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


Project Title: Ground State Energy and Width of 7He from 8Li Proton Knockout
Student Name: Deborah H. Denby
Student's Home Institution: Hope College
Research Advisor: Dr. Paul DeYoung and Dr. Graham Peaslee
Source of Support: This material is based upon work supported by the National Science Foundation under NSF-RUI Grant No. PHY-0354920, NSF- RUI Grant No. PHY-0651627, and the Michigan Space Grant Consortium.

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.

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.

G. Audi et al., Nucl. Phys. A729 , 337 (2003)

F. Skaza et al., Phys. Rev. C73 , 044301 (2000).