Single crystal scintillation time spectrometry

Development of the single-detector time spectrometry procedure for investigation of short-lived isomeric and ground states of radioactive atoms in the nano- and microsecond range is summed up. A distinctive feature of the procedure is measurement in the 4π-geometry, which ensures a high recording efficiency for delayed coincidences. The mode of multidimensional delayed coincidences in one detector was first implemented at the Laboratory of Nuclear problems, JINR. The three-dimensional E1-T-E2 mode allows energy spectra corresponding to transitions exciting and de-exciting isomeric states to be recorded in addition to the time spectrum. Further development of this technique resulted in construction of a two-detector four-dimensional triple-coincidence spectrometer and thus demonstrated that the autocorrelation single-crystal time spectrometer, when included in the Crystal Ball configuration, can be effectively used to search for nuclear isomeric states. It becomes possible to investigate nuclei that have isomeric states without a low-efficiency laser ion source in the mass-separator, which is particularly important for investigation of short-lived nuclei in on-line experiments. The life-time accessible for single-detector delayed-coincidence spectrometers range from 4 ns to 100 s. A set of calibration sources of delayed coincidences for the time range from 4 ns to 4 μs and for energies from 10 keV is developed. Since the low-energy transition overlap the energy spectrum of photomultiplier after-pulsing, the amplitude-time characteristics of after-pulsing were studied for some types of photomultipliers