Picosecond timing of Microwave Cherenkov Impulses from High-Energy Particle Showers Using Dielectric-loaded Waveguides

TL;DR

This paper demonstrates picosecond-level timing of microwave impulses generated by high-energy particle showers using dielectric-loaded waveguides, enabling precise timing in high-energy physics detectors.

Contribution

First measurement of microwave impulses from particle showers in dielectric-loaded waveguides, showing potential for high-precision timing in physics experiments.

Findings

Microwave impulses proportional to bunch energy observed.

Relative timing precision of 2.3 picoseconds achieved.

Waveguides with alumina bars are promising for radiation-hard timing detectors.

Abstract

We report on the first measurements of coherent microwave impulses from high-energy particle-induced electromagnetic showers generated via the Askaryan effect in a dielectric-loaded waveguide. Bunches of 12.16 GeV electrons with total bunch energy of $\sim 10^3-10^4$ GeV were pre-showered in tungsten, and then measured with WR-51 rectangular (12.6 mm by 6.3 mm) waveguide elements loaded with solid alumina ($Al_2 O_3$) bars. In the 5-8 GHz $TE_{10}$ single-mode band determined by the presence of the dielectric in the waveguide, we observed band-limited microwave impulses with amplitude proportional to bunch energy. Signals in different waveguide elements measuring the same shower were used to estimate relative time differences with 2.3 picosecond precision. These measurements establish a basis for using arrays of alumina-loaded waveguide elements, with exceptional radiation hardness, as very high precision timing planes for high-energy physics detectors.