ALCF Science 1 - Argonne National Laboratory

argonne leadership computing facility
Nuclear Structure
Ab-initio Reaction Calculations for Carbon-12
Researchers will calculate several fundamental properties of the 12C
nucleus: the imaginary-time response, the one-body density matrix,
and transition matrix elements between isospin- 0 and -1 states. These
are needed to be able to reliably compute neutrino-12C scattering,
which is needed for neutrino detector calibrations; quasi-elastic
electron scattering, which is currently being measured at Jefferson Lab
(JLab); and the results of older reactions on 12C.
In the past 15 years, researchers have developed Green’s function
Monte Carlo as a powerful and accurate method for computing
properties of light nuclei using realistic two- and three-nucleon
potentials. This will be the basis of all the calculations. Understanding
the propagation of charges and currents in the nucleus is critical to
a real understanding of the physics of nucleonic matter. Electron
scattering experiments in the quasi- elastic regime, where the
dominant process is knocking a single nucleon out of the nucleus,
are under way at Jefferson Lab for a range of nuclei. The separation
into longitudinal and transverse response allows one to study the
propagation of charges and currents, respectively, in the nucleus. The
nontrivial changes as one goes from the nucleon and deuteron to
larger nuclei like carbon require one to consider processes well beyond
simple, one-nucleon knockout. Researchers will compute the transition
density matrices on a two-dimensional grid of the magnitudes of
the initial and final positions. A partial wave expansion of the angle
between the two vectors will be made.
Early Science Program
Allocation:
7.5 Million Hours
EARLY SCIENCE PROGRAM
43
Contact Steven C. Pieper
Argonne National Laboratory | spieper@anl.gov