Employees of MEPhI Departments №10 and №78 have worked out and tested a linear quadrupole ion trap for optical spectroscopy of nuclear and electronic transitions. The ion source construction is based on ultrahigh-vacuum vaporizer in which an atom and ion cloud of different charge is created because of irradiating the object by an electron beam with energy up to 1 keV. The linear ion trap consists of 5 consecutive quadrupole sections: an input quadrupole, a quadrupole mass filter, a quadrupole ion trap and an output quadrupole. A high-frequency stress component is the same in different sections but the breakdown voltage values are different which helps create a flexible instrument for ion assemblies forming and spectroscopy measuring.
The device makes filtration and ion trapping possible in the range of masses and energies of ion beams with a wide energy spectrum and ion localization in the area of ion beam impact. The suggested theory and device allow to effectively produce thorium ions, up to triple-charged ones and trap them for further spectroscopy. The device will be used in optical clock and quantum computer development.
Nowadays creation of an atomic clock is a prior task in time and frequency metrology. The exact measuring of nuclear isomeric transition 229mTh – 229g will allow to develop an optical nuclear frequency standard with a relative precision ~10–20 which exceeds existing “caesium fountain” type of frequency standard (10–15).
However, there are some restriction because of thorium. It is a refractory metal with high boiling temperature and low vapor pressure so ionization requires methods with high energy and leads to the production of ions with large energy range. Moreover, 229Th is radioactive. Hence, the method of ion trapping in a vacuum should be worked out for effective work in different energy ranges.
