Study of repulsive three-body force via

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1 Study of repulsive three-body force via 12 C + 12 C scattering at 100A MeV Weiwei Qu ( 屈卫卫 ) Supervisor: Prof. Isao Tanihata School of Physics and Nuclear Energy Engineering Beihang University Hong Kong

2 Introduction Experimental setup Contents Data reduction Theoretical models Results and discussion Summary and outlook

3 Introduction Understanding the interactions between composite nuclei (AA interactions), starting from NN interaction: One of the fundamental subjects in nuclear physics; One of the key issues to understand mechanism of various nuclear reactions; Important to survey unknown nuclear structures/reactions of unstable nuclei far from the stability lines. Three-body force plays an important role in: In nuclear structure; High density nuclear matter. V ( ) ( ) ( ) ( ) N R r v s R r r r dr dr

4 Introduction The optical potential for nucleons is highly dependent on the incident energy, and the depth of the attractive real part become shallower as the energy increases. Finally, the potential changes its sign from negative (attractive) to positive (repulsive). It become repulsive at lower energy with three-body forces Real (upper) and imaginary (lower) parts of the DFM potentials calculated with CEG07a (left) and CEG07b (right) for the 12 C + 12 C elastic scattering at E/A = MeV. T. Furumoto, Y. Sakuragi, and Y. Yamamoto, Phys. Rev. C 82 (2010)

5 Introduction 12 C + 12 C elastic scattering at E/A= MeV real potential change to repulsive at E/A = MeV TBF No Yes Rutherford ratio of the differential cross sections for the 12 C + 12 C elastic scattering at E/A = 100, 200, 300, and 400 MeV, displayed as the functions of the momentum transfer q. T. Furumoto, Y. Sakuragi and Y. Yamamoto. Phys. Rev. C 82 (2010)

6 Introduction Nearside and farside (N/F) decomposition of the elastic scattering cross sections calculated from the CEG07a interaction with N w = 1.0 for the 12 C + 12 C elastic scattering at E/A = MeV. T. Furumoto, Y. Sakuragi, and Y. Yamamoto, Phys. Rev. C 82 (2010)

7 Introduction Historical studies on 12 C + 12 C system The left figure shows the ratio of differential cross section of elastic scattering to Rutherford cross section for 12 C + 12 C system at an incident energy of 86A MeV. Buenerda M., Pinstonb J., Colea J., et al., Phys. Lett. B, 1981, 102, 4: Observed angular distribution of differential cross sections for the 12 C + 12 C elastic scattering. Ichihara T., Niizeki T., Okamura H., et al.. 7 Nucl. Phys. A, 1994, 569:

8 Introduction Historical studies on 12 C + 12 C system The angular distributions of elastic and inelastic channels with incident energies of 120A MeV and 200A MeV for 12 C + 12 C system. There are no enough data for both the elastic and inelastic scattering data of 12 C + 12 C system with an incident energy of 100A MeV simultaneously. Hostachy J.Y., Buenerd M., Chauvin J., et al. Nucl. Phys. A, :

9 Experimental setup 100A MeV 12 C + 12 C RCNP, Osaka University Beam line: WS course Beam: 100A MeV 12 C Beam intensity: pna Beam energy resolution: 300 kev Target: mg/cm 2 natural C and mg/cm 2 (CH 2 ) n target Detector: VDC1 and VDC2, PS1, PS2 and PS3 Measured angles: degrees, Angular resolution: better than 0.1 degree RCNP, Osaka University 9

10 Experimental setup Grand Raiden magnetic spectrometer 10

11 Experimental setup Focal plane detectors Focal plane detectors: Two Vertical-type Drift Chambers(VDCs) + Three Plastic scintillators(pss) (thickness: 3mm, 10mm and 10 mm ) VDC1 and VDC2: particle trajectory PS1, PS2 and PS3: identify particles 11

12 Data reduction Particle identification The preliminary particle identification during the experiment for 12 C + 12 C scattering. The modified particle identification during the experiment for 12 C + 12 C scattering. 12

13 Data reduction Momentum calibration p p p p c c p x p x pc (1 ) p x fp / 2 pc (1 ) fp a x x0 a a 0 a 0 The horizontal position and horizontal angle of selected 12 C particles on focal plane detectors. x a δ x a y y b Transportation matrix of G.R. 13 b

14 Data reduction Two dimensional plot: E x vs θ lab The two dimensional plot of outgoing 12 C particles excitation energies with laboratory angles when the central angle of the magnetic spectrometer was set to 2.0 for 100A MeV 12 C + 12 C scattering. 14

15 Data reduction The spectrum at a scattering angle of 1.5ºwhen the central angle of magnetic spectrometer is set 2.5º. The horizontal axis represents the excitation energy, the unit is MeV. The vertical axis denotes counts. 2 2 ( x b 0.21) ( x b 0.55) 2 2 f ( x) a exp 1.04a exp 2 (0.72) 2 ( ) The fitting function for the G.S., 4.44 MeV state, 7.65 MeV state, and 9.64 MeV state. 15

16 Data reduction Angular distribution and data checking The renormalized angular distributions for the elastic and inelastic channels in laboratory frame. 16

17 Data reduction Angular distribution and data checking Use (CH 2 ) n target to check the data The comparison of 12 C+p scattering differential cross section between present data and previous experiment. 17 K. STRAUCH, F. TITUS Physics Review 103(1956) 200

18 Data reduction Angular distribution and data checking The angular distribution for 7.65 MeV state, 9.64 MeV state, and MeV state of 12 C + 12 C system with an incident energy of 100A MeV under different background assumptions. 18

19 Data reduction G.S MeV Simultaneous 4.44 MeV The calculated angular distribution obtained from the global optical potential based on CEG07b interaction for 12 C + 12 C with an incident energy of 100A MeV. The calculated angular distribution at laboratory frame. 19

20 Theoretical models Extended Soft-Core Model (ESC08) repulsive cores 20

21 Theoretical models New complex G-matrix interaction(ceg07) T. Furumoto, Y. Sakuragi, Y. Yamamoto, PRC78(2008) , T. Furumoto, Y. Sakuragi, Y. Yamamoto, PRC79(2009) (R), T. Furumoto, Y. Sakuragi, Y. Yamamoto, PRC80(2009) T. Furumoto, Y. Sakuragi, Y. Yamamoto, PRC82 (2010) (E) T. Furumoto, Y. Sakuragi, Y. Yamamoto, PRC82(2010) ( ) 21

22 Theoretical models New complex G-matrix interaction(ceg07) M V (ρ) = M V exp( α v ρ) CEG07 (complex effective potential with Gaussian form factor) CEG07b: ESC+TBA+TBR(α v =0.18) 22

23 Theoretical models The MP model ESC08c + MPP + TNA MPP (multi Pomeron exchange Potential) strength determined by analysis for 16 O + 16 O scattering TNA (three-nucleon attraction) adjusted phenomenologically to reproduce E/A (ρ 0 ) at saturation density Two-body Potential from Pomeron-exchange Three(Four)-body Potential from the Triple(Quadruple)-Pomeron vertex Y. Yamamoto, T. Furumoto, N. Yasutake, and Th. A. Rijken, Phys. Rev. C88, (R) (2013), ibid. arxiv:

24 Theoretical models The difference of every models ESC only two body CEG07b based on the ESC04 interaction TBR: with the triple-meson correlation TBA: density dependent two-body interaction, a tensor-type attraction T. Furumoto, Y. Sakuragi, and Y. Yamamoto, Phys. Rev. C78, (2008), ibid. C80, (2009) MP model based on the ESC08 interaction TBR: with the multi-pomeron exchange potential TBA: density dependent two-body interaction, central attraction Y. Yamamoto, T. Furumoto, N. Yasutake, and Th. A. Rijken, Phys. Rev. C88, (R) (2013), ibid. arxiv:

25 Theoretical models Considered states for coupled channel calculation For the MCC calculations, we used the transition densities obtained by the 3α resonating-group method (RGM) calculations in Ref. [1], which reproduce the electron-scattering form factors of 12 C. The present MCC calculations include the G.S. (0 1+ ), 7.65 MeV (0 2+ ), MeV (0 3+ ), MeV (0 4+ ), 4.44 MeV (2 1+ ), 10.3 MeV (2 2+ ), MeV (2 3+ ), MeV (2 4+ ), and 9.64 MeV (3 1 ) states of the 12 C nucleus. [1] M. Kamimura, Nucl. Phys. A 351 (1981)

26 Theoretical models 26

27 Results and discussion Values of reaction cross sections calculated using different models with N w = 0.6 to reproduce the experimental data of the reaction cross section of around 962±10 mb with an incident energy of 98.8A MeV given by Takechi. M. Takechi, M. Fukuda, M. Mihara, K. Tanaka, et al., Phys. Rev C 79(2009) (R). 27

28 Results and discussion The 1-ch calculation results of the elastic scattering angular distribution for 12 C + 12 C scattering at 100A MeV with N w =0.6 on the basis of the ESC (solid line), CEG07b (dash line), and MPa (dot dash line) interaction models in the center-of-mass frame. 28

29 Results and discussion The experimental and calculated angular distributions for the ESC model for 12 C + 12 C scattering at 100A MeV with N w =0.6 with full CC. 29

30 Results and discussion The experimental and calculated angular distributions for the CEG07b model for 12 C + 12 C scattering at 100A MeV with N w =0.6 with full CC. 30

31 Results and discussion The experimental and calculated angular distributions for the MPa model for 12 C + 12 C scattering at 100A MeV with N w =0.6 with full CC. 31

32 Forthcoming experiments The effects of the real and imaginary coupling potentials on the elastic and inelastic cross sections. T. Furumoto, Y. Sakuragi, Phys. Rev. C 87 (2013)

33 Forthcoming experiments RIBF-SHARAQ facility Beam production Primary beam: 400A MeV 12 C Beam intensity: 10 7 /s Scattering angle: 1.0 ~4.0 Energy degrader (F0): variable Al block 5cm T for 300A MeV 10cm T for 200A MeV Angular collimator (F0):Φ2 mm 20 cm long Momentum slit (F1): ±2 mm 33

34 Forthcoming experiments RIBF-SHARAQ facility Focal Plane detectors 2 Cathode-readout drift chamber (CRDC) detectors 3 Plastic detectors. Scattered particle are identified using time of flight (TOF)-energy deposit (ΔE) technique using Radio Frequency of the cyclotron and of plastic scintillator. 34

35 RIBLL1 RIBLL2 200A-400A MeV 12 C + 12 HIRFL: Heavy Ion Research Facility in Lanzhou SSC SFC SFC: 10 AMeV (H.I.), 17~35 MeV (p) SSC: 100 AMeV (H.I.), 110 MeV (p) CSRm: 1000 AMeV (H.I.), 2.8 GeV (p) CSRe CSRm RIBLL1: RIBLL2: RIBs at tens of AMeV RIBs at hundreds of A MeV 35

36 Target: 2mm natural C; T1: Plastic Scintillator,2 parts, every party: 20cm 10cm 3mm T2: Plastic Scintillator,3 parts, every party: 30cm 10cm 5mm MWPC: 30cm 30cm, wire space=2mm Detector and electronics IMP, Lanzhou CsI: 30cm 30cm, 4 4 array, every part: 7cm 7cm 25cm T1 and T2 give TOF (Time-of-Flight)and ΔE signal, CsI stop all the 12 C particles, give E signal, MWPC(Multi wire proportional Chamber)measure the position of 12 C particles. 36 The particle identification can be done by E-TOF and E-E method. Target chamber, scattering chamber and detectors setup Multi Wire Proportional Chamber (MWPC)

37 RIBLL1 RIBLL2 200A-400A MeV 12 C + 12 HIRFL: Heavy Ion Research Facility in Lanzhou SSC SFC SFC: 10 AMeV (H.I.), 17~35 MeV (p) SSC: 100 AMeV (H.I.), 110 MeV (p) CSRm: 1000 AMeV (H.I.), 2.8 GeV (p) CSRe PISA CSRm RIBLL1: RIBLL2: RIBs at tens of AMeV RIBs at hundreds of A MeV 37

38 Summary and outlook The elastic and inelastic angular distributions of 12 C + 12 C scattering at an incident energy of 100A MeV have been determined in RCNP, Osaka University. The experimental data were investigated using double-folding models with different interaction models. The present data have made clear evidence of the important roles of repulsive three-body force and the CC effect in high-energy heavy-ion collisions. The experiment with higher beam energy (200A to 400A MeV) may be able to provide clearer experimental grounds for the discrimination of interaction models, important roles of three-body force and tensor force.

39 List of collaborators Beihang University Tanihata Isao, Le Xiaoyun, Zhang Gaolong, Terashima Satoru, Wang Taofeng, Pang Danyang Sun Baohua, and Guo Chenlei RCNP, Osaka University Tanihata Isao, Sakaguchi H., Ong Hooi Jin, Matsuda, Tamii A., Miki K., Yassid Ayyad, and Azusa Inoue Ichinoseki National College of Technology Furumoto T. Osaka City University Sakuragi Y. Tsuru University Yamamoto Y. IMP, CAS Chen Zhiqiang, Wada R. 39

40 Thanks for your attention!