SNAQ March 2021

virtual (online)



Link will be provided after registration.
Olivier Sorlin (GANIL) , Konrad Schmidt (HZDR)


Schools on Nuclear Astrophysics Questions

Question in March 2021: How do neutron star mergers impact r elements in the universe?

Update: Below, all talks are available as PDF for download and as video per link to our YouTube channel.

Update: Congratulation to the 3 winners of our SNAQs Scientific Talk Award in recogrecognition and appreciation for giving a scientic talk at the March 2021 edition of SNAQs:

  • Ina Kullmann (Université Libre de Bruxelles, Belgium)
  • Andrés Yagüe López (Konkoly Observatory, Hungary)
  • Camilla Juul Hansen (MPIA, Germany)

And thanks to all other applicants who submitted an abstract.

This is the 2nd event of a new, monthly, virtual school format discussing questions related to nuclear astrophysics.

Previous event:

Next event:

  • SNAQ April 2021 (Registration and abstract submission is open. We highly encourage young scientists (master and PhD students, as well as young postdocs) to give scientific talks related to the question in April: How to get from starlight to stellar abundances? To apply, please submit an abstract of your talk at the lower end of the April registration form. Deadline for abstract submission is March 31, 2021.)

We plan to organize a new event of SNAQs always on the 2nd Wednesday in each month with a break in summer. SNAQs will last about 3.5 hours, including breaks, with lectures and scientific talks around a given question in nuclear astrophysics. Lectures will be held by senior researchers and scientific talks preferably by young researchers, as master and PhD students. Further, SNAQs will put a special focus on the interaction between participants to allow young scientists networking even if traveling to schools, workshops and conferences is not an option.

SNAQs will join the community of schools related to nuclear astrophysics that partner with ChETEC-INFRA:

  • Carpathian Summer School of Physics (well established)
  • European Summer School on Experimental Nuclear Astrophysics (well established)
  • Intercontinental School on Nuclear Astrophysics (new)
  • International school on nuclear physics, neutron physics and applications (well established)
  • Nuclear Physics in Astrophysics School (new)
  • Rußbach School on Nuclear Astrophysics (well established)
  • School on observations and spectroscopic tools (new)

The aim of this community is to give all students and young researchers the same, multidisciplinary knowledge about nuclear astrophysics. SNAQs will support this idea and strengthen the community of schools by providing a frequent lecture series to train and educate the next generation of scientist with knowledge across the three types of infrastructures used by nuclear astrophysicists:

  • astronuclear laboratories supplying reaction data,
  • supercomputer facilities performing stellar structure and nucleosynthesis computations, and
  • telescopes and mass spectrometers collecting elemental and isotopic abundance data.

Those infrastructures will be networked by ChETEC-INFRA, Chemical Elements as Tracers of the Evolution of the Cosmos - INFRAstructures for Nuclear Astrophysics, a new European network of 32 partner institutions. Please note that even the official start of ChETEC-INFRA is planned for May 2021 the involved institutions already jointly created SNAQs.

We are looking forward to meet you at the second SNAQ.

SNAQ March 2021 organizers SNAQs organizing committee
  • Olivier Sorlin (CNRS-GANIL)
  • Konrad Schmidt (HZDR)
  • Marcel Heine (CNRS-IPHC)
  • Andreas Korn (UU)
  • Arūnas Kučinskas (VU)
  • Mohamad Moukaddam (CNRS-IPHC)
  • Gianluca Pizzone (INFN-LNS)
  • Konrad Schmidt (HZDR)
  • Olivier Sorlin (CNRS-GANIL)
  • Livius Trache (IFIN-HH)

Guidelines for participants of SNAQs

Please, …
… rename yourself in the Zoom sessions to match your registration name and institution – this will serve as your “nametag”.
… mute your microphone during talks.
… use the public chat only for questions related to the lecture; for discussions, please use the private chat.
… write your questions in the chat – due to the high number of participants, a moderator will read a selection of questions but can choose a limited number only.
… use breakout rooms to talk and chat to each other in smaller groups. Breakout rooms will be available during coffee breaks and participants can choose rooms freely.
… behave professionally and respectfully.
… follow ethical standards as professional integrity and honesty.
… foster a welcoming and inclusive work environment.


    • 13:45 14:00
      Zoom room available 15m
    • 14:00 14:05
      Welcome 5m

      Introduction of the interactive part of SNAQs

      Speaker: Konrad Schmidt (HZDR, Germany)
    • 14:05 14:10
      Rußbach school on nuclear astrophysics 5m

      Introduction of the annual winter school on nuclear astrophysics

      Speaker: Olivier Sorlin (GANIL, France)
    • 14:10 14:55
      Multi-messenger astrophysics with merging neutron stars 45m

      First lecture on how neutron star mergers and impact r elements in the universe

      Speaker: Stephan Rosswog (Stockholm University, Sweden)
    • 14:55 15:05
      Moderated questions 10m
      Speaker: Andreas Korn (Uppsala University, Sweden)
    • 15:05 15:50
      Heavy element nucleosynthesis in neutron star mergers 45m

      Second lecture on how neutron star mergers and impact r elements in the universe

      Speaker: Gabriel Martínez-Pinedo (GSI, Germany)
    • 15:50 16:00
      Moderated questions 10m
      Speaker: Olivier Sorlin (GANIL, France)
    • 16:00 16:10
      Breakout Session 10m

      Small groups of up to 5 participants are assigned to breakout rooms to (1) very briefly introduce yourself, (2) talk about the lectures, (3) clarify lecture items, and (4) phrase questions for the round table discussion.

      Afterwards, questions can be written in the chat of the main Zoom room. Please tag questions related to lecture 1 with L1 and questions related to lecture 2 with L2. Moderators can only choose a limited number of questions to be discussed at the round table discussion.

      This session also povides the opportunity to establish contacts that can be continued using the private chat. Networking is an important tool not only in science.

    • 16:10 16:25
      Coffee break 15m
    • 16:25 16:37
      Impact of neutrino interaction on neutron star merger nucleosynthesis 12m

      Hydrodynamical simulations of merging binary neutron stars (NS) follow the evolution and expansion of material at extreme densities, sometimes shock-heated to high temperatures, and determine the amount of ejected material and its history. To calculate the nucleosynthesis yields, the hydrodynamical models are complemented by full nuclear reaction networks involving ~5000 nuclear species, where most of the involved reaction rates rely on theoretical predictions. This talk will contribute to the question of whether a more accurate description of neutrino interactions can significantly affect the r-process in neutron star mergers and the decay heat produced by the recently synthesized radioactive r elements. We have studied the material ejected from four NS-NS merger systems based on the hydrodynamical simulations. The models simulate neutrino transport in a realistic way by including neutrino equilibration with matter in optically thick regions and re-absorption in optically thin regions. We find that the neutron richness is significantly affected by the neutrinos emitted by the post-merger remnant, in particular when compared to a case neglecting all neutrino interactions. Our nucleosynthesis results show that a solar-like distribution of r-process elements with mass numbers larger than 90, including actinides, are produced.

      Speaker: Ina Kullmann (Université Libre de Bruxelles, Belgium)
    • 16:37 16:40
      Moderated questions 3m
      Speaker: Gianluca Pizzone (Laboratori Nazionali del Sud, Italy)
    • 16:40 16:52
      Constraining the rapid neutron-capture process with meteoritic I-129 and Cm-247 12m

      Among all radioactive isotopes produced in the Galaxy, a small number of them have relatively short mean lives between 0.1 and 100 million years. Early Solar System abundances of these radioisotopes can be determined through meteoritic analysis and, due to their short half-lives, give us insight into the sites and processes that produced them. In this talk, we discuss the ratio of two of these short-lived radioisotopes, the rapid neutron capture isotopes I-129 and Cm-247. We also show how, due to their remarkably similar half-lives, they give us a unique opportunity to constrain the physical conditions of the last r-process event that contributed to the enrichment of the pre-solar nebula. Following our nucleosynthesis calculations based on compact binary merger and magneto-rotational supernova simulations, we find that moderately neutron-rich conditions often found in merger disk ejecta simulations are most consistent with the meteoritic value.

      Speaker: Andrés Yagüe López (Konkoly Observatory, Hungary)
    • 16:52 16:55
      Moderated questions 3m
      Speaker: Gianluca Pizzone (Laboratori Nazionali del Sud, Italy)
    • 16:55 17:07
      Identification of strontium in the merger of two neutron stars 12m

      Half of all of the elements in the Universe that are heavier than iron were created by rapid neutron capture. Existing models and circumstantial evidence point to neutron-star mergers as a probable r-process site. The optical and infrared transient that emerges in the days after a merger is a likely place to detect the spectral signatures of newly created neutron-capture elements. Detailed spectra were recorded for the kilonova AT2017gfo which was found following the discovery of the neutron-star merger GW170817 by gravitational-wave detectors. The talk will report the identification of the neutron-capture element strontium. The detection of a neutron-capture element associated with the collision of two extreme-density stars establishes the origin of r-process elements in neutron-star mergers, and shows that neutron stars are made of neutron-rich matter.

      Speaker: Camilla Juul Hansen (MPIA, Germany)
    • 17:07 17:10
      Moderated questions 3m
      Speaker: Gianluca Pizzone (Laboratori Nazionali del Sud, Italy)
    • 17:10 17:30
      Round table discussion 20m

      Questions that were compiled in the chat after the breakout session will be discussed by the lecturers.