nucleon-nucleon momentum correlation functions induced by the radioactive beams yu-gang ma
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Nucleon-Nucleon momentum correlation functions induced by the radioactive beams Yu-Gang Ma Shanghai Institute of Applied Physics (SINAP, CAS) Introduction Our results: nn, np, pp vs Ebind, Esep? Halo nuclei? conclusions. - PowerPoint PPT PresentationTRANSCRIPT
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Nucleon-Nucleon momentum correlation functionNucleon-Nucleon momentum correlation functions induced by the radioactive beamss induced by the radioactive beams
Yu-Gang MaYu-Gang MaShanghai Institute of Applied Physics (SINAP, CAS)Shanghai Institute of Applied Physics (SINAP, CAS)
• Introduction• Our results: nn, np, pp vs Ebind, Esep? Halo nuclei?
• conclusions
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
weak correlation function11Li (+ 208Pb) -> 9Li + n + n (+208Pb)Ieki et al., PRL70, 730 (1993)
Our work will focus on the systematic studies on nucleon-nucleon correlation function for light nuclei!
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Two-Proton correlation functions
q (MeV/c)1+
R(q
) p-p correlationfunction
212
1ppq
R(q) sensitive to the space-time properties of emitting sources
Emitting Source Target
Proj
Detector Arrays 22112112 )(1, pYpYqRppY
1p
2p
Final State Interaction (Coulomb + Nuclear: s-wave peak) + Pauli
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Intensity interferometry: from large scales ...
Star
R
d << R
Static systems: exploring the geometry (size, R)
HBT: R. Hanbury Brown, R.Q. Twiss, Phil. Mag., Ser. 7 45 (1954) 663
… to subatomic physic scales (, K-K, , p-p, n-n, IMF-IMF, …)
Fast evolving systems: 10-23-10-15 sec: geometry changing in time
DetectorsNuclear reaction
d >> RR+V
G. Goldhaber et al., PR 120 (1960) 300
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Theoretical Calculation formula of two particles correlation
In particular, the geometry of a collision is not a scale model of imaging a star. But for HBT……
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Source-sizes from angle-averaged correlations
20
23
0
2/exp2
1)( rr
rrS
extracted from C(20 MeV/c)2/12rrrms
Gaussian sources extensively used
One-parameter approach (r0)
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
HI collisions at intermediate energies
Need probes of the space-time properties of the emission
• Transport theory is a tool to treat space-time evolution of nucleonic system, it is a good method to exlore the nucleon-nucleon correlation function.
• Use transport theory to relate dynamics to EOS, NN, …
NN collisions,compression, pre-equilibrium
Breakup, expansion
Secondary decays
Short time scales Long time scales
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
S. Pratt, Physical Review Letters. 53 (1984) 1219
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Our results
stability check Fits to the data (n-n correl. function)
Cp-n vs Ebinding Cp-h vs Esep
Cp-p vs proton halo? EOS, Sigma_nn etc
Y.B. Wei, YGM et al., Phys Lett B 586, 225 (2004)Y.B. Wei, YGM et al., J Phys G 30, 2019 (2004)
YGM et al., Phys. Rev. C 73, 014604 (2006)
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
QMD
Isospin-dependent Quantum Molecular Dynamics Model: N-body transportation theory model Including the most important parts for nuclear reaction at intermediate energy
Nuclear mean field:
.Fragment Recognition, a naive coalescence modelΔR3.5fm; ΔP300MeV/c
Nucleon-nucleon collision and Pauli blocking etc are considered
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Check of stability of IQMD
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Firstly we reproduce the experimental results of two halo neutrons for 14Be +12C @ 35MeV/n:
The reaction channel:
14Be(+12C)-> 12Be + n + n (+12C)
It is obviously that the cal. results reproduce the exp. data very well.
Y.B. Wei, YGM et al.,
Phys. Lett. B 586, 225 (2004)
Data: Marques et al., PLB 476, 219 (2000)
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
11Li (+ 208Pb) -> 9Li + n + n (+208Pb) @ 28MeV/u
The obvious different results were obtained between 2 halo neutrons (solid line) and 2 core neutrons (dash line).
Large space extension low C(q)
Data: Ieki et al., PRL70, 730 (1993)
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Systematical study: n-p correlation Ebinding
11-14B (N,C,Li) + C xn + xp + … @ 800MeV/u
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Just like that of binding energy per nucleon, the relationship between the HBT strength Cph and the separation energy still exits monotonic character.
How about the separation energy ?
In model, we can also explore the correltaion between proton and the most outside neutron (Cph), see what happens? This correlation should reveal the extent of single-neutron separation.
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
A new criterion of halo nuclei?A new criterion of halo nuclei?
Z. Ren et al., PRC (96)Z. Ren et al., PRC (96)
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
0 2 4 6 81E-4
1E-3
0.01
0.1
1
Den
sity
(fm
-3)
Radius (fm)
Mass density SHF
normal 27S
halo 27S
0 2 4 6 8
1E-4
1E-3
0.01
0.1
1
Radius (fm)
Den
sity
(fm
-3)
Proton density SHF
halo 27S
normal 27S
0 20 40 60 80 1000.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
27S halo
28S
29S
30S
27S normal
CP
P (
q)
q (MeV/c)
Mixed p-p phasespace @ the last coll.
Density distribution and pp HBTDensity distribution and pp HBT
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
6.6 6.8 7.0 7.2 7.4 7.6 7.8 8.0 8.2 8.41.4
1.5
1.6
1.7
CP
P (
q=
20M
eV/c
)
Ebinding
(MeV/n)
Ebinding
(MeV/n)27S 6.95928S 7.47929S 7.74830S 8.122
S-isotopes
0 1 2 3 4 5 6 7 81.40
1.45
1.50
1.55
1.60
1.65
1.70s
2p(MeV/n):
27S 0.928S 3.3629S 5.3530S 7.148
Cpp
s2p
(MeV)
The similar behavior is expected for double-neutron halo nuclei.
A new criterion of halo nuclei?A new criterion of halo nuclei?
If two-proton halo structure is assumed
no halo nuclei
no halo nuclei
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Conclusions
Experimental two halo neutrons correlation function (11Li, 14 Be) can be well fitted by the transport model: QMD
n-p correlation function depends on the binding energy of the system. More close binding system, the stronger np correlation.
P-halo n correlation function depends on the single neutron separation energy. However, difficult accessible in the experiment.
p-p correlation function is useful to search for proton-halo nuclei. Weak correlation is expected for 2p halo nuclei.
Systematic experiment should be done in near future.
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
The influences of nuclear transport property on HBT
total pair momentum nuclear EOS
in-medium n-n cross sectionimpact parameterincident energy emission time
YGM et al., Phys. Rev. C 73, 014604 (2005)
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Total pair momentum dependence
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
In-medium cross section dependence
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Impact parameter dependence
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Emission time & evolution time
•in low Ptot, neutron and proton has a similar emission rate;• in higher Ptot, neutron has earlier emission time;•Higher Ptot. Earlier Temission
nucleon-nucleon correlation function is stronger in earlier evolution time
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Conclusions
Experimental two halo neutrons correlation function (11Li, 14 Be) can be well fitted by the transport model: QMD
n-p correlation function depends on the binding energy of the system. More close binding system, the stronger np correlation.
P-halo n correlation function depends on the single neutron separation energy. However, difficult accessible in the experiment.
p-p correlation function is useful to search for proton-halo nuclei. Weak correlation is expected for 2p halo nuclei.
Systematic experiment should be done in near future.
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Thanks for your attention!
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Systems with different binding character leads to different HBT strength and shape.
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
Sensitivity to space-time extent
Final State Interactions (Coulomb+Nuclear) + Pauli
Directional information:Shape, Lifetime
•Pauli exclusion principle
xqx
yqy
zqz
r
eqq
2
min
• Coulomb:
Dip at q ~ 0
1+R
(q)
q (MeV/c)0 50 100
Large source
Small source
q (MeV/c)
• Nuclear:
Peak at cMeVq /20
VcMeVR
1)/20(
Size
(S wave)
),,( zyxr
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil
In the QMD model, we can choose the random initialization or a fixed Stable Initialization. What is the difference on the HBT results?
Yu-Gang Ma 18th Few Body Conference, 2006, Santos, Brazil