Speaker
Michael Paul
(Racah Institute of Physics, Hebrew University, Jerusalem, Israel)
Description
The 146Sm nuclide (t1/2= 1.03x10^8 a) belongs to the small family of nuclides produced by the nucleosynthesis p-process . Its presence as live radionuclide in the Early-Solar System was established by the study of isotopic anomalies of its 142Nd alpha daughter in meteorites. Interestingly, a difference in 142Nd isotopic signatures has been also discovered between terrestrial and chondritic material, leading to new
insight in the chronology of planetary formation. We have developed a method for 146Sm detection by positive-ion high-energy accelerator mass spectrometry at the Argonne ATLAS facility, using a gas-filled magnet for the isobaric 146Sm-Nd separation. 146Sm samples were produced by (gamma,n), (n,2n) and (p,2nEC) activations of enriched 147Sm targets. A new determination of the 146Sm half-life is in progress, based on the measurement of the 146,147Sm alpha activities of the irradiated targets and the AMS determination of their 146Sm/147Sm atom ratio. Special attention is given to the absolute determination of this ratio and methods under development will be described. The present detection sensitivity of the 146Sm/147Sm ratio of the order of 10^-12 will allow us to measure the 147Sm(gamma,n)146Sm reaction cross section, of importance in the p-process synthesis of 146Sm. Activations of 147Sm targets by 50, 25
and 10-MeV electron bremsstrahlung have been performed and the AMS measurements are planned.
Author
Michael Paul
(Racah Institute of Physics, Hebrew University, Jerusalem, Israel)