A cryogenic electrostatic trap for long-time storage of keV ion beams

Abstract

We report on the realization and operation of a fast ion beam trap of the linear electrostatic type employing liquid helium cooling to reach extremely low blackbody radiation temperature and residual gas density and, hence, long storage times of more than 5 min which are unprecedented for keV ion beams. Inside a beam pipe that can be cooled to temperatures <15 K, with 1.8 K reached in some locations, an ion beam pulse can be stored at kinetic energies of 2-20 keV between two electrostatic mirrors. Along with an overview of the cryogenic trap design, we present a measurement of the residual gas density inside the trap resulting in only 2 x 10(3) cm(-3), which for a room temperature environment corresponds to a pressure in the 10(-14) mbar range. The device, called the cryogenic trap for fast ion beams, is now being used to investigate molecules and clusters at low temperatures, but has also served as a design prototype for the cryogenic heavy-ion storage ring currently under construction at the Max-Planck Institute for Nuclear Physics.

Assignment of resonances in dissociative recombination of HD+ions: High-resolution measurements compared with accurate computations

“…For HD + , the present results predict that the collision energy dependence of the DR rate coefficient for rotationally cold (N + i = 0) ions will be dramatically different from that observed here and in previous experiments with similar, near roomtemperature, rotational populations. The development of a cryogenic electrostatic ion storage ring suitable for electron-ion collision experiments with merged beams is in progress [47,48] and will make energy-resolved DR studies possible under conditions where rotational excitation by the thermal blackbody radiation is largely eliminated and the parent ions are rotationally cold.…”

Isobar separation and precision mass spectrometry of short-lived nuclides with a multi- reflection time-of-flight analyzer

“…In this arrangement the ions pass the first mirror ("injection"), are trapped between the mirrors, and are finally released by passing the second mirror ("ejection") towards the ion detector. Thus, this multi-reflection device can not only be used as a time-of-flight mass spectrometer, but also as an ion storage device [19][20][21], in which case it is often referred to as "electrostatic ion-beam trap" or similar.…”

Single-particle detection of products from atomic and molecular reactions in a cryogenic ion storage ring

“…The most advanced set-ups use cryogenic cooling machines to reduce the temperature of their beam guiding vacuum vessels down to values near that of liquid helium [11][12][13][14][15]. On the one hand, this results in a vastly improved residual gas pressure compared to conventional ultra-high vacuum (UHV) set-ups, with correspondingly longer ion storage times [16,17]. On the other hand, storage in such a cold environment allows infra-red-active molecular ions to de-excite to their lowest rovibrational levels prior to starting experiments-a significant improvement over roomtemperature ion-storage facilities [18,19].…”