Probing nuclear potential with reactions Krzysztof Rusek Heavy Ion Laboratory, University of Warsaw,...
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Transcript of Probing nuclear potential with reactions Krzysztof Rusek Heavy Ion Laboratory, University of Warsaw,...
Probing nuclear potential with
reactions
Krzysztof Rusek Heavy Ion Laboratory, University of Warsaw,
www.slcj.uw.edu.plThe Andrzej Soltan Institute for Nuclear Studies,
www.ipj.gov.pl
Going out of the valley of stability
Can we use the standard form of effective nucleus-nucleus potential?
Magic numbers are no longer magic
Nuclear halos
Importance of three-body forces
Granulation of nuclear matter
etc.
Effective nucleus-nucleus potential
V = Vo + iW
Vo :
W = 0.5 Vo
G.R. Satchler, W.G. Love, Phys.Rep. 55 (1979)183
Elastic scattering
Deviation from Rutherford c.s. at very forward angles
6Li + 208Pb
6He + 208Pb
Y. Kucuk, N. Keeley PRC 79 067601 (2009)
The method (continuum-discretized coupled-channels)
[T + εg.s. – E + <ψg.s.(r)I V(r,R) Iψg.s.(r)>] χel(R) = <ψg.s.(r)IV(r,R)Iψinel.(r)> χinel(R)
... . . . . . . . . . . . . . . . . . . . . . .
Φ(r,R) = ψg.s.(r)χel(R) + ψ1exc(r)χinel(R) + ..
The method at work
Structure of 6He is ”reflected” in elastic scattering close to the barrier
K. R. PRC72, 037603↓
The concept of DPP(dynamic polarization potential)
local, L-dependent DPPs, many methods to derive L-independent DPP.
If the method is working well, results (σel ) should be close to CDCC
V = Vo + iW + DPP
Method 1: inversion S → VIP method of R.S. MackintoshReview of IP method: V.I. Kukulin and R.S.Mackintosh, J. Phys. G: Nucl. Part. Review of IP method: V.I. Kukulin and R.S.Mackintosh, J. Phys. G: Nucl. Part. Phys. Phys. 3030, R1 (2004) , R1 (2004)
Method 2: „trivially equivalent potential”
[T + Vo + i W + DPP] χel(R) = E χel(R)
χel(R) from CDCC calculations
Case 1 – 4He + 238U
Solid, dashed – CDCC, Dotted – OM+DPP
Strong repulsion at the surface is due to nuclear interactions (absorption)
Case 1 – 4He + 238U
Solid, dashed – CC, Dotted – OM+DPP
Strong repulsion at the surface is due to nuclear interactions (absorption)
Exp. data of Budzanowski et al., PL 11 (1964) 74
Solid – CDCC, dashed – OM+DPP
Case 2 – 7Li + 208Pb
Coupling with unbound states generates similar DPP as with bound state
Exp. data Keeley et al., NPA 571 (1994) 326
Case 3 – 6He + 208Pb
Long range attraction due to dipole polarizability
Contiunnum dominated by L=1 states
Exp. data A. Sanchez-Benitez et al., NPA803 (2008) 30
Similar tendency – repulsion at the surface and long range attraction reflecting dipole couplings with the continuum
Conclusion
DPPreal = V1 df/dR + V2 g(R)
DPPimag = W1 df/dR + W2 g(R)
f(R) = [1+exp(R-R0,i)/a1]
g(R) = [1+exp(R-R0,i)/a2]
Parametrization
V1 /W1
V2 /W2
Ro,i a1 a2
real 6.5 0.20 10.3 0.80 6.0
imag 6.5 0.35 9.8 0.50 3.0
Prediction for fusion barrier distribution – shifts it to higher energies and make broader
Consequences
K. Zerva et al., PRC80(2009)017601
6Li + 28Si
Recipe
V = Vo + iW + DPP
Vo – from densities
W – a half of V0
DPP – coupling with direct
reaction channels
Parametrization
V1 /W1 V2 /W2 Ro,i a1 a2
real 6.5 0.20 10.3 0.80 6.0
imag 6.5 0.35 9.8 0.50 3.0
V1 /W1 V2 /W2 Ro,i a1 a2
real 6.5 0.05 10.05 0.50 3.0
imag 0.0 6.0 10.30 - 0.40
V1 /W1 V2 /W2 Ro,i a1 a2
real 6.5 0.18 8.2 0.55 2.8
imag 0.3 0.18 10.8 0.55 3.0
α + 238U
7Li + 208Pb
6He + 208Pb
CYCLOTRON
PET QCC H E M I S T R Y
QC
Pro
d.
Pro
d.
CYCLOTRON
GDR
EXPERIMENTAL HALL
SEPARATORICARE
BIOLOGY
CUDAC
K = 160
EAGLE
Energies 2 ÷10 MeV/A
Ions 10B ÷ 40Ar
Potential from transfer reaction analysis
Probability: potential a + A
+ structure
+ potential b + B
a + A
B + b
The method (continuum-discretized coupled-channels)
[T + εi – E + <ψi(r)IV(r,R)Iψi(r)>] χi(R) =
<ψi(r)IV(r,R)Iψk(r)> χk(R)
Φ(r,R) = ψ1(r)χ1(R) + ψ2(r)χ2(R) + …..
prof. G. Rawitscher