Energy Splitting of the Ground-State Doublet in the Nucleus<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>

Beck, Belinda R.; Becker, J. A.; Beiersdörfer, P.; Brown, G. V.; Moody, Κ. J.; Wilhelmy, J. B.; Porter, F. S.; Kilbourne, Caroline A.; Kelley, R. L.

doi:10.1103/physrevlett.98.142501

Cited by 274 publications

(339 citation statements)

References 24 publications

Supporting

Mentioning

321

Contrasting

Unclassified

Order By: Relevance

“…Over the last several years, interest has arisen in the possibility of using the thorium radio-isotope 229 Th as a nuclear clock. 229 Th has an unusually low-level nuclear isomer state, which is only approximately 7.6 (±0.5) eV above the ground state [33], corresponding to a wavelength of 163 nm or 1840 (±120) THz. There are proposals to drive the nuclear transition in 229 Th 3+ , both in a solid-state crystal [34] and in an isolated ion confined within an r.f.…”

Section: Possible Algorithms For a Redefinition Of The Secondmentioning

confidence: 99%

When should we change the definition of the second?

Gill

2011

Phil. Trans. R. Soc. A.

View full text Add to dashboard Cite

The microwave caesium (Cs) atomic clock has formed an enduring basis for the second in the International System of Units (SI) over the last few decades. The advent of laser cooling has underpinned the development of cold Cs fountain clocks, which now achieve frequency uncertainties of approximately 5 × 10 −16 . Since 2000, optical atomic clock research has quickened considerably, and now challenges Cs fountain clock performance. This has been suitably shown by recent results for the aluminium Al + quantum logic clock, where a fractional frequency inaccuracy below 10 −17 has been reported. A number of optical clock systems now achieve or exceed the performance of the Cs fountain primary standards used to realize the SI second, raising the issues of whether, how and when to redefine it. Optical clocks comprise frequency-stabilized lasers probing very weak absorptions either in a single cold ion confined in an electromagnetic trap or in an ensemble of cold atoms trapped within an optical lattice. In both cases, different species are under consideration as possible redefinition candidates. In this paper, I consider options for redefinition, contrast the performance of various trapped ion and optical lattice systems, and point to potential limiting environmental factors, such as magnetic, electric and light fields, collisions and gravity, together with the challenge of making remote comparisons of optical frequencies between standards laboratories worldwide.

show abstract

Section: Possible Algorithms For a Redefinition Of The Secondmentioning

confidence: 99%

When should we change the definition of the second?

Gill

2011

Phil. Trans. R. Soc. A.

View full text Add to dashboard Cite

show abstract

“…In addition, an independent corroboration of the existence of a low-lying state has been achieved experimentally in the reaction 230 Th(d, t) 229 Th [19]. This experiment provides strong evidence that the K π [N n Z Λ] = 3/2 + [631] band head is located very close to the ground state, and, in fact, all available experimental data from these indi- * Electronic address: eugene.tkalya@mail.ru rect measurements of the J π K[N n Z Λ] = 3/2 + 3/2[631] isomeric state energy indicate that E is < 10 eV [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

“…We show how this range affects the determination of the isomeric energy in the experiments of Refs. [22,41], which provide the currently accepted isomeric transition energy range. In Section VI, we briefly discuss the results of this work and present a "favored region", which we recommend the community adopt in order to direct future searches.…”

Section: Introductionmentioning

confidence: 99%

Radiative lifetime and energy of the low-energy isomeric level inTh229

et al. 2015

View full text Add to dashboard Cite

We estimate the range of the radiative lifetime and energy of the anomalous, low-energy 3/2 + (7.8± 0.5 eV) state in the 229 Th nucleus. Our phenomenological calculations are based on the available experimental data for the intensities of M 1 and E2 transitions between excited levels of the 229 Th nucleus in the K π [N nZ Λ] = 5/2 + [633] and 3/2 + [631] rotational bands. We also discuss the influence of certain branching coefficients, which affect the currently accepted measured energy of the isomeric state. From this work, we establish a favored region where the transition lifetime and energy should lie at roughly the 90% confidence level. We also suggest new nuclear physics measurements, which would significantly reduce the ambiguity in the present data.

show abstract

“…The low-lying nuclear isomeric level of 229 Th isotope is not only a unique exception in nuclear physics with uncharacteristically low energy of 7.8 ± 0.5 eV [1], but it also is of exceptional interest due to many possibilities of use in various fields. The nuclear transition, shielded from the environment by the electron shell, is located in the vacuum ultraviolet region which is accessible by laser spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

“…The value of the isomeric transition energy in [1] was obtained by indirect measurements; the direct registration of the transition is a major challenge, and still not realized [7]. This fact is caused by radioactivity of 229 Th isotope, its absence in nature (it can be obtained with the use of nuclear reactions only), narrow spectral line and weak oscillator strength 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

View full text Add to dashboard Cite

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.

show abstract

Energy Splitting of the Ground-State Doublet in the NucleusTh229

Cited by 274 publications

References 24 publications

When should we change the definition of the second?

When should we change the definition of the second?

Radiative lifetime and energy of the low-energy isomeric level inTh229

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

Contact Info

Product

Resources

About