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Towards a nuclear clock with Thorium-229

Deliverables

Gamma spectroscopy

Micro-calorimeters enable high-resolution spectroscopy of gamma photons. This report summarizes the attempt to resolve the 229Th nuclear gound-state doublet structure. A successful measurement would allow for a determination of the energy of the isomeric state.

WP1 progress report 1

This first report of WP 1 will summarize technological advances in the quest of detecting the Th isomer state. The latest state of all four experimental groups (UHEI, LMU, JYU, and TU WIEN) will be described.

Progress report thorium samples

TU WIEN will fabricate 229Th samples, as required by PTB for an ion trap sputter source (tasks 2.1 and 2.2), for collision targets at JYU (task 1.3), and for crystal doping at TU WIEN (task 2.3). The chemical processing of the 229Th will be described, as well as careful investigation of the samples' radioactivity and purity.

WP2 progress report 1

This report will contain new values on the electronic level structure of 229Th+, as well as all relevant advances in the investigation of fundamental building blocks of a nuclear optical clock.

WP2 progress report 2

This report will contain results on the Th:CaF2 crystal characterization, on the spectroscopy of electronic states of 229gTh+, as well as relevant advances in the investigation of fundamental building blocks of a nuclear optical clock.

Collective effects

Collective effects might improve spectroscopy performance tremendously. Theoretical investigations on this topic will be described in this report.

Check meeting 3

Scientific report covering the third RP (M31-M48).

Data management plan

A data management plan will be developed.

WP1 progress report 3

This progress report will summarize all relevant advances on the characterization of the 229Th isomeric state.

WP1 progress report 2

This progress report will summarize all relevant advances on the characterization of the 229Th isomeric state.

Progress report uranium samples

233U samples are required by UHEI for gamma-spectroscopy (task 1.1), by LMU as ion-beam source (task 1.2), by TU WIEN for crystal doping (task 1.4), and potentially JYU as collision target. The chemical procedures developed to produce the required samples will be decribed in a report, along with quantitative measurements of radioactivity, purity, and other relevant parameters.

WP2 progress report 3

This report will contain new values on the electronic level structure of 229Th+, as well as all relevant advances in the investigation of fundamental building blocks of a nuclear optical clock.

VUV comb evaluation

MPG/MPQ will deliver a report on the design and benchmark specifications of a future VUV frequency comb dedicated for thorium, based on the existing 175 nm laser.

VUV cw laser system

The previous three deliverables covered by TOPTICA concerned the development of the three intergal sub-systems of a tunable cw VUV laser system. These subsystems are now integrated into a single transportable unit. Extensive tests of the entire system are performed and will be detailed in a report.

Portable detection unit

A portable detection unit will be developed, centered around a 229Th:CaF2 crystal to be illuminated by light sourced provided by PTB (MLS in Berlin) or TOPTICA (cw VUV solid state laser). On the detection side, either PMTs or a VUV monochromator might be employed.

Image film

Half-way through the 4-year project duration, an image film will be produced. The film will be targeted at a non-expert audience. It will cover the physics behind the research, the daily work of scientists, as well as the current status of the project. The film will be uploaded to online platforms such as the project webpage and facebook account.

International conference

An international conference will be organized, bringing together experts from the field of thorium research, as well as from adjacent research topics.

Project webpage

Brief description of the structure of the website.

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Publications

Feasibility study of measuring the Th 229 nuclear isomer transition with U 233 -doped crystals

Author(s): Simon Stellmer, Matthias Schreitl, Georgy A. Kazakov, Johannes H. Sterba, Thorsten Schumm
Published in: Physical Review C, Issue 94/1, 2016, ISSN 2469-9985
DOI: 10.1103/PhysRevC.94.014302

Towards a measurement of the nuclear clock transition in 229 Th

Author(s): Simon Stellmer, Matthias Schreitl, Georgy Kazakov, Koji Yoshimura, Thorsten Schumm
Published in: Journal of Physics: Conference Series, Issue 723, 2016, Page(s) 012059, ISSN 1742-6588
DOI: 10.1088/1742-6596/723/1/012059

Feasibility study of internal conversion electron spectroscopy of 229mTh

Author(s): Benedict Seiferle, Lars von der Wense, Peter G. Thirolf
Published in: The European Physical Journal A, Issue 53/5, 2017, ISSN 1434-6001
DOI: 10.1140/epja/i2017-12294-5

Nubis et Nuclei: A Study on Noise and Precision

Author(s): Kerstin Ergenzinger, Thorsten Schumm, Simon Stellmer
Published in: Leonardo, 2017, ISSN 0024-094X
DOI: 10.1162/LEON_a_01467

Multi-pass-cell-based nonlinear pulse compression to 115 fs at 75 µJ pulse energy and 300 W average power

Author(s): Johannes Weitenberg, Andreas Vernaleken, Jan Schulte, Akira Ozawa, Thomas Sartorius, Vladimir Pervak, Hans-Dieter Hoffmann, Thomas Udem, Peter Russbüldt, Theodor W. Hänsch
Published in: Optics Express, Issue 25/17, 2017, Page(s) 20502, ISSN 1094-4087
DOI: 10.1364/OE.25.020502

Reduced Transition Probabilities for the Gamma Decay of the 7.8 eV Isomer in Th 229

Author(s): Nikolay Minkov, Adriana Pálffy
Published in: Physical Review Letters, Issue 118/21, 2017, ISSN 0031-9007
DOI: 10.1103/PhysRevLett.118.212501

A Laser Excitation Scheme for Th 229 m

Author(s): Lars von der Wense, Benedict Seiferle, Simon Stellmer, Johannes Weitenberg, Georgy Kazakov, Adriana Pálffy, Peter G. Thirolf
Published in: Physical Review Letters, Issue 119/13, 2017, ISSN 0031-9007
DOI: 10.1103/PhysRevLett.119.132503

Nonlinear Pulse Compression to Sub-40 fs at $4.5~\mu$ J Pulse Energy by Multi-Pass-Cell Spectral Broadening

Author(s): Johannes Weitenberg, Tobias Saule, Jan Schulte, Peter Rusbuldt
Published in: IEEE Journal of Quantum Electronics, Issue 53/6, 2017, Page(s) 1-4, ISSN 0018-9197
DOI: 10.1109/JQE.2017.2761883

Optomechanically induced transparency of x-rays via optical control

Author(s): Wen-Te Liao, Adriana Pálffy
Published in: Scientific Reports, Issue 7/1, 2017, ISSN 2045-2322
DOI: 10.1038/s41598-017-00428-w

Internal conversion from excited electronic states of Th 229 ions

Author(s): Pavlo V. Bilous, Georgy A. Kazakov, Iain D. Moore, Thorsten Schumm, Adriana Pálffy
Published in: Physical Review A, Issue 95/3, 2017, ISSN 2469-9926
DOI: 10.1103/PhysRevA.95.032503

Lifetime Measurement of the Th 229 nuclear isomer

Author(s): Benedict Seiferle, Lars von der Wense, Peter G. Thirolf
Published in: Physical Review Letters, Issue 118/4, 2017, ISSN 0031-9007
DOI: 10.1103/PhysRevLett.118.042501

Toward an energy measurement of the internal conversion electron in the deexcitation of the Th 229 isomer

Author(s): Simon Stellmer, Yudai Shigekawa, Veronika Rosecker, Georgy A. Kazakov, Yoshitaka Kasamatsu, Yuki Yasuda, Atsushi Shinohara, Thorsten Schumm
Published in: Physical Review C, Issue 98/1, 2018, ISSN 2469-9985
DOI: 10.1103/physrevc.98.014317

Attempt to optically excite the nuclear isomer in Th 229

Author(s): Simon Stellmer, Georgy Kazakov, Matthias Schreitl, Hendrik Kaser, Michael Kolbe, Thorsten Schumm
Published in: Physical Review A, Issue 97/6, 2018, ISSN 2469-9926
DOI: 10.1103/PhysRevA.97.062506

Nuclear resonant scattering experiment with fast time response: Photonuclear excitation of Hg 201

Author(s): A. Yoshimi, H. Hara, T. Hiraki, Y. Kasamatsu, S. Kitao, Y. Kobayashi, K. Konashi, R. Masuda, T. Masuda, Y. Miyamoto, K. Okai, S. Okubo, R. Ozaki, N. Sasao, O. Sato, M. Seto, T. Schumm, Y. Shigekawa, S. Stellmer, K. Suzuki, S. Uetake, M. Watanabe, A. Yamaguchi, Y. Yasuda, Y. Yoda, K. Yoshimura, M. Yoshimura
Published in: Physical Review C, Issue 97/2, 2018, ISSN 2469-9985
DOI: 10.1103/physrevc.97.024607

Laser spectroscopic characterization of the nuclear-clock isomer 229mTh

Author(s): Johannes Thielking, Maxim V. Okhapkin, Przemysław Głowacki, David M. Meier, Lars von der Wense, Benedict Seiferle, Christoph E. Düllmann, Peter G. Thirolf, Ekkehard Peik
Published in: Nature, Issue 556/7701, 2018, Page(s) 321-325, ISSN 0028-0836
DOI: 10.1038/s41586-018-0011-8

Non-perturbative generation of DUV/VUV harmonics from crystal surfaces at 108 MHz repetition rate

Author(s): J. Seres, E. Seres, C. Serrat, T. Schumm
Published in: Optics Express, Issue 26/17, 2018, Page(s) 21900, ISSN 1094-4087
DOI: 10.1364/oe.26.021900

Nuclear Charge Radii of Th 229 from Isotope and Isomer Shifts

Author(s): M. S. Safronova, S. G. Porsev, M. G. Kozlov, J. Thielking, M. V. Okhapkin, P. Głowacki, D. M. Meier, E. Peik
Published in: Physical Review Letters, Issue 121/21, 2018, ISSN 0031-9007
DOI: 10.1103/physrevlett.121.213001

Collective effects in Th 229 -doped crystals

Author(s): Brenden S. Nickerson, Wen-Te Liao, Adriana Pálffy
Published in: Physical Review A, Issue 98/6, 2018, ISSN 2469-9926
DOI: 10.1103/physreva.98.062520

All-solid-state VUV frequency comb at 160 nm using high-harmonic generation in nonlinear femtosecond enhancement cavity

Author(s): J. Seres, E. Seres, C. Serrat, E. C. Young, J. S. Speck, T. Schumm
Published in: Optics Express, Issue 27/5, 2019, Page(s) 6618, ISSN 1094-4087
DOI: 10.1364/oe.27.006618

Electronic level structure of Th + in the range of the Th 229 m

Author(s): D.-M. Meier, J. Thielking, P. Głowacki, M. V. Okhapkin, R. A. Müller, A. Surzhykov, E. Peik
Published in: Physical Review A, Issue 99/5, 2019, ISSN 2469-9926
DOI: 10.1103/physreva.99.052514

Hyperfine interaction with the Th 229 nucleus and its low-lying isomeric state

Author(s): Robert A. Müller, Anna V. Maiorova, Stephan Fritzsche, Andrey V. Volotka, Randolf Beerwerth, Przemyslaw Glowacki, Johannes Thielking, David-Marcel Meier, Maksim Okhapkin, Ekkehard Peik, Andrey Surzhykov
Published in: Physical Review A, Issue 98/2, 2018, ISSN 2469-9926
DOI: 10.1103/PhysRevA.98.020503

Electric quadrupole channel of the 7.8 eV Th 229 transition

Author(s): Pavlo V. Bilous, Nikolay Minkov, Adriana Pálffy
Published in: Physical Review C, Issue 97/4, 2018, ISSN 2469-9985
DOI: 10.1103/physrevc.97.044320

Theoretical Predictions for the Magnetic Dipole Moment of Th 229 m

Author(s): Nikolay Minkov, Adriana Pálffy
Published in: Physical Review Letters, Issue 122/16, 2019, ISSN 0031-9007
DOI: 10.1103/physrevlett.122.162502

Towards a 229Th-Based Nuclear Clock

Author(s): L. von der Wense, B. Seiferle, P. G. Thirolf
Published in: Measurement Techniques, Issue 60/12, 2018, Page(s) 1178-1192, ISSN 0543-1972
DOI: 10.1007/s11018-018-1337-1

Improving Our Knowledge on the 229m Thorium Isomer: Toward a Test Bench for Time Variations of Fundamental Constants

Author(s): Peter G. Thirolf, Benedict Seiferle, Lars der Wense
Published in: Annalen der Physik, Issue 531/5, 2018, Page(s) 1800381, ISSN 0003-3804
DOI: 10.1002/andp.201800381

The 229-thorium isomer: doorway to the road from the atomic clock to the nuclear clock

Author(s): Peter G. Thirolf, Benedict Seiferle, Lars von der Wense
Published in: Journal of Physics B: Atomic, Molecular and Optical Physics, 2019, ISSN 0953-4075
DOI: 10.1088/1361-6455/ab29b8

Preparing an Isotopically Pure <sup>229</sup>Th Ion Beam for Studies of <sup>229m</sup>Th

Author(s): Lars von der Wense, Benedict Seiferle, Ines Amersdorffer, Peter G. Thirolf
Published in: Journal of Visualized Experiments, Issue 147, 2019, ISSN 1940-087X
DOI: 10.3791/58516

The concept of laser-based conversion electron Mössbauer spectroscopy for a precise energy determination of 229mTh

Author(s): Lars C. von der Wense, Benedict Seiferle, Christian Schneider, Justin Jeet, Ines Amersdorffer, Nicolas Arlt, Florian Zacherl, Raphael Haas, Dennis Renisch, Patrick Mosel, Philip Mosel, Milutin Kovacev, Uwe Morgner, Christoph E. Düllmann, Eric R. Hudson, Peter G. Thirolf
Published in: Hyperfine Interactions, Issue 240/1, 2019, ISSN 0304-3843
DOI: 10.1007/s10751-019-1564-0

Towards a precise determination of the excitation energy of the Thorium nuclear isomer using a magnetic bottle spectrometer

Author(s): Benedict Seiferle, Lars von der Wense, Ines Amersdorffer, Nicolas Arlt, Benjamin Kotulski, Peter G. Thirolf
Published in: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2019, ISSN 0168-583X
DOI: 10.1016/j.nimb.2019.03.043

Energy of the 229Th nuclear clock transition

Author(s): Benedict Seiferle, Lars von der Wense, Pavlo V. Bilous, Ines Amersdorffer, Christoph Lemell, Florian Libisch, Simon Stellmer, Thorsten Schumm, Christoph E. Düllmann, Adriana Pálffy, Peter G. Thirolf
Published in: Nature, Issue 573/7773, 2019, Page(s) 243-246, ISSN 0028-0836
DOI: 10.1038/s41586-019-1533-4

X-ray pumping of the 229Th nuclear clock isomer

Author(s): Takahiko Masuda, Akihiro Yoshimi, Akira Fujieda, Hiroyuki Fujimoto, Hiromitsu Haba, Hideaki Hara, Takahiro Hiraki, Hiroyuki Kaino, Yoshitaka Kasamatsu, Shinji Kitao, Kenji Konashi, Yuki Miyamoto, Koichi Okai, Sho Okubo, Noboru Sasao, Makoto Seto, Thorsten Schumm, Yudai Shigekawa, Kenta Suzuki, Simon Stellmer, Kenji Tamasaku, Satoshi Uetake, Makoto Watanabe, Tsukasa Watanabe, Yuki Yasuda, Atsushi Y
Published in: Nature, Issue 573/7773, 2019, Page(s) 238-242, ISSN 0028-0836
DOI: 10.1038/s41586-019-1542-3

Nuclear clocks based on resonant excitation of γ-transitions

Author(s): Ekkehard Peik, Maxim Okhapkin
Published in: Comptes Rendus Physique, Issue 16/5, 2015, Page(s) 516-523, ISSN 1631-0705
DOI: 10.1016/j.crhy.2015.02.007

The extraction of 229Th3+ from a buffer-gas stopping cell

Author(s): L.v.d. Wense, B. Seiferle, M. Laatiaoui, P.G. Thirolf
Published in: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Issue 376, 2016, Page(s) 260-264, ISSN 0168-583X
DOI: 10.1016/j.nimb.2015.12.049

Radioluminescence and photoluminescence of Th:CaF2 crystals

Author(s): Simon Stellmer, Matthias Schreitl, Thorsten Schumm
Published in: Scientific Reports, Issue 5, 2015, Page(s) 15580, ISSN 2045-2322
DOI: 10.1038/srep15580

Direct detection of the 229Th nuclear clock transition

Author(s): Lars von der Wense, Benedict Seiferle, Mustapha Laatiaoui, Jürgen B. Neumayr, Hans-Jörg Maier, Hans-Friedrich Wirth, Christoph Mokry, Jörg Runke, Klaus Eberhardt, Christoph E. Düllmann, Norbert G. Trautmann, Peter G. Thirolf
Published in: Nature, Issue 533/7601, 2016, Page(s) 47-51, ISSN 0028-0836
DOI: 10.1038/nature17669

Observation of an unexpected negative isotope shift in Th + 229 and its theoretical explanation

Author(s): M. V. Okhapkin, D. M. Meier, E. Peik, M. S. Safronova, M. G. Kozlov, S. G. Porsev
Published in: Physical Review A, Issue 92/2, 2015, Page(s) 020503, ISSN 1094-1622
DOI: 10.1103/PhysRevA.92.020503

A VUV detection system for the direct photonic identification of the first excited isomeric state of 229Th

Author(s): Benedict Seiferle, Lars von der Wense, Mustapha Laatiaoui, Peter G. Thirolf
Published in: The European Physical Journal D, Issue 70/3, 2016, Page(s) 58, ISSN 1434-6060
DOI: 10.1140/epjd/e2016-60653-4

Experimental search for the low-energy nuclear transition in 229 Th with undulator radiation

Author(s): A Yamaguchi, M Kolbe, H Kaser, T Reichel, A Gottwald, E Peik
Published in: New Journal of Physics, Issue 17/5, 2015, Page(s) 053053, ISSN 1367-2630
DOI: 10.1088/1367-2630/17/5/053053

Von der Atomuhr zur Kernuhr

Author(s): Simon Stellmer
Published in: Physik Journal, Issue 04/2017, 2017, Page(s) 16-17, ISSN 1617-9439