Study on the enhancement mechanism of detecting efficiency based on silica aerogel ultra-fast gamma-ray imaging with energy threshold

This paper develops an ultra-fast gamma-ray imaging detection technique with an energy threshold, based on the Cherenkov radiation effect of silica aerogel materials. The efficiency ratio of gamma to Cherenkov radiation in aerogel with different conversion target materials is studied by Monte Carlo simulation. A metal capillaries array structure is further proposed to enhance the conversion efficiency of gamma rays to electrons. The Monte Carlo simulation results indicate that, compared to aerogel block of equivalent thickness, the silica aerogel filled in metal capillaries array shows no advantage for the detection efficiency of gamma rays with energies below 2 MeV. However, for gamma rays with energies exceeding 2 MeV, the efficiency increases progressively with rising gamma energy; for energies greater than 10 MeV, the detection efficiency increases by 1 order of magnitude. The time response and imaging performance of the aerogel array are preliminarily tested on a 10 ps ultrahigh-speed electron accelerator, and the results prove its suitability for imaging, with a time response of less than 1 ns.