Scintillators with Silicon Photomultiplier Readout for Timing Measurements in Hadronic Showers

The advent of silicon photomultipliers has enabled big advances in high energy physics instrumentation, for example by allowing the construction of extremely granular hadronic calorimeters with photon sensors integrated into small scintillator tiles. Direct coupling of the SiPM to the plastic scintillator, without use of wavelength shifting fibers, provides a fast detector response, making such devices well suited for precise timing measurements. We have constructed a setup consisting of 15 such scintillator tiles read out with fast digitizers with deep buffers to measure the time structure of signals in hadronic calorimeters. Specialized data reconstruction algorithms that allow the determination of the arrival time of individual photons by a detailed analysis of the recorded waveforms and that provide automatic calibration of the gain of the photon sensor, have been developed. We will discuss the experimental apparatus and the data analysis. In addition, we will report on first results obtained in a hadronic calorimeter with tungsten absorbers, providing important constraints on the time development of hadronic showers for the development of simulation models.