high-spin states in octupole -deformed 219 ra
DESCRIPTION
High-spin states in octupole -deformed 219 Ra. By Chris Wilson. Octupole deformation. I. Ahmad and P. Butler, Ann. Rev. Nucl . Part. Sci. 43 (1993). The light actinides. W. Nazarewicz and P. Butler, Rev. Mod. Phys. 68 (1996). Rotational consequences. - PowerPoint PPT PresentationTRANSCRIPT
Institute of Physics NPPD Conference 2011
High-spin states in octupole-deformed 219Ra
By Chris Wilson
Institute of Physics NPPD Conference 2011
Octupole deformation
I. Ahmad and P. Butler, Ann. Rev. Nucl. Part. Sci. 43 (1993)
Institute of Physics NPPD Conference 2011
The light actinides
3 j
W. Nazarewicz and P. Butler, Rev. Mod. Phys. 68 (1996)
Institute of Physics NPPD Conference 2011
Rotational consequences
)2()2(
)1()1(2
)(
)(
IEIE
IEIE
I
I
)1()1(2
1)()( IEIEIEIE
Parity splitting
Ratio of rotational frequencies
W. Nazarewicz and P. Olanders, Nucl. Phys. A441 (1985) 420-444
Institute of Physics NPPD Conference 2011
S. Frauendorf, Phys. Rev. C77, 021304(R)(2008)
Condensation of octupole phonons
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Light-actinide nuclei
18O (95 MeV) + 208Pb → 226Th*226Th* → 222Th* + 4n → 220Ra* + α2n → 219Ra* + α3n
95 %
Experimental method
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Gamma-ray detection
Continuum gamma rays from fast-fission
Discrete gamma rays from evaporation residues
Neutron peaks
Gammasphere: 110 large-volume high-purity germanium detectors for use in gamma-ray spectroscopy experiments.Based at Argonne National Laboratory in Chicago
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HERCULES
HERCULESHigh-Efficiency Residue Counter Under Lots of Elastic Scattering 64 plastic scintillator detectors for evaporation-residue detectionW. Reviol et al. Nucl. Inst. Meth. A451 (2005)
Gammasphere(ball opened)
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Background reduction
Evaporation residues Time of flight
Pulse height
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Gamma-coincidence spectra
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New high-spin states in 219RaP. D. Cottle et al., Phys. Rev. C36 (1987) 2286M. Wieland et al., Phys. Rev. C45 (1992) 1035L. A. Riley et al., Phys. Rev. C62 (2000) 021301
Institute of Physics NPPD Conference 2011
Rotational consequences
Institute of Physics NPPD Conference 2011
Rotational consequences
Institute of Physics NPPD Conference 2011
Rotational consequences
Institute of Physics NPPD Conference 2011
Rotational consequences
Institute of Physics NPPD Conference 2011
Summary
• New high-spin states do not provide evidence for the condensation of rotationally-aligned octupole phonons.
• 219Ra has either: 1. A spherical core unstable to both quadrupole and octupole vibrations,
with the octupole vibration enhanced by the odd g9/2 neutron2. A static octupole deformation strongly coupled to the odd g9/2 neutron
• Greater detection sensitivity is required to probe the highest spin states
Institute of Physics NPPD Conference 2011
C.L.Wilson, J.F.Smith, R.Orlandi, S.D.Pain, K.M.Spohr, and D.A.TorresSchool of Engineering, University of the West of Scotland,
Paisley, PA1 2BE, UK
W.Reviol, D.G.Sarantites, X.Chen, and J.SnyderDepartment of Chemistry, Washington University, St. Louis, MO 63130
M.P.Carpenter, C.J.Chiara, R.V.F Janssens, B.P.Kay, F.G.Kondev, C.J.Lister, D.Seweryniak, and S.ZhuArgonne National Laboratory, Argonne, Il 60439
A.N.WilsonDepartment of Physics, Australian National University,
Canberra ACT 0200, Australia
Thanks to UWS and my collaborators
Institute of Physics NPPD Conference 2011
Enhanced E1 transitions
Institute of Physics NPPD Conference 2011
States labelled by spin and parity (Jp)
g
g
g
g
g
g
Ground state
Rotational excited states