Hope College Physics Department Research Experiences for Undergraduates Summer 2008 Project Summary

Recent studies have brought into question the structure of neutron-rich ⁷He.  To contribute to this discussion, the energy and width of the ground state of ⁷He has been measured with the Modular Neutron Array (MoNA) and Sweeper magnet setup at the National Superconducting Cyclotron Laboratory.  Proton stripping of ⁸Li in a Be target resulted in the production of unbound ⁷He.  Events were then reconstructed based on detected position and energy in MoNA and a bank of charged particle detectors. Simulations made to account for detector acceptances and efficiencies employed a Breit-Wigner distribution with energy-dependent width to model the unbound state.  Best fits of simulation to data indicate a ground state energy of 400(10) keV with a full-width at half-maximum of 125(+40/-15) keV.  This study shows no strong evidence of any excited state below 2 MeV.
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Publications and Presentations:
"First observation of excited states in ¹²Li", C.C. Hall*, E.M. Lunderberg*, P.A. DeYoung, T. Baumann, D. Bazin, G. Blanchon, A. Bonaccorso, B.A. Brown, J. Brown, G. Christian, D.H. Denby*, J. Finck, N. Frank, A. Gade, J. Hinnefeld, C.R. Hoffman, B. Luther, S. Mosby, W.A. Peters, A. Spyrou, and M. Thoennessen. Phys. Rev. C 81, 021301(R) (2010).
"Evidence for a Doubly Magic ²⁴O",  C.R. Hoffman, T. Baumann, D. Bazin, J. Brown, G. Christian, D.H. Denby*, P.A. DeYoung, J.E. Finck, N. Frank, J. Hinnefeld, S. Mosby*, W.A. Peters, W.F. Rogers, A. Schiller, A. Spyrou, M.J. Scott, S.L. Tabor, M. Thoennessen, and P.J. Voss*. Phys. Lett. B672, 17 (2009).
"Efficiency of the Modular Neutron Array (MoNA).”W.A. Peters, T. Baumann, G.A. Christian, D.Denby*, P.A. DeYoung, J.E. Finck, C.C. Hall*, J. Hinnefeld, A. Schiller, M.J. Strongman, and M. Thoennessen. Proceedings of the 20th International Conference of the Application of Accelerators in Research and Industry CAARI 2008, AIP Conference Proceedings 1099, 807 (2009).
"Ground Stake Energy and Width of the ⁷He from ⁸Li Proton Knockout", D.L. Denby*, P.A. DeYoung, T. Baumann, D. Bazin, E. Breitback*, J. Brown, N. Frank, A. Gade, C.C. Hall*, J. Hinnefeld, C.R. Hoffman, R. Howes, R.A. Jenson*, B. Luther, S.M. Mosby, C.W. Olson*, W.A. Peters, A. Schiller, A. Spyrou, and M. Thoennessen. Phys. Rev. C 78, 044303 (2008).
"Production of Nuclei in Neutron Unbound States via Primary Fragmentation of ⁴⁸Ca", G. Christian, W.A. Peters, D. Absalon*, D. Albertson*, T. Baumann, D. Bazin, E. BreitbachI, J. Brown, P.L. Cole*, D. Denby*, P.A. DeYoung, J.E. Finck, H. Frank, A. Fritsch*, C. Hall*, A.M. Hayes, J. Hinnefeld, C.R. Hoffman, R. Howes, B. Luther, E. Mosby*, S. Mosby*, D. Padilla*, P.V. Pancella, G. Peaslee, W.F. Rogers, A. Schiller, M.J. Strongman, M. Thoennessen, and L.O. Wagner*. Nucl. Phys. A801, 101, (2008)
" BaF Array for γ-tagged Studies with Radioactive Nuclear Beams", H. Amro, F.D. Becchetti, Hao Jing, M. Ojaruega, J.J. Kolata, B. Skorodumov, G. Peaslee, P. DeYoung, D. Denby*, and J.D. Hinnefeld. Nucl. Instr. and Meth. A579, 31, (2007).
^"7Be-Induced alpha-Transfer Reaction on ¹²C", H. Amro, F.D. Becchetti, Yu Chen, Hao Jiang, M. Ojaruega, M.J. Golobish, H.C. Griffin, J.J. Kolata, B. Skorodumov, G. Peaslee, P.A. DeYoung, P. Mears, D. Denby*, J. Brown, J.D. Hinnefeld, and A.M. Moro. Euro. Phys. Jour. 150, 1, (2007).
"Analysis of Kinematics and Decay Energy in the Breakup of ⁷He". Deborah Denby*, Paul A. DeYoung, Graham F. Peaslee, and the MoNA Collaboration. Bull. Am. Phys. Soc. 51, 52 (2006). CEU session at the Division of Nuclear Physics of the APS meeting, Poster 3A.00022, Nashville, TN, October 2006.

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