Honour Project

Experimental Particle Physics

ATLAS Experiment

The Search for Emerging Jets with ATLAS

Jesse Heilman and Kevin Graham

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. 

Students working on this project will explore what defines an Emerging Jet as distinct from other jets and develop ways of distinguishing events containing emerging jets from other types of interactions.  This project will focus on the development of these strategies, with a possible emphasis on machine learning techniques, for use with the LHC Run3 dataset that began being collected this year.

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.

Muon Reconstruction Software with the ATLAS New Small Wheel

Alain Bellerive and Jesse Heilman

The Carleton University ATLAS group was a major contributor to the construction of the recently installed New Small Wheel 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 NSW has been installed in the ATLAS experimental cavern and the first data from LHC Run3 has started to come in, the NSW needs to be commissioned and validated in detail.

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 advanced programming skills in ROOT and C++.   

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.