"Hyperfine Splitting, Isotope Shift, and Level Energy of the 3S States of Li-6, Li-7."
- BATTELLE (PACIFIC NW LAB)
- Gesellschaftfur Schwerionenforschung GSI
- GSI, Darmstadt, Germany
- Gesellschaft fr Schwerionenforschung
- Department of Physics, University of Windsor, Ontario, Canada
High-precision laser spectroscopy on lithium isotopes is of fundamental interest, experimentally as well as theoretically. The lithium atom has long served as a test system for the calculation of various atomic properties in few-electron atoms and significant advances have been made in the last decade[1-3]. Recently, calculations of transition energies for the 22S1/2 -> 32S1/2 and the 22S1/2 -> 22P1/2, 3/2 transitions and of the mass-dependant isotope shift (IS) in these transitions have been reported with a relative accuracy of better than 1 X 10-7 and 5 x 10-6, respectively[4, 5]. These calculations are the foundation for experimental efforts, currently underway at GSI Darmstadt, Germany, to determine the root-mean-square (rms) charge radius of the unstable lithium isotopes[6, 7]. The basic principle is that if all mass-dependent contributions to the IS can be calculated with sufficient accuracy, the residual discrepancy between the experimentally observed shift and the computational result is caused by the difference Rrms in the nuclear charge radii between the isotopes[8]. This approach has previously been used to determine the difference between the charge radii of 6,7Li from isotope shift measurements in the helium-like system Li+[9] and the rms charge radius of 3He[10]. In both cases, results were in agreement with nuclear scattering data but with substantially improved accuracy. Data on nuclear charge radii is of fundamental importance for nuclear physics, but for lithium it has been determined by electron scattering only for the stable isotopes 6,7Li. Among the unstable isotopes, the study of 11Li is of particular importance since it consists of a 9Li core surrounded with a halo formed by two loosely-bound neutrons[11]. The mass radius of 11Li has been determined from nuclear cross section measurements[12], but such experiments do not allow a nuclear-model independent determination of charge radius. Thus, the question whether the halo neutrons have any impact on proton distribution inside the 9Li core is still unresolved. With proposed accuracy of 200 kHz, the GSI experiments will allow determination of rms charge radii of short-lived isotopes with a precision of approximately 5%. Comparison of experimental results with predictions from nuclear structure calculations will lead to better understanding of nuclear structure near the neutron drop line.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 15004347
- Report Number(s):
- PNNL-SA-38153; PRLTAO; KC0302020; TRN: US1005152
- Journal Information:
- Physical Review Letters, 91(4):043004-1 - 043004-4, Vol. 91, Issue 4; ISSN 0031-9007
- Country of Publication:
- United States
- Language:
- English
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Isotope-shift measurements of stable and short-lived lithium isotopes for nuclear-charge-radii determination