COST Action blog: nuclear astrophysicists call for a joint global effort


Answering the open questions on the evolution of the Universe requires a step up in global scientific cooperation

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Understanding the history of the Cosmos has become such a complex challenge that national and continental efforts are not sufficient anymore. An upscaling is needed to achieve global sharing of ideas, data, computational power and experimental infrastructures.

This is one of the key messages that emerged from the ChETEC Meeting, that took place in Lisbon and online from 8 to 10 September 2021. The event gathered a group of international researchers in nuclear astrophysics, under the umbrella of ChETEC (Chemical Elements as Tracers of the Evolution of the Cosmos), a European research project started in 2017 that was funded by the COST program.

Chemical fingerprints

Nuclear astrophysics studies the chemical fingerprints of the reactions taking place in stars. Those traces provide insights on how chemical elements were formed and on the nuclear processes that shape astrophysical phenomena.  

ChETEC put together a set of open questions for the discipline. One of them, for example, is how heavy elements came into existence, given that the Big Bang produced only the lighter ones. “These [Elements up to iron] were created by nuclear fusion. But for elements heavier than iron you cannot use fusion because Coulomb repulsion is too strong. You need to capture neutrons”, says Raphael Hirschi, a researcher at Keele University (UK) and ChETEC’s chair.

Photo of the Crab Nebula supernova taken from a telescope. Black sky with a white nucleus surrounded by orange flares.
Supernova explosion that created Crab Nebula. Image credit: NASA/CXC/SAO

Scientists know that one way of doing that is the so-called “r process”, but it is unclear how exactly it plays out: for example, whether it happens mainly in supernova explosions of massive stars, or rather in mergers of neutron stars. “We need to have international cooperation to answer this sort of question. No one is able to do it alone”, says Hirschi.

Photo of a room filled with computer servers
By courtesy of Barcelona Supercomputing Center  –

Big facilities and islands of expertise

One main reason for that is the size of the research facilities needed. The whole discipline pivots between observing astronomical processes, reproducing them in laboratories, and modelling them through computer simulations. Therefore, it needs to optimize the use of world class instruments: telescopes (like the European Southern Observatory – ESO – in Chile), massive nuclear physics experiments (like the LUNA underground laboratory in Italy), and supercomputers (like the Barcelona Supercomputing Center – BSC).

On top of that, nuclear astrophysics is made by a blend of researchers with different backgrounds. “You have hundreds of isolated islands of expertise. In every given institute, maybe just one single group is devoted to a field that is really relevant to nuclear astrophysics. Networking them is critical for rapid scientific progress”, says Hendrick Schatz, researcher at Michigan State University and Principle Investigator of IReNA (International Research Network for Nuclear Astrophysics), a project funded by the US National Science Foundation’s AccelNet scheme.

The long way to cooperation

Cooperation in nuclear astrophysics dates back to 1957, when the famous B2FH article on the origin of chemical elements was published (the name contains the initials of its authors). The conference series “Nuclei in the Cosmos” and “Nuclear Physics in Astrophysics” and the training schools held in e.g. Russbach, Santa Tecla and Sinaia provided more international ties, and then came a sequence of international networks: JINA, Eurogenesis, ENSAR, and ENSAR2.

ChETEC has worked hard to increase the connectivity of the community. For example, by creating “knowledge hubs”, as Alessandra Guglielmetti, researcher at Milan’s La Statale University and member of ChETEC explained during the conference. These are databases of nuclear information that was stored before in a variety of different nuclear physics and astrophysics repositories.

The follow-up project, ChETEC INFRA, is set to develop an Astronuclear Library. “It aims at bridging the gap between individual scientific results and a curated and accepted datum for uptake in interdisciplinary context”, says Guglielmetti. The project should also provide computing, telescope and experimental time in a coordinated way .

The US-backed project IReNA has made a further step along the path of enhanced cooperation, by creating a “network of networks”. The project encompasses six large interdisciplinary project in different continents, including ChETEC. “It is the best success so far”, says Hirschi. By now, IReNA has worked at a platform for exchanging nuclear data for astrophysical applications and at a white paper on direct measurements for nuclear astrophysics, among other issues. “We generate much data but we have to compound them in a way that can be used in nuclear astrophysics” says Schatz.

Nuclear astrophysics’ wish list

Photo of a laptop screen in a room participating in a remote meeting

But all this is not enough, according to the general feeling expressed by those gathered in Lisbon and those that joined remotely. “The inertia of large groups spread across the world is still a challenge, and we see some projects that just stall and stop” Hirschi points out.

Covid-19 has messed with a delicate global scientific conversation, that was already sensitive to issues like disciplinary and cultural diversity. The pandemics posed very practical challenges, like arranging remote meetings with people in broadly different time zones. “In person meetings are still difficult to replace, in order to generate ideas” Schatz points out.

Funds that cover brainstorming discussions and workshops are available at the national level, but researchers called for schemes devoted specifically to support these activities, ideally at the continental and international level.

Another idea that emerged during the conference was having more formal collaboration between COST in Europe and the National Science Foundation in the USA. That could translate into joint calls, or at least in matching calls calendars so that researchers in different continents can synchronize their efforts. That would avoid, for example, the current situation in which the ChETEC COST Action will end in 2021, while IReNA will continue up to 2024.

Those calls would also benefit from adding a third purpose beyond the two they already have (research and networking): that is, funding directly salaries of researchers. While NSF AccelNet already allows for it in a limited percentage and COST supports short terms scientific missions enabling people to visit other countries and learn new techniques, some projects require a more sustained effort involving staff fully dedicated to them.

The recent history of physics has shown multiple times that a long-term effort of international cooperation can yield important discoveries. Many in the nuclear astrophysics’ community are looking at that history as an example of what joining efforts can achieve – and are thinking hard how to streamline it.


Michele Catanzaro, PhD in Physics and freelance journalist.

Disclaimer: this article is the outcome of a Virtual Mobility Grant awarded to the author. The article is not part of the standard journalistic coverage of the author and was checked for approval by ChETEC before publication.

Further information

View the Action website

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Cover image: SN 1006 Supernova Remnant. Image Credit: NASAESA, Zolt Levay (STScI)