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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:

LowB.E.:

Find:


Proton transfer reactions
Proton Transfer Reactions

A

B(A+p)

p

a(b+p)

b

A+a->B+b


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
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

10B(7Be,8B)9Be14N(7Be,8B)13C

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

MARS

Cave

MDM

Cave

NIMROD

Cave

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

halo

2s1/2

normal

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

1/2+

5/2+

23Ne

23Al

23Al versus23Ne

24Mg(7Li,8He)23Al

  • 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.


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 @ 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


B decay study of pure rb samples
b decay study of pure RB samples


23Al - coincidence spectrum

5/2+

7/2+

IAS


Tighe ea, LBL 1995

Perajarvi ea, JYFL 2000

22Mg(p,g)23Al

5/2+√

1/2+

23Al 0.446(4)s

Qec=12240keV

Proton br. total=1.1%

β+

0.25%

β+

0.48%

9548

8456

8164

8003

7877

IAS: ft=2140 s +/-5%

p

7803IAS 5/2+

7787 (5,7/2)+

6985 5/2+

6575 5/2+

2905 (3,5/2)+

2359 1/2+ NO!

20517/2+

4505/2+

0 3/2+

0.38%

22Na

Qp=7580 keV

22Na(p,g)23Mg

resonances

Preliminary results!

Y Zhai thesis

VE Iacob, et al.

23Mg


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.


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