Wigner Crystals of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi>Th</mml:mi><mml:mprescripts /><mml:none /><mml:mn>229</mml:mn></mml:mmultiscripts></mml:math>for Optical Excitation of the Nuclear Isomer

Campbell, C. J.; Radnaev, A. G.; Kuzmich, A.

doi:10.1103/physrevlett.106.223001

Cited by 128 publications

(165 citation statements)

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“…The main disadvantage of the triply ionized thorium for a search for the nuclear transition is the presence of only one electronic state (7p at 9.06 eV) whose energy is closely above the isomer energy range and can be used for NEET. Alternatively, two-photon resonant electronic bridge excitation from the 7s state through the 7p level may be an approach for the search [54]. While this electronic bridge excitation scheme has significantly lower enhancement factor than that for Th + , the advantages of an experiment with lasercooled 229 Th 3+ lie in the high spectral resolution and efficient state detection.…”

Section: Experimental Search For the 229 Th Nuclear Transitionmentioning

confidence: 99%

“…Ion production, laser-cooling and the formation of large Coulomb crystals have first been achieved for the long-lived isotope 232 Th 3+ [28]. Laser-cooled Wigner crystals of 229 Th 3+ were produced in a linear Paul trap [54]. The hyperfine splitting factors of four levels and the isotopic shifts of three transitions were determined.…”

Section: Experimental Search For the 229 Th Nuclear Transitionmentioning

confidence: 99%

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Nuclear clocks based on resonant excitation of γ-transitions

Peik

Okhapkin²

2015

Comptes Rendus. Physique

111

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We review the ideas and concepts for a clock that is based on a radiative transition in the nucleus rather than in the electron shell. This type of clock offers advantages like an insensitivity against field-induced systematic frequency shifts and the opportunity to obtain high stability from interrogating many nuclei in the solid state. Experimental work concentrates on the low-energy (about 8 eV) isomeric transition in 229 Th. We review the status of the experiments that aim at a direct optical observation of this transition and outline the plans for high-resolution laser spectroscopy experiments.

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Section: Experimental Search For the 229 Th Nuclear Transitionmentioning

confidence: 99%

Section: Experimental Search For the 229 Th Nuclear Transitionmentioning

confidence: 99%

Nuclear clocks based on resonant excitation of γ-transitions

Peik

Okhapkin²

2015

Comptes Rendus. Physique

111

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“…Another method consists in embedding 229 Th ions into a crystal [10]; the quality factor of the nuclear transition which is sensitive to the additional influence caused by the presence of crystal structure, remains, nevertheless, much larger compared to any electronic transitions [11]. The advantage of using a crystal is the high density of 229 Th nuclei, which is ~10 19 cm -3 and is many orders of magnitude higher than the value achieved in the ion traps (≤10 8 nuclei [12]). This can greatly facilitate the direct observation of the transition.…”

Section: Introductionmentioning

confidence: 99%

Band structure and decay channels of thorium‐229 low‐lying isomeric state for ensemble of thorium atoms adsorbed on calcium fluoride

Borisyuk

Vasilyev

Krasavin

et al. 2015

Phys. Status Solidi C

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The results are presented on the study of the electronic structure of thorium atoms adsorbed by the liquid atomic layer deposition from aqueous solution of thorium nitrate on the surface of CaF 2 . The chemical state of the atoms and the change of the band structure in the surface layers of Th/CaF 2 system on CaF 2 substrate were investigated by XPS and REELS techniques. It was found that REELS spectra for Th/CaF 2 system include peaks in the region of low energy losses (3-7 eV) which are missing in the similar spectra for pure CaF 2 . It is concluded that the presence of the observed features in the REELS spectra is associated with the chemical state of thorium atoms and is caused by the presence of uncompensated chemical bonds at the Th/CaF 2 interface, and, therefore, by the presence of unbound 6d-and 7s-electrons of thorium atoms. Assuming the equivalence of the electronic configuration of thorium-229 and thorium-232 atoms, an estimate was made on the time decay of the excited state of thorium-229 nuclei through the channel of the electron conversion. It was found that the relaxation time is about 40 μs for 6d-electrons, and about 1 μs for 7s-electrons.

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“…Nuclear transition events will be manifested by interruptions in laser fluorescence on one of the laser cooling transitions. A chain of laser-cooled 229 Th 3+ ions will provide near-unity detection efficiency of isomer state population, as well as strong localization for tight focusing of the isomer search light [12]. In this paper, we demonstrate the first important step in this electron bridge-assisted isomer search by exciting 232 Th 3+ ions to the 7P 1/2 level via the three-step process: (i) 5F 5/2 → 6D 3/2 excitation at 1088 nm, (ii) 6D 3/2 → 7S 1/2 electricquadrupole excitation at 717 nm, and (iii) 7S 1/2 → 7P 1/2 excitation at 269 nm.…”

mentioning

confidence: 99%

“…[12]. The trap rf frequency is increased to 8 MHz, which allows for operation without the aid of buffer gas.…”

mentioning

confidence: 99%

Observation of the 717-nm electric quadrupole transition in triply charged thorium

Radnaev

Campbell²,

Kuzmich³

2012

Phys. Rev. A

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We excite the 717 nm electric quadrupole 6D 3/2 ↔ 7S 1/2 transition in a laser-cooled 232 Th 3+ ion crystal. The transition frequency and the lifetime of the metastable 7S 1/2 level are measured to be 417 845 964(30) MHz and 0.60(7) s, respectively. We subsequently employ the 7S 1/2 level to drive the ions with nanosecond-long 269 nm laser pulses into the 7P 1/2 level. The latter is connected to the 7S 1/2 electronic level within the 229 Th nuclear isomer manifold by the strongest available electron-bridge transition, forming a basis for its laser excitation. 37.10.Rs State-of-the-art trapped ion frequency standards utilize narrow optical transitions between valence electron orbitals within a single ion confined in an rf trap. These clocks are currently limited to fractional inaccuracies of ∼ 10 −17 [1][2][3][4]. A nuclear transition between two levels of identical electronic quantum numbers in a single 229 Th ion could also be used as the basis for a clock [5]. With suitably chosen states in the compound system (nuclear + electronic), all leading-order external-field clock shift mechanisms can be eliminated, leaving only higherorder, significantly smaller shifts. This would relax technical requirements as compared to conventional optical clocks and potentially allow for fractional inaccuracies of ∼ 10 −19 [6].An important potential application of the 229 Th nuclear clock is in the search for temporal variation of fundamental constants, particularly the fine structure constant α. The most accurate laboratory searches for α-variation to date are performed by measuring the ratio of atomic clock frequencies derived from different atomic systems over a long period of time. Because the two different systems have different sensitivities to α-variation, the two clock frequencies would differentially shift, changing the frequency ratio. The keys to a sensitive probe are precise frequency measurement of the clock transitions and largely different sensitivities of the transitions to change in α. In the case of the 229 Th nuclear transition, a large enhancement over atomic systems in α-variation sensitivity is predicted to exist due to near-cancellation of electromagnetic repulsion of the protons and of strong interactions among the nucleons [7,8]. This enhancement, combined with the clock transition's extreme accuracy potential, would lead to an improvement upon the current best measurement of α-variation by possibly as many as five orders of magnitude when using state-of-the-art clock technology.The most recent and precise published measurement of the 229 Th isomer energy is 7.8(5) eV [9]. In order to span ± 3 σ in the search for this nuclear level, direct optical excitation of the isomer in trapped cold ions may not be a viable method, given available UV sources and the large energy uncertainty. Instead, the electron bridge (EB) process may be utilized, Fig. 1 [10]. In this case, hyperfine-induced mixing of the ground and isomer nuclear manifolds opens up electric-dipole transitions between the two. Mixing is expect...

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Wigner Crystals ofTh229for Optical Excitation of the Nuclear Isomer

Cited by 128 publications

References 23 publications

Nuclear clocks based on resonant excitation of γ-transitions

Nuclear clocks based on resonant excitation of γ-transitions

Band structure and decay channels of thorium‐229 low‐lying isomeric state for ensemble of thorium atoms adsorbed on calcium fluoride

Observation of the 717-nm electric quadrupole transition in triply charged thorium

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