The Enigmatic Origins of Lithium

Lithium, the intriguing third element on the periodic table, has long been a source of fascination and debate among scientists. Among its two stable isotopes, lithium-6 (6Li) and lithium-7 (7Li), the latter has emerged as a key player in unraveling the universe’s origins and the intricate chemical processes that shaped our cosmos.

Groundbreaking Research from Space!

In an exciting new study, an international group of researchers harnessed the power of the Alpha Magnetic Spectrometer (AMS-02) aboard the International Space Station to investigate cosmic-ray fluxes of both lithium isotopes. Their impressive data collection spanned an incredible 12 years, from May 2011 to October 2023.

A Hypothesis Emerges!

By analyzing over 2 million cosmic nuclei, the team reinforced the case for a specific origin of lithium while questioning another long-held explanation. Their findings were published in the esteemed Physical Review Letters.

Where Does Lithium Come From?

Lithium is believed to have at least three potential sources: it could be a product of cosmic-ray collisions, a remnant from the Big Bang, or formed from the decay of beryllium (7Be) in low-mass stars or novae. While lithium nuclei are rare within our solar system, they abound in cosmic rays.

The Big Bang Connection

Although some studies hint at a primordial origin for 7Li from the Big Bang, discrepancies exist between the expected amount of lithium produced in the early universe and what's observed in stars and cosmic rays.

Addressing Discrepancies!

Prior measurements of the ratio of 7Li to 6Li revealed mismatches with cosmic-ray propagation models. Most flux calculations were conducted below 1.9 GV rigidity—a measure of a particle's resistance against magnetic deflection—leading the researchers to believe that investigating a broader range could shed light on lithium origins.

New and Improved Measurements!

Conducting meticulous measurements across a rigidity range of 1.9 to 25 GV, the team gathered data from nearly a million nuclei of both isotopes. The AMS-02’s innovative design, featuring a supercooled magnet and multiple detectors, proved invaluable for their analysis.

Stunning Conclusions!

The results showed that both lithium isotopes experienced nearly identical time variations across the rigidity spectrum. Above 4 GV, these variations aligned with those of other cosmic ray elements like helium and carbon, suggesting a common origin.

Paving the Path for Future Discoveries!

With these compelling findings, scientists now lean towards the conclusion that both 6Li and 7Li primarily originate from heavy cosmic-ray collisions within the interstellar medium, casting doubt on the existence of a significant primary source of 7Li. This remarkable study not only tackles foundational questions about elemental origins but also opens up new avenues for enhancing our understanding of cosmic-ray interactions, essential for future space exploration and astronaut safety.