Progress of Experimental Nuclear Astrophysics Weiping Liu China Institute of Atomic Energy (CIAE) August 26-30, 2004, Beijing Beijing Summer School

Nuclear Astrophysics  Marco and Micro  Nuclear physics in energy production and element synthesis  Process, time scales, environment, abundance  Astrophysical model  Mass, cross section, half-life  Low energy and high isospin challenge

®RIKEN proposal

Great discovery in 20 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

Table of contents  Nuclear astrophysics and experimental tools  Examples related to solar neutrino problem  More examples

Related knowledge in this school  RNB Production, Lewitowicz, Zhan  Nuclear astrophysics, Woods, Motobayashi  Nuclear structure, Otsuka, Wyss, Akaishi, Shimoda, Toki, Ye  More, Peitzmann, Akiba

How nuclear physics play role. ®RIA white paper 2001

Exp The Nuclear data Astro Obs Astro Model ExpThe The interplay between nuclear physics and astrophysics Abundance Estimation

H-burning Stellar process Inter stellar buring Primodual He-burning Si/Fe burning Gravational corapsse Supernovae Black Hole/neutron star Brief picture of element evolution

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

The Astrophysical S – factor, Summerfield parameter

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

Nuclear Astrophysics Experiments  Solar neutrino problem  40 Ti  -decay  7 Be(d,n) 8 B reaction  Other experiments

Sun Earth SN1987 Nuclear Reaction pp:p + p  2 H + e + + u e pep:p + e - + p  2 H + u e 7 Be: 7 Be + e -  7 Li + u e 8 B: 8 B  8 B * + e + + u e Detector (Homestake, Gallex, SNO Sage, Kamiokande, ICARUS) MSW Effect (  oscillation  e   x ) Solar Neutrino Neutrinos form Supernovae Where does neutrino come from?

pep 7 Be 8B8B Homestake Gallium Kamiokande 7 Be ICARUS pp Neutrino detection Radiochemical Homestake exp.  e + 37 Cl  37 Ar + e - Gallex and Sage  e + 71 Ga  71 Ge + e - Direct measurement Kamioka, SNO Exp.  + e   + e ICARUS Exp.  e + 40 Ar  40 K + e-  x + e-    + e-

Present: basically sensitive to  e Super Kamiokande Gallex, Sage Homestake SNO Future: Neutrino of all flavor Super Kamiokande ICARUS Underground Lab... Solar neutrino experiments

How nuclear physics connected with solar neutrino problem: example  Nuclear physics from production and detection of solar neutrino detection Solar neutrino problem Solar neutrino detector on earth Predictio n of solar model Detection efficiency Neutrino property Neutrino productio n cross section RNB experime nts 2-3 time diff 40 Ti  - decay 7 Be(d,n) 8 B reaction

Nuclear Astrophysics Experiments  Solar neutrino problem  7 Be(d,n) 8 B reaction  40 Ti  -decay  Other experiments

Two process: Absorption  e + 40 Ar  40 K * + e - 40 K *  40 K +   + e -   ’ + e - ’ M(e - ) = 2 Scattering  x + e -   x ’ + e - ’ M(e - ) = 1 ICARUS and neutrino oscillation ®ICARUS homepage

40 K 39 Ar + p 40 Sc 40 Ar 40 Ti Isospin Mirror IAS IAS -1.5 + TzTz ee 40 Ar + p 40 K + n 40 Sc + e + +  e 40 Ti 40 Ar +  e 40 K * Mirror symmetry in mass 40  40 Ti and 40 Ar Mirror symmetry

IAS (J , T 0 ) ++ (Z-3, N+1) +2p Two-Proton Daughter (Z-2, N+1) + p Proton Daughter Seq. 2p p (Z-1, N+1) Emitter Q EC SpSp (J , T 0 ) (Z, N) Precursor 2 He General  -decay scheme    F GT  -decay measurement

Some basics about  -decay 

Selection rules ClasslogftLFermi transitionGamow-Tellor transition II II Superall owed No(0), 1No Allowed< 5.900No(0), 1No 1 st forbidde n > 8.01(0), 1Yes0, 1, 2Yes 2 nd forbidde n > 10.62(1), 2No2,3No

MUSI C MWPC Slit Degrader SC Silicon array NaI array 40 Ti beam Focal plane detectors

40 Ti selection

SIS Beam Heavy- ion Decay signal 1 s 5 s 200 ms Other 40 Ti T 1/2 Delayed coincidence technique

40 Ti  -delayed protons IAS, F GT

Now: DM = -9096(10) keV, Q EC = 11466(13) keV 4365(8) Trinder et al. 4365(10) This work T z = -2 T z = -1 T z = 0 T z = 1 T z = 2 40 Ti 40 Ar 40 K 40 Ca 40 Sc T = 2 isobars Mass and Q EC for 40 Ti by IAS level energy in 40 Sc using IMME: M(T Z ) = a + b T Z + c T Z 2 Old: DM = -8850(160) keV, Q EC = 11680(160) keV Precise mass determination for 40 Ti

40 Ti  -delayed proton  Half-life 40 Sc IAS level  40 Ti mass Full energy, p-  coin, secondary reaction corrections  F and GT decay strength distributions F/GT distributions

B(GT) + B(F) from this work  /B-E x relation from Ormond et al., Phys. Lett. B345(1995)343.  Absorption cross section = 13.8(6)  pb with Bahcall et al. 8 B solar neutrino flux of F = 6.6(1.0)  10 6 cm -2 s -1  ICARUS reaction rate 9.1(1.4) SNU (once for two days) =2.6 (Fermi) (Gamow-Teller)  3 times larger than Bahcall predictions W. Liu et al., PRC58(1998)2677 Reaction rates for ICARUS

General idea  Production of RIB  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

Beijing Tandem national laboratory, CIAE Tandem: 15 MV Cyclotron: 100 MeV p, 200  A

RIBs expected

CSR in Lanzhou

CSR performance CSRmCSRe ion species Accelerated p, C － Up,C － U, RIB, Highly charged ions, Molecules and cluster Energy (MeV/u) (B max =1.4 — 1.6 T) (p) ( 12 C 6+ ) ( 238 U 72+ ) 2000 (p) ( 12 C 6+ ) ( 238 U >90+ )  P/P <10 -4 <10 -5  P/  P Momentum Acceptance  0.15%  0.5~1% Emittance  5  mm-mrad  1  mm-mrad

Inverse kinematics

Primary chamber Dipole Quadruples MCP Secondary chamber IC PSSD Target Slit RNB Gas target Secondary beam line GIRAFFE

GIRAFFE Target Dipole Quadrapoles Reaction Wien filter W. Liu, NIMB 204(2003)62

Beam quality

Secondary beams provided by GIRAFFE

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.

High energy neutrino cross section: S 17 (0). Direct measurement Coulomb dissociation This work: first measurement of 7 Be(d,n) 8 B, using ANC method to deduce S 17 factor. A independent cross check. 7 Be(p,  ) 8 B reaction

Results － 7 Be W. Liu PRL77(1996)611 NPA 616(1997)131c 7 Be(d,n) 8 B Beam Slits Target EE Er PSSD

From angular distribution to S-factor W. Liu, PRL77(1996)611

 n n  n p di-neutron or n-n halo? n-p halo 6 He 6 Li [4.05] 0 + (T=1) (T=1) 1 + (T=0) F G-T Study of 6 He ( p,n) 6 Li reaction

Z. Li, PLB 527(2002)50 Angular distribution to density distribution

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.

Results － 11 C W. Liu, NPA728 (2003) C(d,n) 12 N EE Er MRSD

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, 8Li(n,  )9Li, 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

The quantitative picture APJ429(1994)499

Results － 8 Li Z. Li, 2004, Submitted 8 Li(d,p) 9 Li Ep

Results for (n,  ) rate Z. Li, 2004, submitted

Network calculation N. Shu, Contribution to NIC8

Summary of what we have done

Summary of experiments

What we have done 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.

What we need  Most astrophysical requirements to nuclear physics are related to RNB.  Novel experimental and theoretical methods have to be applied to meet the astrophysical needs.

Conclusion  Nuclear astrophysics is a merging place for novel experiments, theory and imagination  New ideas have to come out to meet the challenge of experiments and to develop theory  A basic understanding of astrophysics will help, communication is needed to track the new astrophysical discovery  Fast developing field of physics of unstable nuclei is a nice counter part to accelerate the study

Research Team 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