Nuclear Physics for Astrophysics with Radioactive Beams

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Nuclear Physics for Astrophysics with Radioactive
Beams

• Livius Trache
• Texas AM University

EURISOL Workshop ECT Trento, Jan. 2006
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Nuclear Physics for Astrophysics with Radioactive
Beams

• Indirect methods only!
• Seek (structure) information to transform in
  cross sections at astrophysically relevant
  energies and reaction rates
• For charged part radiative capture (p,g) or (a,
  g) reactions - ANC
• (p and a) transfer reactions (7Be,8B),
  (11C,12N), (13N,14O), (6Li,d),
• breakup 8B, 9C, 23Al, 7Be, etc
• charge symmetry study mirror nucleus (or
  reaction) ex. (7Li,8Li) for (7Be,8B)
• Coulomb dissociation - B(El), Trojan Horse Method
• (other) spectroscopic info Jp, Eres, G
• to estimate direct terms Jp, l, config mixings
  variae
• resonances (Jp, Eres, Gs) variae, including
  resonant elastic scatt.
• Need good, reliable data to make credible
  predictions
• Optical model parameters for elastic, transfer
  breakup S-matrices masses, lifetimes, level
  densities, GT strength distributions, etc More
  stable beam studies RNB !

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Radiative proton capture is peripheral e.g.
7Be(p,g)8B
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Direct Radiative proton capture

M is
Integrate over ?
Low B.E.
Find
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Proton Transfer Reactions
A
B(Ap)
p
a(bp)
b
Aa-gtBb
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ANCs measured using stable beams in MDM

• 9Be p 10B 9Be(3He,d)10B9Be(10B,9Be)10B
  
• 7Li n 8Li 12C(7Li,8Li)13C
• 12C p 13N 12C(3He,d)13N
• 12C n 13C 13C(12C,13C)12C
• 13C p 14N 13C(3He,d)14N13C(14N,13C)14N
  
• 14N p 15O 14N(3He,d)15O
• 16O p 17F 16O(3He,d)17F
• 20Ne p 21Na 20Ne(3He,d)21Na
• 22Ne n 23Ne 13C(22Ne,23Ne)12C
• beams 10 MeV/u
• Test cases

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ANCs at TAMU
from radioactive beams _at_ 10-12 MeV/nucleon

• 10B(7Be,8B)9Be, 14N(7Be,8B)13C
• 7Li beam 130 MeV, 7Be beam 84 MeV
• 14N(11C,12N)13C
• 11B beam 144 MeV, 11C beam 110 MeV
• 14N(13N,14O)13C
• 13C beam 195 MeV, 13N beam 154 MeV
• 14N(17F,18Ne)13C
• work at ORNL with TAMU participation

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RB in-flight production
1.5 105 pps
(p,xn), (p,pxn) reactions in inverse kinematics
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Transfer reactions for ANCs 10B(7Be,8B)9Be
14N(7Be,8B)13C
Beam spot F4 mm, Dq1.8 deg, DE/E1-1.5

• Beam Study Detector 1 mm Si strip detector
• Reaction Telescopes
• 105 mm Si strip detector
• 1 mm Si detector

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Better beams sd-shell nuclei
17F (10 MeV/n) on melamine ORNL experiment J.
Blackmon et al, PRC 2005
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Transfer reactions

• Conclusions
• Can extract ANC from proton transfer reactions -gt
  (p,g) rates
• E/A 10 MeV/nucleon (peripherality)
• better beams reaccelerated OK!
• good detection resolution magn spectrom at 0
  deg.
• Need good Optical Model Potentials for DWBA!
  Double folding.
• Study n-transfer and use mirror symmetry
• SpSn gt ANCpconstANCn
• Data further needed for
• Various cases waiting points, breakout reactions
  
• CNO cycle
• hot CNO
• rap
• rp-process
• H He-burning in general

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CI Upgrade (overview)

• Re-activate K150 (88) cyclotron
• Build ion guides and produce RIBs
• Inject RIBs to K500 cyclotron
• Project deliverables (DOE language)
• Use K150 stand-alone and as
• driver for secondary rare-isotope
• beams that are accelerated with
• K500 cyclotron

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K150 Beam Lines
MARS Cave
MDM Cave
NIMROD Cave
Light Ion Guide
Heavy Ion Guide
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Nuclear Astrophysics with upgrade - III
Study sd-shell nuclei for rp-process

• Rare ion beams in MDM at 10 MeV/u
• - accelerated beams for transfer reactions
  around 0o
• large cross sections and high
  sensitivity
• Rare ion beams for resonance studies
• - elastic scattering for resonances with more
  beams
• Rare ion beams into MARS, MDM
• study r-process nuclei masses and lifetimes
  (d,p) react

(c/o R.E. Tribble)
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One-nucleon removal can determine ANC (only!)
Momentum distributions ? nlj Cross section ?
ANC Gamma rays ? config mixing
Need Vp-target Vcore-target and reaction
mechanism
Calc F. Carstoiu Data see later
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One-nucleon removal spectroscopic tool

• Example of momentum distributions all types!
• E. Sauvan et al. PRC 69, 044503 (2004).
• Cocktail beam 12-15B, 14-18C, 17-21N, 19-23O,
  22-25F
• _at_ 43-68 MeV/nucleon.

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Summary of the ANC extracted from 8B breakup
with different interactions

• Data from
• F. Negoita et al, Phys Rev C 54, 1787 (1996)
• B. Blank et al, Nucl Phys A624, 242 (1997)
• D. Cortina-Gil e a, EuroPhys J. 10A, 49 (2001).
• R. E. Warner et al. BAPS 47, 59 (2002).
• J. Enders e.a., Phys Rev C 67, 064302 (2003)
• Summary of results
• The calculations with 3 different effective
  nucleon-nucleon interactions are kept and shown
• JLM (blue squares),
• standard m1.5 fm (black points) and
• Ray (red triangles).

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S17 astrophysical factor (ours)
New S17(0) 18.0 ? 1.9 eV?b (G Tabacaru ea,
2004)
8B breakup

• For comparison
•      (7Be,8B) proton transfer at 12 MeV/u
• A. Azhari e.a. two targets
• 10B S17(0) 18.4 ? 2.5 eVb (PRL 99)
• 14N S17(0) 16.9 ? 1.9 eVb (PRC 99)
• Average Phys Rev C 63, 055803 (2001)
• S17(0) 17.3 ? 1.8 eVb
•      13C(7Li,8Li)12C at 9 MeV/u
• (LT e.a., PRC 66, June 2003))
• C2tot 0.455 ? 0.047 fm-1
• S17(0) 17.6 ? 1.7 eVb

• JLM S1717.42.1 eVb no weights
• standard S1719.61.2 eVb
• Ray S1720.01.6 eVb
• Average all
• C2tot 0.483 ? 0.050 fm-1
• S1718.71.9 eVb
• (all points, no weights)
• Published LT et al.- PRC 69, 2004

New average S17(0) 18.2 ? 1.8 eV?b
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22Mg(p,g)23Al reaction

• Gamma-ray space-based telescopes to detect
  current (on-going) nucleosynthesis
• Astrophysical g-ray emitters 26Al, 44Ti, and
  22Na
• Satellite observed g-rays from 26Al (T1/27 105
  y), 44Ti, etc., but not from 22Na (COMPTEL)
• 20Ne(p,g)21Na(p,g)22Mg(b,n)22Na
• Depleted by 22Mg(p, g)23Al ?!
• Dominated by direct and resonant capture to first
  exc state in 23Al

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23Al versus 23Ne
24Mg(7Li,8He)23Al

• Structure of 23Al poorly known only 2 states, no
  Jp
• Mirror 23Ne has Jp5/2 for g.s. and Jp1/2 for
  1-st exc state (Ex1.017 MeV)
• NNDC says Jp3/2

?
23Al halo nucleus level inversion?!
J. Caggiano et al., PRC 65, 025802 (2001)
X.Z. Cai et al., Phys Rev C 65, 024610 (2002)
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22Mg(p,g)23Al reaction in novae

• Calculating the astrophysical S-factor in the 2
  spin-parity scenarios, if level inversion occurs,
  the difference is dramatic (upper figure)
• The resulting reaction rate is 30-50 times larger
  in the T90.1-0.3 temperature range for the case
  of a 2s1/2 configuration for 23Al g.s.
• This may explain the absence of 22Na thru the
  depletion of its 22Mg predecessor in 22Mg(p,
  g)23Al
• Direct (2s1/2 or 1d5/2) and resonant capture to
  first exc state in 23Al (bottom figure).

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23Al breakup experiment

• Proposed to measure _at_GANIL
• Momentum distributions for 12C(23Al,22Mg) _at_50
  MeV/u
• Calculated in the two scenarios nlj2s1/2 (top)
  or 1d5/2 (bottom).
• One-proton-removal cross section is about 2x
  larger for the 2s1/2 case.
• Detect g-rays in coincidence with 22Mg to
  determine the core excitation contributions.
• Determine Jp from mom distrib
• Determine Asymptotic Normalization Coefficients
  for 23Al from cross sections and from there the
  astrophysical S-factor for proton radiative
  capture leading to 23Al in O-Ne novae.

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Conclusions - Breakup

• Can do proton-breakup for ANC! Need
• E/A 30-100 MeV/nucleon (peripherality and
  model)
• Better data to test models and parameters!!!
• Can extract ANC from breakup of neutron-rich
  nuclei, but the way to (n,g) cross sections more
  complex. Need extra work here.

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MARS
In-flight RB production
24Mg 48A MeV
23Al 40A MeV
Purity 99 Intensity 4000 pps First time -
very pure intense 23Al
Primary beam 24Mg _at_ 48 MeV/A K500 Cycl Primary
target LN2 cooled H2 gas p1.6 atm Secondary
beam 23Al _at_ 39.5 MeV/A
(p,2n) reaction
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b decay study of pure RB samples
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23Al ?-? coincidence spectrum
5/2
7/2
IAS
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Tighe ea, LBL 1995 Perajarvi ea, JYFL 2000
5/2v
1/2
23Al 0.446(4)s Qec12240keV
Proton br. total1.1
ß
0.25
ß
0.48
9548 8456 8164 8003 7877
IAS ft2140 s /-5
p
7803 IAS 5/2 7787 (5,7/2) 6985 5/2 6575
5/2 2905 (3,5/2) 2359 1/2
NO! 2051 7/2 450 5/2 0 3/2
0.38
22Na Qp7580 keV
22Na(p,g)23Mg resonances

• Preliminary results!
• Y Zhai thesis
• VE Iacob, et al.

23Mg
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Conclusions other methods

• Useful to have various methods/tools at hand
• Medium size facilities useful
• may get things done sooner and cheaper!
• Valuable for (hands-on) education of students and
  postdocs!
• Competition is healthy and necessary!

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14O p Resonant Elastic Scattering thick
targets, inverse kinematics
Beam quality crucial (no impurities)! E lt 10
MeV/nucleon

• Will work on
• a resonant elastic scattering
• (a,p) reactions, etc.

V. Goldberg, G. Tabacaru e.a. Texas AM Univ.,
PRC 2004
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Nuclear physics for astrophysics. Summary

• Indirect methods
• transfer reactions (proton or neutron)
• 5-10 MeV/nucleon
• Better beams (energy resol, emittance)
• Magnetic spectrometers at 0 resolution, large
  acceptance, raytrace reconstr.
• breakup
• 30-100 MeV/nucleon
• Can neutron breakup be used for (n,g)?! (yes, but
  need n-nucleus potentials)
• Spectroscopic info
• Jp , Eres, G, (masses, etc) a variety of
  tools at hand
• Resonant elastic scattering Elt10 MeV/nucleon. H2
  and He targets.
• Better models structure and reaction theories
• Need more checks between indirect methods and
  direct measurements!
• Better models/data to predict OMP, make Glauber
  calc, spectroscopy
• Direct methods inverse kinematics measurements
  on windowless gas targets with direct detection
  of product (magnetic separation). E0-5
  MeV/nucleon. All nucleonic species.