相关论文: Astrophysical neutron capture rates in s- and r-pr…
The neutron capture cross section of Bi209 has been measured at the CERN n TOF facility by employing the pulse-height-weighting technique. Improvements over previous measurements are mainly because of an optimized detection system, which…
Light radioactive nuclei play an important role in many astrophysical environments. Due to very low cross sections of some neutron and proton capture reactions by these radioactive nuclei at energies of astrophysical interest, direct…
The $^{58}$Ni$(n,\gamma)^{59}$Ni cross section was measured with a combination of the activation technique and accelerator mass spectrometry (AMS). The neutron activations were performed at the Karlsruhe 3.7 MV Van de Graaff accelerator…
Electron capture rates on neutron-rich nuclei (A>65) were calculated within the Random Phase Approximation with partial number formalism, including allowed and forbidden transitions. The partial occupation numbers were provided as a…
A new instrument for high resolution imaging of fast-neutrons is presented here. It is designed for energy selective radiography in nanosecond-pulsed broad-energy (1 - 10 MeV) neutron beams. The device presented here is based on hydrogenous…
The neutron capture rates and Maxwellian averaged cross sections (MACS) for 90Zr(n,{\gamma}) 91Zr and 92Zr(n,{\gamma}) 93Zr processes have been computed within the framework of Talys v1.96. The effects of phenomenological nuclear level…
A new experimental area, the NEAR station, has recently been built at the CERN n TOF facility, at a short distance from the spallation target (1.5 m). The new area, characterized by a neutron beam of very high flux, has been designed with…
We have analyzed and compared the performance of two novel fast-neutron imaging methods with time-of-flight spectroscopy capability. Using MCNP and GEANT code simulations of neutron and charged-particle transport in the detectors, key…
Neutron capture cross-sections have been calculated in nuclei near the N=82 neutron shell closure. These nuclei are of astrophysical interest, participating in s-process and p-process. A semi-microscopic optical model have been used with…
In past decades a lot of progress has been made towards understanding the main s-process component that takes place in thermally pulsing Asymptotic Giant Branch (AGB) stars. During this process about half of the heavy elements, mainly…
The hyperfine (hf) transition rates for muonic atoms have been re-measured for select light nuclei, using neutron detectors to evaluate the time dependence of muon capture. For $^{19}$F $\Lambda$$_{h}$ = 5.6 (2) $\mu$s$^{-1}$ for the hf…
A technique for establishing the total neutron rate of a highly-collimated monochromatic cold neutron beam was demonstrated using a method of an alpha-gamma counter. The method involves only the counting of measured rates and is independent…
With the R$^{3}$B-LAND setup at GSI we have measured exclusive relative-energy spectra of the Coulomb dissociation of $^{18}$C at a projectile energy around 425~AMeV on a lead target, which are needed to determine the radiative…
Neutron capture measurements on $^{155}$Gd and $^{157}$Gd were performed using the time-of-flight technique at the n\_TOF facility at CERN. Four samples in form of self-sustaining metallic discs isotopically enriched in $^{155}$Gd and…
The detection of long-lived radionuclides through ultra-sensitive single atom counting via accelerator mass spectrometry (AMS) offers opportunities for precise measurements of neutron capture cross sections, e.g. for nuclear astrophysics.…
Modern models of s-process nucleosynthesis in stars require stellar reaction rates with high precision. Most of the neutron capture cross sections in the s-process have been measured and for an increasing number of reactions the required…
One of our two methods for fast-neutron imaging with spectrometric capability is presented here. It is a neutron-counting technique based on a hydrogenous neutron converter coupled to Gaseous Electron Multipliers (GEM). The principles of…
An update on astrophysical models for nucleosynthesis via rapid neutron capture, the r process, is given. A neutrino-induced r process in supernova helium shells may have operated up to metallicities of ~10^-3 times the solar value. Another…
During the slow neutron capture process in massive stars, reactions on light elements can both produce and absorb neutrons thereby influencing the final heavy element abundances. At low metallicities, the high neutron capture rate of 16-O…
Abundances of Mo isotopes predicted by stellar models of the s process are, except for 95Mo, in good agreement with data from single grains of mainstream presolar SiC. Because the meteorite data seemed sound and no reasonable modification…