Pixelated scintillator array response to relativistic electrons
In order to make time resolved measurements of the gamma spectra on DARHT Axis 2 using the Compton Spectrometer (CS), the electron detector in the focal plane must be a scintillator that is optically coupled to a gated or streak camera. There are several issues we would like to address with experiments at Idaho Accelerator Center (IAC) before committing to a full size array (7”x2”), which would cost at least $100k. Two candidates for this application are organic (Bicron 422 or equivalent) or inorganic (LYSO) scintillator. Monte Carlo calculations were performed by Rachel Morneau, P-21, using MCNP to compare the two materials each 1.5mm thick for an energy range of 0.1 to 20MeV. The energy loss per particle in LYSO is much larger (100x) than in the plastic scintillator. We confirmed, by performing experiments with the CS on the Microton, that sensitivity of the LYSO was much larger (10x) than the plastic scintillator. Therefore, we have selected LYSO as the scintillator of choice. However, interest in the response of other organic and plastic scintillators prompted an increase in scope of the project. The goals of this experiment were as follows. First, we need to understand the optical response of the scintillators to electrons as a function of thickness, energy, and deposited charge. We also need to verify level of saturation in the scintillation process. Second, compare the scintillators’ response to an image plate (the current CS detector). Third, we need to quantify the effect of signal bleed through to adjacent pixels.