Beam diagnostics for low energy beams

Abstract

Low-energetic ion and antimatter beams are very attractive for a number of fundamental studies. The diagnostics of such beams, however, is a challenge due to low currents down to only a few thousands of particles per second and significant fraction of energy loss in matter at keV beam energies. A modular set of particle detectors has been developed to suit the particular beam diagnostic needs of the ultralowenergy storage ring (USR) at the future facility for low-energy antiproton and ion research, accommodating very low beam intensities at energies down to 20 keV. The detectors include beam-profile monitors based on scintillating screens and secondary electron emission, sensitive Faraday cups for absolute intensity measurements, and capacitive pickups for beam position monitoring. In this paper, the design of all detectors is presented in detail and results from beam measurements are shown. The resolution limits of all detectors are described and options for further improvement summarized. Whilst initially developed for the USR, the instrumentation described in this paper is also well suited for use in other low-intensity, low-energy accelerators, storage rings, and beam lines.

Laser spectroscopy of indium Rydberg atom bunches by electric field ionization

“…This not only includes collisional ions, but ions created by field ionization of collisionally excited or re-neutralised atoms in the field of the 20 bend to the ion detector, photoionization or molecular breakup, as all of these sources of background ions will remain at the lower beam energy. Alternatively the beam energy could be measured directly 105 , or the difference in detected time of flight of the ions could be used as a gate if the bunch width was sufficiently narrow. For example, the time of flight separation introduced in the ‘post-ionization’ region for the ions travelling at 25 keV is around 15 ns (Fig.…”

Design and construction of a secondary electron suppressed Faraday Cup for measurement of beam current in an electrostatics proton accelerator

“…In fact, as mentioned, the angular distribution of electrons outside the solid closely follows a cosine law. So, since SEs are not simply emitted from the surface perpendicular to the primary beam, their escape solid angle is greatly reduced depending on the selected angle [3,15].…”

Beam Diagnostics for Low Energy Antiprotons

“…Each pair measures the beam position only in one transverse direction and two pairs, rotated by 90˚ with respect to each other, are required. Cylindrical electrodes with a diagonal cut and additional separating rings to reduce parasitic coupling effects are foreseen [8]. The electrodes and rings are made of nonmagnetic stainless steel, whereas the outer shield is made of aluminum to reduce the overall weight of the monitor.…”

“…A Faraday Cup for femtoampere beams was designed, built and commissioned for use at the USR [8]. Its detection limits were determined in measurements with beam at INFN-LNS.…”