Electromagnetic excitation of Li11

Phys. Rev. C 48, 118 – Published 1 July 1993
D. Sackett, K. Ieki, A. Galonsky, C. A. Bertulani, H. Esbensen, J. J. Kruse, W. G. Lynch, D. J. Morrissey, N. A. Orr, B. M. Sherrill, H. Schulz, A. Sustich, J. A. Winger, F. Deák, Á. Horváth, Á. Kiss, Z. Seres, J. J. Kolata, R. E. Warner, and D. L. Humphrey

Abstract

We have performed a kinematically complete measurement of the Coulomb dissociation of 28 MeV/nucleon Li11 into Li9 and two neutrons by a Pb target. From the energies and angles of the emitted neutrons and of Li9, the excitation energy E of Li11 was determined on an event-by-event basis, and the Coulomb dissociation cross section as a function of excitation energy was constructed. The photonuclear cross section σE1(E) and the dipole strength function dB(E1)/dE were determined from the Coulomb dissociation cross section. σE1(E) has a peak at E=1.0 MeV and a width Γ=0.8 MeV. These parameters are consistent with the picture of a soft dipole mode. However, a significant post-breakup Coulomb acceleration of Li9 suggests instead a direct breakup. The complete kinematical measurement also allowed neutron and Li9 momentum distributions to be constructed in the rest frame of the Li11. The momentum distributions were fitted with Gaussian functions, yielding width parameters σ9=18±4 MeV/c and σn=13±3 MeV/c. A more general feature of the breakup mechanism of Li11 could be deduced from these measurements. It was found that the Li9 and neutron momentum distributions and the neutron-neutron relative momentum distribution could be reproduced if the Li11 excitation energy was partitioned between the Li9 and the neutrons by a three-body phase space distribution. This indicates there is no directional correlation between the halo neutrons, and shows that the halo neutrons do not exist as a dineutron bound to a Li9 core.

DOI: http://dx.doi.org/10.1103/PhysRevC.48.118

  • Received 30 November 1992
  • Published in the issue dated July 1993

© 1993 The American Physical Society

Authors & Affiliations

D. Sackett, K. Ieki, A. Galonsky, C. A. Bertulani, H. Esbensen, J. J. Kruse, W. G. Lynch, D. J. Morrissey, N. A. Orr, B. M. Sherrill, H. Schulz, A. Sustich, and J. A. Winger

  • National Superconducting Cyclotron Laboratory and Department of Physics Astronomy, Michigan State University, East Lansing, Michigan 48824

F. Deák, Á. Horváth, and Á. Kiss

  • Department of Atomic Physics, Eötvös University, Puskin utca 5-7, H-1088 Budapest 8, Hungary

Z. Seres

  • KFKI Research Institute for Particle and Nuclear Physics of the Hungarian Academy of Sciences, H-1525 Budapest 114, Hungary

J. J. Kolata

  • Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556

R. E. Warner

  • Department of Physics, Oberlin College, Oberlin, Ohio 44074

D. L. Humphrey

  • Department of Physics, Western Kentucky University, Bowling Green, Kentucky 42101

References (Subscription Required)

Authorization Required


×
×

Images

×

Log In

Cancel
×

Search


Article Lookup
Paste a citation or DOI

Enter a citation
×
  1. Enter a citation to look up or terms to search.

    Ex: "PRL 112 068103", "Phys. Rev. Lett. 112, 068103", "10.1103/PhysRevLett.112.068103"