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

Coulomb dissociation of 16O into 4He and 12C

We measured the Coulomb dissociation of 16O into 4He and 12C at the R3B setup in a first campaign within FAIR Phase 0 at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. The goal was to improve the accuracy of the experimental data for the 12C(a,?)16O fusion reaction and to reach lower center-ofmass energies than measured so far. The experiment required beam intensities of 109 16O ions per second at an energy of 500 MeV/nucleon. The rare case of Coulomb breakup into 12C and 4He posed another challenge: The magnetic rigidities of the particles are so close because of the same mass-To-charge-number ratio A/Z = 2 for 16O, 12C and 4He. Hence, radical changes of the R3B setup were necessary. All detectors had slits to allow the passage of the unreacted 16O ions, while 4He and 12C would hit the detectors' active areas depending on the scattering angle and their relative energies. We developed and built detectors based on organic scintillators to track and identify the reaction products with sufficient precision

Measurement of Nuclear Interaction Cross Sections towards Neutron-Skin Thickness Determination

The accuracy of reaction theories used to extract properties of exotic nuclei from scattering experiments is often unknown or not quantified, but of utmost importance when, e.g., constraining the equation of state of asymmetric nuclear matter from observables as the neutron-skin thickness. In order to test the Glauber multiple-scattering model, the total interaction cross section of 12C on carbon targets was measured at initial beam energies of 400, 550, 650, 800, and 1000 MeV/nucleon. The measurements were performed during the first experiment of the newly constructed R3B (Reaction with Relativistic Radioactive Beams) experiment after the start of FAIR Phase-0 at the GSI/FAIR facility with beam energies of 400, 550, 650, 800, and 1000 MeV/nucleon. The combination of the large-acceptance dipole magnet GLAD and a newly designed and highly efficient Time-of-Flight detector enabled a precise transmission measurement with several target thicknesses for each initial beam energy with an experimental uncertainty of ±0.4%. A comparison with the Glauber model revealed a discrepancy of around 3.1% at higher beam energies, which will serve as a crucial baseline for the model-dependent uncertainty in future fragmentation experiments.Results presented here are based on the experiment S444/S473, which was performed at the beamline infrastructure Cave-C at the GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt (Germany) in the context of FAIR Phase-0. The project was supported by BMBF 05P21WOFN1, 05P19WOFN1, 05P21RDFN2, 05P19RDFN1, HFHF (“Helmholtz Forschungsakademie Hessen für FAIR”) and funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy – EXC 2094 – 390783311. C.A.B. acknowledges support by the U.S. DOE grant DE-FG02-08ER41533. E.C acknowledges the support by the Spanish AEI PGC2018-099746-B-C22. J. Park acknowledges the support by the Institute for Basic Science (IBS-R031-D1). This work has been partly supported by the Spanish Funding Agency for Research (AEI) through Projects No. PID2019104390GB-I00. I.G., A.H, D.J.M. and I.L. have been supported by Croatian Science Foundation (HRZZ) under project no. 1257. Supported by Portuguese FCT Project EXPL/FIS-NUC/0364/2021. J.L.R.S. thanks the support from Xunta de Galicia under the program of postdoctoral fellowships ED481B-2017-002 and ED481D-2021-018, and by the Grant No. RYC2021-031989-I. T.A., Y.A.L, and A.O. thank the State of Hesse within the Research Cluster ELEMENTS through project ID 500/10.006. Support by the Swedish Research Council under Contract No. 2022-04248, 2014-06644-VR and 2021-04576-VR. This research was supported in part by the ExtreMe Matter Institute EMMI at the GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt, Germany.Departamento de Física Aplicad

R3BRoot - Oct 21

Software for simulations and data analysis of Reactions with Relativistic Radioactive Beams experiment at FAI

R3BRoot - Sept 22

Software for simulations and data analysis of Reactions with Relativistic Radioactive Beams experiment at FAI

Fission studies in inverse kinematics with the R3B setup

Nuclear fission is a complex dynamical process, whose description involves the coupling between intrinsic and collective degrees of freedom, as well as different quantum-mechanical phenomena. For this reason, to this day it still lacks a satisfactory and complete microscopic description. In addition to the importance of describing fission itself, studies of the r-process in astrophysics depend on fission observables to constrain the theoretical models that explain the isotopic abundances in the Universe. To improve on the existing data, fission reactions of heavy nuclei in inverse kinematics are produced in quasi-free (p,2p) scattering reactions, which induce fission through particle-hole excitations that can range from few to tens of MeV. In order to study the evolution of the fission yields with temperature, the excitation energy of the fissioning system must be reconstructed, which is possible by measuring the four-momenta of the two outgoing protons. Performing this kind of experiment requires a complex experimental setup, providing full isotopic identification of both fission fragments and an accurate measurement of the momenta of the two outgoing protons. This was realized recently at the GSI/FAIR facility and some of the results obtained for the charge distributions are presented in this work

Study of (p,2p) fission reactions in inverse kinematics using the R3B set-up

A new experimental fission approach is presented in the context of the R3B (Reactions with Relativistic Radioactive Beams) collaboration, at the GSI/FAIR facility, in which knockout reactions in inverse kinematics are used to induce fission of 238U that will allow to characterise the excitation energy of the fission process and all the fission products. The CALIFA (CALorimeter for In-Flight detection of γ-rays and high energy charged pArticles) calorimeter, a key part of the R3B set-up, is used to reconstruct the momenta of the two protons from the (p, 2p) reactions. Preliminary results show that kinematic variables and first estimates for nucleon-removal cross sections are well reconstructed and in good agreement with other experimental measurements

Coulomb dissociation of ¹⁶O into ⁴He and ¹²C

Abstract We measured the Coulomb dissociation of 16O into 4He and 12C at the R3B setup in a first campaign within FAIR Phase 0 at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. The goal was to improve the accuracy of the experimental data for the 12C(α,γ)16O fusion reaction and to reach lower center-ofmass energies than measured so far. The experiment required beam intensities of 109 16O ions per second at an energy of 500 MeV/nucleon. The rare case of Coulomb breakup into 12C and 4He posed another challenge: The magnetic rigidities of the particles are so close because of the same mass-to-charge-number ratio A/Z = 2 for 16O, 12C and 4He. Hence, radical changes of the R3B setup were necessary. All detectors had slits to allow the passage of the unreacted 16O ions, while 4He and 12C would hit the detectors’ active areas depending on the scattering angle and their relative energies. We developed and built detectors based on organic scintillators to track and identify the reaction products with sufficient precision.</jats:p

Coulomb dissociation of ¹⁶O into ⁴He and ¹²C

We measured the Coulomb dissociation of ¹⁶O into ⁴He and ¹²C at the R³B setup in a first campaign within FAIR Phase 0 at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. The goal was to improve the accuracy of the experimental data for the ¹²C(α,γ)¹⁶O fusion reaction and to reach lower center-ofmass energies than measured so far. The experiment required beam intensities of 10⁹ ¹⁶O ions per second at an energy of 500 MeV/nucleon. The rare case of Coulomb breakup into ¹²C and ⁴He posed another challenge: The magnetic rigidities of the particles are so close because of the same mass-to-charge-number ratio A/Z = 2 for ¹⁶O, ¹²C and ⁴He. Hence, radical changes of the R³B setup were necessary. All detectors had slits to allow the passage of the unreacted ¹⁶O ions, while ⁴He and ¹²C would hit the detectors’ active areas depending on the scattering angle and their relative energies. We developed and built detectors based on organic scintillators to track and identify the reaction products with sufficient precision