BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Process and Stellar Weak Interaction Rates of Waiting Point Nuclei DTSTART;VALUE=DATE-TIME:20190701T074500Z DTEND;VALUE=DATE-TIME:20190701T080000Z DTSTAMP;VALUE=DATE-TIME:20260611T011634Z UID:indico-contribution-81-1357@indico.tlabs.ac.za DESCRIPTION:Speakers: Alexandrina Petrovici (IFIN-HH)\nThe stellar weak in teraction rates of proton-rich N≃Z nuclei in the A ∼70 mass region pla y a critical role during the rapid proton capture process (rp process) in type-I x-ray bursts taking place on the surface of neutron stars accreting hydrogen/helium-rich material from a low-mass close companion star. Nucle osynthesis in explosive hydrogen burning at high temperatures and densitie s is characterized mainly by the rp-process\, a sequence of proton capture s and weak interaction processes\, β+ decays and continuum electron captu res. An essential role for the rp-process reaction network studies is play ed by the waiting point nuclei like 68Se and 72Kr on which our studies wer e focused. The competition between the proton capture rates and the rates of the weak interaction processes at the waiting points affects the proces s significantly influencing the nuclear energy production rate and consequ ently the luminosity curves\, direct observables of a type I x-ray burst. This competition also determines the burst time scale\, the extent of the abundance flow to heavier masses as well as the final composition of the b urst ashes. \n\nSelf-consistent nuclear structure models able to describe the properties of the experimentally accessible proton-rich nuclei are nee ded to predict the characteristics of nuclei beyond the experimental reach . Robust predictions on Gamow-Teller strength distributions for the ground state and the thermally populated low-lying excited states in the stellar environment\, temperature dependence of the β + -decay rates as well as temperature and density evolution of the continuum electron capture rates during the rp-process are needed to realistically evaluate the effects of weak interaction rates of waiting point nuclei on nucleosynthesis in x-ray bursts. We investigated the impact of complex Excited Vampir beyond-mean- field predictions of stellar weak interaction rates of 68 Se and 72 Kr nuc lei dominated by shape coexistence and mixing [1\,2] on the rp-process in type-I x-ray bursts.\n\nTo explore the influence on burst simulations we u sed a post-processing approach based on a one-zone model that was adjusted to match a 1-D multizone hydrodynamic result. We performed a series of ca lculations based on different accreted compositions of hydrogen/helium mix ing and metallicity. A comparison of the results obtained using the comple x Excited Vampir predictions to the ones based on standard values for the β + -decay rates is outlined discussing the energy generation rates\, the hydrogen and helium consumption\, and the abundance flow to Sn isotopes r eached during the burst. The results are relevant steps towards improved e stimates of x-ray burst nucleosynthesis\, and consequently\, of the final abundances of the x-ray bursts required for modelling neutron star crust p roperties.\n\n[1] A. Petrovici\, O. Andrei\, Eur. Phys. J. A 51\, 133 (201 5).\n[2] A. Petrovici\, O. Andrei\, A. Chilug\, Phys. Scr. 93\, 114001 (20 18).\n\nhttps://indico.tlabs.ac.za/event/81/contributions/1357/ LOCATION: URL:https://indico.tlabs.ac.za/event/81/contributions/1357/ END:VEVENT BEGIN:VEVENT SUMMARY:Photoneutron reaction cross section measurements on 94Mo and 90Zr relevant to the p-process nucleosynthesis DTSTART;VALUE=DATE-TIME:20190701T081500Z DTEND;VALUE=DATE-TIME:20190701T083000Z DTSTAMP;VALUE=DATE-TIME:20260611T011634Z UID:indico-contribution-81-1359@indico.tlabs.ac.za DESCRIPTION:Speakers: Adriana Banu (James Madison University\, Department of Physics and Astronomy\, Harrisonburg\, Virginia 22807\, USA)\nThe photo disintegration cross sections for the 94Mo(γ\,n) and 90Zr(γ\,n) reaction s have been experimentally investigated with quasi-monochromatic photon be ams at the High Intensity γ-ray Source (HIγS) facility of the Triangle U niversities Nuclear Laboratory (TUNL). The energy dependence of the photon eutron reaction cross sections was measured with high precision from the r espective neutron emission thresholds up to 13.5 MeV.These measurements co ntribute to a broader investigation of nuclear reactions relevant to the u nderstanding of the p-process nucleosynthesis. The results are compared wi th the predictions of Hauser-Feshbach statistical model calculations using two different models for the dipole γ-ray strength function. The resulti ng 94Mo(γ\,n) and 90Zr(γ\,n) photoneutron stellar reaction rates as a fu nction of temperature in the typical range of interest for the p-process n ucleosynthesis show how sensitive the photoneutron stellar reaction rate c an be to the experimental data in the vicinity of the neutron threshold.\n \nhttps://indico.tlabs.ac.za/event/81/contributions/1359/ LOCATION: URL:https://indico.tlabs.ac.za/event/81/contributions/1359/ END:VEVENT BEGIN:VEVENT SUMMARY:Experimental study with light RIB at ACCULINNA-2 DTSTART;VALUE=DATE-TIME:20190701T160000Z DTEND;VALUE=DATE-TIME:20190701T161500Z DTSTAMP;VALUE=DATE-TIME:20260611T011634Z UID:indico-contribution-81-1375@indico.tlabs.ac.za DESCRIPTION:Speakers: Grzegorz Kaminski (FLNR\, JINR)\nAn important upgrad e of the Flerov Laboratory of Nuclear Reactions Radioactive Ion Beam facil ity at JINR is start of the operation of a new high acceptance device call ed ACCULINNA-2. An overview of the design\, construction and commissioning studies of the ACCULINNA-2 separator are presented. The separator will be equipped with a modern cryogenic tritium target cell\, with zero degree s pectrometer including a neutron detector array\, and the TPC detector. Thi s opens a wide range of experimental possibilities. Preliminary results of the experimental study of $^6$He + d scattering and search for the $^7$H nucleus are presented. An overview of light radioactive ion beams experime ntal program is given.\n\nhttps://indico.tlabs.ac.za/event/81/contribution s/1375/ LOCATION: URL:https://indico.tlabs.ac.za/event/81/contributions/1375/ END:VEVENT END:VCALENDAR