Cyclotron trap

Abstract

The cyclotron trap was developed at SIN/PSI to increase the stopping density of negatively charged particle beams for the formation of exotic atoms in low pressure gases. A weak focusing magnetic field, produced by superconducting solenoids, is used. Particles are injected radially through the fringe field to a moderator, which decelerates them into orbits bound by the field. Further deceleration by moderators and/or low-pressure gases leads the particles to the centre of the device, where they can be stopped or eventually extracted. Experiments became feasible with this technique, such as those dealing with pionic hydrogen/deuterium at SIN/PSI. Muonic hydrogen laser experiments also became possible with the extraction of muons from the cyclotron trap. The formation of antiprotonic hydrogen in low pressure targets led to successful experiments at LEAR/CERN.

Pionic hydrogen and deuterium

“…In order to improve the quality of the results for the strong-interaction effects compared to previous experiments [27][28][29][30][31], a specifically developed cyclotron trap [32] was used together with a Johann-type spectrometer equipped with spherically bent Bragg crystals as well as a large area array of charge-coupled devices (CCDs) [33]. The experiment benefited from a 4-fold higher beam intensity provided at the Paul Scherrer Institute (Villigen, Switzerland).…”

Pionic hydrogen and deuterium

“…The possibility of performing high-statistics experiments of exotic hydrogen even in dilute targets with high-resolution devices like crystal spectrometers became possible by using the cyclotron trap (Section 13 [8]). Figure 14.1 shows the set-up of cyclotron trap and crystal spectrometer for the studies described here [7,[9][10][11].…”

“…Consequently, the ultimate knowledge of the spectrometer response is of great importance. Here, the cyclotron trap offers another unique possibility when extended to operate as ECR source (Section 13 [8]). The ECR source yields narrow X-rays at high rates from helium-like low Z elements like sulphur, chlorine, and argon which almost coincide in energy with the pionic hydrogen and deuterium X-ray transitions.…”