Electromagnetic excitation of [sup 11]Li

Journal Article · Thu Jul 01 04:00:00 EDT 1993 · Physical Review, C (Nuclear Physics); (United States)

DOI:https://doi.org/10.1103/PhysRevC.48.118· OSTI ID:6188282

Sackett, D; Ieki, K; Galonsky, A; Bertulani, C A; Esbensen, H; Kruse, J J; Lynch, W G; Morrissey, D J; Orr, N A; Sherrill, B M; Schulz, H; Sustich, A; Winger, J A ^[1]; Deak, F; Horvath, A; Kiss, A ^[2]; Seres, Z ^[3]; Kolata, J J ^[4]; Warner, R E ^[5]; Humphrey, D L ^[6]

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1. National Superconducting Cyclotron Laboratory and Department of Physics Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States)
2. Department of Atomic Physics, Eoetvoes University, Puskin utca 5-7, H-1088 Budapest 8 (Hungary)
3. KFKI Research Institute for Particle and Nuclear Physics of the Hungarian Academy of Sciences, H-1525 Budapest 114 (Hungary)
4. Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)
5. Department of Physics, Oberlin College, Oberlin, Ohio 44074 (United States)
6. Department of Physics, Western Kentucky University, Bowling Green, Kentucky 42101 (United States)

We have performed a kinematically complete measurement of the Coulomb dissociation of 28 MeV/nucleon [sup 11]Li into [sup 9]Li and two neutrons by a Pb target. From the energies and angles of the emitted neutrons and of [sup 9]Li, the excitation energy [ital E] of [sup 11]Li 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 [sigma][sub [ital E]1]([ital E]) and the dipole strength function [ital dB]([ital E]1)/[ital dE] were determined from the Coulomb dissociation cross section. [sigma][sub [ital E]1]([ital E]) has a peak at [ital E]=1.0 MeV and a width [Gamma]=0.8 MeV. These parameters are consistent with the picture of a soft dipole mode. However, a significant post-breakup Coulomb acceleration of [sup 9]Li suggests instead a direct breakup. The complete kinematical measurement also allowed neutron and [sup 9]Li momentum distributions to be constructed in the rest frame of the [sup 11]Li. The momentum distributions were fitted with Gaussian functions, yielding width parameters [sigma][sub 9]=18[plus minus]4 MeV/[ital c] and [sigma][sub [ital n]]=13[plus minus]3 MeV/[ital c]. A more general feature of the breakup mechanism of [sup 11]Li could be deduced from these measurements. It was found that the [sup 9]Li and neutron momentum distributions and the neutron-neutron relative momentum distribution could be reproduced if the [sup 11]Li excitation energy was partitioned between the [sup 9]Li 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 [sup 9]Li core.

• OSTI ID: 6188282
• Journal Information: Physical Review, C (Nuclear Physics); (United States), Journal Name: Physical Review, C (Nuclear Physics); (United States) Vol. 48:1; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALKALI METAL ISOTOPES
BARYONS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHARGED-PARTICLE REACTIONS
CROSS SECTIONS
DISSOCIATION
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HEAVY ION REACTIONS
INTEGRAL CROSS SECTIONS
ISOTOPES
LEAD 208 TARGET
LIGHT NUCLEI
LITHIUM 11 REACTIONS
LITHIUM 9
LITHIUM ISOTOPES
MANY-BODY PROBLEM
MILLISEC LIVING RADIOISOTOPES
NEUTRONS
NUCLEAR REACTIONS
NUCLEI
NUCLEONS
ODD-EVEN NUCLEI
PHOTONUCLEAR REACTIONS
RADIOISOTOPES
SECONDS LIVING RADIOISOTOPES
TARGETS
THREE-BODY PROBLEM