Coulomb Dissociation of 27P at 498 A MeV: an indirect measurement of the astrophysical 26Si(p,) reaction.

Esta tesis doctoral se centra en el estudio experimental de la Disociación Coulombiana del 27P a 498 MeV por nucleon en el laboratorio aleman Helmholstz zentrum fur Schwerionenforschung (GSI) con sede en Darmstadt. La Disociaci on Coulombiana se usa en este caso para estudiar en cinem atica inversa la reacci on de captura de protones 26Si(p,)27P de alto inter es astrofísico

Ground-state configuration of neutron-rich ³⁵Al via Coulomb breakup

The ground-state configuration of ³⁵Al has been studied via Coulomb dissociation (CD) using the LAND-FRS setup (GSI, Darmstadt) at a relativistic energy of ~ 403 MeV/nucleon. The measured inclusive differential CD cross section for ³⁵Al, integrated up to 5.0 MeV relative energy between the ³³Al core and the neutron using a Pb target, is 78(13) mb. The exclusive measured CD cross section that populates various excited states of ³³Al is 29(7) mb. The differential CD cross section of ³⁵Al -> ³⁴Al + n has been interpreted in the light of a direct breakup model, and it suggests that the possible ground-state spin and parity of ³⁵Al could be, tentatively, 1/2⁺ or 3/2⁺ or 5/2⁺. The valence neutrons, in the ground state of ³⁵Al, may occupy a combination of either l = 3,0 or l = 1,2 orbitals coupled with the ³⁴Al core in the ground and isomeric state(s), respectively. This hints of a particle-hole configuration of the neutron across the magic shell gaps at N = 20,28 which suggests narrowing the magic shell gap. If the 5/2⁺ is the ground-state spin-parity of ³⁵Al as suggested in the literature, then the major ground-state configuration of ³⁵Al is a combination of ³⁴Al (g. s.; 4⁻) circle times ν_(p_(3/2)) and ³⁴Al (isomer; 1⁺) circle times ν _(d_(3/2)) states. The result from this experiment has been compared with that from a previous knockout measurement and a calculation using the SDPF-M interaction

Coulomb dissociation of P 27 at 500 MeV/u

The proton-capture reaction Si26(p,γ)P27 was studied via Coulomb dissociation (CD) of P27 at an incident energy of about 500 MeV/u. The three lowest-lying resonances in P27 have been populated and their resonance strengths have been measured. In addition, a nonresonant direct-capture component was clearly identified and its astrophysical S factor measured. The experimental results are compared to Monte Carlo simulations of the CD process using a semiclassical model. Our thermonuclear reaction rates show good agreement with the rates from a recent compilation. With respect to the nuclear structure of P27 we have found evidence for a negative-parity intruder state at 2.88-MeV excitation energy. © 2016 American Physical Society

Isotopic cross sections of fragmentation residues produced by light projectiles on carbon near 400A MeV

We measured 135 cross sections of residual nuclei produced in fragmentation reactions of 12C, 14N, and 13−16,20,22 O projectiles impinging on a carbon target at kinetic energies of near 400 A MeV, most of them for the first time, with the R3B/LAND setup at the GSI facility in Darmstadt (Germany). The use of this state-of-the-art experimental setup in combination with the inverse kinematics technique gave the full identification in atomic and mass numbers of fragmentation residues with a high precision. The cross sections of these residues were determined with uncertainties below 20% for most of the cases. These data are compared to other previous measurements with stable isotopes and are also used to benchmark different model calculations.This work has been partially supported by the Spanish Ministry for Science and Innovation under Grants No. PGC2018-099746-B-C21, No. PGC2018-099746-B-C22, and No. PID2019-104390GB-100; Xunta de Galicia under program “Grupos de referencia competitiva” (Project No. ED431C 2017/54); the German Bundesministerium für Bildung und Forschung (BMBF) (Grants No. 05P12RDFN8, No. 05P15RDFN1, and No. 05P19RDFN); the Swedish Research Council; and U.S. Department of Energy Grant No. DE-FG02-08ER41533. J.J.R.S. acknowledges the support of Xunta de Galicia under Grant No. ED481B-2017/002.S

Quasifree (p, 2p) Reactions on Oxygen Isotopes: Observation of Isospin Independence of the Reduced Single-Particle Strength

Quasifree one-proton knockout reactions have been employed in inverse kinematics for a systematic study of the structure of stable and exotic oxygen isotopes at the R3B=LAND setup with incident beam energies in the range of 300–450 MeV=u. The oxygen isotopic chain offers a large variation of separation energies that allows for a quantitative understanding of single-particle strength with changing isospin asymmetry. Quasifree knockout reactions provide a complementary approach to intermediate-energy onenucleon removal reactions. Inclusive cross sections for quasifree knockout reactions of the type AOðp; 2pÞA−1 N have been determined and compared to calculations based on the eikonal reaction theory. The reduction factors for the single-particle strength with respect to the independent-particle model were obtained and compared to state-of-the-art ab initio predictions. The results do not show any significant dependence on proton-neutron asymmetryThis work was supported by the German Federal Ministry for Education and Research (BMBF project 05P15RDFN1), and through the GSI-TU Darmstadt cooperation agreement. The work of C. B., W. C., and G. W. was supported by the United Kingdom Science and Technology Facilities Council (STFC) under Grants No. ST/L005743/1 and No. ST/P005314/1. SCGF calculations were performed at the DiRAC Complexity system of the University of Leicester (BIS National E-1023 infrastructure capital Grant No. ST/K000373/1 and STFC 1024 Grant No. ST/K0003259/1). C. A. B. acknowledges support by the U.S. DOE Grant No. DE-FG02- 08ER41533 and the U.S. NSF Grant No. 1415656. L. M. F. acknowledges funding from MINECO FPA2015-65035-P project.S

Quasi-free neutron and proton knockout reactions from light nuclei in a wide neutron-to-proton asymmetry range

The quasi-free scattering reactions 11C and 10,11,12C have been studied in inverse kinematics at beam energies of 300–400 MeV/u at the R3B-LAND setup. The outgoing proton-proton and proton-neutron pairs were detected in coincidence with the reaction fragments in kinematically complete measurements. The efficiency to detect these pairs has been obtained from GEANT4 simulations which were tested using the 12C() and 12C( ) reactions. Experimental cross sections and momentum distributions have been obtained and compared to DWIA calculations based on eikonal theory. The new results reported here are combined with previously published cross sections for quasi-free scattering from oxygen and nitrogen isotopes and together they enable a systematic study of the reduction of single-particle strength compared to predictions of the shell model over a wide neutron-to-proton asymmetry range. The combined reduction factors show a weak or no dependence on isospin asymmetry, in contrast to the strong dependency reported in nucleon-removal reactions induced by nuclear targets at lower energies. However, the reduction factors for are found to be 'significantly smaller than for reactions for all investigated nuclei.This work was supported by the German Federal Ministry of Education and Research (BMBF projects 05P2015RDFN1 and 05P15WOFNA), through the GSI-TU Darmstadt cooperation agreement, by the State of Hesse through the LOEWE center HIC for FAIR, and the Helmholtz-Gemeinschaft through the graduate school HGS-HIRe. This work was supported by the European Union by means of the European Commission within its Seventh Framework Program (FP7) via ENSAR (Contract No. 262010), and the Spanish CICYT research grants FPA2012-32443, FPA2015-64969-07387, and FPA2015-69640-C2-1-P. This work has supported by the Swedish Research Council under contract number 621-2011-5324. C.A.B. acknowledges support from the U.S. NSF grant No. 1415656 and the U.S. DOE grant No. DE-FG02-08ER41533. Supported by the Portuguese FCT under the project PTDC/FIS/103902/2008.S