Development of Micromegas-based Active-Target Time Projection Chamber for Nuclear Astrophysics Studies

Abstract

A Micromegas-based active-target detector named SAT-TPC (Saha Active Target TPC) has been designed and fabricated at the Saha Institute of Nuclear Physics. The SAT-TPC was tested with Ar-CO2 (90:10) and Ar-iC4H10 (95:5) at atmospheric pressure. The Micromegas detector was first characterized in a small test chamber to optimize the ratio between the drift and amplification fields to maximise electron transparency. After establishing the optimal operating parameters, the same Micromegas detector was employed as the readout plane of the SAT-TPC prototype. The energy resolution for 55Fe and 241Am was estimated. A straightforward analysis of α-particle tracks has been carried out, demonstrating the pad plane's capability to accurately reconstruct the direction and length of trajectories. A hydrodynamic model based on Geant4, Garfield++ and COMSOL was used to emulate the reconstructed α-tracks in the active gas volume. The results show good agreement with simulations, confirming the accuracy of the models employed for α-particles in Ar-CO2 (90:10) and Ar-iC4H10(95:5) gas.

Figures (16)

• Figure 1: Images of (a) Stainless-steel wire mesh with $\sim$63 $\mu$m pitch, (b) Mesh surface showing supporting pillars of $\sim$400 $\mu$m diameter and 2 mm pitch.
• Figure 2: Experimental setup with Micromegas
• Figure 3: Typical 5.9 keV X-ray spectrum recorded by the anode plane of prototype Micromegas operated with Ar+CO$_2$ (90:10) mixture at atmospheric pressure
• Figure 4: Electron transmission as a function of drift field for the Micromegas detector. The measurement was performed at a constant amplification field of 40.8 kV in Ar+CO$_2$ (90:10) and 26.5 kV in Ar+iC$_4$H$_{10}$ (95:5) mixtures at atmospheric pressure
• Figure 5: Schematic diagram of the prototype SAT-TPC setup