Towards a compensatable Muon Collider calorimeter with manageable backgrounds

Abstract

Muon Collider detectors pose very challenging problems in detectortechnology due to extremely large backgrounds present in the detectorvolume as a result of muon decays. Current designs of a 750 GeV/c perbeam Muon Collider envisage 4.28 × 105 muon decays per meter in the beam pipeclose to the interaction region. The decay electrons after intenseshielding still manage to produce large backgrounds in the detectorvolume of low energy photons, neutrons and higher energy Bethe Heitlermuons. There are 170/184/6.8/177 TeVs energy entering the detector volume per crossingdue to EM particles/Muons/Mesons/Baryons respectively. Weinvestigate the capabilities of an iron calorimeter with pixelatedreadout where each pixel gives a yes/no answer as to whether a chargedparticle passed through it or not, to solve this problem. Each pixel is individuallytriggered by a ``travelling gate trigger'' with a gate of 2 ns wherethe beginning of the gate is the time of arrival of a light signalfrom the interaction region to the pixel. We show that such acalorimeter is compensatable and propose two schemes to compensate thedigital output in software to improve the resolution of thecalorimeter. We show that such a calorimeter is capable of digitizingphysics signals from the interaction region and as a result,the backgrounds fromthe muon decays are much reduced and under control.