Coulomb dissociation of O-16 into He-4 and C-12

We measured the Coulomb dissociation of O-16 into He-4 and C-12 within the FAIR Phase-0 program at GSI Helmholtzzentrum fur Schwerionenforschung Darmstadt, Germany. From this we will extract the photon dissociation cross section O-16(alpha,gamma)C-12, which is the time reversed reaction to C-12(alpha,gamma)O-16. With this indirect method, we aim to improve on the accuracy of the experimental data at lower energies than measured so far. The expected low cross section for the Coulomb dissociation reaction and close magnetic rigidity of beam and fragments demand a high precision measurement. Hence, new detector systems were built and radical changes to the (RB)-B-3 setup were necessary to cope with the high-intensity O-16 beam. All tracking detectors were designed to let the unreacted O-16 ions pass, while detecting the C-12 and He-4

Single and pair neutron transfers at sub-barrier energies

Multinucleon transfer cross sections in the (96)Zr+(40)Ca system have been measured,in inverse kinematics,at bombarding energies ranging from the Coulomb barrier to similar to 25% below. Targetlike recoils have been identified in A,Z and velocity with the large solid angle magnetic spectrometer PRISMA. The experimental data for one- and two-neutron transfer channels have been compared with semiclassical microscopic calculations. For the two-neutron transfer channels the relevance of the transitions to the ground state and to the 0(+) excited states of (42)Ca are discussed by employing,for the reaction mechanism,the successive approximation. It is found that the transition to the 0(+) state at similar to 6 MeV,whose wave function is dominated by the two neutrons in the 2p(3/2) shell,is much larger than the ground state one. The comparison with the inclusive data reveals that transitions to states with high multipolarity and non-natural parity are important. This suggests that more complex two-particle correlations have to be incorporated in the treatment of the transfer process

Recent experiments in inverse kinematics with the magnetic spectrometer PRISMA

This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.ISBN: 978-88-7438-101-2International audienceIn the last period, two classes of experiments have been carried outwith the large acceptance magnetic spectrometer PRISMA. In particular,the one- and two-neutron transfer processes at energies rangingfrom the Coulomb barrier to deep below it and the population of exoticneutron rich nuclei in the A∼130 and A∼200 mass regions have beenstudied. Both kinds of experiments have been performed in inversekinematics identifying in A, Z and velocity the light target-like recoilswith PRISMA placed at very forward angles in order to have, at thesame time, high efficiency and good energy and mass resolutions

Multinucleon transfer processes in the 197^{197} Au+130^{130}Te reaction studied with a high-resolution kinematic coincidence

International audienceMultinucleon transfer processes in the $^{197}$Au+$^{130}$Te at E$_{lab}$ =1.07 GeV system were studied with the PRISMA magnetic spectrometer in coincidence with an ancillary particle detector. For neutron transfer channels we extracted total cross sections and compared them with calculations performed with the GRAZING code. We associated to each light fragment identified in PRISMA the corresponding mass distribution of the heavy partner and, through the comparison with Monte Carlo simulations, we could infer about the role of neutron evaporation in multinucleon transfer for the population of neutron-rich heavy nuclei

Evolution of deformation in the neutron-rich krypton isotopes: The Kr-96 nucleus

The energy of the first excited 2+ state in 96Kr was measured as 241 keV. The nucleus was produced in the fission of 238U induced by a 954-MeV 136Xe beam and prompt \u3b3 rays were observed using the clover array CLARA in coincidence with fission products identified with the PRISMA spectrometer. The evolution of the quadrupole collectivity in the Kr isotopes with N\u2a7e50 is discussed by comparison with that from the Rb to Mo isotones and with predictions of various theoretical calculations

Response function of the magnetic spectrometer PRISMA for the multinucleon transfer reaction [sup 40]Ar+[sup 208]Pb

Multinucleon transfer reaction Ar-40+Pb-208 has been investigated with the PRISMA-CLARA experimental setup in LNL, INFN, Italy. The experimental differential cross sections have been obtained for different transfer channels by measuring more than Delta theta(lab) = 20 degrees covered by three angular settings of PRISMA. Results have been compared with the semiclassical calculation GRAZING. Since the understanding of the reaction mechanism depends strongly on the determination of absolute cross section, effect of transport of ions through PRISMA has been studied via a Monte Carlo simulation code

Multinucleon transfer processes in the 197^{197} Au+130^{130}Te reaction studied with a high-resolution kinematic coincidence

Multinucleon transfer processes in the $^{197}$Au+$^{130}$Te at E$_{lab}$ =1.07 GeV system were studied with the PRISMA magnetic spectrometer in coincidence with an ancillary particle detector. For neutron transfer channels we extracted total cross sections and compared them with calculations performed with the GRAZING code. We associated to each light fragment identified in PRISMA the corresponding mass distribution of the heavy partner and, through the comparison with Monte Carlo simulations, we could infer about the role of neutron evaporation in multinucleon transfer for the population of neutron-rich heavy nuclei

Interplay between single-particle and collective excitations in argon isotopes populated by transfer reactions

International audienceNew γ transitions have been identified in argon isotopes in 40 Ar + 208 Pb multiple transfer reactions by exploiting, in a fragment-γ measurement, the new generation of magnetic spectrometers based on trajectory reconstruction coupled to large γ arrays. The coupling of single-particle degrees of freedom to nuclear vibration quanta was discussed. The interpretation of the newly observed states within a particle-phonon coupling picture was used to consistently follow, via their excitation energies, the evolution of collectivity in odd Ar isotopes. The proposed level schemes are supported by the results of sd-pf shell-model calculations, which have been also employed to evaluate the strength functions of the populated states

Interplay between single-particle and collective excitations in argon isotopes populated by transfer reactions

New \u3b3 transitions have been identified in argon isotopes in 40Ar + 208Pb multiple transfer reactions by exploiting, in a fragment-\u3b3 measurement, the new generation of magnetic spectrometers based on trajectory reconstruction coupled to large \u3b3 arrays. The coupling of single-particle degrees of freedom to nuclear vibration quanta was discussed. The interpretation of the newly observed states within a particle-phonon coupling picture was used to consistently follow, via their excitation energies, the evolution of collectivity in odd Ar isotopes. The proposed level schemes are supported by the results of sd-pf shell-model calculations, which have been also employed to evaluate the strength functions of the populated states