Nuclear Charge Radii of Th 229 from Isotope and Isomer Shifts

authored by: M. S. Safronova, S. G. Porsev, M. G. Kozlov, J. Thielking, M. V. Okhapkin, P. Głowacki, D. M. Meier, E. Peik
Abstract: The isotope Th229 is unique in that it possesses an isomeric state of only a few electron volts above the ground state, suitable for nuclear laser excitation. An optical clock based on this transition is expected to be a very sensitive probe for variations of fundamental constants, but the nuclear properties of both states have to be determined precisely to derive the actual sensitivity. We carry out isotope shift calculations in Th+ and Th2+ including the specific mass shift, using a combination of configuration interaction and all-order linearized coupled-cluster methods and estimate the uncertainty of this approach. We perform experimental measurements of the hyperfine structure of Th2+ and isotopic shift between Th2+229 and Th2+232 to extract the difference in root-mean-square radii as δâr2â232,229=0.299(15) fm2. Using the recently measured values of the isomer shift of lines of Th229m, we derive the value for the mean-square radius change between Th229 and its low-lying isomer Th229m to be δr2229m,229=0.0105(13) fm2.
External Organisation(s): University of Delaware
University of Maryland
RAS - Saint Petersburg Nuclear Physics Institute
St. Petersburg State Electrotechnical University
Physikalisch-Technische Bundesanstalt PTB
Poznan University of Technology
Type: Article
Journal: Physical review letters
Volume: 121
ISSN: 0031-9007
Publication date: 21.11.2018
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: General Physics and Astronomy
Electronic version(s): https://doi.org/10.1103/PhysRevLett.121.213001 (Access: Open)

BibTeX

@article{c035ab9a1aac4d82bbaa751955b0a7db,
title = "Nuclear Charge Radii of Th 229 from Isotope and Isomer Shifts",
abstract = "The isotope Th229 is unique in that it possesses an isomeric state of only a few electron volts above the ground state, suitable for nuclear laser excitation. An optical clock based on this transition is expected to be a very sensitive probe for variations of fundamental constants, but the nuclear properties of both states have to be determined precisely to derive the actual sensitivity. We carry out isotope shift calculations in Th+ and Th2+ including the specific mass shift, using a combination of configuration interaction and all-order linearized coupled-cluster methods and estimate the uncertainty of this approach. We perform experimental measurements of the hyperfine structure of Th2+ and isotopic shift between Th2+229 and Th2+232 to extract the difference in root-mean-square radii as δ{\^a}r2{\^a}232,229=0.299(15) fm2. Using the recently measured values of the isomer shift of lines of Th229m, we derive the value for the mean-square radius change between Th229 and its low-lying isomer Th229m to be δr2229m,229=0.0105(13) fm2.",
author = "Safronova, {M. S.} and Porsev, {S. G.} and Kozlov, {M. G.} and J. Thielking and Okhapkin, {M. V.} and P. G{\l}owacki and Meier, {D. M.} and E. Peik",
note = "Funding information: We acknowledge financial support from the European Union{\textquoteright}s Horizon 2020 Research and Innovation Programme under Grant Agreement No. 664732 (nuClock) and from DFG through CRC 1227 (DQ-mat, project B04). This work was supported in part by the Office of Naval Research, U.S., under Grant No. N00014-17-1-2252, and Russian Foundation for Basic Research under Grant No. 17-02-00216.",
year = "2018",
month = nov,
day = "21",
doi = "10.1103/PhysRevLett.121.213001",
language = "English",
volume = "121",
journal = "Physical review letters",
issn = "0031-9007",
publisher = "American Physical Society",
number = "21",
}