Supernova and r-process radionuclides engraved on million-years old archives from Earth and Moon

Objetivo

The Solar System is exposed to nearby cosmic events. These cosmic explosions generate unique signatures that leave traces over
millions of years on Earth and Moon. This proposal aims at unearthing this treasure to study the past 500 million years. It tackles the
fundamental questions: how and where are the heavy elements made in nature? Did nearby supernovae (SNe) have an impact on
Earth’s climate and biotic history?
SUPREME is based on my break-through work on ultrasensitive detection of interstellar radionuclides that probe heavy-element
nucleosynthesis via nearby SNe and the rapid neutron capture process (r-process) events. Production sites and yields of the r-process
are still a mystery and heavily disputed.
Detection of interstellar nuclides remains extremely challenging. SUPREME will tap the potential of HAMSTER, a new world-leading
accelerator mass spectrometry (AMS) system that I combine with an innovative type of an ion-cooler – laser-photodetachment
concept. This instrument, not existing elsewhere, is capable of complete or nearly complete reduction of measurement background.
The setup bears an enormous potential for ultra-sensitive single-atom counting in many additional applications.
Unique sets of lunar samples, awarded to me by NASA, as well as deep-sea archives, ice cores and rocks, will allow measurements to
study the time-resolved interstellar influx from present and up to 500 million years into the past. Proven by a first detection of an
interstellar r-process signature, utilizing zepto-scale sensitivity - through SUPREME I will be able to identify an interstellar nuclide
influx of only 100 atoms per cm² and million years.
The challenge tackled by SUPREME is to leverage the demonstrated AMS sensitivity to an unprecedented level (1) to enable detection
of a set of radionuclides to probe nearby cosmic explosions and (2) simultaneously extend it to several other interstellar actinide
signatures and other r-process elements for timing these events.