Project acronym ATOMKI-PPROCESS
Project Nuclear reaction studies relevant to the astrophysical p-process nucleosynthesis
Researcher (PI) Gyoergy Gyuerky
Host Institution (HI) ATOMMAGKUTATO INTEZET
Country Hungary
Call Details Starting Grant (StG), PE2, ERC-2007-StG
Summary The astrophysical p-process, the stellar production mechanism of the heavy, proton rich isotopes (p-isotopes), is one of the least studied processes in nucleosynthesis. The astrophysical site(s) for the p-process could not yet be clearly identified. In order to reproduce the natural abundances of the p-isotopes, the p-process models must take into account a huge nuclear reaction network. A precise knowledge of the rate of the nuclear reactions in this network is essential for a reliable abundance calculation and for a clear assignment of the astrophysical site(s). For lack of experimental data the nuclear physics inputs for the reaction networks are based on statistical model calculations. These calculations are largely untested in the mass and energy range relevant to the p-process and the uncertainties in the reaction rate values result in a correspondingly uncertain prediction of the p-isotope abundances. Therefore, experiments aiming at the determination of reaction rates for the p-process are of great importance. In this project nuclear reaction cross section measurements will be carried out in the mass and energy range of p-process to check the reliability of the statistical model calculations and to put the p-process models on a more reliable base. The accelerators of the Institute of Nuclear Research in Debrecen, Hungary provide the necessary basis for such studies. The p-process model calculations are especially sensitive to the rates of reactions involving alpha particles and heavy nuclei. Because of technical difficulties, so far there are practically no experimental data available on such reactions and the uncertainty in these reaction rates is presently one of the biggest contributions to the uncertainty of p-isotope abundance calculations. With the help of the ERC grant the alpha-induced reaction cross sections can be measured on heavy isotopes for the first time, which could contribute to a better understanding of the astrophysical p-process.
Summary
The astrophysical p-process, the stellar production mechanism of the heavy, proton rich isotopes (p-isotopes), is one of the least studied processes in nucleosynthesis. The astrophysical site(s) for the p-process could not yet be clearly identified. In order to reproduce the natural abundances of the p-isotopes, the p-process models must take into account a huge nuclear reaction network. A precise knowledge of the rate of the nuclear reactions in this network is essential for a reliable abundance calculation and for a clear assignment of the astrophysical site(s). For lack of experimental data the nuclear physics inputs for the reaction networks are based on statistical model calculations. These calculations are largely untested in the mass and energy range relevant to the p-process and the uncertainties in the reaction rate values result in a correspondingly uncertain prediction of the p-isotope abundances. Therefore, experiments aiming at the determination of reaction rates for the p-process are of great importance. In this project nuclear reaction cross section measurements will be carried out in the mass and energy range of p-process to check the reliability of the statistical model calculations and to put the p-process models on a more reliable base. The accelerators of the Institute of Nuclear Research in Debrecen, Hungary provide the necessary basis for such studies. The p-process model calculations are especially sensitive to the rates of reactions involving alpha particles and heavy nuclei. Because of technical difficulties, so far there are practically no experimental data available on such reactions and the uncertainty in these reaction rates is presently one of the biggest contributions to the uncertainty of p-isotope abundance calculations. With the help of the ERC grant the alpha-induced reaction cross sections can be measured on heavy isotopes for the first time, which could contribute to a better understanding of the astrophysical p-process.
Max ERC Funding
750 000 €
Duration
Start date: 2008-07-01, End date: 2013-06-30
Project acronym QCDTHERMO
Project QCD thermodynamics on the lattice
Researcher (PI) Sandor Katz
Host Institution (HI) EOTVOS LORAND TUDOMANYEGYETEM
Country Hungary
Call Details Starting Grant (StG), PE2, ERC-2007-StG
Summary Quantum Chromodynamics (QCD) at finite temperature and non-zero density describes phenomena relevant to the early universe and heavy-ion collisions. The applicability of perturbation theory is limited to large temperatures and densities. We plan to use lattice simulations to study QCD thermodynamics. There are different regularizations of QCD on the lattice. The computationally most effective one is the staggered formulation, while Wilson or chiral fermions are theoretically more established. We have to distinguish studies at vanishing baryon densities from the ones concerning non-zero density. At vanishing densities the order of the QCD transition between the hadronic phase and the quark-gluon plasma was studied using staggered fermions. In the physical, continuum limit the transition was found to be a crossover. The transition temperature has also been determined. These studies should be and will be extended using Wilson and chiral fermions. This way the staggered results can be checked. At non-vanishing densities direct lattice simulations are prohibited by the infamous sign problem. Recently the multi-parameter reweighting method was developed to study moderate densities using simulations at zero baryon density. The phase diagram as well as the critical point of QCD was determined using staggered fermions with a single lattice resolution. We plan to extend these studies in two ways. In the first step finer lattices will be studied with staggered fermions and a continuum extrapolation will be attempted. In the second step Wilson and possibly chiral fermions will be used. At large densities where the sign problem is the most severe the density of states method will be used. Based on our experience with PC clusters we will build a new, high performance cluster to achieve these goals. The establishment of a strong new research group certainly will improve the competitivity of the European lattice community.
Summary
Quantum Chromodynamics (QCD) at finite temperature and non-zero density describes phenomena relevant to the early universe and heavy-ion collisions. The applicability of perturbation theory is limited to large temperatures and densities. We plan to use lattice simulations to study QCD thermodynamics. There are different regularizations of QCD on the lattice. The computationally most effective one is the staggered formulation, while Wilson or chiral fermions are theoretically more established. We have to distinguish studies at vanishing baryon densities from the ones concerning non-zero density. At vanishing densities the order of the QCD transition between the hadronic phase and the quark-gluon plasma was studied using staggered fermions. In the physical, continuum limit the transition was found to be a crossover. The transition temperature has also been determined. These studies should be and will be extended using Wilson and chiral fermions. This way the staggered results can be checked. At non-vanishing densities direct lattice simulations are prohibited by the infamous sign problem. Recently the multi-parameter reweighting method was developed to study moderate densities using simulations at zero baryon density. The phase diagram as well as the critical point of QCD was determined using staggered fermions with a single lattice resolution. We plan to extend these studies in two ways. In the first step finer lattices will be studied with staggered fermions and a continuum extrapolation will be attempted. In the second step Wilson and possibly chiral fermions will be used. At large densities where the sign problem is the most severe the density of states method will be used. Based on our experience with PC clusters we will build a new, high performance cluster to achieve these goals. The establishment of a strong new research group certainly will improve the competitivity of the European lattice community.
Max ERC Funding
1 300 000 €
Duration
Start date: 2008-07-01, End date: 2014-03-31
