Speaker
Description
TRIUMF Annular Chamber for Tracking and Identification of Charged Particles (TACTIC) is a cylindrical Active Target Time Projection Chamber (TPC) designed to study alpha-induced charged-particle reactions of astrophysical importance at the relevant energies. The reaction cross section measurements rely on the tracking and identification of the reaction products by means of differential energy loss in the gaseous detection volume. In order to detect the reaction products over a wide range of energies (tens of keV to a few MeV), the novel μ-RWELL (micro-Resistive WELL) detectors are used in TACTIC as the gas multiplication stage. An unique central cathode cage configuration enables the detector to accommodate higher beam intensities (in the order of 107 pps) compared to other active target detectors. This specific feature, combined with a high detection efficiency, allows the measurements of low cross sections (in the order of μb) utilising radioactive ion beams in the astrophysically important energy regions of interest. The thick target technique enables the excitation function over the energy region of interest to be measured simultaneously with one beam energy, resulting in a time-efficient measurement.
We evaluate the performance of large-area μ-RWELL detectors in both planar and cylindrical geometries across various gas mixtures. Key parameters including gas gain and energy resolution achievable are investigated using alpha and 55Fe X-ray sources. Particular emphasis is placed on the characterisation of μ-RWELL in helium-based gas mixtures, motivated by the use of helium as the most common target gas in Active-Target detectors for studying alpha-induced nuclear reactions.
Furthermore, we demonstrate sub-keV energy detection capability and an energy resolution of 9%, highlighting the sensitivity to low-ionising charged particles for ion beam experiments. Finally, we report the successful in-beam experiments with TACTIC at TRIUMF, demonstrating for the first time the implementation of μ-RWELL detectors in a curved geometry for such applications.