under construction at INFN (National Institute of Nuclear Physics) of Legnaro, Italy. Despite the potentially important safety implications of human errors for ISOL facilities, only a limited number of studies addressing this issue have been performed worldwide. This paper tries to address this need by means of an integrated approach of Hierarchical Task Analysis (HTA) and three human error quantification methods: HEART (in an enhanced version), SPAR-H, and CREAM. The application of multiple Human Reliability Analysis (…

Neutron yield from a 13C thick target irradiated by protons of intermediate energy

Abstract Angular and energy distributions of neutrons produced by the interaction of protons of 20, 25 and 40 MeV in 13C targets, in which they are stopped, have been measured by time-of-flight and activation methods. Neutron yields are compared with a Monte-Carlo based model prediction and with the experimental neutron yields of proton and deuteron beams impinging on natural carbon thick targets. The gain with respect to p + 12C is only sizeable at the lowest proton energies. The neutron yield curve of p + 13C versus proton energy is definitely lower than the one of d + 12C, in contrast to the suggestion by an earlier published measurement at 30 MeV.

Thermal-hydraulic analysis on the cooling system of the target in the SPES plant

Yields of neutron-rich rubidium and cesium isotopes from fast-neutron induced fission of 238U, obtained by studying their release from a thick ISOL target

Abstract In the framework of the EURISOL project, the production of neutron-rich isotopes of rubidium and cesium has been studied. The intensities of mass-separated beams of rubidium and cesium isotopes generated from a thick 238 UC x target connected to a surface ionizer have been measured. The release properties of 140 Cs and 91 Rb have been investigated. The obtained results allowed us to determine the relative fission yields of rubidium and cesium isotopes with high accuracy.

Evaporation channel as a tool to study fission dynamics

The dynamics of the fission process is expected to affect the evaporation residue cross section because of the fission hindrance due to the nuclear viscosity. Systems of intermediate fissility constitute a suitable environment for testing such hypothesis, since they are characterized by evaporation residue cross sections comparable or larger than the fission ones. Observables related to emitted charged particle, due to their relatively high emission probability, can be used to put stringent constraints on models describing the excited nucleus decay and to recognize the effects of fission dynamics. In this work model simulations are compared with the experimental data collected via the ^{32}…

Fuzzy FMECA analysis of radioactive gas recovery system in the SPES experimental facility

Abstract Selective Production of Exotic Species is an innovative plant for advanced nuclear physic studies. A radioactive beam, generated by using an UCx target-ion source system, is ionized, selected and accelerated for experimental objects. Very high vacuum conditions and appropriate safety systems to storage exhaust gases are required to avoid radiological risk for operators and people. In this paper, Failure Mode, Effects, and Criticality Analysis of a preliminary design of high activity gas recovery system is performed by using a modified Fuzzy Risk Priority Number to rank the most critical components in terms of failures and human errors. Comparisons between fuzzy approach and classic…

Is nuclear viscosity dependent on temperature?

Nuclear viscosity is an indispensable ingredient of the nuclear fission collective dynamical models. It governs the exchange of energy between the collective variables and the thermal bath. Its dependence on the shape and temperature is a matter of controversy. By using systems of intermediate fissility we have demonstrated in a recent study that the viscosity parameters is larger for compact shapes, and decreases for larger deformations of the fissioning system, at variance with the conclusions of the statistical model modified to include empirically viscosity and time scales. In this contribution we propose an experimental scenario to highlight the possible dependence of the viscosity fro…

Human Reliability Analysis to support operational planning of an experimental facility

This paper reports the results obtained by using different techniques of Human Reliability Analysis (HRA) to identify potential operator errors at the SPES (Selective Production of Exotic Species) facility, a second generation Isotope Separation On Line (ISOL) plant for advanced nuclear physic applications. The paper presents scoping-level HRA applications, with the main goal to evaluate the applicability of HRA techniques for the specific domain. In particular, two aspects challenge a standard HRA. First, the facility is under construction so that a number of aspects related to its operation (e.g. procedures and operator interfaces) are still under definition. Second, the context of operat…

Clustering effects inCr48composite nuclei produced via theMg24+Mg24reaction

The nuclear properties of $^{48}\mathrm{Cr}$ composite $\ensuremath{\alpha}$-like nuclei produced at 60 MeV of excitation energy via the $^{24}\mathrm{Mg}+^{24}\mathrm{Mg}$ reaction were investigated. This excitation energy corresponds to a resonance with a narrow width (170 keV) observed in the elastic and inelastic channels, which was interpreted as a highly deformed state. To gain insight on the deformation of this state exclusive measurements of light charged particles were carried out with $8\ensuremath{\pi}\mathrm{LP}$ apparatus at Laboratori Nazionali di Legnaro and compared to statistical model predictions. The measured of $\ensuremath{\alpha}$-particle energy spectra, $\ensuremath{…

RELAP5-3D thermal hydraulic analysis of the target cooling system in the SPES experimental facility

The SPES (Selective Production of Exotic Species) experimental facility, under construction at the Italian National Institute of Nuclear Physics (INFN) Laboratories of Legnaro, Italy, is a second generation Isotope Separation On Line (ISOL) plant for advanced nuclear physic studies. The UCx target-ion source system works at temperature of about 2273 K, producing a high level of radiation (10^5 Sv/h), for this reason a careful risk analysis for the target chamber is among the major safety issues. In this paper, the obtained results of thermofluid-dynamics simulations of accidental transients in the SPES target cooling system are reported. The analysis, performed by using the RELAP5-3D 2.4.2 …

Production of neutron-rich surface-ionized nuclides at PARRNe

Yields of neutron-rich isotopes produced by fast neutron induced fission of 238 U were measured at the ISOL set-up Production dAtomes Radioactifs Riches en Neutrons. A surface ion source was used to ionize selectively elements with low ionization potentials. In order to observe also the most n-rich isotopes, the identification was achieved by a combined measurement of b- and c-rays and b-delayed neutrons. The flux of fast neutrons inducing fission was generated by a 1 lA beam of 26 MeV deuterons stopped in a graphite converter. The target was a standard ISOLDE type 238 UC