20 research outputs found
Complete calculation of evaluated Maxwellian-averaged cross sections and their uncertainties for s-process nucleosynthesis
Present contribution represents a significant improvement of our previous
calculation of Maxwellian-averaged cross sections and astrophysical reaction
rates. Addition of newly-evaluated neutron reaction libraries, such as ROSFOND
and Low-Fidelity Covariance Project, and improvements in data processing
techniques allowed us to extend it for entire range of s-process nuclei,
calculate Maxwellian-averaged cross section uncertainties for the first time,
and provide additional insights on all currently available neutron-induced
reaction data. Nuclear reaction calculations using ENDF libraries and current
Java technologies will be discussed and new results will be presented.Comment: 6 pages, 2 figure
Stellar Nucleosynthesis Nuclear Data Mining
Stellar nucleosynthesis is an important nuclear physics phenomenon that is
responsible for presently observed chemical elements and isotope abundances. It
is also one of the corner stone hypotheses that provides basis for our
understanding of Nature. Its theoretical predictions are often verified through
the astrophysical observation and comparison of calculated isotopic abundances
with the observed values. These calculations depend heavily on the availability
of nuclear reaction rate, cross section and decay data. In this work, we will
provide a review of theoretical and experimental nuclear reaction data for Big
Bang, stellar and explosive nucleosynthesis and modern computer tools. Examples
of evaluated and compiled nuclear reaction data will be given. Major databases
and their input in nuclear reaction calculations will be discussed.Comment: 20 pages, 9 figures, 4 table
White paper on nuclear astrophysics and low energy nuclear physics Part 1: Nuclear astrophysics
This white paper informs the nuclear astrophysics community and funding agencies about the scientific directions and priorities of the field and provides input from this community for the 2015 Nuclear Science Long Range Plan. It summarizes the outcome of the nuclear astrophysics town meeting that was held on August 21–23, 2014 in College Station at the campus of Texas A&M University in preparation of the NSAC Nuclear Science Long Range Plan. It also reflects the outcome of an earlier town meeting of the nuclear astrophysics community organized by the Joint Institute for Nuclear Astrophysics (JINA) on October 9–10, 2012 Detroit, Michigan, with the purpose of developing a vision for nuclear astrophysics in light of the recent NRC decadal surveys in nuclear physics (NP2010) and astronomy (ASTRO2010). The white paper is furthermore informed by the town meeting of the Association of Research at University Nuclear Accelerators (ARUNA) that took place at the University of Notre Dame on June 12–13, 2014. In summary we find that nuclear astrophysics is a modern and vibrant field addressing fundamental science questions at the intersection of nuclear physics and astrophysics. These questions relate to the origin of the elements, the nuclear engines that drive life and death of stars, and the properties of dense matter. A broad range of nuclear accelerator facilities, astronomical observatories, theory efforts, and computational capabilities are needed. With the developments outlined in this white paper, answers to long standing key questions are well within reach in the coming decade
Catching Element Formation In The Act
Gamma-ray astronomy explores the most energetic photons in nature to address
some of the most pressing puzzles in contemporary astrophysics. It encompasses
a wide range of objects and phenomena: stars, supernovae, novae, neutron stars,
stellar-mass black holes, nucleosynthesis, the interstellar medium, cosmic rays
and relativistic-particle acceleration, and the evolution of galaxies. MeV
gamma-rays provide a unique probe of nuclear processes in astronomy, directly
measuring radioactive decay, nuclear de-excitation, and positron annihilation.
The substantial information carried by gamma-ray photons allows us to see
deeper into these objects, the bulk of the power is often emitted at gamma-ray
energies, and radioactivity provides a natural physical clock that adds unique
information. New science will be driven by time-domain population studies at
gamma-ray energies. This science is enabled by next-generation gamma-ray
instruments with one to two orders of magnitude better sensitivity, larger sky
coverage, and faster cadence than all previous gamma-ray instruments. This
transformative capability permits: (a) the accurate identification of the
gamma-ray emitting objects and correlations with observations taken at other
wavelengths and with other messengers; (b) construction of new gamma-ray maps
of the Milky Way and other nearby galaxies where extended regions are
distinguished from point sources; and (c) considerable serendipitous science of
scarce events -- nearby neutron star mergers, for example. Advances in
technology push the performance of new gamma-ray instruments to address a wide
set of astrophysical questions.Comment: 14 pages including 3 figure