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Nuclear Physics for Astrophysics with Radioactive Beams. Livius Trache Texas A&M University. EURISOL Workshop ECT * Trento, Jan. 2006. Nuclear Physics for Astrophysics with Radioactive Beams. Indirect methods only!

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nuclear physics for astrophysics with radioactive beams

Nuclear Physics for Astrophysics with Radioactive Beams

Livius Trache

Texas A&M University

EURISOL Workshop

ECT* Trento, Jan. 2006

nuclear physics for astrophysics with radioactive beams1
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, G’s) – 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 !
direct radiative proton capture
DirectRadiativeproton capture

M is:

Integrate overξ:



proton transfer reactions
Proton Transfer Reactions







anc s measured using stable beams in mdm
ANC’s measured using stable beams in MDM
  • 9Be+p«10B* [9Be(3He,d)10B;9Be(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)14N;13C(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

anc s at tamu

from radioactive beams @ 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]


RB in-flight production

1.5 105 pps

(p,xn), (p,pxn) reactions

in inverse kinematics


“dream”?! Better beam!

Transfer reactions for ANCs


Beam spot ~F=4 mm, Dq=1.8 deg, DE/E~1-1.5%

  • Beam Study Detector: 1 mm Si strip detector
  • Reaction Telescopes:
      • 105 mmSistrip detector
      • 1 mmSidetector
better beams sd shell nuclei
Better beams & sd-shell nuclei

17F (10 MeV/n) on melamine; ORNL experiment

J. Blackmon et al, PRC 2005

transfer reactions
Transfer reactions
  • Conclusions:
    • Can extract ANC from proton transfer reactions -> (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:
      • Sp=Sn => ANCp=const*ANCn
  • Data further needed for:
    • Various cases: waiting points, breakout reactions …
    • CNO cycle
    • hot CNO
    • rap
    • rp-process
    • H & He-burning in general
ci upgrade overview
CI Upgrade (overview)
  • Re-activateK150 (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


K150 Beam Lines







Light Ion Guide

Heavy Ion Guide

nuclear astrophysics with upgrade iii
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)

one nucleon removal can determine anc only
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

one nucleon removal spectroscopic tool




Config mixing

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

@ 43-68 MeV/nucleon.

summary of the anc extracted from 8 b breakup with different interactions
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” m=1.5 fm (black points) and

Ray (red triangles).

s 17 astrophysical factor ours
JLM S17=17.4±2.1 eVb no weights

“standard” S17=19.6±1.2 eVb

Ray S17=20.0±1.6 eVb

Average all:

C2tot = 0.483  0.050 fm-1

S17=18.7±1.9 eVb

(all points, no weights)

Published: LT et al.- PRC 69, 2004

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

S17astrophysical factor(ours)

New: S17(0) = 18.0  1.9 eVb

(G Tabacaru ea, 2004)

8B breakup

New average: S17(0) = 18.2  1.8 eVb

22 mg p g 23 al reaction
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 (T1/2=7 ·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
23 al versus 23 ne





23Al versus23Ne


  • Structure of 23Al poorly known: only 2 states, no Jp
  • Mirror 23Ne has Jp=5/2+ for g.s. and Jp=1/2+ for 1-st exc state (Ex=1.017 MeV)
  • NNDC says: Jp=3/2+


23Al halo nucleus; level inversion?!

J. Caggiano et al., PRC 65, 025802 (2001)

X.Z. Cai et al., Phys Rev C 65, 024610 (2002)

22 mg p g 23 al reaction in novae
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 T9=0.1-0.3 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).
23 al breakup experiment
23Al breakup experiment

Proposed to measure @GANIL:

Momentum distributions for 12C(23Al,22Mg) @50 MeV/u

Calculated in the two scenarios: nlj=2s1/2 (top) or 1d5/2 (bottom).

One-proton-removal cross section is about 2x larger for the 2s1/2 case.

Detectg-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.

conclusions breakup
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.



In-flight RB production

24Mg 48A MeV

23Al 40A MeV

Purity: 99%

Intensity: ~ 4000 pps

First time - very pure & intense 23Al

Primary beam 24Mg @ 48 MeV/A – K500 Cycl

Primary target LN2 cooled H2 gas p=1.6 atm

Secondary beam 23Al @ 39.5 MeV/A

(p,2n) reaction


Tighe ea, LBL 1995

Perajarvi ea, JYFL 2000




23Al 0.446(4)s


Proton br. total=1.1%










IAS: ft=2140 s +/-5%


7803IAS 5/2+

7787 (5,7/2)+

6985 5/2+

6575 5/2+

2905 (3,5/2)+

2359 1/2+ NO!



0 3/2+



Qp=7580 keV



Preliminary results!

Y Zhai thesis

VE Iacob, et al.


conclusions other methods
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!

14O + p Resonant Elastic Scattering – thick targets, inverse kinematics

Beam quality – crucial (no impurities)!

E < 10 MeV/nucleon

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

V. Goldberg, G. Tabacaru e.a. – Texas A&M Univ., PRC 2004

nuclear physics for astrophysics summary
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: E<10 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). E=0-5 MeV/nucleon. All nucleonic species.