155 research outputs found
Cross section of
At the Karlsruhe pulsed 3.75 MV Van de Graaff accelerator the
cross section was measured by the fast
cyclic activation technique via the 3.103 MeV -ray line of the
S-decay. Samples of elemental sulfur enriched in S by 5.933 %
were irradiated between two gold foils which served as capture standards. The
capture cross section was measured at the neutron energies 25, 151, 176, and
218 keV, respectively. The -cross section in the
thermonuclear and thermal energy range has been calculated using the
direct-capture (DC) model combined with the folding procedure used for the
determination of the potentials. The non-resonant experimental data for this
reaction can be reproduced excellently using this method. The input parameters
of the DC-calculation (masses, Q-values, nuclear density distributions,
spectroscopic factors, spin-parity assignments and excitation energies of the
low-lying states of the residual nucleus) have been taken from the available
experimental data.Comment: 8 pages, using revtex.sty plus postscript figures 4 and 5 available
as separate files. The uuencoded postscript file with the text and figures 4
and 5 is available at ftp://is1.kph.tuwien.ac.at/pub/ohu/sulfur.uu, figures
1, 2 and 3 are available upon reques
Measurement of direct neutron capture by neutron-rich sulfur isotopes
Thermal neutron capture cross sections for S(n,)S and
S(n,)S have been measured and spectroscopic factors of
the final states have been extracted. The calculated direct-capture cross
sections reproduce the experimental data.Comment: 4 pages (uses espcrc1.sty), 1 postscript figure (uses psfig),
accepted for publication in Nucl. Phys. A (Suppl.), uuencoded tex-files and
postscript-files available at ftp://is1.kph.tuwien.ac.at/pub/ohu/Stherm.u
Direct neutron capture of 48Ca at kT = 52 keV
The neutron capture cross section of 48Ca was measured relative to the known
gold cross section at kT = 52 keV using the fast cyclic activation technique.
The experiment was performed at the Van-de-Graaff accelerator, Universitaet
Tuebingen. The new experimental result is in good agreement with a calculation
using the direct capture model. The 1/v behaviour of the capture cross section
at thermonuclear energies is confirmed, and the adopted reaction rate which is
based on several previous experimental investigations remains unchanged.Comment: 9 pages (uses Revtex), 2 postscript figures, accepted for publication
as Brief Report in Phys. Rev.
Measurement of neutron capture on Ca at thermal and thermonuclear energies
At the Karlsruhe pulsed 3.75\,MV Van de Graaff accelerator the thermonuclear
Ca(n,)Ca(8.72\,min) cross section was measured by the
fast cyclic activation technique via the 3084.5\,keV -ray line of the
Ca-decay. Samples of CaCO enriched in Ca by 77.87\,\% were
irradiated between two gold foils which served as capture standards. The
capture cross-section was measured at the neutron energies 25, 151, 176, and
218\,keV, respectively. Additionally, the thermal capture cross-section was
measured at the reactor BR1 in Mol, Belgium, via the prompt and decay
-ray lines using the same target material. The
Ca(n,)Ca cross-section in the thermonuclear and thermal
energy range has been calculated using the direct-capture model combined with
folding potentials. The potential strengths are adjusted to the scattering
length and the binding energies of the final states in Ca. The small
coherent elastic cross section of Ca+n is explained through the nuclear
Ramsauer effect. Spectroscopic factors of Ca have been extracted from
the thermal capture cross-section with better accuracy than from a recent (d,p)
experiment. Within the uncertainties both results are in agreement. The
non-resonant thermal and thermonuclear experimental data for this reaction can
be reproduced using the direct-capture model. A possible interference with a
resonant contribution is discussed. The neutron spectroscopic factors of
Ca determined from shell-model calculations are compared with the values
extracted from the experimental cross sections for Ca(d,p)Ca and
Ca(n,)Ca.Comment: 15 pages (uses Revtex), 7 postscript figures (uses psfig), accepted
for publication in PRC, uuencoded tex-files and postscript-files also
available at ftp://is1.kph.tuwien.ac.at/pub/ohu/Ca.u
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