Neutron-induced fission cross section ofnatPb andBi209from threshold to 1 GeV: An

Abstract

Neutron-induced fission cross sections for nat Pb and 209 Bi were measured with a white-spectrum neutron source at the CERN Neutron Time-of-Flight (n TOF) facility. The experiment, using neutrons from threshold up to 1 GeV, provides the first results for these nuclei above 200 MeV. The cross sections were measured relative to 235 U and 238 U in a dedicated fission chamber with parallel plate avalanche counter detectors. Results are compared with previous experimental data. Upgraded parametrizations of the cross sections are presented, from threshold energy up to 1 GeV. The proposed new sets of fitting parameters improve former results along the whole energy range.

Dissipative effects in spallation-induced fission ofPb208at high excitation energies

“…A possible explanation relies on the impact parameter because for the most peripheral collisions, only one of the nucleons of the deuterium will impact with the lead nuclei. Recently, a total fission cross section for the n + nat Pb reaction at 500 MeV of 97 ± 7 mb was reported [40], which is a factor 1.5 smaller than the one obtained in [32] for protons. This could explain the reduction of the partial fission cross section in deuteroninduced fission for the largest impact parameters.…”

Publisher's Note: Measurement of resolved resonances of232Th(n,γ) at the n_TOF facility at CERN [Phys. Rev. C85, 064601 (2012)]

“…The second collimator is located near the experimental area at a distance of 175 m and has an outer diameter of 40 cm and a variable inner diameter. For this capture experiment we used an inner diameter of 1.8 cm while for most fission experiments [36][37][38][39] a diameter of 8 cm has been used. The collimation resulted in a nearly symmetric Gaussian-shaped beam profile at the sample position of 185.2 m with a standard deviation of about 0.77 cm at low neutron energies.…”

Present status and future programs of the n_TOF experiment

“…Gonçalves 12) , E. González-Romero 7) , F. Gramegna 18) , E. Griesmayer 2) , C. Guerrero 1) , F. Gunsing 9) , M. Heil 16) , D.G. Jenkins 22) , E. Jericha 2) , Y. Kadi 1) , F. Käppeler 23) , D. Karadimos 24) , M. Kokkoris 14) , M. Krtička 8) , J. Kroll 8) , C. Lederer 25) , H. Leeb 2) , L.S. Leong 4) , R. Losito 1) , M. Lozano 13) , A. Manousos 19) , J. Marganiec 3) , T. Martinez 7) , C. Massimi 26) , P.F.…”

“…Leong 4) , R. Losito 1) , M. Lozano 13) , A. Manousos 19) , J. Marganiec 3) , T. Martinez 7) , C. Massimi 26) , P.F. Mastinu 18) , M. Mastromarco 6) , M. Meaze 6) , E. Mendoza 7) , A. Mengoni 27) , P.M. Milazzo 28) , M. Mirea 5) , C. Paradela 17) , A. Pavlik 25) , J. Perkowski 3) , J. Praena 13) , J.M. Quesada 13) , T. Rauscher 29) , R. Reifarth 16) , A. Riego 11) , F. Roman 1,5) , C. Rubbia 1,30) , R. Sarmento 12) , G. Tagliente 6) , J.L.…”

“…Quesada 13) , T. Rauscher 29) , R. Reifarth 16) , A. Riego 11) , F. Roman 1,5) , C. Rubbia 1,30) , R. Sarmento 12) , G. Tagliente 6) , J.L. Tain 21) , D. Tarrìo 17) , L. Tassan-Got 4) , A. Tsinganis 1) , S. Valenta 8) , G. Vannini 26) , V. Variale 6) , P. Vaz 12) , A. Ventura 27) , M.J. Vermeulen 22) , R. Versaci 1) , R. Vlastou 14) , A. Wallner 25) , T. Ware 10) , T.J. The neutron time-of-flight facility n_TOF at CERN, Switzerland, operational since 2001, delivers neutrons using the Proton Synchrotron (PS) 20 GeV/c proton beam impinging on a lead spallation target.…”