A cylindrical ionization chamber with a grid is used to search for dou
ble positron decay and atomic electron conversion to a positron in Kr-
78. Krypton is the working gas material of the chamber. The spectromet
ric characteristics of the chamber filled with krypton and xenon are p
resented. The energy resolution is 2.1% for an energy of 1.84 MeV (the
source of gamma-quanta is Y-88) when the chamber is filled with a mix
ture of Kr+0.2% H-2 under a pressure of 25 atm.