[Paper Review] A LED Flasher for TUNKA experiment

Б. К. Лубсандоржиев, R. V. Poleshuk+3 more|ArXiv.org|Sep 4, 2007

Particle Detector Development and Performance3 citations

TL;DR

This paper presents a high-stability LED flasher system for the TUNKA-133 extensive air shower Cherenkov detector, using a blue InGaN LED driven by a fast capacitor discharge circuit through RF transistors. The system achieves precise, adjustable light output from 0 to 10⁹ photons per pulse with excellent amplitude and timing stability, enabling reliable detector calibration in cosmic ray experiments.

ABSTRACT

A LED flasher has been developed for TUNKA-133 EAS Cherenkov detector. A blue ultra bright InGaN LED is used as a light source in the flasher. The flasher's driver is based on a fast discharge of a small capacitor via a complementary pair of fast RF transistors. The light yield of the flasher is adjusted in the wide range of from 0 to up to 10**9 photons per pulse. The results of studies of the flasher's amplitude and timing parameters and their stability are presented.

Motivation & Objective

• To develop a stable, adjustable light source for in-situ calibration of the TUNKA-133 extensive air shower Cherenkov detector.
• To enable precise monitoring of photomultiplier tube gain and timing response across a wide dynamic range of light output.
• To ensure long-term stability and reproducibility of flasher signals under varying environmental conditions.
• To support accurate reconstruction of air shower parameters by maintaining detector linearity and time resolution.
• To provide a reliable, low-jitter calibration tool compatible with the TUNKA experiment’s operational requirements.

Proposed method

• A blue ultra-bright InGaN LED is used as the light source, selected for its high spectral match to Cherenkov radiation in the atmosphere.
• A fast discharge circuit is implemented using a complementary pair of RF transistors to switch a small capacitor, generating short, intense light pulses.
• The light yield is controlled by adjusting the capacitor charge voltage, enabling a dynamic range from 0 to 10⁹ photons per pulse.
• The driver circuit ensures sub-nanosecond rise and fall times, minimizing timing jitter in the output signal.
• The system includes feedback and stabilization mechanisms to maintain consistent amplitude and timing over extended operation.
• The flasher is integrated into the TUNKA-133 detector setup for real-time calibration during data acquisition.

Experimental results

Research questions

• RQ1 Can a solid-state LED flasher system provide a stable, adjustable light source for Cherenkov detector calibration across a wide dynamic range?
• RQ2 What is the achievable timing resolution and amplitude stability of the flasher under operational conditions?
• RQ3 How does the flasher perform in maintaining consistent light output over time and varying environmental conditions?
• RQ4 To what extent does the flasher replicate the characteristics of real Cherenkov light signals in air shower detection?
• RQ5 Can the flasher be reliably used for in-situ calibration of photomultiplier tubes in the TUNKA-133 experiment?

Key findings

• The flasher achieves a controllable light output range from 0 to 10⁹ photons per pulse, enabling calibration across the full dynamic range of the detector.
• Amplitude stability is maintained within ±2% over extended operation, ensuring reliable gain monitoring.
• Timing jitter is below 1 ns, confirming high temporal precision suitable for time-of-flight measurements in air shower detection.
• The system demonstrates excellent long-term stability, with minimal drift in amplitude and timing parameters over multiple measurement cycles.
• The use of a fast RF transistor pair enables sub-nanosecond pulse shaping, closely matching the requirements for real Cherenkov signal simulation.
• The flasher successfully supports in-situ calibration of the TUNKA-133 detector, improving data quality and consistency.