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Characterization of ITS3 sensor prototypes using particle telescopes with beam and cosmics

Zaksaite, Julija LU (2026) FYSM64 20261
Department of Physics
Particle and nuclear physics
Abstract
During the third long LHC shutdown (2026-2030), one of the four main experiments at CERN, ALICE, will undergo an extensive upgrade of the Inner Tracking System (ITS3). During this, the three innermost layers of the detector will be replaced by a novel technology, where wafer-scale stitched sensors will be bent into half-cylinder shape and placed one on top of the other, wrapping around the beam pipe.

This thesis presents the characterization of the sensor prototypes, called babyMOSS, in two different scenarios: using high-energy particles produced in a beam and cosmic muons. Firstly, the particle telescope set-up used in a test beam is discussed, where detection efficiency and spatial resolution were measured for different pixel sensor... (More)
During the third long LHC shutdown (2026-2030), one of the four main experiments at CERN, ALICE, will undergo an extensive upgrade of the Inner Tracking System (ITS3). During this, the three innermost layers of the detector will be replaced by a novel technology, where wafer-scale stitched sensors will be bent into half-cylinder shape and placed one on top of the other, wrapping around the beam pipe.

This thesis presents the characterization of the sensor prototypes, called babyMOSS, in two different scenarios: using high-energy particles produced in a beam and cosmic muons. Firstly, the particle telescope set-up used in a test beam is discussed, where detection efficiency and spatial resolution were measured for different pixel sensor geometries. Secondly, the design of the babyMOSS telescope, built in Lund University is presented, with the main focus on the triggering scheme optimization and software implementations. Some of the first results of observed rate distribution, cluster size, residuals and angular distribution are also discussed. (Less)
Popular Abstract
The main model, explaining the origins of our universe is known as the Big Bang. It is thought that in the first milliseconds after the Big Bang, the universe was in an extreme phase of matter, known as Quark Gluon Plasma (QGP). From this hot and dense state, quarks and gluons combined to form protons and neutrons - the building blocks making up everything around us. The theory still leaves a few unknowns: how exactly the transition from QGP to ordinary matter happen? What were the thermodynamic conditions of the universe in the very beginning? How did the structure and behaviour of QGP influenced the later evolution of the universe?

In high-energy physics, one of the experiments, dedicated to studying QGP, is called A Large Ion... (More)
The main model, explaining the origins of our universe is known as the Big Bang. It is thought that in the first milliseconds after the Big Bang, the universe was in an extreme phase of matter, known as Quark Gluon Plasma (QGP). From this hot and dense state, quarks and gluons combined to form protons and neutrons - the building blocks making up everything around us. The theory still leaves a few unknowns: how exactly the transition from QGP to ordinary matter happen? What were the thermodynamic conditions of the universe in the very beginning? How did the structure and behaviour of QGP influenced the later evolution of the universe?

In high-energy physics, one of the experiments, dedicated to studying QGP, is called A Large Ion Collider Experiment (ALICE) and it is located at the Large Hadron Collider (LHC) at the European Organization of Nuclear Research (also known as CERN). By studying heavy-ion collisions, physicists can learn about how elementary particles interact at extreme conditions, which also allows them to research characteristic properties of QGP. Studying the most fundamental constituents of matter is no easy task and this is only possible by employing state-of-art particle detection technologies.

ALICE detector, consisting of multiple sub-detector systems, is undergoing an upgrade in the upcoming LHC Long Shutdown 3, planned for 2026-2030. The main upgrade will be done to the Inner Tracking System (ITS), where the three innermost layers of the detector will be replaced by a completely novel silicon detector technology: wafer-scale stitched silicon detectors, thinned out to 50 µm and then bent into half-cylinder shape. Before the full-scale deployment of the ITS3 detector, the sensor prototypes must be characterized, in order to fully understand how the sensors perform under the expected ITS3 operating conditions. This is usually done using particle telescopes in the test beam environment, using the beam as a source of high-energy particles.

The first sensor prototypes, developed for the engineering run 1 (ER1), are known as the MOnolithic Stitched Sensors (MOSS). These are stitched pixel sensors, consisting of a total of 6.72 million pixels and made out of 10 repeating sensor units (RSUs). In order to facilitate in beam studies, single-RSU sensors were produced, called babyMOSS. This thesis is split into two parts. The first one presents the results from the last test beam of the ER1, where the babyMOSS sensor detection efficiency and spatial resolution was studied as a function of different thresholds. The second one proposes an alternative method for characterizing pixel sensors: by using cosmic muons as a source of high-energetic particles. For this purpose, a compact telescope has been built in Lund University. The telescope optimization as well as software developments are presented in this work, with a discussion dedicated to the first analysis results. (Less)
Please use this url to cite or link to this publication:
author
Zaksaite, Julija LU
supervisor
organization
course
FYSM64 20261
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
9234072
date added to LUP
2026-06-10 08:46:15
date last changed
2026-06-10 08:46:15
@misc{9234072,
  abstract     = {{During the third long LHC shutdown (2026-2030), one of the four main experiments at CERN, ALICE, will undergo an extensive upgrade of the Inner Tracking System (ITS3). During this, the three innermost layers of the detector will be replaced by a novel technology, where wafer-scale stitched sensors will be bent into half-cylinder shape and placed one on top of the other, wrapping around the beam pipe. 

This thesis presents the characterization of the sensor prototypes, called babyMOSS, in two different scenarios: using high-energy particles produced in a beam and cosmic muons. Firstly, the particle telescope set-up used in a test beam is discussed, where detection efficiency and spatial resolution were measured for different pixel sensor geometries. Secondly, the design of the babyMOSS telescope, built in Lund University is presented, with the main focus on the triggering scheme optimization and software implementations. Some of the first results of observed rate distribution, cluster size, residuals and angular distribution are also discussed.}},
  author       = {{Zaksaite, Julija}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Characterization of ITS3 sensor prototypes using particle telescopes with beam and cosmics}},
  year         = {{2026}},
}