Hope College Physics Department
Research Experiences for Undergraduates
Summer 2007
Project Summary

 

Project Title:

Determination of 7He Ground State Energy
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 Michigan Space Grant Consortium and the National Science Foundation under Grant Number 0354920.


Recent studies have brought into question the structure of neutron-rich 7He. In an effort to contribute to this discussion, the MoNA (Modular Neutron Array) collaboration has made a measurement of the 7He ground state energy using MoNA at the National Superconducting Cyclotron Laboratory in tandem with a large high-field sweeper magnet and charged particle detectors. A 41 MeV/A 8Li beam was directed toward a beryllium target and proton stripping produced the nuclei of interest. The neutrons and 6He fragments resulting from the breakup of the unstable 7He were then detected in coincidence. From the decay energy spectrum, parameters were then extracted (E = 415 +/- 10 keV, Γ = 200 +/- 15 keV) by comparison with Monte Carlo simulations modeling a Breit-Wigner distribution with energy-dependent width that takes into account experimental acceptances and thermal background contributions. Comparing this measurement with others, the energy resolution of the experimental setup was also determined and the accuracy of the method verified.

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