The role of broken Cooper pairs

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The role of broken Cooper pairs in warm
nuclei M. Guttormsen, U. Agvaanluvsan (LLNL), R.
Chankova, A.C. Larsen, J. Rekstad, A. Schiller
(MSU), S. Siem, N.U.H. Syed, and A. Voinov (Ohio)

• Introduction
• Experimental method
• Thermodynamics
• Conclusions

Zakopane Conference on Nuclear Physics September
4 - 10, 2006
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Z 13 N 16
E 2e E 0
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Thermal single quasiparticles
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Entropy in nuclei
Zakopane Conference on Nuclear Physics September
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Cactus Silicon telescopes
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167Er(3He,3He)167Er
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The Brink Axel hypothesis
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Does it work?
Zakopane Conference on Nuclear Physics September
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Experimental level densities
Zakopane Conference on Nuclear Physics September
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Experimental nuclear entropy
Zakopane Conference on Nuclear Physics September
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?S S(oe) - S(ee) n
S(ee) / ?S
Zakopane Conference on Nuclear Physics September
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Constant temperature approximation
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Preliminary
Z 50 Only breaking neutron Cooper pairs
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Preliminary
J.Lee and J.M.Kosterlitz, Phys. Rev. Lett. 65,
137 (1990)
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Summary and conclusions

• Experimental level density -gt entropy
• Extensive single particle (hole) entropy of S
  1.5 - 2.0 k for mid-shell
  nuclei
• Number of excited particles with Ex
• Critical T for various processes

Zakopane Conference on Nuclear Physics September
4 - 10, 2006
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Zakopane Conference on Nuclear Physics September
4 - 10, 2006
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Zakopane Conference on Nuclear Physics September
4 - 10, 2006