Nuclear radii of thorium isotopes from laser spectroscopy of stored ions

Kälber, W.; Rink, J.; Bekk, K.; Faubel, W.; Göring, S.; Meisel, G.; Rebel, H.; Thompson, R. C.

doi:10.1007/bf01294392

Cited by 20 publications

(33 citation statements)

References 26 publications

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“…The long observation times that are achievable for trapped ions make this technique superior to all other techniques if it comes to the investigation of species that have sufficiently long half-lives but are produced with extremely small rates, as it is the case for some transactinides and superheavy elements that are produced in fusion reactions. In-trap laser spectroscopy and optical-microwave double resonance spectroscopy of ion species that have a complicated level structure and therefore unfavorable excitation schemes has been reported in Paul [101,102] and Penning traps [103] to obtain HFS constants and nuclear g-factors. Buffer-gas cooled ion clouds have been used in these experiments to quench metastable states that would otherwise form dark states and render laser spectroscopy impossible due to the large ARTICLE IN PRESS Fig.…”

Section: Expected Performancementioning

confidence: 99%

TRIGA-SPEC: A setup for mass spectrometry and laser spectroscopy at the research reactor TRIGA Mainz

Ketelaer

Krämer

Beck³

et al. 2008

Nuclear Instruments and Methods in Physics Research Section A:

118

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The research reactor TRIGA Mainz is an ideal facility to provide neutron-rich nuclides with production rates sufficiently large for mass spectrometric and laser spectroscopic studies. Within the TRIGA-SPEC project, a Penning trap as well as a beamline for collinear laser spectroscopy are being installed. Several new developments will ensure high sensitivity of the trap setup enabling mass measurements even on a single ion. Besides neutron-rich fission products produced in the reactor, also heavy nuclides such as 235U or 252Cf can be investigated for the first time with an off-line ion source. The data provided by the mass measurements will be of interest for astrophysical calculations on the rapid neutron-capture process as well as for tests of mass models in the heavy-mass region. The laser spectroscopic measurements will yield model-independent information on nuclear ground-state properties such as nuclear moments and charge radii of neutron-rich nuclei of refractory elements far from stability. TRIGA-SPEC also serves as a test facility for mass and laser spectroscopic experiments at SHIPTRAP and the low-energy branch of the future GSI facility FAIR. This publication describes the experimental setup as well as its present status

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Section: Expected Performancementioning

confidence: 99%

TRIGA-SPEC: A setup for mass spectrometry and laser spectroscopy at the research reactor TRIGA Mainz

Ketelaer

Krämer

Beck³

et al. 2008

Nuclear Instruments and Methods in Physics Research Section A:

118

View full text Add to dashboard Cite

show abstract

“…For these measurements, the ions were confined for many hours in an r .f . trap [1][2][3][4][5][6][7] . Laser spectroscopy of stored ions has been shown to be highly sensitive [5], since the ions can be stored for a long time allowing for many photon scattering processes for each trapped ion .…”

mentioning

confidence: 99%

Two-step Optical Excitation for Doppler Linewidth Reduction and Motion Study of Ions Stored in a Paul Trap

Kälber

Meisel

Rink

et al. 1992

Journal of Modern Optics

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Atomic thorium ions were stored in an r .f. quadrupole trap and excited by tunable laser light . One-step and two-step excitation schemes were applied; a four to eightfold reduction of the Doppler linewidth is obtained for the two-step scheme with essentially no loss in signal strength . The Doppler-free two-photon transition was also observed . The lineshapes were calculated using a simple model ; the observed profiles were well reproduced proving that the velocity and acceleration features of stored ions are properly accounted for . A further reduction of the Doppler linewidth is expected for the two-step method if a short lived intermediate level is used . . IntroductionIn previous experiments [1, 2], laser spectroscopic investigations were performed on thorium ions for the determination of isotope shifts and hyperfine splittings of several thorium isotopes . For these measurements, the ions were confined for many hours in an r .f . trap [1][2][3][4][5][6][7] . Laser spectroscopy of stored ions has been shown to be highly sensitive [5], since the ions can be stored for a long time allowing for many photon scattering processes for each trapped ion . The method was found [1] to be well suited for the study of radioactive atomic ions ; in the case of Th, samples of only 10 pg, i .e . 3 x 10 10 atoms, were required for the measurements .The resolution, however, is rather low because of the relatively large Doppler broadening due to the fast motion of the ions in the confining electric field . The low resolution had the disadvantage that, for example, the hyperfine splitting of odd Th isotopes [1] could not be resolved . In order to improve the resolution, we have investigated two-step excitation as a means of reducing the Doppler broadening of spectral lines of stored ions . The methods developed proved to be useful for the study of details of the motion of stored ions allowing a deeper insight into their kinematics . . Experimental detailsThe technique of storing ions in a Paul trap is well known ; reviews are found, e .g ., in references [6,7] . For our experiments we have used an ion trap with a radius parameter r0 = 1 cm . The electrodes of the trap were made of stainless steel . It is mounted inside an ultra high vacuum chamber that is evacuated to a residual gas

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“…[1,2]. Previously, laser excitation of Th + has been reported on a few transitions at lower excitation energy [14,15]. In our experiment, the first excitation step is done on the resonance line at 402 nm wavelength which couples the (6d 2 7s)J =3/2 ground state with the (6d 7s7p)J =5/2 state at 24874 cm −1 .…”

Section: Introductionmentioning

confidence: 99%

Energy levels of Th+between 7.3 and 8.3 eV

et al. 2013

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Using resonant two-step laser excitation of trapped 232 Th + ions, we observe 43 previously unknown energy levels within the energy range from 7.3 to 8.3 eV. The high density of states promises a strongly enhanced electronic bridge excitation of the 229m Th nuclear state that is expected in this energy range. From the observation of resonantly enhanced three-photon ionization of Th + , the second ionization potential of thorium can be inferred to lie within the range between 11.9 and 12.3 eV. Pulsed laser radiation in a wide wavelength range from 237 to 289 nm is found to provide efficient photodissociation of molecular ions that are formed in reactions of Th + with impurities in the buffer gas, leading to a significantly increased storage time for Th + in the ion trap.

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Nuclear radii of thorium isotopes from laser spectroscopy of stored ions

Cited by 20 publications

References 26 publications

TRIGA-SPEC: A setup for mass spectrometry and laser spectroscopy at the research reactor TRIGA Mainz

TRIGA-SPEC: A setup for mass spectrometry and laser spectroscopy at the research reactor TRIGA Mainz

Two-step Optical Excitation for Doppler Linewidth Reduction and Motion Study of Ions Stored in a Paul Trap

Energy levels of Th+between 7.3 and 8.3 eV

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