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Abstract

The Cryogenic electrostatic Trap for Fast ion beams (CTF) has been successfully built, fulfilling the Cryogenic Storage Ring (CSR) project goals of developing and testing the technologies and concepts to build this instrumentally challenging device, and demonstrating rest-gas-densities on the order of 2000 particles/cm^3 (or a room-temperature equivalent pressure of 8x10^{-14} mbar) with mean storage lifetimes of over 5 min for 7.1 keV N_2^+ ions. Since this is the first cryogenic electrostatic ion beam trap (EIBT), the resulting environment of greatly reduced blackbody radiation was exploited by investigating the time dependence of delayed electron emission from aluminum cluster anions at different temperatures. Dramatic deviations from the commonly observed 1/t decay of hot clusters were observed, demonstrating this decay's dependence on the temperature of the storage environment. Delayed emission following the excitation of the aluminum clusters with a pulsed laser was also observed. The results indicate a considerable reduction in the cluster temperature than seen so far and raises questions about the validity of the present model. The very low rest gas densities achieved also enabled the exploration of many properties of self-bunching and RF bunching with unprecedented sensitivity. An in-situ mass-selection technique exploiting the resonant transverse excitation of the stored ions was also demonstrated inside an EIBT for the first time.