We Are Now One Step Closer To Constructing The First Nuclear Clocks

A nuclear clock searches for these transitions in an atomic nucleus, whereas an atomic clock analyzes excited electron transitions inside of an atom to measure time. There are certain benefits to this. Since the nucleus is considerably smaller than an atom, it is less vulnerable to outside factors that could have an impact on the frequency of oscillations. With a precision of 1018, the finest optical atomic clocks have a 1-second error every 30 billion years. The accuracy of a nuclear clock would be at least ten times greater.

So why are we still waiting? For most atoms, nuclear transitions take more energy than electron transitions. There is just one potential element that functions with our knowledge and technology at this time: thorium-229.

It doesn't take much energy to excite this nucleus to its initial higher-energy state, also referred to as its isomer. Radiative decay is the process by which an isomer returns to its ground state and emits a photon. The nuclear clock setup depends on this photon, but until today, scientists were unable to observe this disintegration.

At the Ludwig Maximilian University of Munich in Germany, a group under the direction of Sandro Kraemer recorded ultraviolet photons with a wavelength of 148 nanometers and a transition energy of 8.338 electronvolts. The average energy levels are hundreds, if not thousands, of times greater. This is the most accurate way to estimate an isomer's energy, which enhances the idea of a nuclear clock in theory.

In a statement, co-author Dr. Mustapha Laatiaoui, a junior research group leader at Johannes Gutenberg University Mainz, said, "We have finally succeeded in observing a clear signature for the radiative decay of the thorium-229 nuclear isomer in our experiments."

As a consequence, we were able to quantify the excitation energy with a measurement precision that was seven times better than the prior findings. Based on our findings, we have even been able to estimate the half-life of the radiative transition, which we placed at around 10 minutes.

The ISOLDE facility at CERN was utilized by physicists. We allowed the actinium-229 atoms implanted in the crystal to deteriorate and transform into thorium-229. They have the best level of accuracy yet in determining this element's characteristics thanks to a method called vacuum ultraviolet spectroscopy.

According to Kraemer, actinium-229 isotope production is now limited to just two sites worldwide. We created a lot more isomeric thorium-229 nuclei by adding these isotopes to calcium fluoride or magnesium fluoride crystals, which also boosted our odds of seeing their radiative disintegration.

A magnesium fluoride crystal containing thorium-299 had earlier been thought of as a possible location for a nuclear clock. This latest study demonstrates that it's a smart bet even though further investigation is required. The journal Nature reported the findings.

Extremely positive attitude

The results that have been revealed are significant steps in the creation of a nuclear clock. On the one hand, the possible search range is reduced due to the excitation energy's lower degree of uncertainty, which is also an essential preliminarily parameter for the creation of a suitable vacuum-ultraviolet laser control system. On the other hand, the detection of radiative decay in large-bandgap crystals demonstrates that it is possible to build a solid-state nuclear clock with stability orders of magnitude better than that of modern atomic clocks.

The realistic implementation of a clock that employs nuclear transition as a timekeeper would have an interesting range of possible applications, from tests to see whether basic constants display any time fluctuations to geodesy and seismology.