1. Indirect Methods in Nuclear Astrophysics
ECT* workshop
Trento, Italy, Nov. 5-9, 2018

2. Useful information Organizers: Carlos Bertulani – TAMUC
Angela Bonaccorso – INFN Pisa
Zsolt Fulop – Atomki Debrecen
Tohru Motobayashi – RIKEN
Livius Trache – IFIN-HH Bucharest
Secretariat - Ines Campo
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INMA ECT* Nov 5-9

3. Indirect Methods in Nuclear Astrophysics
Main topics
Nuclear astrophysics for practitioners. Nuclear data needs, stellar dynamics, nucleosynthesis modeling, observations
Review of existing indirect methods in nuclear astrophysics
“the list”.
Specifics. Assessment of problems with the accuracy of indirect methods, importance of calculated absolute values
The need for modern theories and codes; parameters to use in calculations
Review of experimental methods, equipment and specifics
New facilities, including RIB facilities, and their nuclear astrophysics programs
Related topics – new directions
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INMA ECT* Nov 5-9

4. Premises
Nuclear astrophysics is important part of all nuclear labs’ scientific programs
Nuclear astrophysics now consists or is close to
Nuclear physics for astrophysics
Stellar dynamics
Nucleosynthesis modelling
(specific) astronomy observations: X-ray and Gamma-ray space telescopes, cosmochemistry …
Cosmology (?!)
and there is need for closer interaction among specialists in these fields!
11/5/2018
INMA ECT* Nov 5-9

5. Status of nuclear data needs Stellar dynamics Cosmic signals
Space telescopes
Cosmochemistry on Earth
Reactions in laser induced plasmas
Contribution of excited states to actual reaction rates and decay
EoS of nuclear matter
Exotic nuclei
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INMA ECT* Nov 5-9

6. Nuclear physics for astrophysics
Direct measurements – very low energies, mostly stable targets/projectiles
Indirect methods - measurements at lab energies → cross sections at stellar energies:
experiments at 10, … 100, 300 MeV/nucleon to assess cross sections at 10, 100, 300 keV
how we connect →?! How reliable?!
11/5/2018
INMA ECT* Nov 5-9

7. Indirect methods for nuclear astrophysics
Measurement at lab energies
Comparison with (reaction) calculations
Extract (nuclear structure) information
Calculate astrophysical S-factor
or reaction rates
Need good additional knowledge (data).
Reliable absolute values
Compare with
direct measurements
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INMA ECT* Nov 5-9

8. The “list” Dedicated methods: Coulomb dissociation
Single-particle transfer reactions – ANC method
(Nuclear) breakup reactions
Trojan Horse Method
Spectroscopy of resonances:
transfer reactions
Gamma-ray spectroscopy
Beta-delayed proton emission
TTIK –
Most involve RIBs (some not!)
New?! Contribution of excited states
Reactions in laser induced plasmas
11/5/2018
INMA ECT* Nov 5-9

9. A. Coulomb dissociation
Radiative capture - direct process
X(p,g)Y
Photodissociation - inverse process
Y(g,p)X
Use detailed balance theorem
virtual photons – Coulomb Dissociation
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INMA ECT* Nov 5-9

10. B. Transfer reactions: the ANC method
Transfer reaction B+d→A+a peripheral (absorption)
Transfer matrix element:
The DWBA cross section is parameterized in terms of spectroscopic factors of the initial and final nuclei and can be written as:
Add more comments
In this transfer reaction two possibilities can occur. If X and B are the same nuclei, we have an elastic exchange reaction, and the DWBA cross section is expressed in terms of C4. If X and B are not the same, one has to know the ANC for the other vertex from an independent measurement.
How one ensures peripherality?
How we calculate cross sections?
Do we have the right OMP?
11/5/2018
INMA ECT* Nov 5-9

11. Nuclear breakup: Y->X+p for X(p,g)Y
(p,g) happens here
transfer happens here
breakup happens here
Model-independent shape w. ANC
(Whittaker function)
11/5/2018
INMA ECT* Nov 5-9

12. Trojan Horse Method The most direct from indirect methods! D
18O + p  ao + 15N
20 keV
90 keV
144 keV
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INMA ECT* Nov 5-9

13. Does it need further confirmation? Theory?! PWBA or DWBA?!
THM with RIBs?!
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INMA ECT* Nov 5-9

14. E Resonant Capture a two-step process Identify states and
Radius
Energy p
Coulomb Barrier
Nuclear Potential
Resonant Capture
a two-step process
Same compound system: 23Mg Gp Gg
Identify states and
Decay properties Sp
g+23Mg 23Mg*22Na+p
Resonance strength
Resonant contributions to reaction rate:
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15. wg=(2J+1)/(2j+1)(2I+1)bgbp*G
Radius
Energy p
Coulomb Barrier
Nuclear Potential
Resonant Capture
a two-step process
Same compound system: 23Mg Gp Gg
Decay spectroscopy
5/2+
23Al Sp
g+23Mg 23Mg*22Na+p
23Mg
Resonance strength
wg=(2J+1)/(2j+1)(2I+1)bgbp*G
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16. Also expected, desired …
- Assessment of problems with the accuracy of indirect methods, importance of calculated absolute values
- The need for modern theories and codes; parameters to use in calculations
Review of experimental methods, equipment and specifics
New facilities, including RIB facilities, and their nuclear astrophysics programs
11/5/2018
INMA ECT* Nov 5-9