The SpecMAT active target

Abstract

SpecMAT is a magnetic active target (AT) for transfer reaction studies with low-intensity radioactive ion beams at the ISOLDE facility (CERN). SpecMAT combines two types of detectors: a gas-filled time projection chamber (TPC), the core detector for tracking charged particles emitted in nuclear reactions, and an array of auxiliary scintillation detectors for in-flight γ-ray spectroscopy. All active target components are optimised for operation in a strong background magnetic field. The TPC has a cylindrical shape. Its electron detector is a bulk Micromegas segmented into 2916 triangular pads for sampling charged particle tracks. The scintillation array is composed of 45 detectors with cubic 48 × 48 × 48 mm3 CeBr3 crystals. The General Electronics for TPC (GET) is used in SpecMAT to read out both detector types allowing correlation of the detected γ-rays with the TPC events. This article describes the SpecMAT active target and its characterisation with the α-decay of 241Am. A γ-ray spectrum obtained in correlation with 3D tracks left by charged particles in an active target is reported for the first time for such detectors.