New publication by the LMU group

The LMU Munich group has published a new paper on the characterization of their experimental set-up. Th-229 recoils (hopefully many of them in the isomeric state) are extracted from a thin U-233 source. The ions are cooled, collimated, and mass-filtered before being gently deposited on a micro-electrode. This part of the set-up has already been published here. Once the Th-229m ion settles on the micro-electrode, it might de-excite into the nuclear and electronic ground state under emission of photons: either the VUV gamma, or secondary photons generated during the de-excitation process. The present paper describes the optical set-up that allows for the detection of these photons: two annular parabolic mirrors image the emission from the micro-electrode onto an MCP, which is monitored by a CCD camera. Given the efficiency of all parts of the experiment and the noise of the detector, a signal-to-noise of 7000:1 can be achieved. The paper can be found on the arXiv preprint server.