Progress%20of%20Experimental%20Nuclear%20Astrophysics%20in%20CIAE

1
Progress of Experimental Nuclear Astrophysics in
CIAE

• Wei-ping Liu
• wpliu_at_iris.ciae.ac.cn
• China Institute of Atomic Energy (CIAE)
• CCAST symposium on physics of isospin and nuclear
  phase transition
• August 19-21, Beijing

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Nuclear Astrophysics

• From macro to micro
• Nuclear physics in energy production and element
  synthesis
• Process, time scales, environment, isotope
  abundance
• Astrophysical model

3
Some of the great discovery of astrophysics in
20th and 21th 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 26Al g-ray, 1980, direct support of
  explosive nuclear synthesis, development of g-ray
  astronomy
• Detection of SN1987A supernova explosion,1987
• Experimental explanation of solar neutrino
  missing, 2003

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The interplay between nuclear physics and
astrophysics
Exp
Exp
The
The
Nuclear data
Astro Model
Abundance Estimation
Astro Obs
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Nuclear physics plays role
RIA white paper 2001
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RIKEN proposal
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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

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Where is reaction and decay data in network
calculation
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Extra low energies
11C(p,?)12N
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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,g)
  astrophysical S-factor or (n,g) reaction rate

H. M. Xu, PRL 73(1994)2027
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More basics
For peripheral transfer reaction B(d,n)A
two virtual captures
B p ? A n p ? d
and
two ANCs
known value
can be obtained from
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The Cross Section for E1 capture
ANC or spec factor
is the kinetic factor
eeff eN/A for Protons -eZ/A for
Neutrons
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BRIF
Tandem 15 MV Cyclotron 100 MeV p, 200 mA
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RIBs expected
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BIRFII
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Inverse kinematics
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GIRAFFE
Target
Dipole
Quadrapoles
Wien filter
Reaction
W. Liu, NIMB 204(2003)62
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Unstable beams produced
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Secondary beams summary

Now, with velocity filter the new beam and beam
purity enhancement 7Be, purity gt 99 17F, 15O,
13N, purity gt 90 10C, new beam, purity gt 90
With the future new beams of 14O and 8B etc by
using 3He gas target
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15 years of research in CIAE
95 2000 2005
7Be(d,n)8B, CIAE, PRL96, CPL2000
6He(p,n)6Li, CIAE, PLB2002
11C(d,n)12N, CIAE, NP2003
8Li(d,p)9Li, PRC2005
11C(p,g)12N, TRIUMF
17F(d,n)18Ne, CIAE
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Physics of 7Be

• The astrophysical S factor for the 7Be(p,g)8B
  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 7Be, with an accuracy
  comparable to that from direct radiative capture
  or Coulomb Dissociation reaction.

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Results-7Be
W. Liu PRL77(1996)611 NPA 616(1997)131c
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Physics of 11C

• Proton- and a-capture reactions on proton-rich
  unstable nuclei of A13 involved in the hot pp
  chains are thought to be another alternative way
  to the 3a 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 ß
  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 11C(p,g)12N which is believed to play an
  important role in the evolution of Pop ? stars.

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From (d,n) to (p,g)
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Results-11C
W. Liu, NPA728(2003)275
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Network calculation
N. Shu, Nucl. Phys. A 758 (2005) 419c
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E983_at_DRAGON
Wei-ping Liu, E983 Proposal
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Physics of 8Li

• 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 8Li, 7Be and 8B play key role
• 8Li generating reactions 7Li(n,g)8Li and
  7Li(d,p)8Li,
• 8Li destroying reactions 8Li(a,n)11B,
  8Li(n,g)9Li, 8Li(d,p)9Li, 8Li(d,t)7Li,
  8Li(d,n)9Be, etc.
• 8Li(a,n)11B and 8Li(n,g)9Li are key of them
• 8Li has short half life of 0.83 s, so indirect
  approach is the only way to get (n,g) rates

APJ429(1994)499
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Results-8Li
Z. H. Li, W. P. Liu et al., Phys. Rev. C 71,
052801(R) (2005)
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Some details of calculation 1
In agreement with ANL results, A. H. Wuosmaa et
al., PRL94(2005)082502, which is 0.90 - 0.13
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Some details of calculation 2
Fitted by experimental known 6,7Li and 12C (n,g)
reactions
1
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Results for (n,g) rate
Z. H. Li, W. P. Liu et al., PHYSICAL REVIEW C
71, 052801(R) (2005)
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Application to mirror system

• Angular distribution 8Li(d,p)9Lig.s. _at_ Ecm 7.8
  MeV
• ANC of 9Li ?8Li n is 1.33 -0.27 fm-1
• Charge symmetry, ANC for 9C?8B p is 1.10
  -0.23 fm-1.
• S-factor and reaction rate for direct capture in
  8B(p,g)9C using the ANC

B. Guo et al., Nucl. Phys., in press
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Summary
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Summary of experiments
1.33-0.27
3970-950
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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 7Be(p,g)8B, 11C(p,g)12N, 8Li(n,g)9Li were
  deduced by using the measurements of 7Be(d,n)8B
  ,11C(d,n)12N, and 8Li(d,p)9Li reactions at the
  energies of astrophysical interest.

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Research Team and support
CIAE
NAO, U of Tokyo Toshitaka Kajino
Baoxiang Wang
Zhanwen Ma
Youbao Wang
Xiaodong Tang
Research project supported by Ministry of science
and technology, by National science foundation of
China.
Bing Guo
Xixiang Bai
Sheng Zeng
Gang Lian
Yun Lu
Zhihong Li
Shengquan Yan
Yongshou Chen Nengchuan Shu Kaisu Wu
Zhanwen Ma
Weiping Liu, wpliu_at_iris.ciae.ac.cn