Physical Society Colloquium
Sorting needles in a haystack and cooling a
‘sandwich’:
data analysis and detector
development with ATLAS at the Large Hadron Collider
Department of Physics and Astronomy
York University
The multi-purpose ATLAS detector at the Large Hadron Collider (LHC) has recorded
petabytes of proton-proton collisions to observe extremely rare processes;
this helps us deepen our understanding of matter at the smallest scales: the
elementary particles and their interactions. I will detail my contributions in
one of the key searches of the LHC program: the observation of a Higgs boson
produced in association with a top and anti-top quark pair. This challenging
analysis combines complex variables and techniques to extract the signal-like
topology — the needles — among an overwhelming background
— the haystack. More difficult: some needles can be fake! They are hay
mis-reconstructed as needles. This ‘fake background’
has to be quantified. Studying the Higgs boson interaction with top quarks
leads to estimating its ‘coupling’, a key parameter in the
current model of particle physics. Any observed deviation from the theoretical
prediction could give a good direction on where to explore more. For this,
precision is needed. I will then present another aspect of my research:
detector development for the future of the ATLAS experiment. Indeed, to
increase the precision of the next measurements as well as the discovery
potential at the LHC, entire parts of the ATLAS detector will be rebuilt for
both withstanding and recording harsher collisions. I will present my work
on assessing the thermal performance of the ‘sandwich’,
i.e. the support structures holding the silicon sensors of the future inner
tracking detector. The goal is to ensure there will not be overheating of
the sensors due to the radiative environment or the powered electronics. I
will present the current cooling technology and show that the sandwich design
prevents overheating and is adapted for higher collision rates.
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