Nuclear Physics with a Laser: 229Thorium

01.01.2010 - 31.12.2015
Forschungsförderungsprojekt
Atoms, as building blocks of nature, consist of an atomic nucleus and the electron shell. Both systems are governed by similar laws and forces. However, the required energies to create changes (e.g. excitations) in the nucleus or the electron shell differ by many orders of magnitudes. This reflects in largely different tools and methods used for their investigation: atomic physics probes the electron shell mainly by means of lasers. Nuclear physicists create excitations at high energies using particle accelerators such as CERN in Switzerland/France. The radio isotope 229Thorium is the only atom with the potential to bridge the gap between atomic and nuclear physics. It provides an unnaturally low-energy nuclear excited state, accessible to atomic physics tools, most notably laser excitation. It is the aim of the proposed research project to identify the “optical nuclear transition” and make it usable for fundamental investigations and applications. Currently, our „second“ is defined as 9.192.631.770 oscillations of a light wave that leads to a specific excitation in the electron shell of the Cesium atom. Using the nuclear excited state of 229Thorium instead would increase the time standard accuracy by many orders of magnitudes, at the same time reducing the experimental complexity considerably. Building such a “nuclear clock” is the main goal of the research proposal. This will directly lead to improved accuracy in satellite based navigation (GPS) and enhanced bandwidth in communication networks. The frequency of the 229Thorium transition is determined by the „strong force“ inside the nucleus in contrast to all other common frequency standards, based on transitions inside the electron shell. Comparing a “nuclear atomic clock” to standard time standards will hence allow addressing one of the most fundamental questions in physics: "are nature’s constants really constant?". Performing the above comparison twice with one year time distance immediately outperforms all existing measurements on fine structure constant variations by a factor of 100. In summary, applying atomic physics methods to 229Thorium holds enormous potential both for most fundamental research as well as applications in a next generation of atomic clocks. The proposed START project will be carried out at the Atomic Institute in Vienna which combines our world wide accepted atom physics group with a vast experience and infrastructure in radio chemistry and nuclear physics. The extremely rare and delicate 229Thorium can be extracted from in-house stocks of 233Uranium or directly be produced in the institute’s research reactor. This combination of atomic and nuclear physics is with few exceptions unique in the world and provides the ideal background for the success of the proposed START project.

Personen

Projektleiter_in

Projektmitarbeiter_innen

Institut

Grant funds

  • FWF - Österr. Wissenschaftsfonds (National) Austrian Science Fund (FWF)

Forschungsschwerpunkte

  • Quantum Metrology and Precision Measurements: 100%

Schlagwörter

DeutschEnglisch
AtomuhrAtomic clock
LaserspektroskopieLaser spectroscopy
FrequenzkammFrequency comb
KernübergangNuclear transition
ThoriumThorium

Publikationen