Cross section of 36S(n,γ)37S^{36}S(n,\gamma)^{37}S

At the Karlsruhe pulsed 3.75 MV Van de Graaff accelerator the $^{36}S(n,\gamma)^{37}S(5.05 min)$ cross section was measured by the fast cyclic activation technique via the 3.103 MeV $\gamma$-ray line of the $^{37}$S-decay. Samples of elemental sulfur enriched in $^{36}$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 $^{36}S(n,\gamma)^{37}S$-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

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 48^{48}Ca at thermal and thermonuclear energies

At the Karlsruhe pulsed 3.75\,MV Van de Graaff accelerator the thermonuclear $^{48}$Ca(n,$\gamma$)$^{49}$Ca(8.72\,min) cross section was measured by the fast cyclic activation technique via the 3084.5\,keV $\gamma$-ray line of the $^{49}$Ca-decay. Samples of CaCO$_3$ enriched in $^{48}$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 $\gamma$-ray lines using the same target material. The $^{48}$Ca(n,$\gamma$)$^{49}$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 $^{49}$Ca. The small coherent elastic cross section of $^{48}$Ca+n is explained through the nuclear Ramsauer effect. Spectroscopic factors of $^{49}$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 $^{49}$Ca determined from shell-model calculations are compared with the values extracted from the experimental cross sections for $^{48}$Ca(d,p)$^{49}$Ca and $^{48}$Ca(n,$\gamma$)$^{49}$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

The 33S(n,α)30Si cross section measurement at n-TOF-EAR2 (CERN) : From 0.01 eV to the resonance region

The 33S(n,α)30Si cross section measurement, using 10B(n,α) as reference, at the n-TOF Experimental Area 2 (EAR2) facility at CERN is presented. Data from 0.01 eV to 100 keV are provided and, for the first time, the cross section is measured in the range from 0.01 eV to 10 keV. These data may be used for a future evaluation of the cross section because present evaluations exhibit large discrepancies. The 33S(n,α)30Si reaction is of interest in medical physics because of its possible use as a cooperative target to boron in Neutron Capture Therapy (NCT)