Langer, C. et al, & Domingo-Pardo, C. (2014). Determining the rp-Process Flow through Ni-56: Resonances in Cu-57(p,gamma)Zn-58 Identified with GRETINA. Phys. Rev. Lett., 113(3), 032502–5pp.
Abstract: An approach is presented to experimentally constrain previously unreachable (p,gamma) reaction rates on nuclei far from stability in the astrophysical rp process. Energies of all critical resonances in the Cu-57(p,gamma)Zn-58 reaction are deduced by populating states in Zn-58 with a (d, n) reaction in inverse kinematics at 75 MeV/u, and detecting.-ray-recoil coincidences with the state-of-the-art gamma-ray tracking array GRETINA and the S800 spectrograph at the National Superconducting Cyclotron Laboratory. The results reduce the uncertainty in the Cu-57(p,gamma) reaction rate by several orders of magnitude. The effective lifetime of Ni-56, an important waiting point in the rp process in x-ray bursts, can now be determined entirely from experimentally constrained reaction rates.
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n_TOF Collaboration(Lederer-Woods, C. et al.), Domingo-Pardo, C., & Tain, J. L. (2021). Destruction of the cosmic gamma-ray emitter Al-26 in massive stars: Study of the key Al-26(n, p) reaction. Phys. Rev. C, 104(2), L022803–7pp.
Abstract: The Al-26(n, p) Mg-26 reaction is the key reaction impacting on the abundances of the cosmic gamma-ray emitter Al-26 produced in massive stars and impacts on the potential pollution of the early solar system with Al-26 by asymptotic giant branch stars. We performed a measurement of the Al-26(n, p) Mg-26 cross section at the high-flux beam line EAR-2 at the n_TOF facility (CERN). We report resonance strengths for eleven resonances, nine being measured for the first time, while there is only one previous measurement for the other two. Our resonance strengths are significantly lower than the only previous values available. Our cross-section data range to 150 keV neutron energy, which is sufficient for a reliable determination of astrophysical reactivities up to 0.5 GK stellar temperature.
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n_TOF Collaboration(Lederer-Woods, C. et al.), Domingo-Pardo, C., & Tain, J. L. (2021). Destruction of the cosmic gamma-ray emitter Al-26 in massive stars: Study of the key Al-26(n, alpha) reaction. Phys. Rev. C, 104(3), L032803–6pp.
Abstract: Neutron destruction reactions of the cosmic gamma-ray emitter Al-26 are of importance to determine the amount of Al-26 ejected into our galaxy by supernova explosions and for Al-26 production in asymptotic giant branch stars. We performed a new measurement of the Al-26(n, alpha) reaction up to 160-keV neutron energy at the neutron time-of-flight facilities n_TOF at CERN and GELINA at EC-JRC. We provide strengths for ten resonances, six of them for the first time. We use our data to calculate astrophysical reactivities for stellar temperatures up to 0.7 GK. Our results resolve a discrepancy between the two previous direct measurements of this reaction, and indicate higher stellar destruction rates than the most recently recommended reactivity.
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Esposito, R. et al, & Domingo-Pardo, C. (2021). Design of the third-generation lead-based neutron spallation target for the neutron time-of-flight facility at CERN. Phys. Rev. Accel. Beams, 24(9), 093001–17pp.
Abstract: The neutron time-of-flight (n_TOF) facility at the European Laboratory for Particle Physics (CERN) is a pulsed white-spectrum neutron spallation source producing neutrons for two experimental areas: the Experimental Area 1 (EAR1), located 185 m horizontally from the target, and the Experimental Area 2 (EAR2), located 20 m above the target. The target, based on pure lead, is impacted by a high-intensity 20-GeV/c pulsed proton beam. The facility was conceived to study neutron-nucleus interactions for neutron kinetic energies between a few meV to several GeV, with applications of interest for nuclear astrophysics, nuclear technology, and medical research. After the second-generation target reached the end of its lifetime, the facility underwent a major upgrade during CERN's Long Shutdown 2 (LS2, 2019-2021), which included the installation of the new third-generation neutron target. The first- and second-generation targets were based on water-cooled massive lead blocks and were designed focusing on EAR1, since EAR2 was built later. The new target is cooled by nitrogen gas to avoid erosion-corrosion and contamination of cooling water with radioactive lead spallation products. Moreover, the new design is optimized also for the vertical flight path and EAR2. This paper presents an overview of the target design focused on both physics and thermomechanical performance, and includes a description of the nitrogen cooling circuit and radiation protection studies.
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Dillmann, I., Coquard, L., Domingo-Pardo, C., Kappeler, F., Marganiec, J., Uberseder, E., et al. (2011). Cross sections for proton-induced reactions on Pd isotopes at energies relevant for the gamma process. Phys. Rev. C, 84(1), 015802–11pp.
Abstract: Proton-activation reactions on natural and enriched palladium samples were investigated via the activation technique in the energy range of E(p) = 2.75-9 MeV, close to the upper end of the respective Gamow window of the. process. We have determined cross sections for (102)Pd(p,gamma)(103)Ag, (104)Pd(p,gamma)(105)Ag, and (105)Pd(p,n)(105)Ag, as well as partial cross sections of (104)Pd(p,n)(104)Ag(g), (105)Pd(p,gamma)(106)Ag(m), (106)Pd(p,n)(106)Ag(m), and (110)Pd(p,n)(110)Ag(m) with uncertainties between 3% and 15% for constraining theoretical Hauser-Feshbach rates and for direct use in gamma-process calculations.
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