A microchannel detection system for DRAGON



The DRAGON facility at TRIUMF-ISAC was designed to measure the rates of astrophysically important nuclear reactions involving radioactive reactants. To this end, the mass spectrometer was designed to separate the result of a radiative proton or alpha capture reaction, between beam and target nuclei, from the beam itself. Yields are typically on the order 10−9 to 10−15, thus, the feasibility of a particular reaction is driven by the suppression of the relatively intense beam, to that of the capture product. In the case of Nova explosions, important resonances occur at low beam energies (0.15 to 1.0 MeV/u) where the DRAGON suppression may be reduced.

An MCP (Micro Channel Plate) detection system has been commissioned to be used in a local time-of-flight approach for particle identifcation at the focal plane of the DRAGON recoil mass separator. It is the goal of this additional detection system to enhance the current suppression systems without signifcant loss in effciency. Three properties of the MCP system have been investigated: the timing resolution, the effciency and the position resolution. Two sources, 68Ge and 148Gd, were used off-line to test the detection system performance. The timing studies were performed with the use of a fast PMT (Photo Multiplier Tube) as a second detection system. A DSSSD (Double Sided Silicon Strip Detector) was used for the effciency tests and masks were used during the position resolution studies. These off-line tests were followed by on-line studies of the well known resonance (Ecm = 258.6 keV) in the 21Ne(p,γ)22Na reaction. A simulation using the RELAX3D software along with a custom made tracking code, both written at TRIUMF, has also been studied, and its results pertaining to the three aforementioned important properties will be discussed.

Author: Lamey, M. J.