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王建松、杨彦云、金仕纶等 湖州师范学院 中国科学院近代物理研究所
晕核结构与反应机制实验研究 王建松、杨彦云、金仕纶等 湖州师范学院 中国科学院近代物理研究所 2/3/2020
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报告内容 晕结构研究背景 直接反应与晕结构 结论和展望 2/3/2020
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What does nuclear physics do?
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 2/3/2020
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New Phenomena Shell Evolution Exotic Structure Exotic Decay Mode
Rep.prog.Phys.71,046301 Exotic Structure Exotic Decay Mode New Collective Motion CSR-RIBLL2 HIRFL-RIBLL1 2/3/2020
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原子核晕结构的发现 I. Tanihata et al., PRL55(1985)2676 2/3/2020 核物理大会@华中师大
Phys.Rep.389,1-59 I. Tanihata et al., PRL55(1985)2676 2/3/2020
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晕结构存在的条件 价核子处于s或p轨道 价核子的分离能很小
A.S. Jensen, K. Riisager,Physics Letters B 480(2000)39–44 2/3/2020
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核物质半径唯像公式 2/3/2020
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一些候选核 Sp /S2p(MeV) Sn 8B 0.136 6He 0.976(2n) 9C 1.300 8He 3.1 (4n) 12N
0.600 11Li 0.369(2n) 13O 1.512 11Be 0.502 17F 14Be 1.266 (2n) 17Ne 0.933 (2p) 17B 1.385 19C 0.577 2/3/2020
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Light Halo Nuclei 8B: Sp= 136.4 keV 10, T1/2=770 ms 3
found in 1950 at Berkley linear accelerator [Phys. Rev. 80 (1950) 519] 2/3/2020
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晕结构存在的判据 实验判据: 理论判据: 反应截面(总截面、相互作用截面、去除价核子截面) 核芯核的动量分布宽度测量 弹性散射测量
几何判据:rh/rc 正常核 ,8B、6He、11Li,分别为:1.75,1.8,2.17(B. Jonson / Physics Reports 389 (2004) 1– 59 2/3/2020
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在RIBLL1开展的核反应截面测量 12-16C, 14-17N, and 16-18O,D. Q. Fang et al.,Phys. Rev. C61(2000)064311 27P, D. Q. Fang et al., Eur. Phys. J. A12(2001)335 12N,宁振江等,《物理学报》50(2001)644 23Al, X. Z. Cai et al., Phys. Rev. C65(2002)024610 Proton-rich (A<30) H. Y. Zhang et al., Nuclear Physics A 707 (2002)303 8B,王全进等,《自然科学进展》12 (2002)29 6He,陈志强等,《原子核物理评论》19 (2002)287 Mod. Phys. Lett. A 18(2003)151 Phys Rev C 69,034326(2004) 17Ne,李家兴等,《高能物理与核物理》29(2005)28 NIMB 247 (2006) 155–160 8He,李琛等,《高能物理与核物理》31(2007)52 17B,胡正国等,《中国科学 G 辑》38(2008) 1046 ~ 1052; 17B,王猛等,Chinese Physics C32(2008)548 2/3/2020
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the longitudinal momentum distribution of 31Cl fragmentation
SINAP Group The calculation shows that the width of momentum distribution for a valence proton with l = 2 is consistent with the experimental data,which indicates a dominant d-wave component for the valence proton in 31Cl Y. Fu, D. Q. Fang et al., PHYSICAL REVIEW C 84, (2011) 2/3/2020
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8B的质子晕证据 2/3/2020
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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)R1166 rms radius=2.72fm F. Negoita et al., PRC54(1996)1787 rms radius=2.55fm Proton halo pygmy proton halo/proton skin 2/3/2020
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Quadruple Moment T. Minamisono et al.,PRL69(1992)2058 :
Q(8B) =68.3 ±2. 1 mb, Partly from core deformation, PLB315,24 Rn=2.20 Rp=2.98 Cohen-Kurath shell model calculation 2/3/2020
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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 2/3/2020
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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 2/3/2020
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8B破裂反应实验装置 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 2/3/2020
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Identifying the reaction mechanism
MSU D.Bazin et al., PRL 102,232501 Present work Width by fitting: Diffractive: 92±7MeV/c Stripping: 124±17MeV/c 2/3/2020
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A summary of width calculated in different model
85±4 PRL77(1996)5020 91±5 PLB –7 The experimental data show the width of longitudinal momentum distribution for stripping breakup is obviously wider than diffraction breakup. S.L.Jin, J.S.Wang et al., Phys. Rev. C91,054617(2015) 2/3/2020
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晕结构对弹性散射的影响 2/3/2020
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中子晕核11Be、11Li对弹性散射的影响 9、11 Li+208Pb 9、10、11 Be+64Zn
A. Di Pietro et al., PRL 105 (2010)022701 M. Cubero et al., PRL 109 (2012) 2/3/2020
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轻质量奇特核的弹性散射研究 研究并提出了弹性散射1/4角的规律。 提出了描述不同核反应系统在低能区的核反应总截面的唯像公式
发展了在RIBLL上精确测量不稳定核弹性散的实验方法。 发现质子滴线核8B、9C与重靶弹性散射中没有库仑核势干涉峰的削弱现象。 Phys.Rev.C86 (2012)057602 Phys.Rev.C86 (2012)057603 Phys.Rev.C87 (2013)044613 Phys.Rev.C90 (2014)014606 Nucl.Inst.Meth.Phys.Res.A701(2013)1-6 Phys.Rev.C94 (2016)034614 Phys.Rev.C98 (2018)044608 2/3/2020
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How to Obtain the Correct ES Angular Distribution
Y(θ)Exp Simulated Y(θ)Ruth Because the secondary beams are dispersed widely, we have to simulate the Rutherford scattering events and compare with the experimental data to obtain the normalized differential cross section as the following: σ/σRuth (θ) = Y(θ)Exp/ Y(θ)Sim Y(θ)Exp, Y(θ)Sim are the counts at a given angle θ from the experiment and the simulation, respectively. Y.Y.Yang, J.S.Wang et al. NIMA701(2013)1 2/3/2020
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Elastic scattering of Proton Drip Line Nuclei
The experimental data can be reproduced by the optical model calculations with the systematic nucleus-nucleus potential of Xu and Pang. Yanyun Yang et al., PRC98(2018)044608 2/3/2020
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Why the Coulumb rainbow peak not suppressed for proton-rich nuclei ?
preliminary NO proton halo The different structure between proton and neutron halo 2/3/2020
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New detector for E. S. studies
Next experiment: 12N + TAMU Cyclotron Primary beam: 55AMeV 12C RIB: 11Be, 143MeV Intensity: 1000pps Purity: 97% Done in Oct. MARS can provide 12MeV/u 12N with 2×105 pps, A. Banu et al., Phys. Rev. C 79, 2/3/2020
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总结与展望 中子晕核有明确一致的实验特征和理论解释。 8B是不是质子晕?有没有质子晕核存在? 如何确认8B是否是质子晕核:
2)测量8B破裂碎片p与7Be的关联 RIBLL1是研究奇特核晕结构的一个重要平台 2/3/2020
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Collaborators IMP: Y. Y. Yang(杨彦云),S. L. Jin(金仕纶), P. Ma(马朋),M. R. Huang(黄美容),J. B. Ma(马军兵),F. Fu(付芬),Q. Wang(王琦), D. P. Wu(武大鹏),Q. Hu(胡强),Z. Bai(白真),L. Jin (金磊),J. B. Chen(陈江波),Y. Li(李勇),M. H. Zhao(赵明辉),Y. J. Zhou(周远杰),W. H. Ma(马维虎),J. Chen(陈杰),余功明, D. B. Patel,金树亚, 段芳芳 (LZU),王康,杨过, 王煜峰(YNU) 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),Y. H. Zhang(张玉虎),H. S. Xu(徐瑚珊) and G. Q. Xiao(肖国青) CIAE:C. J. Lin(林承键)研究组; Peking Univ:Y. L. Ye (叶沿林)研究组 Beihang Univ:D. Y. Pang(庞丹阳); Poland:N. Keely, K. Rusek Spain:A. Moro ;India:S. Mukerjee Nanjing Univ.:Z. Z. Ren(任中洲),C. Xu(许昌),D. D. Ni(倪冬冬) Surrey Univ.: J. A. Tostevin Grateful to George Bertsch, Carlos Bertulani, and Henning Esbensen for informative discussions 2/3/2020
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Thanks for your attention !
2/3/2020
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