Fission barriers of heavy and superheavy nuclei analyzed in multidimensional deformation space I. Introduction II. Method III. Deformation space IV. Results and discussion V. Conclusions XIII Nuclear Physics Workshop Kazimierz Dolny, 27. 09 - 1.10. 2006 M. Kowal, L. Shvedov and A. Sobiczewski Sołtan Institute for Nuclear Studies, Warsaw, Poland
26
Embed
Fission barriers of heavy and superheavy nuclei analyzed in multidimensional deformation space I.Introduction II.Method III.Deformation space IV.Results.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Fission barriers of heavy and superheavy nuclei analyzed in multidimensional deformation space
I. IntroductionII. Method III. Deformation space IV. Results and discussion V. Conclusions
XIII Nuclear Physics WorkshopKazimierz Dolny, 27. 09 - 1.10. 2006
M. Kowal, L. Shvedov and A. Sobiczewski
Sołtan Institute for Nuclear Studies, Warsaw, Poland
I. Introduction
1. Two main problems with heaviest nuclei (HN):
cross sections (~1 pb ~50 fb) Bfst
half-lives
2. Present state of HN (f1,f1a)
3. Role of Bfst (f2)
sensitivity of to Bfst
a need for a large accuracy of Bfst
98
99
100
101
102
103
104
Db 267Db 267
115 287115 287 115 288115 288
113 283113 283 113 284113 284
111 279111 279 111 280111 280
Mt 275Mt 275 Mt 276Mt 276
Bh 271Bh 271 Bh 272Bh 272
120120120120
119119119119
118118118118
117117117117
116116116116
115115115115
114114114114
113113113113
112112112112
111111111111
Hs 264Hs 264
Ds 267Ds 267
Mt 266Mt 266
111 272111 272
Mt 268Mt 268
Hs 266Hs 266 Hs 267Hs 267
Bh 262Bh 262 Bh 264Bh 264
Sg 263Sg 263
Bh 267Bh 267Bh 266
Db 263Db 263
Rf 263Rf 263
Es 248 Es 249 Es 250 Es 251 Es 252 Es 253 Es 254 Es 255 Es 256Es 256
Fm 249 Fm 250 Fm 251 Fm 252 Fm 253 Fm 254 Fm 255 Fm 256
Macro-micro (same as used for description of many properties of HN)
III. Deformation space
1. As large as possible
2. Larger space, better description of the properties
(e.g. mass, especially Tsf)
3. Specification of the space: axial, non-axial and reflection-asymmetric
shapes included
A large, 10-dimensional spaceOne to one correspondence between values of parameters and shape
IV. Results1. Axial symmetry - example: 278112 (f4)
- dependence on max (f5)
2. Quadrupole non-axiality ( =2) (f6-8)
- mechanism of decreasing Bfst by non-axial shapes
3. Hexadecapole non-axiality ( =4) (f9-9a)
- also a discussion by M. Kowal
4. Comparison with exp. (f10)
5. Reflexion asymmetry (f11)
The barrier: thin but high, created totally by shell effects
Effect of total hexadecapole deformation
Effect of non-axial hexadecapole deformations
Effect of non-axiality parameter
2 4 6 80,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
4,0
4,5
5,0
5,5
6,0
6,5
7,0
7,5
8,0
2 4
AxialB
fst (
MeV
)
max
250Cf Non-axial
Effect of reflection-asymmetric deformations
-0,50
-1,0
-0,50
-1,0
-1,5-2,0
-2,5
-0,50
-3,0-3,5
-4,0-4,5 -5,0
-1,5
-2,0
-2,5
0,0 0,2 0,4 0,6 0,8 1,0 1,2
-0,1
0,0
0,1
0,2
0,3
0,4
(3,6)
250Cf
(-4,7)
Conclusions
1. Barriers of HN are totally created by shell effects. They are thin, but high.
2. Their height Bfst strongly depends on the deformation space, in
which they are calculated.
3. An increase of the dimension of the space results in an increase of Bf
st for deformed nuclei, and in a decrease of it for spherical ones, in the case of axial symmetry.
4. Non-axial shapes are important for Bfst . They may decrease it by up
to about 2 MeV. This is again due to shell effects, because macr. part of the energy is stiff against non-axiality. Only after the inclusion of non-axiality, calculated Bf
st well reproduces exp. value of it.
5. Reflexion-asymmetric shapes do not contribute to Bfst for heaviest