Search results for "Coulomb barrier"
showing 10 items of 54 documents
RBS and ERD cross-sections and optical model parameters for the analysis of lithium, boron and nickel
2000
Abstract Elastic scattering cross-sections for RBS analysis of nickel by 7 Li and 11 B ion backscattering near the Coulomb barrier have been determined. The lithium ion measurements were performed in the energy range of 8–15 MeV at the laboratory angles of 115° and 135°. For boron ions the energies between 14 and 24 MeV and scattering angles of 89°, 110° and 130° were used. For the analysis of lithium and boron by ERD the scattering cross-sections have been calculated by kinematically reversing the backscattering process. The calculated 58 Ni ion energies thus varied between 65 and 125 MeV for lithium and between 75 and 130 MeV for boron recoils. For the Li + Ni and B + Ni systems the thres…
Collision Theory for Two- and Three-Particle Systems Interacting via Short-Range and Coulomb Forces
1996
In two- and three-particle reactions with light nuclei, a rich body of precise experimental data exists in which both projectile and target and/or the fragments occurring in the final state are charged. In order to make optimal use of these data for extracting physically interesting information about the nuclear interactions, the effects of the Coulomb force must be separated out in a reliable manner. For this purpose the mastering of the intricacies of charged-particle scattering theory is of vital importance.
Multiply charged metal cluster anions
2000
Formation, stability patterns, and decay channels of silver dianionic and gold trianionic clusters are investigated with Penning-trap experiments and a shell-correction method including shape deformations. The theoretical predictions pertaining to the appearance sizes and electronic shell effects are in remarkable agreement with the experiments. Decay of the multiply anionic clusters occurs predominantly by electron tunneling through a Coulomb barrier, rather than via fission, leading to appearance sizes unrelated to those of multiply cationic clusters.
Absence of structure in the $^{20,22}$Ne + $^{118}$Sn quasi-elastic barrier distribution
2005
Abstract Motivated by the extreme deformation parameters of the projectile, we have measured quasi-elastic scattering for 20 Ne + 118 Sn. In contrast to calculations based on known collective states, the experimental barrier distribution is structureless. A comparison with the system 22 Ne + 118 Sn shows that this smoothing is unlikely to be due to nucleon- or α -transfer channels, and is more likely to be due to coupling to many other weak channels.
Multiphonon couplings in the sub-barrier fusion of 36S+140Ce
2006
Fusion cross sections have been measured for the system 36S + 140Ce in the energy range encompassing the Coulomb barrier. A representation of the fusion barrier distribution has been obtained from the second energy derivative of the excitation function. The data are well described by coupled‐channels calculations including two‐phonon states of quadrupole and octupole character in the target (140Ce) and one octupole phonon in the projectile. The importance of 140Ce low‐lying inelastic excitations has been pointed out.
Experimental study of the quasifission, fusion-fission, and de-excitation of Cf compound nuclei
2015
Background: The fusion-evaporation reaction at energies around the Coulomb barrier is presently the only way to produce the heaviest elements. However, formation of evaporation residues is strongly hindered due to the competing fusion-fission and quasifission processes. Presently, a full understanding of these processes and their relationships has not been reached.Purpose: This work aims to use new fission measurements and existing evaporation residue and fission excitation function data for reactions forming Cf isotopes to investigate the dependence of the quasifission probability and characteristics on the identities of the two colliding nuclei in heavy element formation reactions.Method:…
Multinucleon transfer reactions and proton transfer channels
2019
Transfer reactions have always been of great importance for nuclear structure and reaction mechanism studies. So far, in multinucleon transfer studies, proton pickup channels have been completely identified in atomic and mass numbers at energies close to the Coulomb barrier only in few cases. We measured the multinucleon transfer reactions in the 40Ar+208Pb system near the Coulomb barrier, by employing the PRISMA magnetic spectrometer. By using the most neutron-rich stable 40Ar beam we could populate, besidesneutron pickup and proton stripping channels, also neutron stripping and proton pickup channels. Comparison ofcross sections between different systems with the 208Pb target and with pro…
Selective properties of neutron transfer reactions in the 90Zr + 208Pb system for the population of excited states in zirconium isotopes
2015
Abstract Nuclei produced via multineutron transfer channels have been studied in 90 Zr + 208 Pb close to the Coulomb barrier energy in a fragment- γ coincident measurement employing the PRISMA magnetic spectrometer coupled to the CLARA γ -array. The selective properties of the reaction mechanism have been discussed in terms of states and their strength excited in the neutron transfer channels leading to 89–94 Zr isotopes. A strong population of yrast states, with energies up to ∼7.5 MeV has been observed.
Production and investigation of neutron-rich Osmium isotopes with and around N=126 using gas flow transport method
2014
Neutron-rich isotopes of heavy nuclei are until now poorly studied. In this work we investigate neutron-rich osmium isotopes produced in multi-nucleon transfer reactions. The reaction 136Xe+208Pb at energy near Coulomb barrier is used for production of osmium isotopes. The CORSAR-V setup is used to record the characteristics of osmium isotopes. The separation of the reaction products is based on their respective volatility. Experimental results are presented and discussed. © Published under licence by IOP Publishing Ltd.
Multinucleon transfer reactions: an overview of recent results
2012
Large acceptance magnetic spectrometers, such as PRISMA installed at Laboratori Nazionali di Legnaro, gave a further boost to the renewed interest for multinucleon transfer reactions in the last decade. The large solid angles of these devices and the high resolving powers of their detection systems allowed to investigate the transfer process around and well below the Coulomb barrier and to perform nuclear structure studies in several mass regions of the nuclide chart when coupled with large γ-ray arrays such as CLARA. Selected results obtained with the PRISMA-CLARA set-up in odd argon isotopes populated by using the multinucleon transfer process and in sub- barrier transfer measurements are…