Seminarium Fizyki Jądra Atomowego
join us / spotkanie
2024-04-11 (10:15) 
Prof. Dr. Peter G. Thirolf (Ludwig-Maximilians-Universität München, 85748 Garching, Germany)
The Thorium Isomer 229mTh: From the Atomic to the Nuclear Clock
Today’s most precise timekeeping is based on optical atomic clocks. However, those could potentially be outperformed by a nuclear clock, based on a nuclear transition instead of an atomic shell transition. Such a nuclear clock promises intriguing applications in applied as well as fundamental physics, ranging from geodesy and seismology to the investigation of possible time variations of fundamental constants and the search for Dark Matter [1,2].
Only one nuclear state is known so far that could drive a nuclear clock: the ‘Thorium Isomer 229mTh’, i.e. the isomeric first excited state of 229Th, representing the lowest nuclear excitation so far reported in the whole landscape of nuclear isotopes. Since its first direct detection in 2016 [3], considerable progress could be achieved in characterizing the properties and decay parameters of this elusive nuclear excitation: the half-life of the neutral isomer was determined [4], the hyperfine structure was measured via collinear laser spectroscopy, providing information on nuclear moments and the nuclear charge radius [5] and also the excitation energy of the isomer could be directly determined 8.28(17) eV [6].
In a recent experiment at CERN’s ISOLDE facility, the long-sought radiative decay of the Thorium isomer could be observed for the first time via implantation of (β decaying) 229Ac into a VUV transparent crystal and subsequent fluorescence detection in a VUV spectrometer. Thus, the excitation energy of 229mTh could be determined with much improved precision to 8.338(24) eV, corresponding to a wavelength of 148.71(42) nm [7]. This recent breakthrough opened the door towards a laser-driven control of the isomeric transition. A most recent achievement in this direction will be briefly introduced. Thus the realization of an ultra-precise nuclear frequency standard and quantum sensor comes even closer into reach. The talk will review recently completed, ongoing and planned activities towards this goal.
[1] E. Peik et al., Quantum Sci. Technol. 6, 034002 (2021).
[2] P.G. Thirolf, B. Seiferle, L. v.d. Wense, Annalen der Physik 531, 1800391 (2019).
[3] L. v.d. Wense et al., Nature 533, 47-51 (2016).
[4] B. Seiferle, L. v.d. Wense, P.G. Thirolf, Phys. Rev. Lett. 118, 042501 (2017).
[5] J. Thielking et al., Nature 556, 321 (2018).
[6] B. Seiferle et al., Nature 573, 243 (2019).
[7] S. Kraemer et al., Nature 617, 706 (2023).
Seminarium odbędzie się zdalnie na zoom-ie. Link jest dostępny od 10.00:
https://uw-edu-pl.zoom.us/j/93219123946?pwd=T21tTVA1ejhxK3JuMzBDbEFNZGpCZz09
Identyfikator spotkania: 932 1912 3946
Only one nuclear state is known so far that could drive a nuclear clock: the ‘Thorium Isomer 229mTh’, i.e. the isomeric first excited state of 229Th, representing the lowest nuclear excitation so far reported in the whole landscape of nuclear isotopes. Since its first direct detection in 2016 [3], considerable progress could be achieved in characterizing the properties and decay parameters of this elusive nuclear excitation: the half-life of the neutral isomer was determined [4], the hyperfine structure was measured via collinear laser spectroscopy, providing information on nuclear moments and the nuclear charge radius [5] and also the excitation energy of the isomer could be directly determined 8.28(17) eV [6].
In a recent experiment at CERN’s ISOLDE facility, the long-sought radiative decay of the Thorium isomer could be observed for the first time via implantation of (β decaying) 229Ac into a VUV transparent crystal and subsequent fluorescence detection in a VUV spectrometer. Thus, the excitation energy of 229mTh could be determined with much improved precision to 8.338(24) eV, corresponding to a wavelength of 148.71(42) nm [7]. This recent breakthrough opened the door towards a laser-driven control of the isomeric transition. A most recent achievement in this direction will be briefly introduced. Thus the realization of an ultra-precise nuclear frequency standard and quantum sensor comes even closer into reach. The talk will review recently completed, ongoing and planned activities towards this goal.
[1] E. Peik et al., Quantum Sci. Technol. 6, 034002 (2021).
[2] P.G. Thirolf, B. Seiferle, L. v.d. Wense, Annalen der Physik 531, 1800391 (2019).
[3] L. v.d. Wense et al., Nature 533, 47-51 (2016).
[4] B. Seiferle, L. v.d. Wense, P.G. Thirolf, Phys. Rev. Lett. 118, 042501 (2017).
[5] J. Thielking et al., Nature 556, 321 (2018).
[6] B. Seiferle et al., Nature 573, 243 (2019).
[7] S. Kraemer et al., Nature 617, 706 (2023).
Seminarium odbędzie się zdalnie na zoom-ie. Link jest dostępny od 10.00:
https://uw-edu-pl.zoom.us/j/93219123946?pwd=T21tTVA1ejhxK3JuMzBDbEFNZGpCZz09
Identyfikator spotkania: 932 1912 3946