International Conference on Nuclear Data for Science and Technology 2007
DOI: 10.1051/ndata:07762

Volatile elements production rates in a proton-irradiated molten lead-bismuth target

Y. Tall¹, S. Cormon¹, M. Fallot¹, Y. Foucher¹, A. Guertin¹, T. Kirchner¹, L. Zanini², M. Andersson², K. Berg³, H. Frånberg^{2, 3}, F. Gröschel², E. Manfrin², W. Wagner², M. Wohlmuther², P. Everaerts³, U. Köster^{3, 4}, H. Ravn³, E. Noah Messomo³, C. Jost⁵ and Y. Kojima<sup>6

1</sup>  SUBATECH Laboratory, CNRS/IN2P3-EMN-Université, 44307 Nantes, France
²  Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
³  Paul Scherrer Institut, 5232 Villigen PSI, Switzerland 3 CERN, 1211 Genève, Switzerland
⁴  Institut Laue-Langevin, 38042 Grenoble, France
⁵  Universtät Mainz, Institut für Kernchemie, Fritz-Strassmann-Weg 2, 55128 Mainz, Germany
⁶  Hiroshima University, 1-4-1-Higashi-Hiroshima 7398527, Japan

yoro.tall@subatech.in2p3.fr

Published online: 21 May 2008

Abstract
The IS419 experiment at the ISOLDE facility at CERN dedicated to the measurement of production and release rates of volatile elements from an irradiated Pb/Bi target by a proton beam of 1/1.4 GeV has been completed. The release of He, Ne, Ar, Br, Kr, Cd, I, Xe, Hg, Po and At isotopes was investigated at different target temperatures, ranging from 250 °C to 600 ° C. Three experimental methods were used for the mass-separated, ionized beams: i) implantation of short- and medium-lived isotopes in a tape and on-line detection with a HPGe γ detector; ii) implantation of longer-lived isotopes in Al foils and off-line detection with a HPGe detector; iii) a Faraday Cup used mainly for stable nuclides. The results were compared with predictions from the FLUKA and MCNPX codes using different options for the intra-nuclear cascades and evaporation/fission models. Results show good agreement with calculations for Hg and for noble gases. For other elements such as iodine it is apparent that only a fraction of the produced isotopes is released. The results from FLUKA and MCNPX with the INCL4/ABLA models are in general more satisfactory than those obtained using MCNPX with the standard Bertini/Dresner model combination. Interestingly also significant yields of ^204-210At isotopes were observed. At isotopes are produced either by (p, π^-xn) charge exchange reactions on ²⁰⁹Bi or by secondary reactions involving ³He and ⁴He. Despite the non-release of polonium from Pb/Bi targets at typical operation temperatures, a smaller amount of highly radiotoxic Po isotopes can actually be liberated indirectly as decay daughters of the released astatine.

© CEA 2008