  In-situ purification of the gas used as stopping medium in a noble gas ion
catcher by operating the device at low temperatures of 60 to 150 K was
investigated. Alpha-decay recoil ions from a 223Ra source served as energetic
probes. The combined ion survival and transport efficiencies for 219Rn ions
saturated below about 90 K, reaching 28.7(17) % in helium, 22.1(13) % in neon,
and 17.0(10) % in argon. These values may well reflect the charge exchange and
stripping cross sections during the slowing down of the ions, and thus
represent a fundamental upper limit for the efficiency of noble gas ion catcher
devices. We suggest the cryogenic noble gas ion catcher as a technically
simpler alternative to the ultra-high purity noble gas ion catcher operating at
room temperature.
