Speaker
Description
Conventional muon-spin rotation, relaxation, and resonance ($\mu$SR) experiments rely on trigger-based data acquisition systems, in which the arrival of an individual muon initiates a fixed readout window. At continuous muon sources, this approach fundamentally limits the achievable muon rate. To overcome these constraints, we present the design and implementation of a fully triggerless data acquisition (DAQ) system tailored for high-rate $\mu$SR applications.
The proposed DAQ operates in a continuous readout mode, recording all detector hits from silicon pixel sensors and fast scintillators without the use of a hardware trigger. Event building is performed retrospectively by correlating the timing and spatial information of muon and positron tracks, enabling the reconstruction of decay pairs entirely in software or firmware.
The system is based on FPGA front-end boards originally developed for the high-rate particle physics experiment Mu3e, supporting zero-suppressed, time-unsorted data streams at 1.25 Gbit/s per detector chip. Multiple front-end boards are synchronized and aggregated using an Arria~10 FPGA board with high-speed optical links and PCIe readout to a host PC. This architecture supports sustained data rates corresponding to muon intensities of up to $10^8$ $\mu$/s.
We discuss the DAQ concept, synchronization strategy, data flow, and scalability, and present results from test beam measurements conducted at the Paul Scherrer Institute using silicon pixel and fast scintillating detectors. The system establishes a flexible and extensible DAQ framework for next-generation $\mu$SR experiments at continuous beam facilities.
| Minioral | Yes |
|---|---|
| IEEE Member | No |
| Are you a student? | No |