Active gas target project at Michigan State University: toward more versatile and selective studies of radioactive beam reactions

by Dr Daisuke Suzuki (NESTER, IPN)

Wednesday 18 Jul 2012, 14:30 → 15:10 Europe/Zurich

26-1-0022 (CERN)

Nuclear reactions have been a robust tool throughout the history of nuclear physics. Their capability of giving access to various observables and their selective nature, for instance, in populating a specific state of interest, are instrumental in enhancing our view of the subatomic world. Experimentally, an essential element to ensure these qualities – versatility and selectivity – is reaction targets. In the past decade, reaction studies using radioactive beams have been growing in importance as a probe of structures or reaction dynamics of unstable nuclei, but at the same time it has been a big experimental challenge. The critical bottle neck is target thickness. A thin target is necessary to detect low energy ions from collision between a heavy ion beam and a light ion target, while it limits luminosity and thus narrows down the path to rarer processes or more exotic nuclei. A time projection chamber, AT-TPC, currently under development at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University, is meant to provide an ‘active target’ for high resolution and efficient reaction studies at the future re-accelerated radioactive beam facility of the NSCL. The defining feature of this time projection chamber is its tracking gas medium simultaneously acting as a reaction target, which enables us to measure trajectories as well as energy losses inside the reaction target, thus making it possible to increase the target thickness with retaining the quality of ion detection. To study feasibility of envisioned detector technologies as well as to produce scientific results at early stages of the project, a half scale prototype was constructed and commissioned in 2011. Two radioactive beam experiments were performed at the Twinsol facility at the University of Notre Dame. In this talk, the current status of the AT-TPC project will be presented with a focus on the prototype and the experiments at Notre Dame.