Speaker
Description
Decay spectroscopy at DESPEC requires an active implanter for reliable implantation–decay correlations under cocktail-beam conditions, at high rates, over a large dynamic range, and in strong background conditions. In the current DESPEC setup, AIDA serves as the workhorse implanter, but its decay-event time resolution exceeds 1 μs, and its implantation/decay-pair efficiency in real experiments is typically 25–35%, which limits fast-timing applications. To address this, the Fibre IMPlanter (FIMP) is being developed as a scintillator-based alternative to conventional DSSSD implant detectors.
FIMP is based on orthogonal layers of 0.5 × 0.5 mm² scintillating fibres read out by SiPMs, forming a highly segmented three-dimensional active volume with 2 × 2 × 2 mm³ voxels. Its key novelty is the combination of active stopping, fine 3D segmentation, timing information relevant for implantation–decay correlation studies, and the possibility of charged-particle tracking of implanted ions, β particles, α particles, and secondary fragments. This is particularly attractive for complex cocktail beams, where high granularity and tracking can support isotope identification, background suppression, and improved correlation efficiency. For this geometry, the single-layer detection threshold is of the order of 100 keV, while the effective voxel size is expected to be about 3–4 mm for 1 MeV β particles.
Prototype studies, simulations, and in-beam tests in 2024 and 2025 validated the active-stopping concept, demonstrated detector response to heavy fragments and correlated β/α signals, and guided the next detector iteration. In the July 2025 test, FIMP was operated with fragments ranging from 132Sn to 225Th in four settings, with stable detector performance under beam conditions. Current development is focused on improving detector sensitivity and reducing the β-detection threshold. FIMP thus represents a realistic active implanter for future fast decay-spectroscopy experiments at DESPEC/FAIR.