Introduction
Ion traps open up a new field of precision experiments in fundamental basic research as well as in applied fields. This is due to the fact that ion traps allow one to control the system under investigation for an extended period of time in a small well known location under well defined conditions. This is particularly important when working with short-lived synthesized isotopes, because the production is often rather cumbersome, and the yield is dropping if one approaches the specifically interesting regions further away from stability.
Ion traps, here in particularly Penning traps, can be employed to measure one of the intrinsic properties of such exotic isotopes, its mass. Systems that are capable of performing these important measurements exist presently at the following facilities for exotic species: ISOLDE, CERN, Switzerland (ISOLTRAP [1]); ATLAS, ANL, USA (CPT [2]); in preparation: SHIP, GSI, Germany (SHIPTRAP [3]); NSCL, MSU, USA (LEBIT [4]); IGISOL, JYFL, Finland (JYFLTRAP [5]). With ISAC having the potential to be the leading on-line facility, with the highest production yields and the possibilities to reach the most exotic isotopes, and the experiences from the existing trap systems, a second-generation facility for accurate mass measurements would have at this location the highest prospects and potentials. In fact, the Canadian Subatomic Five Year Plan Committee (SFYPC) made a clear statement in its June 2001 report [6]: ‘The committee also recommends that the CPT (this is the Canadian Penning Trap system at ANL; ed) group, together with a team located at TRIUMF, develop a detailed proposal in a timely fashion to establish a state-of-the-art Penning trap facility at TRIUMF (…) to exploit the available high intensity beams of exotic nuclei at ISAC. This could be a strong candidate for funding as a new initiative.’
Figure 1 shows the schematic layout of the TITAN (TRIUMF’s Ion Trap for Atomic and Nuclear science) facility. The separated continuous ion beam from ISAC is cooled and bunched using a gas-filled linear radio frequency quadrupole (RFQ) Paul trap. The ions are injected into an electron beam ion trap (EBIT), where charge breeding via electron stripping takes place. The beam is extracted and sent through an additional separation stage where contaminants (other charge states or isobars) could be removed by an m/q selection. The beam of high purity is transferred into the Penning trap where the mass of the ion of interest is determined.
The main purpose of the proposed facility is high accuracy mass measurements, but the novel scheme to couple a Penning trap mass spectrometer via an EBIT to an ISOL facility will also open up new experimental opportunities in nuclear, atomic and solid state physics. The research program will be outlined in the following sections.
Fig 1: Schematic layout of the TITAN system