Studies of uranium carbide targets of a high density (original) (raw)
Related papers
On-line production of Rb and Cs isotopes from uranium carbide targets
The European Physical Journal A, 2005
A series of on-line mass separation experiments have been performed at the IRIS facility to measure the yield and release of Rb and Cs neutron-rich isotopes produced by fission reaction of 238 U. A 1 GeV proton beam was used to bombard uranium carbide targets with the densities of 11 g/cm 3 and 1.5 g/cm 3 held at temperatures in the range (2000-2230) • C. The release curves of Rb and Cs long-lived isotopes were measured from both kinds of targets. The overall production efficiency was determined making use of experimentally measured cross-sections of that isotope production. Comparison of the experimental yields of Rb and Cs isotopes with the calculated ones after corrections for losses due to finite release times suggests that the diffusion is the dominating process reducing the efficiency for short-lived isotopes. When normalized to the same thickness, an enhancement for the high-density rod target of the measured isotope yields is observed when going far from stability. This is possibly explained by the reactions induced by secondary neutrons. A significant odd-even effect with higher yields of Cs even neutron isotopes has been observed, confirming a similar effect obtained in earlier experiments.
Development of uranium carbide targets for the on-line production of neutron-rich isotopes
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2005
A number of on-line and off-line tests have been performed at the IRIS (investigation of radioactive isotopes at synchrocyclotron) facility in order to develop uranium carbide targets with a high density (11 g/cm 3 ) for the on-line production of neutron-rich isotopes by fission of 238 U. A 1 GeV proton beam was used to bombard two kinds of targets held at temperatures in the range of 1900-2100°C. The first one was a target-ion source assembly slightly modified to withstand 3 months of continuous heating at a temperature of about 2050°C. The second unit was of a new kind, where ionisation takes place in the target volume itself. A comparison of the on-line isotopic yields before and after heating for 3 months is here reported. The yields and release times of Rb, Cs and In are compared with the ones obtained from a standard reference target, as measured in previous experiments. (V.N. Panteleev), dfedorov@pnpi.spb.ru (D.V. Fedorov). Nuclear Instruments and Methods in Physics Research B 240 (2005) 888-894 www.elsevier.com/locate/nimb PACS: 25.40.Sc; 28.60.+S; 29.25.Ni; 29.25.Rn
Production of Cs and Fr isotopes from a high-density UC targets with different grain dimensions
European Physical Journal A, 2009
A UC target material of 11.3±0.5 g/cm^3 uranium density with the grain size of 20 and 5μm manufactured in a form of pills by the method of powder metallurgy has been tested on-line within the temperature range of 1800-2100 °C . The mass of uranium exposed to the beam was 4-7g. The yields and release rates of Cs and Fr isotopes produced by fission and spallation reactions of 238U by 1GeV protons have been measured. The yields of Cs and Fr isotopes obtained from the tested target materials have been compared, including yields of very short-lived Fr isotopes with half-lives down to 1ms. Temperature-resistant materials (porous graphite and tantalum foil) have been used for the internal-container construction, which holds the UC target pills inside a tungsten external container heated by the resistant heating. The fastest release and the highest efficiency for short-lived isotopes have been obtained for the targets with the internal container manufactured from the tantalum foil. Results of on-line tests of a big mass target (730g of 5μm grain UC target material) have been discussed.
The European Physical Journal Special Topics, 2007
The capacity of uranium carbide target materials of different structure and density for production of neutron-rich and heavy neutron-deficient nuclides have been investigated. The yields of Cs and Fr produced by a 1 GeV proton beam of the PNPI synchrocyclotron and release properties of different targets have been measured. Yields and release efficiencies of Cs and Fr produced from a high density UC target material and from low density UCx prepared by the ISOLDE method at IRIS in the collaboration with PARRNe group from Orsay are compared. The yields from ISOLDE original target are presented for comparison as well.
Uranium carbide fission target R&D for RIA - an update
Nuclear Physics A, 2004
For the Rare Isotope Accelerator (RIA) facility, ISOL targets employing refractory compounds of uranium are being developed to produce radioactive ions for post-acceleration. The availability of refractory uranium compounds in forms that have good thermal conductivity, relatively high density, and adequate release properties for short-lived isotopes remains an important issue. Investigations using commercially obtained uranium carbide material and prepared into targets involving various binder materials have been carried out at ANL. Thin sample pellets have been produced for measurements of thermal conductivity using a new method based on electron bombardment with the thermal radiation observed using a two-color optical pyrometer and performed on samples as a function of grain size, pressing pressure and sintering temperature. Manufacture of uranium carbide powder has now been achieved at ANL. Simulations have been carried out on the thermal behavior of the secondary target assembly incorporating various heat shield configurations.
Proton- and neutron-induced fission on uranium carbide target
The European Physical Journal A - Hadrons and Nuclei, 2004
In the frame of the R&D program for the SPES project of the Legnaro Laboratories, the production yields of Rb, In and Cs isotopes have bean measured at the synchrocyclotron of the Petersburg Nuclear Physics Institute (PNPI) of Gatchina (Russia). Production yields for direct proton fission and neutron-induced fission on a high-density UC 2 powder target are compared. The overall efficiencies as a function of the target temperature have been measured.
Neutron-rich isotope production using the uranium carbide multi-foil SPES target prototype
The European Physical Journal A, 2011
The SPES (Selective Production of Exotic Species) project, under development at the Istituto Nazionale di Fisica Nucleare -Laboratori Nazionali di Legnaro (INFN-LNL), is a new-generation Isotope Separation On-Line (ISOL) facility for the production of radioactive ion beams by means of the protoninduced fission of uranium. In the framework of the research on the SPES target, seven uranium carbide discs, obtained by reacting uranium oxide with graphite and carbon nanotubes, were irradiated with protons at the Holifield Radioactive Ion Beam Facility (HRIBF) of Oak Ridge National Laboratory (ORNL). In the following, the yields of several fission products obtained during the experiment are presented and discussed. The experimental results are then compared to those obtained using a standard uranium carbide target. The reported data highlights the capability of the new type of SPES target to produce and release isotopes of interest for the nuclear physics community.
The European Physical Journal A, 2011
The diffusion-effusion model has been used to analyse the release and yields of Fr and Cs isotopes from uranium carbide targets of very different thicknesses (6.3 and 148 g/cm 2 ) bombarded by a 1 GeV proton beam. Release curves of several isotopes of the same element and production efficiency versus decay half-life are well fitted with the same set of parameters. Comparison of efficiencies for neutron-rich and neutron-deficient Cs isotopes enables separation of the contributions from the primary (p + 238 U) and secondary (n + 238 U) reactions to the production of neutron-rich Cs isotopes. A rather simple calculation of the neutron contribution describes these data fairly well. The FLUKA code describes the primary and secondary-reaction contributions to the Cs isotopes production efficiencies for different targets quite well.
Tests of high-density UC targets developed at Gatchina for neutron-rich radioactive-beam facilities
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2008
Production of on-line mass-separated neutron-rich isotopes using fission induced by 1 GeV protons on high-density uranium targets (typically 11 g/cm 3 ) has been investigated for several years at the IRIS facility. Here we review some of the achievements during the years up to 2006 and the perspectives. In particular, we present a comparison of yields in p and n-induced fission, enhancements by secondary neutrons, a comparison with lower-density targets used at PARRNe and ISOLDE for Rb and Cs isotopes and preliminary results obtained with a new UC target material.
Preparation and optimization of targets for the production of radioactive ions at VECC
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2005
The Radioactive Ion Beam (RIB) facility, now under construction at the Variable Energy Cyclotron Centre (VECC), Kolkata, is based on the use of the well-known Isotope Separator On-Line (ISOL) technique in which the radioactive nuclei are produced by nuclear reactions with the primary beam in selected thick targets. The present article deals with the various aspects of a thick target design for the production of RIB using compound nuclear reactions with proton and alpha particle beams from the VEC cyclotron. The design involves, to start with, an optimum choice of the target compounds necessary for the production of various RIBs of interest, which satisfy a number of selection criteria. The requirements that a target should be mechanically stable, highly permeable and has a short diffusion length for radioactive atoms, limit the choice of target forms to a few. In our design, we have worked out in detail the prospect of using fibrous and composite targets like carbon fiber as backing matrix for deposition of several selected target compounds. The performance of the composite target system has been tested in beam.