Search results for "nuclear astrophysics"
showing 10 items of 63 documents
Nuclear Level Density and the Determination of Thermonuclear Rates for Astrophysics
1997
The prediction of cross sections for nuclei far off stability is crucial in the field of nuclear astrophysics. We discuss the model mostly employed for such calculations: the statistical model (Hauser-Feshbach). Special emphasis is put on the uncertainties arising from nuclear level density descriptions and an improved global description is presented. Furthermore, criteria for the applicability of the statistical model are investigated and a "map" for the applicability of the model to reactions of stable and unstable nuclei with neutral and charged particles is given.
Challenges for solid state detectors tracking detectors in nuclear physics experiments at FAIR
2007
The compelling scientific goals of future nuclear physics experiments demand significant advances in detector technology. Nuclear physics opportunities at future facility FAIR have never been so bright, but the detector challenges must be met. With the essential questions concerning nuclear structure and dynamics, nuclear astrophysics, limits of nuclear stability, tests of fundamental interactions and symmetries all being realistic targets of studies of exotic nuclei, detector development efforts are strongly motivated. Several examples of developments for future fixed target experiments as well as experiments at storage ring are outlined.
IRiS—Exploring new frontiers in neutron-rich isotopes of the heaviest elements with a new Inelastic Reaction Isotope Separator
2011
Abstract A dedicated Inelastic Reaction Isotope Separator (IRiS) for multi-nucleon transfer products will be designed and installed at GSI. Research at IRiS will focus on the investigation of new neutron-rich isotopes of the heaviest elements, study of which will advance various research fields, such as nuclear chemistry, nuclear and atomic physics, as well as nuclear astrophysics. The scientific motivation for this project and the alternative design options for the separator and its main components are discussed.
Resonant Nuclear Fusion Processes and the Gamma Rays of SS 433
1984
Gamma-ray spectral lines have recently been reported coming from the celestial object SS 433, which is known to emit high-speed jets in opposite directions. The proposed identification of the lines as coming from fusion reactions on nitrogen nuclei as part of the carbon-nitrogen-oxygen cycle operating in the jets has now received observational support. Predictions of strengths and widths of additional lines which, if seen, would provide valuable new information about conditions giving rise to the jets are presented.
Very Low Energy Protons From the Beta Decay of Proton Rich Nuclei For Nuclear Astrophysics
2010
The MARS group at TAMU has developed a new experimental technique to measure very low energy protons from β-delayed proton-decay of proton-rich nuclei produced and separated with the MARS recoil spectrometer at TAMU. Recently we have investigated the β-delayed p-decays of 23Al [1], and 31Cl [2], and obtained information on the resonances in the 22Na(p,γ)23Mg and 30P(p,γ) 31S reactions, respectively. These reactions are important in explosive H-burning in Novae [3]. Recently an experiment looking at the β-delayed p-decay of 20Mg was also done in order to obtain information on resonances in the 19Ne(p,γ)20Na reaction. A simple setup consisting of a telescope made of a thin double sided Si str…
Nuclear masses in astrophysics
2009
Among all nuclear ground-state properties, atomic masses are highly specific for each particular combination of N and Z and the data obtained apply to a variety of physics topics. One of the most crucial questions to be addressed in mass spectrometry of unstable radionuclides is the one of understanding the processes of element formation in the Universe. To this end, accurate atomic mass values of a large number of exotic nuclei participating in nucleosynthesis are among the key input data in large-scale reaction network calculations. In this paper, a review on the latest achievements in mass spectrometry for nuclear astrophysics is given.
The Beta-Delayed Proton and Gamma Decay of 27P for Nuclear Astrophysics
2013
The creation site of 26Al is still under debate. It is thought to be produced in hydrogen burning and in explosive helium burning in novae and supernovae, and possibly also in the H-burning in outer shells of red giant stars. Also, the reactions for its creation or destruction are not completely known. When 26Al is created in novae, the reaction chain is: 24Mg(p,γ)25AI(β+v)25 Mg(p,γ)26Al, but this chain can be by-passed by another chain, 25Al(p, γ)26Si(p, γ)27P and it can also be destroyed directly. The reaction 26m Al (p, γ)27 Si* is another avenue to bypass the production of 26Al and it is dominated by resonant capture. We find and study these resonances by an indirect method, through the…
CERN's longest serving experimental facility
2004
The On-Line Isotope Separator ISOLDE has operated continuously at CERN since 1967. Today ISOLDE and its Post accelerator REX-ISOLDE, dedicated to the production of a large variety of radioactive ion beams with energies from 1 keV/u up to 3.1 MeV/u, are used for a great number of different experiments in the fields of nuclear and atomic physics, nuclear astrophysics, material physics and life sciences. The facility, originally located at the CERNs first accelerator Synchrocyclotron (SC), has been located at the Proton-Synchrotron Booster (PSB) since 1992. Long and outstanding operation of ISOLDE has had important impact on the evolution of nuclear physics and its applications. ISOLDE has bee…
The Astrophysical r-process
2002
In 1957, Burbidge, Burbidge, Fowler and Hoyle (B2FH) provided a basis for forty years of research in various aspects of nucleosynthesis in stars. We will focus in this paper on progress in r-process nucleosynthesis, with emphasis on the most recent developments in nuclear physics. In 1986, the first experimental data on two crucial, neutron-magic “waiting-point” nuclei provided valuable clues to the astrophysical conditions and the nature of the r-process site. Beginning in the 1990’s, our group (FK2L) presented considerably improved r-abundance calculations, which were for the first time based on a modern, internally consistent nuclear-theory input. The phenomenon of shell-quenching far fr…
First determination of β-delayed multiple neutron emission beyond A = 100 through direct neutron measurement : The P2n value of 136Sb
2018
Background: β-delayed multiple neutron emission has been observed for some nuclei with A≤100, being the Rb100 the heaviest β2n emitter measured to date. So far, only 25P2n values have been determined for the ≈300 nuclei that may decay in this way. Accordingly, it is of interest to measure P2n values for the other possible multiple neutron emitters throughout the chart of the nuclides. It is of particular interest to make such a measurement for nuclei with A>100 to test the predictions of theoretical models and simulation tools for the decays of heavy nuclei in the region of very neutron-rich nuclei. In addition, the decay properties of these nuclei are fundamental for the understanding of a…