An LED pulser for measuring photomultiplier linearity

TL;DR

This paper presents an LED pulser system designed to accurately measure the linearity of photomultiplier tubes, offering a calibration-free approach that achieves high precision in response mapping.

Contribution

The novel LED pulser design enables precise PMT linearity testing without requiring multiple calibrated LEDs, improving measurement accuracy and simplicity.

Findings

Achieves better than 1% response mapping accuracy

Insensitive to LED gain drifts

Effective for developing linear PMT bases

Abstract

A light-emitting diode (LED) pulser for testing the low-rate response of a photomultiplier tube (PMT) to scintillator-like pulses has been designed, developed, and implemented. This pulser is intended to simulate 80 ns full width at half maximum photon pulses over the dynamic range of the PMT, in order to precisely determine PMT linearity. This particular design has the advantage that, unlike many LED test rigs, it does not require the use of multiple calibrated LEDs, making it insensitive to LED gain drifts. Instead, a finite-difference measurement is made using two LEDs which need not be calibrated with respect to one another. These measurements give a better than 1% mapping of the response function, allowing for the testing and development of particularly linear PMT bases.