Transport Efficiency of the St. Benedict RF Carpet

The Superallowed Transition BEta NEutrino Decay Ion Coincidence Trap (St. Benedict), currently under construction at the University of Notre Dame Nuclear Science Laboratory (NSL) will be used to measure the mixing ratio of mirror nuclides to test the Standard Model. The St. Benedict will include four major components: a gas catcher, a differentially-pumped extraction system, a radio-frequency quadrupole (RFQ) cooler and buncher, and a Paul trap. The differentially-pumped extraction system  will include two chambers pumped separately. Assuming the gas catcher is operated at 100 mbar, the first chamber will be pumped down to about 3 mbar, while the second chamber will have a pressure of about 10^-3 mbar. The first chamber will use a radio-frequency carpet for the ion transport while the second chamber will use a RFQ ion guide. To test the transport of ions on the RF carpet several tests were first done in a chamber with static gas, reaching transport efficiency above 90%. Then we installed the carpet in the differentially-pumped extraction system chamber and tested ion transport with gas flow. We also studied RF carpet transport efficiency for different pressures.