1. Recent studies of direct reactions at RIBLL
Jiansong Wang
Institute of Modern Physics,CAS
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

2. SINAP-CUSTIPEN WORKSHOP,Shanghai
Outline
Motivation
Elastic scattering of 8B an other proton-rich nuclei
Breakup mechanism of 8B
Summary and Outlook
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

3. Background The precise and accurate experimental data is the benchmark
First principal Theory
(QCD
Ab initio)
Phenomenological Theory
Nuclear
Force
Elastic scattering ……
Knockout reaction
Coulomb excitation
Direct breakup
Decay (γ,β,α,n,p…)
The precise and accurate experimental data is the benchmark
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

4. SINAP-CUSTIPEN WORKSHOP,Shanghai
New Phenomena
Rep.prog.Phys.71,046301
Shell Evolution
Exotic Structure
Exotic Decay Mode
New Collective Motion
Phys.Rep.389,1-59
HIRFL-RIBLL1
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

5. SINAP-CUSTIPEN WORKSHOP,Shanghai
Light Halo Nuclei
8B: Sp= keV 10, T1/2=770 ms 3 found in 1950 at Berkley linear accelerator [Phys. Rev. 80 (1950) 519]
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

6. SINAP-CUSTIPEN WORKSHOP,Shanghai
S17(0) factor
Coulomb dissociation
T. Motobayashi et al., PRL73(1994)2680，
B. Davids et al., PRL81(1998)2019,
N. Iwasa et al., PRL83(1999)2910,
B. Davids et al., PRL86(2001)2750,
F. Schumann et al., PRL90(2003)
7Be(d,n)8B，
Weiping Liu et al., PRL77（1996）611.
7Be(p,γ)8B,
F. Hammache et al., PRL86(2001)3985,
R. Junghans et al., PRL88(2002)041101,
L.T. Baby et al., PRL90(2003)022501,.
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

7. SINAP-CUSTIPEN WORKSHOP,Shanghai
Neutrino Spectrum
8B β decay α spectrum,
C. E. Ortiz et al., PRL85(2000)2909，
W.T.Winter et al., PRL91(2003)252501,
T. Roger et al., PRL108(2012)162502
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

8. Reaction Cross Section
I. Tanihata et al., PLB206(1988) ，J. S. Al-Khalili and J. A. Tostevin, PRL76(1996)3903
the intrinsic few-body structure of these projectiles and the adiabatic nature of the projectile-target interaction are considered
R.E. Warner et al., PRC52(1995)R （total reaction cs）
rms radius=2.72fm
F. Negoita et al., PRC54(1996)1787 （reaction CS,Breakup CS, momentum distribution）
rms radius=2.55fm
Proton halo
pygmy proton halo/proton skin
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

9. Reaction Cross Section（cont’d）
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

10. SINAP-CUSTIPEN WORKSHOP,Shanghai
Quadruple Moment
T. Minamisono et al.,PRL69(1992)2058 :
Q(8B) =68.3 ±2. 1 mb,
Partly from core deformation,
PLB315,24
Cohen-Kurath shell model calculation
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

11. Longitudinal Momentum of 7Be
△r△p～h
GSI 8B(1471AMeV) ±6MeV/c ZPA,350,283
GSI 8B(1440AMeV) ±5MeV/c PLB,452,1
GSI 8B(936AMeV) ±5MeV/c PLB,529,31
7Be fragment Measured by Magnet Spectrometer
GANIL 8B(40AMeV) ±7MeV/c PRC,54,1787
7Be fragment Measured by Si telescope
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

12. Longitudinal Momentum of 7Be(cont’d)
MSU 8B(41AMeV) ± 7MeV/c PRL77 (1996) 5020
Using 0 degree telescope
Theoretical Calculation: 160MeV/c
( transparent limit of the Serber model)
Conclusion:
1, Reaction mechanisms influence the 7Be momentum distributions
2, they do not directly reflect the Valence proton momentum wave function
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

13. Elastic scattering of 8B near to the Coulomb barrier
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

14. Current Main Exp. Setups at HIRFL-CSR
SHANS
Spectrometer of Heavy Atoms & Nuclear Structure
RIBLL 1
RIBs produced via PF & transfer with primary beams up to Kr
ETF
RIB Physics at intermediate energy
EOS of asymmetric nuclaer matter
High baryon density matter
CSRe
Mass measurement
Decay spectroscopy
Atomic physics with cooling storage ring
CSRm
CSRe
SFC
SSC
SFC:  10 AMeV (A/q=2)
SSC:  100 AMeV (A/q=2)
CSRm: 1.0 AGeV (A/q=2)
CSRe:  0.76 AGeV (A/q=2)
HIRFL - CSR
RIBLL 1
ETF
SHANS
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

15. Elastic Scattering Measurement SINAP-CUSTIPEN WORKSHOP,Shanghai
The incident particles are identified by TOF
Two PPACs Tracking the incident particles
Two sets of Silicon Telescope, composed with a strip Si dE detector and square Si E detector,are used to identify the elastic scattering events.
Elastic Events Identification
Angular Distribution
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

16. Sytematic OMP Calculation
Y.Y.Yang, J.S.Wang et al., PRC87(2013)044613
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

17. Coulomb Breakup Effects Is Small for 8B
Y.Y.Yang, J.S.Wang et al., PRC87(2013)044613
A. Di Pietro et al., PRL105(2010)022701
8B → 7Be + p breakup have a small influence on the elastic scattering at three time of Coulomb barrier.
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

18. The Coulumb Rainbow Peak is Enhanced for 8B?
The different structure
between proton and neutron halo
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

19. Effects of Coulomb and centrifugal barriers: 8B
Courtesy of Danyang Pang
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

20. Breakup effects in 8B and 11Be: CDCC Calculations
Courtesy of Danyang Pang
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

21. Experimental data for 10B,10,11C
The optical model calculations with a single-folding model with the Bruyeres Jeukenne-Lejeune-Mahaux (JLMB) model nucleon-nucleus potentials (seeing Y.P. Xu and D.Y. Pang, Phys. Rev. C87, (2013)) can reproduce the experimental angular distribution well.
Y.Y.Yang, J. S. Wang et al. Phys.Rev.C90 (2014)014606
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

22. Experimental Results for N=3 isotones
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

23. Experimental Setup for Breakup Reactions
 PPAC： 50×50 1mm space Resolution，Charge distribution Readout
 DSSD： thickness，1000um 40×40 strip width 1mm
 CsI Array：8 ×8 Forward size 21×21mm2 Length 50mm Readout by PMT, FWHM ～7% for 5.8MeV
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

24. Identifying the reaction mechanism
Present work PRC91,054617
MSU PRL 102,232501
Width by fitting:
Diff: 92±7MeV/c
Strip:124±17MeV/c
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

25. Theoretical Calculations-Stripping
Calculation done by Prof. J. A. Tostevin
The stripping momentum distributions were calculated using the eikonal approximation formalism (PRC70, ) and the eikonal phase shifts and S-matrices of the following potentials (denoted KDe)
The complex 7Be-target optical potential was calculated using the double-folding method of PRC74,064604, assuming Gaussian 7Be and 12C densities of rms radii 2.31and 2.32 fm. The proton-target potential was calculated from the Koning and Delaroche global parameterization (NPA713, 231)
In addition, due to the relatively low beam energy, calculations were repeated using the improved description of the proton-target S-matrix (denoted KDp).
The 8B(g.s.) to 7Be final state radial overlaps and spectroscopic factors were taken from PRL102,232501
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

26. Theoretical Calculations-Diffraction
The diffraction mechanism differential cross sections were calculated using a CDCC (Coupled Discretized Continuum Channels) breakup model space as PRL102,232501, and the resulting momentum distributions constructed by integration over the solid angles covered by the current detection system, as is discussed in Phys. Rev. C 66,
Calculation done by Prof. J. A. Tostevin
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

27. A summary of width calculated in different model
85±4
PRL77(1996)5020
The experimental data show the width of longitudinal momentum distribution for stripping breakup is obviously wider than diffraction breakup.
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

28. SINAP-CUSTIPEN WORKSHOP,Shanghai
Summary and Outlook
The angular distribution of the elastic scattering of 8B + Pb does not show an suppression at the CNIP region which are observed for neutron halo nuclei.
Longitudinal momentum distributions for both stripping and diffraction mechanisms have been obtained by a coincidence technique. The present experimental data show a marginal difference of the longitudinal momentum distributions between stripping and diffraction.
Further studies of 8B are needed both experimentally and theoretically.
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

29. SINAP-CUSTIPEN WORKSHOP,Shanghai
Collaborators
IMP: Y. Y. Yang(杨彦云)，P. Ma(马朋)，M. R. Huang(黄美容)，J. B. Ma(马军兵)，F. Fu(付芬)，Q. Wang(王琦)，M. Wang(王猛)，Z. Y. Sun (孙志宇)，Z.G.Hu(胡正国)，R. F. Chen(陈若富)，X. Y. Zhang(张雪荧)，X. H. Yuan(袁小华)， X. L. Tu (涂小林)，Z. G. Xu(徐治国)，K. Yue(岳珂)，J. D. Chen(陈金达)，B. Tang(唐彬)，Y. D. Zang(臧永东)，D. P. Wu(武大鹏)，Q. Hu(胡强)，Z. Bai(白真)，Y. J. Zhou(周远杰)，W. H. Ma(马维虎)，J. Chen(陈杰)，Y. H. Zhang(张玉 虎)，H. S. Xu(徐瑚珊) and G. Q. Xiao(肖国青), Roy Wada Beihang University：Danyang Pang（庞丹阳） The Andrzej Sołtan Institute ,Warsaw, Poland：N. Keeley, R. Rusek M.S. University of Baroda, India： Surjit Mukhejee Nanjing Univ.：Z. Z. Ren(任中洲)，C. Xu(许昌)，D. D. Ni(倪冬冬) CIAE：C. J. Lin(林承键)，X. X. Xu(徐新星) Surrey Univ.: J. A. Tostevin Grateful to George Bertsch, Carlos Bertulani, and Henning Esbensen for informative discussions
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

30. SINAP-CUSTIPEN WORKSHOP,Shanghai
RIBLL Collaboration
Physics Goal:
Studying RIB physics based on RIBLL1 and RIBLL2
Spokespersons: Yanlin Ye(PKU, former)
Chenjian Lin (CIAE)
Jiansong Wang(IMP)
We have a collaboration based on RIBLL1 and RIBLL2. The spokespersons are Prof. Yanlin Ye from Peking Univ. and me. We have two collaboration meetings a year. The members include many nuclear research groups all over China.
Member Institute：
Peking Univ.，Tsinghua Univ.，Nanjing Univ.，Beihang Univ.，Shanghai Jiaotong Univ.，Southwest Univ., Chongqing Univ.，Haerbing Engineer Univ., China Institute of Atomic Energy，Shanghai Institute of Nuclear Application，Institute of Theoretical Physics，Institute of Modern Physics, etc.
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai

31. Thanks for your attention ! SINAP-CUSTIPEN WORKSHOP,Shanghai
2018/12/7
SINAP-CUSTIPEN WORKSHOP,Shanghai