SPORT: A new sub-nanosecond time-resolved instrument to study swift heavy ion-beam induced luminescence - Application to luminescence degradation of a fast plastic scintillator

TL;DR

This paper introduces SPORT, a sub-nanosecond time-resolved instrument for studying luminescence dynamics under heavy ion irradiation, revealing significant degradation mechanisms in plastic scintillators at high excitation densities.

Contribution

The paper presents a novel high-resolution instrument and applies it to analyze luminescence degradation in a plastic scintillator under heavy ion irradiation, highlighting new damage mechanisms.

Findings

Luminescence intensity decreases with increasing ion fluence.

Decay constant of scintillator reduces under high-density excitation.

Degradation is mainly due to static quenching mechanisms.

Abstract

We developed a new sub-nanosecond time-resolved instrument to study the dynamics of UV-visible luminescence under high stopping power heavy ion irradiation. We applied our instrument, called SPORT, on a fast plastic scintillator (BC-400) irradiated with 27-MeV Ar ions having high mean electronic stopping power of 2.6 MeV/\mu m. As a consequence of increasing permanent radiation damages with increasing ion fluence, our investigations reveal a degradation of scintillation intensity together with, thanks to the time-resolved measurement, a decrease in the decay constant of the scintillator. This combination indicates that luminescence degradation processes by both dynamic and static quenching, the latter mechanism being predominant. Under such high density excitation, the scintillation deterioration of BC-400 is significantly enhanced compared to that observed in previous investigations, mainly performed using light ions. The observed non-linear behaviour implies that the dose at which luminescence starts deteriorating is not independent on particles' stopping power, thus illustrating that the radiation hardness of plastic scintillators can be strongly weakened under high excitation density in heavy ion environments.