Neutron capture surrogates on astrophysical radionuclei: how the 205Pb radioactive clock can unlock the formation of our Sun

Descrizione del progetto

Gli isotopi instabili del piombo possono determinare l’età del Sole

I neutroni catturati dai nuclei atomici instabili forniscono i dati fondamentali necessari per datare la nascita del nostro Sole e far progredire la ricerca sui reattori nucleari basati su acceleratori di particelle. Calcolare questa interazione per l’isotopo radioattivo 205Pb è difficile perché il materiale è troppo volatile per essere trasformato in un bersaglio sperimentale stabile. Ciò impedisce agli scienziati di utilizzarlo come «cronometro cosmico» per datare la formazione del Sole. Sostenuto dal programma di azioni Marie Skłodowska-Curie, il progetto NECTARINE supererà questa limitazione utilizzando reazioni surrogate presso un anello di accumulo di ioni pesanti. Anziché sparare neutroni direttamente contro il 205Pb, i ricercatori innescheranno collisioni nucleari alternative che riproducono esattamente il sottoprodotto energetico della reazione desiderata. NECTARINE fornirà le sezioni d’urto nucleari precise necessarie per mappare l’evoluzione stellare e progettare reattori raffreddati a piombo.

Obiettivo

"Understanding neutron capture reactions on short-lived nuclei is important for uncovering how the heavy elements in our universe were created, and for advanced nuclear energy applications. Neutron capture on the radioactive nucleus 205Pb has not yet been measured at astrophysical neutron energies because of the extreme difficulties involved in making the target. This is despite 205Pb's considerable potential as a radioactive clock for timing how long it took our Sun to form and its important role in advanced nuclear reactors driven by particle accelerators that use lead as a target and coolant. I am proposing to conduct three nuclear reactions at the Experimental Storage Ring at the GSI/FAIR facility that will form the same intermediary state as neutron capture of 205Pb, namely the excited 206Pb compound nucleus. This method of simulating the neutron capture reaction with an experimentally feasible reaction is called a ""surrogate reaction"". To achieve this experiment, I will partner with Beatriz Jurado at the Laboratoire de Physique des Deux Inifis de Bordeaux (LP2iB), who is currently the world expert on surrogate reactions in heavy-ion storage rings. Beatriz will guide me through the process of being the spokesperson for a nuclear physics experiment and assist me in supervising a PhD student, both key missing skills in my research portfolio. I will bring expertise in nuclear astrophysics to LP2iB by involving the group with my established collaborations around my PhD work with 205Pb. Our combination makes a perfect match to go beyond the state-of-the-art by implementing the first surrogate reaction with a radioactive beam in a heavy-ion storage ring, and take us one step closer to using 205Pb as a radioactive clock to extract how long it took for our Sun to form."