Investigating photomultiplier tube nonlinearities in high-speed phosphor thermometry using light emitting diode simulated decay curves

Abstract

Photomultiplier tube (PMT) nonlinearities relevant for single shot high-speed lifetime phosphor thermometry were investigated by simulating decay curves with a light emitting diode (LED) at repetition rates between 1 Hz and 10 kHz. The PMT gain, LED decay time, and background radiant flux were also varied to investigate their impact on the measured decay time error. Errors in the measured decay time due to nonlinear PMT performance lead to temperature measurement errors; therefore, having the measured decay time sensitive to only phosphor temperature is highly valuable for more reliable temperature measurements. Photocathode bleaching had a significant impact on the signal level linearity for PMTs with excitation frequency in the kHz regime but had a smaller impact on the decay time error. Space charge effects were most noticeable at high radiant flux levels and high repetition rates. Strong background radiant flux may lead to decay time errors, and a gateable photocathode could be an effective method to reduce decay time errors. The best decay time measurement configuration to maximize precision without sacrificing accuracy is to use PMT gain in the recommended range and the highest radiant flux where the PMT response is still linear. The degree of nonlinearity in the PMT response is partly detector dependent; therefore, the results in this work may differ among detectors; however, the analysis presented in this work provides guidelines for improving the temperature accuracy of kHz lifetime phosphor thermometry measurements.

Overview of high-power LED life prediction algorithms

“…The light source life serves as a pivotal technical parameter for evaluating the reliability and quality of a light source, necessitating research into life prediction (Lee and Kim, 2021). Accelerated aging life tests demonstrate that factors such as temperature, humidity, and chemical corrosion induce light decay (Feuk et al, 2021), impacting the overall service life of the light source. Therefore, this chapter initiates by elucidating the influence of LED device materials on the light source's lifespan, delving into the characteristics of different devices, and encapsulating the future development trends.…”

Study on nonlinearity measurement of photomultiplier tubes by continuous neutral optical attenuator

“…With the increase in the number of photoelectrons, the voltage loss between PMT multipliers increases, which is called the space charge effect [6,7] . This effect interferes with the signal output of the tail multiplier and anode, making the PMT output signal nonlinear [8][9][10] . The accurate calibration of PMT charge nonlinearity is very important for some energy-measuring detectors or detectors with high requirements for charge measurement accuracy.…”