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

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 11/5/2018 INMA ECT* Nov 5-9

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 11/5/2018 INMA ECT* Nov 5-9

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

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 11/5/2018 INMA ECT* Nov 5-9

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

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 11/5/2018 INMA ECT* Nov 5-9

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

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 11/5/2018 INMA ECT* Nov 5-9

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

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

Trojan Horse Method The most direct from indirect methods! D 18O + p  ao + 15N 20 keV 90 keV 144 keV 11/5/2018 INMA ECT* Nov 5-9

Does it need further confirmation? Theory?! PWBA or DWBA?! THM with RIBs?! 11/5/2018 INMA ECT* Nov 5-9

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: 11/5/2018 INMA ECT* Nov 5-9 14

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 11/5/2018 INMA ECT* Nov 5-9 15

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