Design and development of calorimetry at SHiP and SND@LHC
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Abstract
This thesis focuses on calorimetry in the context of searches for rare particle interactions at the
SHiP and SND@LHC experiments at CERN.
The SHiP (Search for Hidden Particles) experiment at CERN SPS is going to be the flagship
experiment for investigating low-coupling physics in the O(10 MeV) to a couple of GeV range.
Its calorimeter system will achieve very good particle identification capabilities and be able
to reconstruct the directionality of electromagnetic shower with excellent precision. This will
enable significant background reduction and the ability to reconstruct neutral final states arising
from possible new physics decays. For this, it relies on plastic scintillator bars traversed by
wavelength-shifting fibres and readout by SiPMs on the one hand and high-precision layers on
the other. The physics requirements of the calorimeter have been studied with Monte Carlo
simulations. The plastic scintillator layers’ light yield was optimised both in simulations and
laboratory studies, yielding a design for usage in the final experiment. The readout electronics
must cover a very large dynamic range, four systems were investigated with the KLauS chip
being identified as having potential for usage in the end experiment. Three test beams were lead
using a modular and custom-built prototype of the SHiP electromagnetic calorimeter system.
There, different readout electronics and detector configurations were evaluated. Preliminary
results allow to establish the robustness of the design for energy reconstruction and particle
identification. These studies are in use for the final design of the energy reconstruction and
particle identification.
The SND@LHC (Scattering Neutrino Detector at the Large Hadron Collider) is a running
experiment placed off-axis at the ATLAS interaction point at 7.2 < η < 8.6. The experiment’s
position enhances the charm parentage of final state νe and ντ from decays inside of ATLAS. A
hadronic calorimeter based on scintillator bars readout by SiPMs is used to identify muons and
measure the energy of hadronic final states from interactions in an emulsion target. The perfor-
mance of the hadronic calorimeter has been studied. Its response to hadronic showers as well
as the development and testing of tagging algorithms used for the calorimeter calibration are
presented. In addition, muon deep inelastic scattering and catastrophic muon bremsstrahlung
background studies have been performed in the emulsion detector together with the develop-
ment of electromagnetic calorimetry techniques. These evaluations are currently being used for
searches for νe in the emulsion detector at SND@LHC.