4π- and 8π-spectrometers for gamma-radiation studies

4π- and 8π-spectrometers for gamma-radiation studies on accelerated hard ion beam are described. Various operational aspects of the 8π-spectrometer, consisting of an internal 4π- spectrometer, used to measure total absorption energy of gamma-quant cascade and being its (gamma-quant) multiplicity filter and external 4π-spectrometer involving a system of anticompton spectrometer with semiconductor detectors are analyzed. Data on such spectrometers in operation and on those that will be in operation in future as well as on spectrometers being under design at present are considered. Calculation results of multiplicity coincidence probability at different multiplicity values of gamma-quant ejection are given. 8π-spectrometers will efficiently be used in the ion beam researches from lithium to uranium in the energy region from 3-5 to 60-70 MeV/nuclei