Prospects for measuring the 229Th isomer energy using a metallic magnetic microcalorimeter☆

  title={Prospects for measuring the 229Th isomer energy using a metallic magnetic microcalorimeter☆},
  author={Georgy A. Kazakov and Viktoria Schauer and Janine Schwestka and Simon Stellmer and Johannes H. Sterba and Andreas Fleischmann and Loredana Gastaldo and A. Pabinger and Christian Enss and Thorsten Schumm},
  journal={Nuclear Instruments \& Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment},
  pages={229 - 239}
  • G. Kazakov, V. Schauer, +7 authors T. Schumm
  • Published 13 June 2013
  • Medicine, Physics
  • Nuclear Instruments & Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment
The Thorium-229 isotope features a nuclear isomer state with an extremely low energy. The currently most accepted energy value, 7.8±0.5 eV, was obtained from an indirect measurement using a NASA x-ray microcalorimeter with an instrumental resolution 26 eV. We study, how state-of-the-art magnetic metallic microcalorimeters with an energy resolution down to a few eV can be used to measure the isomer energy. In particular, resolving the 29.18 keV doublet in the γ-spectrum following the α-decay of… 
Towards a precise determination of the excitation energy of the Thorium nuclear isomer using a magnetic bottle spectrometer
Abstract 229Th is the only known nucleus with an excited state that offers the possibility for a direct laser excitation using existing laser technology. Its excitation energy has been measured
Preparing an Isotopically Pure 229Th Ion Beam for Studies of 229mTh.
The presented method allowed for a first direct identification of the decay of the thorium isomer, laying the foundations to study its decay properties as prerequisite for an optical control of this nuclear transition.
X-ray pumping of the 229Th nuclear clock isomer
Active optical pumping is presented using narrow-band 29-kiloelectronvolt synchrotron radiation to resonantly excite the second excited state of 229Th, which then decays predominantly into the isomer, enabling accurate determination of the 229mTh isomer’s energy, half-life and excitation linewidth.
Energy of the 229Th nuclear clock transition
The method combines nuclear and atomic physics measurements to advance precision metrology, and the findings are expected to facilitate the application of high-resolution laser spectroscopy on nuclei and to enable the development of a nuclear optical clock of unprecedented accuracy.
Feasibility study of internal conversion electron spectroscopy of 229mTh
Abstract.With an expected energy of 7.8(5) eV, the isomeric first excited state in 229Th exhibits the lowest excitation energy of all known nuclei. Until today, a value for the excitation energy has
The concept of laser-based conversion electron Mössbauer spectroscopy for a precise energy determination of 229mTh
Abstract229Th is the only nucleus currently under investigation for the development of a nuclear optical clock (NOC) of ultra-high accuracy. The insufficient knowledge of the first nuclear excitation
Experimental search for the low-energy nuclear transition in 229Th with undulator radiation
To search for the lowest energy nuclear isomeric transition in 229Th in solid samples, a novel adsorption technique which prepares 229Th atoms on a surface of CaF2 is developed. Adsorbed 229Th is
Recent progress in laser spectroscopy of the actinides
The interest to perform laser spectroscopy in the heaviest elements arises from the strong impact of relativistic effects, electron correlations and quantum electrodynamics on their atomic structure.
Direct detection of the 229Th nuclear clock transition
The direct detection of this nuclear state of 229mTh is reported, which is further confirmation of the existence of the isomer and lays the foundation for precise studies of its decay parameters.
Nuclear clocks based on resonant excitation of γ-transitions
Abstract 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


Energy splitting of the ground-state doublet in the nucleus 229Th.
The energy splitting of the 229Th ground-state doublet is measured to be 7.6+/-0.5 eV, significantly greater than earlier measurements. Gamma rays produced following the alpha decay of 233U (105
Towards a direct transition energy measurement of the lowest nuclear excitation in229Th
The isomeric first excited state of the isotope 229Th exhibits the lowest nuclear excitation energy in the whole landscape of known atomic nuclei. For a long time this energy was reported in the
Observation of the deexcitation of the (229m)Th nuclear isomer.
The first direct observation of the deexcitation of the lowest-lying isomeric state in (229)Th is reported, which lays the groundwork for optical and laser spectroscopy of (229m)Th nuclear isomer and the development of a new type of clock based on this nuclear transition.
Optical spectroscopy of an atomic nucleus: Progress toward direct observation of the 229Th isomer transition
Abstract The nucleus of the thorium-229 isotope possesses a first excited nuclear state ( 229m Th) at an exceptionally low energy of 7.8±0.5 eV above the nuclear ground state ( 229g Th), as
The search for the existence of 229mTh at IGISOL
An overview of preparatory work aiming at the identification of the low-lying 7.6 eV isomer in 229Th through a measurement of its hyperfine structure is presented. A 233U recoil gas cell has been
Features of the low-energy level scheme of 229Th as observed in the α-decay of 233U
Abstract The γ-radiation emitted following the α-particle decay of 233 U has been studied using a variety of Ge(Li) spectrometers and a Si(Li) spectrometer system. Analysis of γ-singles and γγ
Nuclear laser spectroscopy of the 3.5 eV transition in Th-229
We propose high-resolution laser spectroscopy of the 3.5 eV nuclear transition in Th-229 in isolated atoms. Laser excitation of the nucleus can be detected efficiently in a double-resonance method by
Improved Value for the Energy Splitting of the Ground-State Doublet in the Nucleus 229mTh
We have made an improved estimate of the {sup 229m}Th isomer energy. The new value, 7.8(5) eV, includes an estimate of possible spectral contamination effects due to the out-of-band E2 transition
An excited state of 229Th at 3.5 eV.
  • Helmer, Reich
  • Physics, Medicine
    Physical review. C, Nuclear physics
  • 1994
It has been known for many years that the first excited state of [sup 229]Th lies close to the ground state, and in an attempt to improve the value for this level energy, a number of [gamma] rays from [sup 223]U whose positions in the [sup229]Th level scheme can be used to establish it.
Constraining the evolution of the fundamental constants with a solid-state optical frequency reference based on the 229Th nucleus.
It is argued that the 229Th optical nuclear transition may be driven inside a host crystal with a high transition Q to allow for the construction of a solid-state optical frequency reference that surpasses the short-term stability of current optical clocks, as well as improved limits on the variability of fundamental constants.