Progress of Experimental Nuclear Astrophysics in CIAE Wei-ping Liu China Institute of Atomic Energy (CIAE) CCAST symposium on physics of isospin and nuclear phase transition August 19-21, Beijing
Nuclear Astrophysics From macro to micro Nuclear physics in energy production and element synthesis Process, time scales, environment, isotope abundance Astrophysical model
Some of the great discovery of astrophysics in 20 th and 21 th century 3K microwave background radiation,1965, experimental support for Big-Bang theory Detection of solar neutrino, 1960, message from solar interior Element distribution anomaly in metal star Detection of 26 Al -ray, 1980, direct support of explosive nuclear synthesis, development of - ray astronomy Detection of SN1987A supernova explosion,1987 Experimental explanation of solar neutrino missing, 2003
Exp The Nuclear data Astro Obs Astro Model ExpThe The interplay between nuclear physics and astrophysics Abundance Estimation
Nuclear physics plays role ®RIA white paper 2001
®RIKEN proposal
Important NP data S-factor, focus on NP, down to astrophysics Reaction rates, direct input to network calculation Direct capture, direct reactions Resonance, level scheme, level width, and partial width
Where is reaction and decay data in network calculation
Maxwellan dist. e -E/kT Gamow peak Coulomb penetration e -bE^(1/2) Res. Peak Probability 温度（能量） kTE0E0 ErEr Extra low energies 11 C(p, ) 12 N
General idea Production of RIB ( In-flight method) Measurement of (d,n) or (d,p) angular distribution Fit the distribution by DWBA Get ANC or spec factor Use ANC or spec factor to deduce (p, ) astrophysical S-factor or (n, ) reaction rate H. M. Xu, PRL 73(1994)2027
More basics For peripheral transfer reaction: B(d,n)A two virtual captures: B + p A n + p d two ANC’s : and known value can be obtained from
The Cross Section for E1 capture is the kinetic factor e eff = eN/A for Protons -eZ/A for Neutrons ANC or spec factor
BRIF Tandem: 15 MV Cyclotron: 100 MeV p, 200 A
RIBs expected
BIRFII
Inverse kinematics
GIRAFFE Target Dipole Quadrapoles Reaction Wien filter W. Liu, NIMB 204(2003)62
Unstable beams produced
Secondary beams summary Now, with velocity filter the new beam and beam purity enhancement: 7 Be, purity > 99 % 17 F, 15O, 13N, purity > 90 % 10 C, new beam, purity > 90 % With the future new beams of 14 O and 8 B etc by using 3 He gas target
15 years of research in CIAE Be(d,n) 8 B, CIAE, PRL96, CPL He(p,n) 6 Li, CIAE, PLB C(d,n) 12 N, CIAE, NP Li(d,p) 9 Li, PRC C(p, ) 12 N, TRIUMF 17 F(d,n) 18 Ne, CIAE
Physics of 7 Be The astrophysical S factor for the 7 Be(p, ) 8 B reaction at solar energies is a crucial nuclear physics input for the “solar neutrino problem”. It was proposed that the S factor can be indirectly determined through the asymptotic normalization constant (ANC) extracted from the proton pickup reactions of 7 Be, with an accuracy comparable to that from direct radiative capture or Coulomb Dissociation reaction.
Results － 7 Be W. Liu PRL77(1996)611 NPA 616(1997)131c
Physics of 11 C Proton- and -capture reactions on proton-rich unstable nuclei of A≤13 involved in the hot pp chains are thought to be another alternative way to the 3 process for transforming material from the pp chains to the CNO nuclei in the peculiar astrophysical sites where the temperature and density are high enough so that the capture reaction becomes faster than the competing β decay These linking reactions between the nuclei in the pp chains and the CNO nuclei might be of immense importance for the evolution of massive stars with very low metallicities. One of the key reactions in the hot pp chains is the 11 C(p, ) 12 N which is believed to play an important role in the evolution of Pop Ⅲ stars.
From (d,n) to (p,g)
Results － 11 C W. Liu, NPA728 (2003) C(d,n) 12 N EE Er MRSD
Network calculation N. Shu, Nucl. Phys. A 758 (2005) 419c
Wei-ping Liu, E983 Proposal
Physics of 8 Li Inhomogeneous model predict that short-lived isotopes are created which allow for more reaction pathways to the heavier elements Reactions involving short-lived radioactive nucleus 8 Li, 7 Be and 8 B play key role 8 Li generating reactions: 7 Li(n, ) 8 Li and 7 Li(d,p) 8 Li ， 8 Li destroying reactions: 8 Li( ,n) 11 B, 8 Li(n, ) 9 Li, 8 Li(d,p) 9 Li, 8 Li(d,t) 7 Li, 8 Li(d,n) 9 Be, etc. 8 Li( ,n) 11 B and 8 Li(n, ) 9 Li are key of them 8 Li has short half life of 0.83 s, so indirect approach is the only way to get (n, ) rates APJ429(1994)499
Results － 8 Li 8 Li(d,p) 9 Li Ep Z. H. Li, W. P. Liu et al., Phys. Rev. C 71, (R) (2005)
Some details of calculation 1 In agreement with ANL results, A. H. Wuosmaa et al., PRL94(2005)082502, which is
Some details of calculation 2 1 Fitted by experimental known 6,7 Li and 12 C (n,g) reactions
Results for (n, ) rate Z. H. Li, W. P. Liu et al., PHYSICAL REVIEW C 71, (R) (2005)
Application to mirror system Angular distribution 8 Li(d,p) 9 Li E cm = 7.8 MeV ANC of 9 Li 8 Li + n is fm -1 Charge symmetry, ANC for 9 C 8 B + p is fm -1. S-factor and reaction rate for direct capture in 8 B(p,g) 9 C using the ANC B. Guo et al., Nucl. Phys., in press
Summary
Summary of experiments
Summary GIRAFFE, a tandem based one stage unstable beam facility proved to be effective to produce secondary beams suitable for the study of nuclear astrophysics reactions. Angular distribution measurements of transfer reaction in inverse kinematics, together with DWBA/ANC theoretical approach have been used to study the astrophysical reactions indirectly. The astrophysical S-factors and/or reaction rates for 7 Be(p, ) 8 B, 11 C(p, ) 12 N, 8 Li(n, ) 9 Li were deduced by using the measurements of 7 Be(d,n) 8 B, 11 C(d,n) 12 N, and 8 Li(d,p) 9 Li reactions at the energies of astrophysical interest.
Research Team and support Bing Guo Gang Lian Weiping Liu, Xixiang Bai Baoxiang Wang Sheng Zeng Yun Lu Zhihong Li Shengquan Yan Yongshou Chen Nengchuan Shu Kaisu Wu Youbao Wang Zhanwen Ma Xiaodong Tang NAO, U of Tokyo Toshitaka Kajino CIAE Zhanwen Ma Research project supported by Ministry of science and technology, by National science foundation of China.