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Cluster structures in light nuclei with ACTIVE TARGET DETECTORS present and next future
Wolfgang Mittig
MSU-NSCL
Shanghai 2015

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Subjects to be discussed
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- Cluster structure in 10Be
- A candidate for a linear structure in 14C
A possible new domain,
correlated statistical emission:
2 proton emission
Wolfgang Mittig, Shanghai 2015

3. Principle of detection- proto AT-TPC
Insulator gas volume
N2 gas 30 kV/cm x 6 cm = 180 kV
- 50 kVDC (1kV/cm) e- e- e- e- e- e- e- e- e- e- e- e-
Beam e-
Electric field
Position
->(x, y)
He, H, D …
Drift time -> z
NIM A 691 (2012)39
by D. Suzuki, et al.

4. Specifications Commissioning: 2014-2015 Large volume 100 cm x 60 cm
e.g. D atm
High granularity
10,000 pads, ~5 x 5 mm2
Bρ analysis
Solenoid 2 T (Triumf)
Commissioning:

6. S. Beceiro-Novo, T. Ahn, D. Bazin, W
S. Beceiro-Novo, T. Ahn, D. Bazin, W. Mittig, Active targets for the study of nuclei far from stability, PPNP, 84, 2015,

7. Nuclear Equation of State: Cluster States
from low density gas to nuclear systems n p a d
Low density gas:
chemical equilibrium n,p,d,a,…
Nuclei: r=r0

8. Nuclear Equation of State: Cluster States
from low density gas to nuclear systems n p a d
Low density gas:
chemical equilibrium n,p,d,a,…
Low density nuclei:
Loosely bound clusters: r~r0/10
Nuclei: r=r0

9. Cluster States: from low density gas to nuclear systems
….,M.Girod,… constrained HFB
22C AQMD calculation by Xi-Guang Cao et al.,
private communication, RMS=3.689(3.0) fm

10. Quasi-molecular Cluster Structure of 10Be

11. 6He +4He 2.5MeV/n AT-TPC proto at NDG
6He beam
r = 0
Ereac
r < 0
TKE B O α
θlab
6He
Phys. Rev. C 87, (2013)

13. discussion
Dissociation of alpha clusters in gs band is attributed to the nuclear spin-orbit force
AMD:N. Itagaki, S. Aoyama, S. Okabe, and K. Ikeda, Phys. Rev. C 70, (2004)
The fact that we don’t observe the second 4+ shows that it does not have a strong cluster structure:Such a difference is unexpected as both 4+ states belong to the
548 rotational bands of the clusterized 0+ states. Nearly the same spectroscopic amplitudes of 6He + are predicted for these 4+ states in the microscopic 2 + 2n four-cluster-model [21]. The present result does not agree with this prediction K. Arai, Phys. Rev. C 69, (2004).. The second scenario is that the 4+ state does belong to the 0+g.s. band, but with a reduced degree of clusterization that hinders the decay branch for alpha emission. On the other hand, recent AMD studies on12C [63, 68], an isotone of 10Be, point out that the effect of the spin-orbit force is pronounced by the sub-shell closure at N = 6 and this explains the small degree of clusterization for its ground state. [63] N. Itagaki, S. Aoyama, S. Okabe, and K. Ikeda, Phys. Rev. C 70, (2004).
740 [64] Y. Kanada-En’yo, Phys. Rev. Lett. 81, 5291 (1998).

14. 14C (T.Suhara(Kyoto)and Y.Kanada-En’yo(YITP),2010)
Structures which are expected to appear on the (β、γ) plane
Obtuse-angle triangular
(triaxial)
Equilateral-triangular
(oblate) α n n α α α α n α n
Shell Model
(Spherical)
Linear-Chain
(prolate)
14C n α α α α n α n α
Excess neutrons deform largely (triaxial)

15. 10Be+4He 14C

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Questions
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Is this a proof of the linear structure
Where is the 0+ state
- Other models
Better description of spectroscopic factors Gexp=|Sl|*Gsp*Ssp
Wolfgang Mittig, Shanghai 2015

19. 1

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Questions: correlated emission
- Can correlated particle evaporation be a signature for cluster (pairing cluster) structure
-Will it manifest as enhancement over pure statistical model
-How to estimate theoretically
Wolfgang Mittig, Shanghai 2015

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Conclusion
- Cluster structure in 10Be: limited to spin 4+, 8He+4He started
- A candidate for a linear structure in 14C: evidence from 2+,4+ states identified, inelastic
A possible new domain, correlated statistical emission: 2 proton emission
Wolfgang Mittig, Shanghai 2015

25. AT-TPC Collaboration
Lawrence Berkeley National Laboratory I-Yang Lee, Larry Phair Lawrence Livermore National Laboratory Mike Heffner University Notre Dame Jim Kolata, Tan Ahn,… Michigan State University Daniel Bazin, Wolfgang Mittig, Bill Lynch,Y.Ayyad, Daisuke Suzuki, Z. Chajecki, Saul Beceiro Novo, Adam Fritsch, Lisa Carpenter, Josh Bradt, … Saint Mary's University (Canada) Rituparna Kanungo Western Michigan University Michael Famiano

26. 4He+10Be (39MeV) 14C*  10Be(gs,2+) + 4He
A.Fritsch et al.

27. The Energy Levels (+ parity states) (S.+EK.)④ ⑤ ③ ②
ρp ρn 　ρn-ρp ①
①, Shell Model
②, Triaxial (K=0)
③, Triaxial (K=2)
④, Linear-chain
⑤, Other states