2009 APS April Meeting
Volume 54, Number 4
Saturday–Tuesday, May 2–5, 2009;
Denver, Colorado
Session J3: Puzzles and Challenges Near Doubly Magic 100Sn, the Heaviest Self-Conjugate Nucleus
1:30 PM–3:18 PM,
Sunday, May 3, 2009
Room: Plaza E
Sponsoring
Unit:
DNP
Chair: Rick Casten, Yale University
Abstract ID: BAPS.2009.APR.J3.2
Abstract: J3.00002 : Single-Neutron States in $^{101}$Sn populated via $\alpha$-decay*
2:06 PM–2:42 PM
Preview Abstract
Abstract
Author:
Iain Darby
(University of Tennessee)
The region of exotic nuclei around doubly-magic $^{100}$Sn is an
important test-field for the nuclear shell model. A requirement for
an accurate understanding of this nucleus and nearby higher mass
nuclei is knowledge of single-particle energies, particularly the
energy separation between the $\nu$d5/2 -$\nu$g7/2 orbitals. This
information can be obtained by studying the low excitation energy
states generated by the interactions between valence d5/2 and
g7/2 neutrons in the odd-N Sn isotopes above $^{100}$Sn. In
particular for the $^{100}$Sn region, the energy separation can
be best extracted from the energy of the first excited state in
$^{101}$Sn.
In experiments performed at the Holifield Radioactive Ion Beam
Facility using sophisticated signal processing equipment
we have studied the alpha-decay chain:
$^{109}$Xe$\rightarrow^{105}$Te$\rightarrow^{101}$Sn. This decay
chain has been observed to proceed through ground state to ground
state transitions via pure alpha decay and also to proceed via
alpha decay fine structure branches which subsequently depopulate
via gamma-decay. The observation of coincidences between
alpha-alpha and gamma signals has enabled us to unambiguously
conclude that the first excited state in $^{101}$Sn is at an
excitation energy of 172keV and that, surprisingly, the majority
of the $\alpha$-decay branching ratio from $^{105}$Te populates
the first excited state in $^{101}$Sn.
We assert that these observations support assignment of a d5/2
neutron single particle character to the first excited state
in $^{101}$Sn and a g7/2 character to the ground state, in stark
contrast to previously held views on the structure of
neutron-deficient Sn isotopes.
Using the most recent parametrizations of the nucleon-nucleon
potential, a set of realistic residual interactions has been
derived (M. Hjorth-Jensen, this conference) which we have used in
order to apply the shell model interpretation of the lowest
excited states in this series of neutron deficient tin isotopes.
The result of this approach is not only in agreement with the
experimental result, but provides a clear explanation of the
properties of heavier Sn isotopes.
I shall present our experimental results and discuss the
implications of them with regard to the properties of heavier tin
isotopes.
*This work was supported in part by U.S. DOE Grants DE-AC05-00OR22725 (ORNL), DEFG02- 96ER40983 (UT), by the UNIRIB consortium, by the NNSA through DOE Cooperative Agreement DEFC03- 03N and the United Kingdom Science and Technologies Facilities Council.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.APR.J3.2