Unresolved Question of the 10He Ground State Resonance

Sharon Stephenson, Gettysburg College
Z. Kohley, Michigan State University
J. Snyder, Michigan State University
T. Baumann, Michigan State University
G. Christian, Michigan State University
P. A. DeYoung, Hope College
J. E. Finck, Central Michigan University
R. A. Haring-Kaye, Ohio Wesleyan University
M. Jones, Michigan State University
E. Lunderberg, Hope College
B. Luther, Concordia College
S. Mosby, Michigan State University
A. Simon, Michigan State University
J. K. Smith, Michigan State University
A. Spyrou, Michigan State University
M. Thoennessen, Michigan State University

Abstract

The ground state of ¹⁰He was populated using a 2p2n-removal reaction from a 59 MeV/u ¹⁴Be beam. The decay energy of the three-body system, ⁸He+n+n, was measured and a resonance was observed at E=1.60(25) MeV with a 1.8(4) MeV width. This result is in agreement with previous invariant mass spectroscopy measurements, using the ¹¹Li(-p) reaction, but is inconsistent with recent transfer reaction results. The proposed explanation that the difference, about 500 keV, is due to the effect of the extended halo nature of ¹¹Li in the one-proton knockout reaction is no longer valid as the present work demonstrates that the discrepancy between the transfer reaction results persists despite using a very different reaction mechanism, ¹⁴Be(-2p2n).