Honour Project

Experimental Particle Physics

Table of Contents

GridPix Detector Research and Development

Simulation of Ion Backflow in a GridPix detector using Garfield

Jesse Heilman 

Many novel subatomic particle detectors are currently under development to advance experimental programs in particle physics.  One such detector is the so called GridPix. Based on a pixelated CMOS, solid state detector, a Gridpix also includes a lithographically developed metallic grid on its face allowing for the amplification if incident electrons which are measured by the detector.  This device has potential applications ranging from large particle collider experiments to small scale medical applications to perform high precision, 4D, low mass tracking of charged particles.

This project will focus on simulating the ion backflow created during the amplification and detection of drift electrons while using a GridPix in a Time Projection Chamber. Backflowing ions in large numbers can disrupt the electric field in the drift volume of the TPC and distort the ability to precisely measure the passing of other charged particles through the detector.  This project will use the Garfield simulation package to make predictions of ion backflow measurements to inform a future test bench experiment. Interested students should have a keen interest in particle physics, subatomic particle detectors, and knowledge of computer programming languages.    

Commissioning of a Pixel Time Projection demonstrator using GridPix

Many novel subatomic particle detectors are currently under development to advance experimental programs in particle physics.  One such detector is the so called GridPix. Based on a pixelated CMOS, solid state detector, a Gridpix also includes a lithographically developed metallic grid on its face allowing for the amplification if incident electrons which are measured by the detector.  This device has potential applications ranging from large particle collider experiments to small scale medical applications to perform high precision, 4D, low mass tracking of charged particles.

This project will focus on commissioning a benchtop setup for operating and making measurements with a GrixPix based Time Projection Chamber.  Interested students should have a keen interest in particle physics, subatomic particle detectors, and strong laboratory skills.    


ATLAS

Muon Reconstruction with the ATLAS New Small Wheel at the LHC

Alain Bellerive

In 2022, the CERN Large Hadron Collider (LHC) beneath the France–Switzerland border near Geneva turned on after a major upgrade that double its delivered instantaneous luminosity. This is an important milestone that follows a very successful two periods of running that saw, among other things, the discovery of the Higgs boson. To cope with the anticipated LHC operating conditions, an extensive overhauling of the detector reconstruction algorithms for ATLAS is underway to reflect the introduction of a new subsystem called the New Small Wheel (NSW). These hardware and software enhancements will allow ATLAS to maintain its capability to perform cutting edge physics studies under the new experimental conditions during 2023/2024 and beyond. The Carleton University ATLAS group was a major contributor to the construction of the recently installed NSW upgrade to the ATLAS endcap muon spectrometer.  The small-Strip Thin Gap Chambers (sTGCs) allow for a much better rejection of fake tracks at the trigger level, as well as improved reconstruction of muon candidates.  Now that the sTGC has been deployed in the ATLAS experimental cavern and the first data from LHC Run3 has started to come in, the NSW needs to be optimized for data mining and validated for physics analyses.

Interested students will participate in the various aspects of the performance evaluation of the new muon tracking using Monte Carlo simulation and real collision data. The student will be developing advanced patter recognition algorithm for the reconstruction of tracks from hits in the NSW. This will enable the Carleton ATLAS team to be ready for the new 2024 LHC data.  While the honours project will be during Fall2023-Winter2024, the student selected for this project will be giving the opportunity to be hired as a summer research assistant and be located at CERN during the May-August 2024 period. Students who work on this project will contribute to the development and validation of the muon reconstruction software.  This will require learning the basics of particle physics, particle detector design and operation, and programming skills in ROOT, Python and C++.   

 

Characterization of the electrical properties of silicon sensors for the ATLAS detector upgrade at the LHC

Thomas Koffas

In 2025-2028, the Large Hadron Collider and the ATLAS detector will undergo major upgrades to prepare for the High Luminosity LHC (HL-LHC) that will start in about 2029. The HL-LHC will operate at a significantly higher intensity: the instantaneous luminosity of the proton beams will be seven times that of the design criteria. This significantly enhances the overall physics potential, but also makes the experimental conditions harsher and more challenging. The entire inner tracking detector of ATLAS will need to be replaced with a new silicon Inner Tracker detector (ITk) to cope with this situation.

The particle physics group at Carleton University is actively working on this detector upgrade, and is looking for interested students to work on the characterization and performance evaluation of the ITk detector sensors. This work will include the study of the state-of-the-art thin silicon sensors, as well as specially designed test structures that will be probed by dedicated equipment in order to understand their physics performance under carefully controlled environmental conditions. As a separate task, the evaluation of the performance of silicon test structures under high radiation conditions and the study of radiation-induced effects on semiconductor materials, will also be pursued. Both projects will require the development of the required experimental setups, including LabView-based readout and control software, as well as C++-based analysis of the measurement data. In both projects, students will acquire extensive experience in working in clean rooms under environmentally controlled conditions, in handling state-of-the-art experimental equipment, in performing extensive data analysis using ROOT and other software packages and in basic database operations.

 

3D Modelling of Emerging Jet Events in the ATLAS Detector using Blender

Jesse Heilman and Dag Gillberg

One of the physics analyses that is ongoing within the Carleton Physics Department is a search for Emerging Jets. This hypothetical signature is predicted by certain models in which so-called dark hadrons are produced in the LHC collisions. Dark hadrons travel a short distance in the detector before decaying into ordinary particles which can be measured directly. This process might be produced frequently in the LHC interactions but could be mistaken for common interactions. The key distinguishing feature of emerging jets is the presence of displaced vertices: points a short distance away from the interaction points where ordinary particles, such as pions, kaons, protons, and neutrons, ‘appear’ when a dark hadron decays. 

The goal of this project is to develop a code package to create attractive and informative 3D models of potentially interesting collision events inside the ATLAS detector. Students working on this project will explore the flow of particle energy as it comes from proton-proton collisions as well as the translation of ATLAS data structures into artistic interpretations.  Students will take advantage of the Python scripting language to translate relevant objects from ATLAS simulations and data into the open-source 3D modelling software, Blender.  Interested students should have keen interests in particle physics, knowledge communication, and computer-generated art and animation.  


The EXO Experiment

Razvan Gornea

Noble liquid time projection chambers (TPC) are excellent detectors for rare event searches in neutrino physics. For example, the EXO-200 detector employs a 200 kg liquid xenon (LXe) with a TPC configuration which allows the collection of the electric charge produced by ionizing particles. When energy is deposited in a noble liquid, pairs of electron/hole are formed and can be collected by applying an external electric field. The amount of electrons collected is proportional to the initial energy of the ionizing particle.

During their drift in the TPC, electrons may encounter impurities with a large electron affinity and, therefore, part of the initial electric charge could be lost. When the noble liquid in a TPC is of low purity a large amount of charge is lost and then accurate event energy reconstruction becomes challenging. The average time for the electron to get captured is called the "electron lifetime". Experimentally, it often occurs that a LXe TPC can easily suffer from a short electron lifetime or, equivalently, a large concentration of impurities. On the other hand, the accurate measurement of a very long electron lifetime is challenging when using a compact device.

In this project, the student will design, optimize and build a compact purity monitoring device able to measure both short and long electron lifetimes using a custom pulsed VUV-LED-based electron source previously developed at Carleton. SIMION simulations will be employed to design and optimize a compact drift volume able to recycle the probing electron cloud. Hardware development, construction and testing will also be part of the project. Elements of front-end electronics, computer control and system programing using LabVIEW complete the program. A full year commitment is better suited for this project.