TACTIC: A new detector for Nuclear Astrophysics Experiments

Directly measuring nuclear astrophysics reactions presents unique challenges. Low energy reaction products and small reaction cross sections are just two of the issues that the TACTIC detector addresses. TACTIC is the "TRIUMF Annular Chamber for Tracking and Identification of Charged-particles" detector being developed by TRIUMF and the University of York, UK. TACTIC is a cylindrical, active-target TPC providing high detection efficiency; a "shielding" cathode traps the ionization created by the beam and allows for higher intensities than typical TPCs. The 480 anode signals are collected through custom preamplifiers, digital electronics and acquisition systems. Acquisition and analysis software is also undergoing extensive development. Amplification of the small signals is accomplished using a Gas Electron Multiplier (GEM). The fill gas, He-CO₂, provides both particle detection and a homogeneous, variable-thickness target for studying reactions on αs, such as ⁸Li(α,n)¹¹B. A preliminary study of this flagship reaction was carried out in June 2009 and the results are providing feedback into the development of the final detector and infrastructure.