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Transcript of Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 1/33
Position of the problem : why should we worry about N=50 ?1
Valence space above 78Ni ?2
Collectivity in the vicinity of 78Ni ?3
The N=50 shell closure and beyondStructure of nuclei “Northeast of 78Ni”
D. Verney, IPN Orsay
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 2/33
N=50 : a bit of history
(d,3He)
-decay
« border » of the knowledge on nuclear structure
fission
(t,p)
Zendel et alInorg Nucl Chem 42, 1387 (1980)
Kratz et alNucl Phys A
250, 13 (1975)
Del Marmol et alNucl Phys A
194, 140 (1972)
Hoff -FogelbergNucl Phys A
368, 210 (1981)Ge83
Experimental status in year 2003
Sr88
Rb87
Kr86
Br85
Se84
As83
Ge82
Ga81
Zn80
Cu79
Ni78Ni77Ni71 Ni72 Ni73 Ni74 Ni75 Ni76Ni70Ni69Ni68Ni67Ni66Ni65Ni64
Ge76Ge74Ge72
Y89
Zr90 Z=40
28
N=40 50
Cu65
Zn66 Zn67 Zn68 Zn70
Ga69 Ga71
Ge70 Ge73
As75
Se76Se74 Se77 Se78 Se80 Se82
Br79 Br81
Kr78 Kr80 Kr82 Kr83 Kr84
Rb85
Sr86 Sr87Sr84
Zr91
Se75 Se79 Se81 Se83
Kr85
Cu74
Zn75 Zn76 Zn77 Zn78
Ga79 Ga80fra
gmentation
Winger et alPhys Rev C
36, 758 (1987)
Beginning of -decay studies at PARRNe
OSIRIS /Studsvik
TRISTAN /Brookhaven
On
-lin
e m
as
s
se
pa
rati
on
Ch
imic
al
se
pa
rati
on
First structure data (’s) came from -decay (for N=50)1
Fission + ISOL technique
N=50 : present status
Sr88
Rb87
Kr86
Br85
Se84
As83
Ge82
Ga81
Zn80
Cu79
Ni78Ni77Ni71 Ni72 Ni73 Ni74 Ni75 Ni76Ni70Ni69Ni68Ni67Ni66Ni65Ni64
Ge76Ge74Ge72
Y89
Zr90 Z=40
28
50
Cu65
Zn66 Zn67 Zn68 Zn70
Ga69 Ga71
Ge70 Ge73
As75
Se76Se74 Se77 Se78 Se80 Se82
Br79 Br81
Kr78 Kr80 Kr82 Kr83 Kr84
Rb85
Sr86 Sr87Sr84
Zr91
Ge84Ge83
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 3/33
isomeric decay: LISE-GANIL
radioactive beam: REX ISOLDECu75
Zn77 Zn78 Zn79
As84
Se85 Se86
-decay Orsay direct reaction in inverse kinematics :
Oak Ridge
DIC at Legnaro
ISOLDE laser
Experimental status in year 2008
-decay is still in the competition, good complementarities with DIC2
Fission + ISOL technique + post acceleration
BE(2)
Spectroscopic factors
DIC at Legnaro
Fusion-fission
Spontaneous fission
JYFLTRAP IGISOL
-decay Orsay
Why should we worry about N=50 ?
Historically from astrophysical considerations (and -decay experiments)
By Kratz et al. PRC 38 (1988)
Waiting point nucleus at N=50 80Zn
By Winger et al. PRC 36 (1987)
« »
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 4/33
« it’s a joke » M. Bernas, private communication (2005)
1
d5/2
p1/2f5/2
g9/2
g7/2
s1/2
d3/2
h11/2
d5/2
g9/2
g7/2
s1/2
d3/2
h11/2
p1/2f5/2
50 40
70
40
70
N=3
N=4
N=5
HO
82
N>>ZN~Z
N~Z
Diffuse surface
N>>Z -
+
-From Dobaczewski et al. PRL72 (1994) 981.
Historically from structural considerations 2
Why should we worry about N=50 ?
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 5/33
Why should we worry about N=50 ?
Because the N=28 shell effect is seen disappear in 42Si (see L. Gaudefroy’s Talk) 3B. Bastin et al., Phys. Rev. Lett. 99 (2007) 022503
First occurrence of the vanishing of shell effect originating from spin orbit
Probably due to tensor force in the residual interaction via an Otsuka-like mechanism
The same tragic destiny is predicted for Z=28T. Otsuka et al. PRL95, 232502 (2005)
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 6/33
E (MeV)
-14,386
-13,233
-11,831
-7,121
40
f5/2
p3/2
p1/2
g9/2
Proton single particles
From Ji et Wildenthal Phys. Rev. C 38, 2849
(1988)
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 7/33
Is 78Ni doubly magic ? Persistence of Z=28 and N=50
How fast those collectivity sets in?What is the nature of valence space which opens up just above ?
Why should we worry about N=50 ?
At the beginning of the PARRNe project at IPN (very end of the 90’s)4
Sr88
Rb87
Kr86
Br85
Se84
As83
Ge82
Ga81
Zn80
Cu79
Ni78Ni77Ni71 Ni72 Ni73 Ni74 Ni75 Ni76Ni70
Ge76Ge74
Y89
Zr90
50
As75
Se76 Se77 Se78 Se80 Se82
Br79 Br81
Kr78 Kr80 Kr82 Kr83 Kr84
Rb85
Sr86 Sr87Sr84
Zr91
Se79 Se81 Se83
Kr85
Cu74
Zn75 Zn76 Zn77 Zn78
Ga79 Ga80
Proton single particles
From Ji et Wildenthal Phys. Rev. C 38, 2849
(1988)
d5/2 d3/2s1/2gZ/2
Neutron single particles
Zr93Zr92 Zr92 Zr93 Zr94 Zr95
f5/2
p3/2
p1/2
g9/2
Zr96
Known part of t
he
valence sp
ace
Unknown part of t
he
valence sp
ace
OK
OK
??
?
-Residual
interaction
1236(9/2-)
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 8/33
Single particle ordering close to 78Ni Protons : odd-N=50 isotones
hot subject ! -decay experiment redone at ISOLDE and Oak Ridge
(same lines as us)
observed in -decay at Orsay (PARRNe)D. Verney et al PRC 76 (2007)
054312
observed in DIC experiments at
LegnaroG. De Angelis et al. NPA 787
(2007) 74c
unchallenged! nor by spontaneous fission nor by fusion-
fission data
Zn81
Sr88
Rb87
Kr86
Br85
Se84
As83
Ge82
Ga81
Zn80
Cu79
Ni78
Y89
Zr90
50
Zr91 Zr93Zr92 Zr92 Zr93 Zr94 Zr95 Zr96
Se85 Se86
As84
Ge83 Ge84
3 protons out of a 78Ni core
PARRNe
Exp
A.F. Lisetskiy et a
l.,
PRC 70 (2004)
JW modifie
d,
PRC 76 054312(2007)
Ji & Wildenthal,
PRC 40, 389 (1989)
BA Brown (jj4b)
Private communication
= 2p3/2 qp state
Single particle ordering close to 78Ni Protons : odd-N=50 isotones
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 9/33
Sr88
Rb87
Kr86
Br85
Se84
As83
Ge82
Ga81
Zn80
Cu79
Ni78
Y89
Zr90
50
Zr91 Zr93Zr92 Zr92 Zr93 Zr94 Zr95 Zr96
Se85 Se86
As84
Ge83 Ge84
3 protons out of a 78Ni core
2p3/2
1f5/2
81Ga Z=31 N=50
2p3/2
1f5/2
83As Z=33 N=50
Single particle ordering close to 78Ni Protons : odd-N=50 isotones
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 10/33
Sr88
Rb87
Kr86
Br85
Se84
As83
Ge82
Ga81
Zn80
Cu79
Ni78
Y89
Zr90
50
Zr91 Zr93Zr92 Zr92 Zr93 Zr94 Zr95 Zr96
Se85 Se86
As84
Ge83 Ge84
3 protons out of a 78Ni core
E (MeV)
40
f5/2
p3/2
p1/2
g9/2
Proton SPE ordering in a 78Ni mean field
351.1 keV
0 keV
802.8 keV
Experiment
351.
1 ke
V45
1.7
keV
0
200
400
600
800
1000
1200
1400
1600
1800
keV 81Ga Z=31 N=50
f5/22
p3/2
J=3/2
f5/23
J=5/2, v=1
J=3/2, v=3
To be definitely validated in (d,p) reaction (Oak Ridge ? REX ISOLDE ? SPIRAL2 ?)
f5/23
Ga84
247.81/2+observed in
2H(82Ge,p)83Ge at Oak Ridge
Thomas et al. PRC 71 (2005) p. 021302
observed in -decay at PARRNe
O. Perru et al.EPJ A 28 (2006) 307
Single particle ordering close to 78Ni Neutrons : odd-N=51 isotones
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 11/33
Ga83
Sr88
Rb87
Kr86
Br85
Se84
As83
Ge82
Ga81
Zn80
Cu79
Ni78
Y89
Zr90
50
Zr91 Zr93Zr92 Zr92 Zr93 Zr94 Zr95 Zr96
Se85 Se86
As84
Ge83 Ge84
4 protons + 1 neutron out of a 78Ni core
observed in n-decay at ALTO
M. Lebois article in preparation
2d5/2
3s1/2
(3/2,5/2+)
7/2+
Single particle ordering close to 78Ni Neutrons : odd-N=51 isotones
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 12/33
Core – particle (weak) coupling model
Zn81
Sr88
Rb87
Kr86
Br85
Se84
As83
Ge82
Ga81
Zn80
Cu79
Ni78
Y89
Zr90
50
Zr91
Se85
Ge83
Kr87
Sr89
Even-even semi-magic core
L. S. Kisslinger & R. A. Sorensen Rev. Mod. Phys., 35, 853, (1963)
Thankappan & TruePhys. Rev. B, 137, 793 (1965)
Neutron single particle
Core excitation energies taken from experiment : E(2+), E(4+), E(0+2) etc
Parameters :
Q>0Q=0 Q<0
Vector space :0+1 2d5/22+1 2d5/22+1 3s1/2Etc…
Single particle ordering close to 78Ni Neutrons : odd-N=51 isotones
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 13/33
M. Lebois, Thesis Univ. Paris-Sud XI (Sept 2008)
Sr88
Rb87
Kr86
Br85
Se84
As83
Ge82
Ga81
Zn80
Cu79
Ni78
Y89
Zr90
50
Zr91
Sr89
Thomas et al. PRC 71 (2005) p. 021302
Single particle ordering close to 78Ni Neutrons : odd-N=51 isotones
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 14/33
2d5/2
3s1/2
Single particle ordering close to 78Ni Neutrons : odd-N=51 isotones
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 15/33
Sr88
Rb87
Kr86
Br85
Se84
As83
Ge82
Ga81
Zn80
Cu79
Ni78
Y89
Zr90
50
Zr91
Ge83
M. Lebois, Thesis Univ. Paris-Sud XI (Sept 2008)
Single particle ordering close to 78Ni Neutrons : odd-N=51 isotones
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 16/33
N=58 ?
Single particle ordering close to 78Ni Neutrons : odd-N=51 isotones
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 17/33
M. Lebois, Thesis Univ. Paris-Sud XI (Sept 2008)
Sr88
Rb87
Kr86
Br85
Se84
As83
Ge82
Ga81
Zn80
Cu79
Ni78
Y89
Zr90
50
Zr91
Zn81
Single particle ordering close to 78Ni Neutrons : odd-N=51 isotones
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 18/33
d5/2
d3/2
s1/2
gZ/2
Neutron single particles
Proton SPE ordering in a 78Ni mean field
351.1 keV
0 keV
802.8 keV
1621.6 keV
351.
1 ke
V45
1.7
keV
0
200
400
600
800
1000
1200
1400
1600
1800
keV
1236 keV
(5/2-)
(3/2-)
(3/2-)
(9/2-)
As83
Ge82
Ga81
Zn80
Cu79
Ni78
+1p
+3p
+5p
Ge83
81Zn
2d5/2
3s1/2?
Fed in -decay
Low spins only
Sr88
Rb87
Kr86
Br85
Se84
As83
Ge82
Ga81
Zn80
Cu79
Ni78
Y89
Zr90
50
Zr91 Zr93Zr92 Zr92 Zr93 Zr94 Zr95 Zr96
Se85 Se86
As84
Ge83 Ge84
Zn80
How fast those collectivity sets in?
Sr88
Rb87
Kr86
Br85
Se84
As83
Ge82
Ga81
Zn80
Cu79
Ni78Ni77Ni71 Ni72 Ni73 Ni74 Ni75 Ni76Ni70
Ge76Ge74
Y89
Zr90
50
As75
Se76 Se77 Se78 Se80 Se82
Br79 Br81
Kr78 Kr80 Kr82 Kr83 Kr84
Rb85
Sr86 Sr87Sr84
Zr91
Se79 Se81 Se83
Kr85
Proton single particles
d5/2 d3/2s1/2 gZ/2
Neutron single particles
Zr93Zr92 Zr92 Zr93 Zr94 Zr95
f5/2
p3/2
p1/2
g9/2
Zr96
Known valence sp
ace
Unknown valence
space
OK
OK
?
-Residual
interaction
Single particle ordering close to 78Ni
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 19/33
Collectivity close to 78Ni
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 20/33
Ga85Ga84
Sr88
Rb87
Kr86
Br85
Se84
As83
Ge82
Ga81
Zn80
Cu79
Ni78
Y89
Zr90
50
Zr91 Zr93Zr92 Zr92 Zr93 Zr94 Zr95 Zr96
Se85 Se86
As84
Ge83 Ge84
4 protons + 2 neutrons out of a 78Ni core
-decay ALTO+ ISOLDE and Oak Ridge
See contribution by F. Ibrahim Wednesday
(0¯)
(4¯)
1/2+
52
24
7.8
5/2+
n
Even-even nuclei
Collectivity close to 78Ni Z=32 even-even nuclei
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 21/33
Collectivity close to 78Ni N=52 even-even nucleiN=42 N=44
N=46 N=48
N=50 N=52
O Perru thesis Paris-Sud XI (2004) & J. Libert private communication
HFB calculation using the Gogny interactionGCM Bohr dynamics
0.1 0.2 0.3 0.40 0.1 0.2 0.3 0.40
0.1 0.2 0.3 0.40 0.1 0.2 0.3 0.40
0.1 0.2 0.3 0.40 0.1 0.2 0.3 0.4041
+ exp
41
+ hfb
21
+ exp
21
+ th
N=50
N=54
0.1 0.2 0.3 0.40
HFB calculations
triaxial static shape predicted !
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 22/33
Strong increase of collectivity
Collectivity close to 78Ni N=52 even-even nuclei
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 23/33
Exp
ect
ed Z
=2
8 s
hell
closu
re
Z+
40 s
ubsh
ell
eff
ect
Ge : a special case ?
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 24/33
Ge : a special case ?
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 25/33
Local minimum at Z=32
Ge : a special case ?
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 26/33
Local minimum, not at mid distance Z=28-40 !
REX-ISOLDE
J. Van de Walle et al.PRL 99, 142501 (2007)
80Zn 82Ge84Se
86Kr
88Sr
90Zr
A Prévost et al. EPJ A 22 (2004) 391Medium/high spin states obtained from fusion/fission at the Vivitron (Euroball IV)
-
f7/2
p3/2
p1/2
f5/2
g9/2
28
50
40
f7/2
p1/2
g9/2
d5/2
p3/2f5/2
protons neutrons
-
+
+ +
Ge : a special case ?
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 27/33
A first explanation for the observed downsloping of the p-h states
Y.H. Zhang et al. PRC 70 (2004) 024301Medium/high spin states fed in DIC at Legnaro (GASP)
84Se
SM calculation proton valence space
SM calculation proton valence space + neutron 1phf7/2
p3/2
p1/2
f5/2
g9/2
28
p1/2
g9/2
d5/2
protons neutrons
504 MeV
The gap used in the calculation has the good size
Ge : a special case ?
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 28/33
Collectivity close to 78Ni Even-even nuclei
Sr88
Rb87
Kr86
Br85
Se84
As83
Ge82
Ga81
Zn80
Cu79
Ni78
Y89
Zr90
50
Zr91 Zr93Zr92 Zr92 Zr93 Zr94 Zr95 Zr96
Se85 Se86
As84
Ge83 Ge84
REX ISOLDE J. Van de Walle et al.PRL 99, 142501 (2007)
“The results for N=50 isotones indicate a good N=50 shell closure and a strong Z=28 proton core polarization.”
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 29/33
1492 keV
O Perru thesis Paris-Sud XI (2004) & J. Libert private communication
HFB calculation using the Gogny interactionGCM Bohr dynamicsSr88
Rb87
Kr86
Br85
Se84
As83
Ge82
Ga81
Zn80
Cu79
Ni78
Y89
Zr90
50
Zr91 Zr93Zr92 Zr92 Zr93 Zr94 Zr95 Zr96
Se85 Se86
As84
Ge83 Ge84
Collectivity close to 78Ni Even-even nuclei
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 30/33
Collectivity close to 78Ni Even-even nuclei
Sr88
Rb87
Kr86
Br85
Se84
As83
Ge82
Ga81
Zn80
Cu79
Ni78
Y89
Zr90
50
Zr91 Zr93Zr92 Zr92 Zr93 Zr94 Zr95 Zr96
Se85 Se86
As84
Ge83 Ge84
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 31/33
80Zn78Zn
76Zn74Zn72Zn
66Zn 68Zn 70Zn
Potentials Zn
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 32/33
Conclusions
A new single particle ordering appears close to 78Ni1
N=50 offers nothing but a local parenthesis of rigidity2
The underlying microscopic mechanism remains to be understood
3
Proton single particles
d5/2
d3/2
s1/2
gZ/2
Neutron single particles
f5/2
p3/2
p1/2
g9/2
Local minimum of the N=50 shell gap for Z=32 seems to have considerable influence on structureCollectivity sets in very rapidly just below and just above N=50
From the shell model point of view : description is alright up to N=50, beyond N=50 much work to do. Is 78Ni a good core ?Bohr dynamics very efficient….
Workshop LEA COLLIGA Catania – 13 - 16 Oct 2008
N=50status
D. Verney Page 33/33
Thank you !