Angela Bonaccorso
Physics at the proton and neutron
drip lines
Theoretical perspectives
NuPAC 2005
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Why do the driplines exist?
•
•
•
•
Because there are unstable nuclei…
Because the neutron is unstable…
Because it is heavier than the proton…
The neutron is unstable in order for the
hydrogen atom and nature to be stable.
NuPAC 2005
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I
E
M
CSI C
Experimental Studies at the drip line
Grupo de F ’s ica
Nuclear Experimental
Elastic
Elastic
Scattering
Scattering
Reaction
Reaction
Cross
CrossSections
Sections
Spins
Spins
Moments
Moments
Masses
Masses
Beta
Beta
Decay
Decay
Momentum
Momentum
Distributions
Distributions
Unbound
Nuclei
Nuclei
NUPAC, 10-12 October 2005
M.J.G. Borge, IEM, CSIC, Madrid ( Spain)
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Let us see how the “center-left” Physics
needs ISOLDE and even an upgrade of it.
NuPAC 2005
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Unbound
Nuclei
Nuclei at the driplines
They are what the reaction mechanism
makes them to be…
Interplay between structure and reaction
aspects…bound vs. continuum…stronger
than in any other part of the nuclear chart.
A perfect balance between short and long range
parts of the nuclear interaction.
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13Be:
an example of creation by the reaction
mechanism
•14B fragmentation: GANIL (Lecouey, Orr) (2002).
•transfer to the continuum: 12Be (d,p) RIKEN
(Korsheninnikov) (1995).
cf. 10Li at REX-ISOLDE
•GSI (U. Datta Pramanik)( 2004).Unpublished
•14Be nuclear breakup , GSI (Simon),
287AMeV, n-core angular correlation
•14Be nuclear breakup: RIKEN
(Nakamura, Fukuda) (2004).Unpublished
H.B. Jeppesen, et al.,
NP A748, (2005)374
•
•
•
14Be
nuclear and Coulomb
breakup: GANIL (K. Jones thesis,
2000).
14C+ 11B multinucleon transfer:
(Berlin Group ,1998).
18O fragmentation MSU
(Thoennessen, 2001) n-core
relative velocity spectra.
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.7
14B
.... .
+a2
1s1/2
. .. .
..
d5/2
p1/2
2s
p3/2
1s1/2
.. . .
+a3
..
d5/2
p1/2
2s
p3/2
1s1/2
.6
- =p p3/2+n 2s
=
2
g.s.
12Be
g.s.
= 0+
14Be
+ (?)
=
0
g.s.
d3/2
2s
d5/2
p1/2
threshold
NuPAC 2005
p3/2
1s1/2
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inversion
a1
d5/2
p1/2
2s
p3/2
Potential corrections due to the particle-vibration
coupling (N. Vinh Mau and J. C. Pacheco, NPA607 (1996) 163.
also T. Tarutina, I.J. Thompson, J.A. Tostevin NPA733 (2004) 53 )
…can be modeled as:
U( r ) = VWS + Vso + dV
dV ( r ) = 16 a e(r-R)/a / (1+e(r-R)/a)4
n+12Be:
d3/2
2s
d5/2
p1/2
threshold
p3/2
1s1/2
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s-state potential:long range added
p-state potential:long range subtracted
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G. Blanchon, A. B. and N. Vinh Mau
Unbound exotic nuclei studied by transfer
to the continuum reactions
Nucl. Phys. A739 (2004) 259.
12Be
(d,p)
NuPAC 2005
G. Blanchon, A. B., D. M. Brink and N. Vinh Mau,
Unbound exotic nuclei studied by projectile
fragmentation reactions.
IFUP-TH 29/2004: submitted to NPA
Final s-state bound vs continuum
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Bound to unbound transitions
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Core excitation simulated by
imaginary part of n-core optical
potential
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effective range theory (10 order)
k cotan d = -
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1 +
as
1 r k2
o
2
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All aspects of the nuclear interaction discussed in
structure models: short range vs. long range,
real vs. imaginary…volume vs. surface…
amplified at the driplines
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Spin-orbit coupling effects
J.Enders et al.,
19C+9Be
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Momentum
Distributions
NuPAC 2005
88 A.MeV
Reaction
Cross Sections
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Spectroscopic factors from knockout reactions
(P.G.Hansen et al.)
• Spectroscopic factors from excited states of
fragment.
 ( nI )  ∑ C S ( j , n I )  sp ( j, B n )
p
2
p
j
 sp ( j, B n )   spstrip ( j, B n ) +  spdiffr ( j, B n )
• l of nucleon from momentum distribution of
fragment.
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Elastic
Scattering
Elastic Scattering and Optical Potentials of Halo
Nuclei
GANIL data P. Russel-Chomaz, unpublished
10Be
11Be
NuPAC 2005
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A. B. and F. Carstoiu
Optical potentials of halo and
weakly bound nuclei
Nucl. Phys. A706 (2002) 322.
NuPAC 2005
A.A. Ibraheem and A. B.,
Recoil effects on the optical
potentials of weakly bound nuclei
Nucl. Phys. A748 (2005) 414.
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a2 ≈1/2g , g 2mei /ћ
decay length of initial wave function
NuPAC 2005
b3 ≈(ef -ei)/ ћ v
adiabaticity parameter of Coulomb
excitation theory
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…see also a classical reference
Effect of the breakup channel on 11Li elastic scattering,
J.S. Al-Khalili, Nucl. Phys. A 581 (1995) 315-330
…and one of the most recent
at 10A.MeV
…and references therein.
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For the
structure aspect…see also
“Evolution of nuclear structure, shapes, and fission”
http://www.df.unipi.it/~angela/talks.html
http://www.df.unipi.it/~angela/finalprogram.html
Structure of proton-radioactive nuclei
Lídia S Ferreira and Enrico Maglione 2005 J. Phys. G: Nucl. Part. Phys. 31 S1569-S1572
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Conclusions and Outlook
.“Exotic” threshold characteristics of dripline nuclei
enhanced by low energy experiments at Einc≤ 20A.MeV.
. Study of dripline nuclei will lead us to the best possible
phenomenological energy dependent nuclear potential
for bound and scattering states.
My guess for the future:
• We will have to redefine the
n-n interaction in terms
of a ”n-body“ interaction ( 3-body terms are already necessary !! ).
n-p ) will be understood ( I hope!! ) on a
• Paring (
microscopic basis…( effective field theories ?? ).
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Spectroscopic Factors, Trento 04
UPGRADE
UPGRADE
ISOLDE !!
ISOLDE !!
Hi Gregers, would you agree…?
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Appendix I: transfer vs. inelastic
transfer to the continuum
projectile fragmentation:inelastic excitation
Broglia & Winther book
S and ‾S correspond to different
phase shifts
transfer
inelastic
check of sudden approximation Einc: independent
eif : important
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Appendix II: potential from phase shift.
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