Hope College Department of Physics and Engineering Research Experiences for Undergraduates Summer 2005 Project Summary

When an accelerated beam of radioactive 6 He nuclei collides with a 209 Bi target, there is a high probability of a nuclear interaction. Unlike regular nuclei, 6 He consists of an a -particle core and a halo of two loosely bound neutrons. Being loosely bound, these halo neutrons are more easily separated from the nucleus than regular core nucleons and thus greatly affect how 6 He will interact with other nuclei. Frequently, a -particles are emitted from these interactions. In the 6 He + 209 Bi reaction at energies near the Coulomb barrier, the 6 He is expected to produce a -particles according to one of three mechanisms: 1-n transfer, 2-n transfer, and direct projectile breakup. Previous measurements 1,2 by Hope College students found that the 1-n and 2-n transfer reactions accounted for approximately 20% and 55% of the a cross section. The goal of this experiment is to confirm that the remaining a cross section can be attributed to direct projectile breakup. Analysis is in progress.
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Publications and Presentations:
“Neutron-Decay Spectroscopy of Neutron-Rich Oxygen Isotopes.” M.Thoennessen, C.R. Hoffman, T. Baumann, D. Bazin, J. Brown, G. Christian, P.A. DeYoung, J.E. Finck, N. Frank, J. Hinnefeld, R. Howes, P. Mears*, E.Mosby, S.Mosby, J.Reith*, B. Rizzo*, W.F. Rogers, G. Peaslee, W.A. Peters, A. Schiller, M.J. Scott, S.L. Tabor, P.J. Voss, and T. Williams. ENAM08, book of abstracts page 30, (2008).
“ Determination of the N = 16 shell closure at the oxygen drip line.” C.R. Hoffman, T. Baumann, D. Bazin, J. Brown, G. Christian, P.A. DeYoung, J.E. Finck, N. Frank, J. Hinnefeld, R. Howes, P. Mears*, E. Mosby*, S. Mosby*, J. Reith*, B. Rizzo*, W.F. Rogers, G. Peaslee, W.A. Peters, A. Schiller, M.J. Scott*, S.L. Tabor, M. Thoennessen, P.J. Voss*, and T. Williams. Phys. Rev. Lett. 100, 152502 (2008).
“ Breakup of ⁶He Incident on ²⁰⁹Bi near the Coulomb Barrier.” J.J. Kolata, H. Amro, F.D. Becchetti, J.A. Brown, P.A. DeYoung, M. Hencheck, J.D. Hinnefeld, G.F. Peaslee, A.S. Fritsch, C. Hall*, U. Khadka*, Patrick J. Mears*, P. O’Rourke, D. Padilla*, J. Reith*, Tabatha Spencer, and T. Williams. Phys. Rev. C 75, 031302 (2007).
“ A Large Segmented Neutron Detector for Reaction Studies with Radioactive Beams Near the Coulomb Barrier.” J.J. Kolata, H. Amro, M. Cloughesy, P.A. DeYoung, J.P. Bychowski*, J. Reith*, and G. Peaslee. Nucl. Instr. And Meth. A557, 594 (2006).