4H-Silicon Carbide as particle detector for high-intensity ion beams

TL;DR

This study explores 4H-Silicon Carbide sensors as fast, radiation-hard detectors for high-intensity ion beams, demonstrating their potential for precise beam monitoring in medical and physics applications.

Contribution

It presents measurements on 4H-SiC sensors with different geometries, testing their performance across a wide intensity range and analyzing their suitability for high-rate beam detection.

Findings

Micro-strip SiC sensors with ASIC readout can partially recover signals.

Sensors can measure ionization energy and electron/hole pairs.

Detection of MIP particles is limited with current electronics setup.

Abstract

In ion cancer therapy, high-intensity ion beams are used to treat tumors by taking advantage of the Bragg-Peak. Typical ion therapy centers use particle rates up to $10^{10}$ ions/second for treatment. On the other hand, such intensities are often too high when using these beamlines for particle physics experiments or as a test-beam environment in general. The project presented here aims to develop a beam position and intensity monitor, to cover a wide intensity range from a few Hz up to GHz rates, as used in clinical settings. Silicon carbide (SiC) is an attractive detector material for this application because it combines potential high radiation hardness with high thermal conductivity to avoid cooling. Moreover, its high electron saturation velocity allows very fast signals to mitigate pile-ups. However, some special properties of the material like different crystal polytypes have to be considered. In this paper, measurements on both a pad and a micro-strip SiC sensor prototype of 4H lattice geometry are shown. The sensors were tested in the laboratory using radioactive sources and with a proton beam in a wide intensity range (kHz-GHz) and with different energies (60-800 MeV) available at MedAustron, an ion cancer therapy center located in Austria. The measurements show that MIP particles cannot be detected reliably with the used discrete electronics setup in combination with the single-channel sensor. However, the strip sensor combined with an ASIC-based readout electronics from the CMS/Belle-II experiments allows to recover a certain part of the signal. This makes it possible to determine the ionization energy and average number of electron/hole pairs generated in the studied sensor samples.