The Paul trap: A radiofrequency-quadrupole ion trap for precision studies

The β - decay Paul trap is a linear radiofrequency-quadrupole ion trap that has been developed for precision β - decay studies. The design of the trap electrodes allows a variety of radiation detectors to surround the cloud of trapped ions. The momentum of the low-energy recoiling daughter nuclei following β decay is negligibly perturbed by scattering and is available for study. This advantageous property of traps allows the kinematics of particles that are difficult or even impossible to directly detect to be precisely reconstructed using conservation of energy and momentum. An ion-trap system offers several advantages over atom traps, such as higher trapping efficiencies and element-independent capabilities. The first precision experiment using this system is a measurement of β - decay angular correlations in the decay of 8Li performed by inferring the momentum of the neutrino from the kinematic shifts imparted to the breakup α particles. Many other β - decay studies that would benefit from a determination of the nuclear recoil can be performed with this system.