Looks like researchers are closing in on the elusive Thorium transition! A group from Los Alamos reports to have measured the lifetime of the isomer state, using the recoil-catcher method. 229-Th* in the isomer state is produced from the 2% decay channel from 233-U decay, recoil atoms are implanted into a MgF catcher plate. Zhao et al. measure luminescence photons in the UV range, that they attribute to the direct “optical” nuclear gamma photon, after substracting signal originating from other presses. According to their recent PRL, the lifetime of the isomer state would be 6(1) hours, the wavelength of the transition above 160 nm. This would indicate essentially no coupling between the nuclear dynamics and the electron shell.
Although these values would be phantastic news (long isomer lifetime, weak coupling to electronic levels, direct access to the nuclear photon, convenient wavelength), the Thorium community remains skeptical. Similar experiments have been performed previously without success at PTB (Peik group) and Lawrence Livermore (Burke group) as recently reported at the GSI meeting. From our own experience we know, that it is very easy to observe optical activity from a crystal once it has been exposed to nuclear energies. To settle the issue, Jason Burke has set out to repeat the experiments by Zhau at al. as fast as possible. We will keep you updated…
The Thorium Team is looking for a PostDoc! If you are an experimentalist with a background in laser spectroscopy, quantum physics, or solid-state physics and are interested to work and live in beautiful Vienna, feel free to contact us! We can offer an exciting research project, a slightly crazy but adorable team and the worlds best Schnitzel (vegetarians welcome).
!!! Position filled !!!
Sorry, we already found “our man”, Joszef Seres will joint the team in January.
This week, 25.-27. September, Thorium researchers from 15 countries met at the GSI in Darmstadt to discuss their status, findings, and perspective. The meeting was generously supported by the ExtreMe Matter Institute (EMMI). Thanks to the brilliant organization of Carsten Brandau and Iain Moore, the meeting was held in a familial and non-formal way, where ideas where spread openly. New collaborations and contacts where made. Following the immense success of the meeting, a follow-up in two years was anticipated. With some chances, this one is going to be in Vienna. Also, an international Thorium collaboration is about to form, we will keep you posted. You can find the conference website here, this one will also feature the talks, once they are all collected. Also check out the conference poster, prominently featuring our “zero-version” Thorium clock;-)
Once again, researchers of all areas of science have united for a „Long Night of Science“ („Lange Nacht der Forschung“) to present their work to the general public. More than 25.000 people visited over 260 stations all over Vienna on Friday, April 27. Of course the Thorium team was taking part, presenting the beautiful „ion trap“ by Wolfgang (actually trapping ionized dust particles – but the principle is the same) and helping out presenting other stations concerned with quantum physics. As the Technical University could not officially participate in the event due to financial difficulties, the team from the Atominstitut was generously hosted by our CoQuS friends at the Vienna University. You can find some press info about the event here: Krone.at, tv.derstandard.at, and of course, on the CoQuS homepage, thanks to Christiane.
A BIG THANKS to Kathrin Buczak, Dominik Fischer, Maximilian Kuhnert, Wolfgang Rohringer, Wolfgang Schlichtner, Florian Steiner, Matthias Schreitl, and Michael Trupke from ATI, TU Vienna.
MORE THANKS to Stefanie Barz, Garrett Cole, Uros Delic, Nadine Dörre, David Grass, Hans Hepach, Michael Keller, Nikolai Kiesel, Christiane Losert-Valiente Kroon, Philipp Schmid, Max Tillmann, Mathias Tomandl. and Witlef Wieczorek from Vienna University.
For them, the “Long Night” is the one BEFORE the actual event, to get everything ready in time.
Finally, the hard work of the Thorium team (in this case to a great extend Georgy) pays off in publishable (hopefully!) results. This one is about the idea of constructing a “Solid-state nuclear clock” by doping Thorium into transparent crystals and performing precision spectroscopy. We find that of course, doing spectroscopy within a material leads to all sorts of line shifts and broadenings. In particular, the magnetic moment of the Thorium nucleus interacts with neighboring nuclear spins, leading to a decoherence rate of the order 1 kilohertz. This renders the usual “coherent” clock interrogation schemes like Ramsey or Rabi useless. However, we show that doing the kind of naive direct fluorescence laser spectroscopy, we gain from the fact that we have a huge number of oscillators in the sample and that they are kind of “frozen” in the crystal, so that we can interrogate them continuously. If everything works ideally (especially the interrogation laser) we show that one can reach a fractional inaccuracy of 10-19 with this clock is almost surprisingly good. Good news for us, let’s hope the referee’s like it too!
P.S. The figure comes from Philipp Dessovic, with whom we are working on the next publication on the electronic structure of the Thorium within a crystal.
…Well, actually, she’s with us quite a while already, blame Thorsten for not being up to date with the blogging;-( Anyways, we’re proud and happy to welcome Bianka as our first diploma student! Bianka is quite a celebrity among the local university politics, check out her Blog for her many activities. Some of you might also have seen her in the latest students theatre, staging Nestroy’s “Höllenangst”. Within the Thorium project, she will do crystal characterizations, especially looking at laser-induced luminescence/fluorescence, that will help us design the optimal measurement setup for finding the transition. Bianka prefers cider to beer, just for your information…
This October 24.-27. the European Space Agency (ESA) organized the „4th International Workshop on Optical Atomic Frequency Standards and Clocks“ in the beautiful city of Trani in southern Italy. The meeting resumed the current status of projects and efforts in bringing optical clocks into space. The organizer Eamonn Murphy did a great job in mixing talks on already very technologically advanced approaches (like neutral atoms lattice clocks and laser stabilization using ULE cavities) with fundemantally new approaches like spectral hole-burning stabilization or (of course) the Thorium project. It was nice to experience, how much interest the clock community takes in our research, there where many questions and discussions AND a lot offers for help and collaboration. The incredible scenery of Trani’s old town (picture shows the view from my hotel room!) and the above 20 °C temperatures (not to mention the seafood) did the rest to make this meeting a memorable experience. You can find the program here.
To ESA people: YES, I’d be happy to come again any time;-)
This week, the brave Marc Fischer from Menlo Systems drove all the way from Munich to Vienna to bring us the long-expected frequency comb system. All parts arrived in good shape (thanks again to the unknown soldiers of science who helped in unloading) and since Tuesday May 17 and after an intense crash course by Marc, we have all the colors of the rainbow in our lab. Everybody is invited to have a look, no special weather conditions required. Now we ONLY have to create the fifth harmonic in a build-up cavity filament to get to the VUV range – piece of cake! (Here and here are some papers on how this has been done by other groups) Thanks again to Marc for all your patience and help! To the rest of you: buy MENLO products, officially selected (by the Thorium team) the nicest and most helpful laser company on this planet (also check out their cool frequency comb community page).
Good news for those of us who are more afraid of integrals and tensors than femtolasers and vacuum (e.g. the author): The Thorium project now has its own theorist. Georgy Kazakov, long standing collaborator from St. Petersburg has won a prestigious Lise Meitner fellowship from the Austrian Science Fund (FWF) and joined the team in April. Welcome! With a background in atomic clocks, he will guide the experimentalists to sensible measurements. As an extra bonus, he can read the original nuclear physics papers (published in Russian, obviously).
(this message is exclusively by Thorsten and does by no means represent the opinions and views of the Thorium team, no animals were harmed). I really love the idea of a science blog (thanks Julia from Datenwerk for talking me into it) and your comments always make my day. Unfortunately, I have to filter them out of hundreds of fake messages, promoting pills in all shapes of colors, various enlargements or reductions of extremities and generous offerings to write my thesis for me (?). I don’t know how you guys get around the spam blocker but you really should meditate your aims in life. Dr. T. pities you!
To the rest of you: sorry for loosing my temper, breathe, 10, 9, 8, 7, … ok, back to science now…