Prototype AT-TPC: Toward a new generation active target time projection chamber for radioactive beam experiments

The Prototype AT-TPC, a detector based on time projection chamber (TPC) technology was built at the National Superconducting Cyclotron Laboratory, Michigan State University. The chamber gas, called the active target, of the Prototype AT-TPC is utilized simultaneously as a reaction target and a tracking medium of charged particles for measuring low-energy nuclear reactions. In pursuit of luminosity, efficiency and resolution for reaction studies at a new generation of radioactive isotope facilities, the Prototype AT-TPC provides one of the largest active volumes in the world measuring 25 cm in diameter and 50 cm long along the beam axis, millimeter-precision tracking capability, and a high electric field of 1 kV/cm/atm for fast electron drift, which limits the detector dead time. Commissioning of the detector using standard alpha sources and radioactive 6He beams has demonstrated the detector's long-term stability as well as its performance, which allowed good reconstruction of reaction kinematics.