Lanthanum : An s- and r-process indicator

The neutron capture cross section of 139La has been measured at a thermal energy of kT = 5 keV by means of the activation technique. Three irradiations were performed in a quasi-stellar neutron spectrum at the Karlsruhe 3.7 MV pulsed Van de Graaff accelerator, and the induced activities were measured by means of HPGe clover detectors. The final cross section of 113.7 ± 4.0 mbarn was found to be 10% higher than that previously assumed. Together with an earlier measurement at kT = 25 keV, Maxwellian-averaged neutron capture cross sections at the relevant thermal energies of the main s-process component, i.e., at kT = 8 and 23 keV, could be reliably interpolated. The s-abundances obtained on the basis of these data showed that the r-process contribution to solar lanthanum, Nr = N☉ - Ns, is 30%. This is in good agreement with the lanthanum abundance of extremely metal-poor and very r-process-rich stars

Neutron capture cross section of 139 La

The neutron capture cross section of ${}^{139}\mathrm{La}$ has been measured relative to that of ${}^{197}\mathrm{Au}$ by means of the activation method. The sample was irradiated in a quasistellar neutron spectrum for $kT=25\mathrm{keV}$ generated via the ${}^{7}\mathrm{Li}{(p,n)}^{7}\mathrm{Be}$ reaction with the proton energy adjusted 30 keV above the threshold. Maxwellian averaged neutron capture cross sections were calculated for energies $kT=5--100\mathrm{keV}.$ The new value for $kT=30\mathrm{keV}$ is found to be 31.6\ifmmode\pm\else\textpm\fi{}0.8\mathrm{mb}, 18% lower and considerably less uncertain than the previously recommended value of 38.4\ifmmode\pm\else\textpm\fi{}2.7\mathrm{mb}. With these results the s- and r-process components could be more accurately determined, making lanthanum a reliable s- and r-process indicator in stellar spectroscopy

Evaluation of production cross-sections for 61Cu non-standard PET radionuclide via light-ion-induced nuclear reactions on Co, Ni, Zn targets

Production cross-sections of 61Cu, a promising radionuclide for PET imaging applications, were evaluated for the light-ion-induced nuclear reactions on Co, Ni, Zn targets. Simultaneous Evaluation on KALMAN (SOK) code combined with least squares concept was used to obtain the evaluated data together with covariances. The various production routes of 61Cu were compared, and recommended excitation functions were derived using a well-defined statistical procedure. The evaluated data were also compared with the predictions of the nuclear reaction model codes TALYS and EMPIRE, and found a partial agreement among them. This study indicates that the 60Ni(d,n)61Cu reaction is the method of choice for 61Cu production; however, the 58Ni(α,p)61Cu and 59Co(α,2n)61Cu reactions also appears to have great potential