Challenges on phase transitions and

1
Challenges on phase transitions and gamma-ray
strength functions Magne Guttormsen Department
of Physics, University of Oslo

• Oslo method
• Thermodynamics
• Electromagnetic transitions
• Challenges

Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
2
Spin-energy diagram
Yrast line (no levels)
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
3
The first generation method
F0
F1
F2
F3
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
4
Gamma-ray multiplicity
E
Spin
E
Spin
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
5
The Brink Axel hypothesis
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
6
Does it work?
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
7
Nuclear entropy
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
8
Level density at Bn
Egidy and Bucurescu
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
9
??canonical - canonical ensemble
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
10
Rare-earth region, case erbium
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
11
Preliminary
Proton number Z 50 Neutron Cooper pairs
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
12
J.Lee and J.M.Kosterlitz, Phys. Rev. Lett. 65,
137 (1990)
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
13
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
14
Challenges, new thermodynamic
Negative Cv(E) and T(E)
Smoothed (up to E 100 MeV)
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
15
Loved child, many names

• Radiative strength function (RSF)
• Photon strength function (PSF)
• Gamma-ray strength function

Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
16
Simulation tests of the Oslo method
Event-by-event data generated in Prague with
DICEBOX Sorted in Oslo into (Ex, E?) matrix
Ex
8
5
2
E?
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
17
Results from the blind test
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
18
Radiative strength functions
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
19
Pygmy resonance
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
20
Scissors mode
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
21
Giant dipole resonance
Kadmenskii, Markushev and Furman (KMF) model
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
22
Unexpected RSF upbend
Physics News Update
Voinov et al., Physical Review Letters,1 October
2004.
Also observed in Mo, V, Sc, Ni, Ti (3He, 3He)
and (3He, 4He) reactions
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
23
Upbend in iron
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
24
Temperature dependence?
Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007
25
Verifications
Budapest Research Reactor (n, ??) reaction
INPP, Ohio University (d,n) reaction
Subatomic and Astrophysics Division Annual
Meeting 2007
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Challenges

• Normalization
• ?-canonical or canonical ensemble - or another
  theory?
• Critical T, how to interpret and measure?
• Single quasi-particle entropy

• Same quantities observed in different experiments
• Pygmy resonance
• GEDR-tail match
• Low energy ?-strength
• Spin distribution
• Parity asymmetry
• Thermalization

Workshop on?Level Density and?Gamma Strength in
Continuum, Oslo, May 21 - 24, 2007