Design of a β-detector for TITAN-EC and the first electron-capture branching ratio measurement in a Penning trap

At TRIUMF's ion trap for atomic and nuclear science (TITAN) a new experimental technique is being developed to measure electron-capture branching ratios of intermediate nuclei in double-β decays. The key feature of this novel technique is the use of an open access Penning trap. Radioactive ions are stored inside the trap while their decays are observed. X-rays following an electron capture are detected by x-ray detectors radially installed around the trap. Electrons originating from β-decays are guided out of the trap by the Penning trap's strong magnetic field where they are then detected by a Si-detector. Detailed simulations have been performed to determine the size and characterize the efficiency of this detector. During a beam time with radioactive ¹⁰⁷In this β-detector has been used and for the first time an electron capture branching ratio has been determined with this novel technique of in-trap decay spectroscopy.