Application of material budget imaging for the design of the ATLAS ITk strip detector

• Published in: Journal of instrumentation Vol. 17; no. 10; p. C10014
• Main Authors: Arling, J.-H., Gregor, I.-M.
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.10.2022
• Subjects: Budgets; Deflection; Interaction of radiation with matter; Multiple scatter; Particle tracking detectors (Solid-state detectors); Particle trajectories; Radiation; Radiation counters; Solid state detectors; Strip; Trajectory measurement
• ISSN: 1748-0221; 1748-0221
• DOI: 10.1088/1748-0221/17/10/C10014

Abstract The technique of material budget imaging (MBI) allows to experimentally assess the material budget ϵ = x / X 0 of a material with thickness x and its radiation length X 0 . Here, multi-GeV electrons from a test beam facility such as the DESY-II test beam are used. This novel technique exploits the fact that the beam particles are deflected by multiple Coulomb scattering following a distribution of the deflection angle with a center at zero and a width depending on the traversed material. By reconstructing the individual kink angles from the measured particle trajectories in a high resolution beam telescope, the material budget can be extracted by applying appropriate models of multiple scattering theory, such as the Highland formula. On the one hand, various materials with known material budgets were measured to calibrate the MBI technique and study also different systematic effects such as the beam telescope’s acceptance and the variation of the beam energy. On the other hand, a number of material samples planned in the design of the local support structures of the new ATLAS Inner Tracker (ITk) strip detector were investigated to extract the according radiation length values not known beforehand. This paper shows therefore the potential of the MBI technique to give an input for the design of high-energy particle detectors by providing experimentally measured numbers of the radiation length for various material compounds with not a-priori known X 0 values.