A laser diode based system for calibration of fast time-of-flight detectors

TL;DR

This paper presents a cost-effective laser diode-based system for calibrating multi-channel time-of-flight detectors with photomultiplier readouts, achieving high timing precision suitable for advanced particle detection applications.

Contribution

It introduces a novel calibration system using commercially available components, overcoming power limitations and component availability issues in the visible spectrum.

Findings

Achieved calibration resolution of 20-30 ps.

Demonstrated calibration of detectors with 50-100 ps timing resolution.

Validated optical components for visible light calibration systems.

Abstract

A system based on commercially available items, such as a laser diode, emitting in the visible range $\sim 400$ nm,and multimode fiber patches, fused fiber splitters and optical switches may be assembled,for time calibration of multi-channels time-of-flight (TOF) detectors with photomultipliers' (PMTs') readout. As available laser diode sources have unfortunately limited peak power, the main experimental problem is the tight light power budget of such a system. In addition, while the technology for fused fiber splitters is common in the Telecom wavelength range ($\lambda \sim 850, 1300-1500$ nm), it is not easily available in the visible one. Therefore, extensive laboratory tests had to be done on purpose, to qualify the used optical components, and a full scale timing calibration prototype was built. Obtained results show that with such a system, a calibration resolution ($\sigma$) in the range 20-30 ps may be within reach. Therefore, fast multi-channels TOF detectors, with timing resolutions in the range 50-100 ps, may be easily calibrated in time. Results on tested optical components may be of interest also for time calibration of different light detection systems based on PMTs, as the ones used for detection of the vacuum ultraviolet scintillation light emitted by ionizing particles in large LAr TPCs.