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:
M. Thoennessen, C.R. Hoffman, T. Baumann, D. Bazin, J. Brown, G. Christian, P.A. DeYoung, J.E. Fink, 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, "Neutron-Decay Spectroscopy of Neutron-Rich Isotopes", ENAM08, (2008).

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, "Determination of the N=16 shell closure at the oxygen drip line", Phys Rev. Lett. 100, 152502 (2007).

J.J. Kolate, H. Amro, F.D. Becchetti, J.A. Brown, P.A. DeYoung, M. Hencheck, J.D. Hinnefeld, G.F. Peaslee, A.L. Fritsch, C. Hall*, U. Khadka*, Patrick J. Mears*, P. O'Rourke, D. Padilla*, J. Reith*, Tabatha Spencer, and T. Williams, " Breakup of ⁶He Incident on ²⁰⁹Bi Near the Coulomb Barrier". Phys Rev. C 75, 031302 (2007).

J.J. Kolata, H. Amro, M. Cloughesy, P.A. DeYoung, J.P. Bychowski, J. Reith*, and G. Peaslee, "A Large Segmented Neutron Detector for Reaction Studies with Radioactive Beams Near the Coulomb Barrier", Nucl. Instr. and Meth. A557, 594 (2006).

P.J. Mears et al., Phys. Rev. C 71, 051601(R) (2005).

J.P. Bychowski et al., Phys. Lett. B596 , 26 (2004).