Short-Lived Radioactive Molecules
Precision measurements of molecular systems provide highly sensitive laboratories for exploring the possible violation of fundamental symmetries and search for new physics beyond the standard model physics [Barr14,Demi17,Safr18]. Radioactive molecules compound of heavy and deformed short-lived isotopes are predicted to offer unprecedented sensitivity to investigate parity and time reversal violation effects. However, the experimental knowledge of short-lived radioactive molecules is scarce, and quantum chemistry calculations has constituted the only source of spectroscopy information.
[Barr14] Barry, J. et al. Nature 512, 286 (2014).
[Demi17] DeMille et al. Science 357, 990 (2017).
[Safr18] Safronova et al. Rev Mod Phys 90, 025008 (2018).
Precision Measurements in Light Nuclei
The experimental knowledge of few-body nuclear systems act as a stepping stone towards the description of complex nuclear many-body systems.
Figure: Lightest isotopes of the nuclear chart. Distinct physical phenomena are highlighted for particular isotopes.
The experimental knowledge of the properties of light nuclear systems is essential to provide answers to three major questions in nuclear science: How do nuclear phenomena emerge from microscopic descriptions and what are their connections with the fundamental forces of nature? Can we constrain the properties of nuclear matter in extreme conditions from our understanding of finite nuclei? What is the role of the electroweak interactions in the description of nuclei? A consistent description of electromagnetic operators is essential to understand nuclear dynamics, and to extract fundamental physics quantities from a wide range of modern high-precision experiments [1].
Exotic isotopes of light elements such as carbon, oxygen, fluorine and silicon are suggested to exhibit some of the most exciting phenomena of the atomic nucleus, e.g. clustering of nucleons [2-5], formation of halos [6,7], bubble structures [8,9], emergence of shell structures [10,11] and appearance of single-particle behaviour [12]. Nevertheless, most of their ground-state electromagnetic properties are unknown and cannot be accessed by current experimental techniques. Laser spectroscopy is well established as a unique tool to access not only the charge radii of exotic nuclei, but also nuclear spins, and nuclear electromagnetic moments [13-15]. However, applying laser spectroscopy techniques to the aforementioned elements poses major experimental challenges for the current techniques:
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Atomic or ionic transitions from the ground state lie mainly in the vacuum UV region (< 90 nm), which is not accessible with conventional narrow-linewidth (< 20 MHz) laser technology.
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The sensitivity to nuclear structure observables dramatically decreases with atomic number. Therefore, extracting nuclear structure information from the hyperfine structure spectra requires exceptionally high precision (<1 MHz).
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Trapping and manipulation of such light atomic/ionic species is particularly challenging.
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Light elements exist mainly as molecular compounds (e.g. O2 , CO, CO2 , AlF3), which are not suitable for atomic hyperfine structure studies. For oxygen and carbon, for example, only a fraction (1-10%) of the ion beam of interest is produced in the elemental form (most of the ions form molecular compounds).
Our group is developing a new experimental device (PRECIOSA) to overcome these experimental challenges, which will allow laser spectroscopy studies of exotic light nuclear systems.
Do not hesitate to contact us if you are interested in this project.