The Ghent Experimental Particle Physics Group belongs to the Department of Physics and Astronomy. The Experimental Particle Physics research group at Ghent University studies the fundamental building blocks of matter. We are active in different fields: low energy neutrino physics (through the SoLid experiment), astroparticle physics (the IceCube experiment) and theoretical studies in accelerator physics with the LHC through the CMS Experiment. Our research is concentrated on four topics:
Particle physics at the energy and intensity frontier: CMS
The Large Hadron Collider (LHC) was constructed by a world-wide collaboration over the course of 20 years. It is currently the world’s most powerful particle accelerator, colliding protons at TeV scale energies. CMS is one of two main purpose experiments, intent on unearthing new physics at these prodigious energies. The primary goals of the LHC and CMS were the discovery of the Higgs Boson, and the discovery of new particles or interactions. The first goal has been completed in 2012 when the Higgs Boson was discovered, but thus far no discovery of new physics has been made.
Over the last few years the LHC has been delivering proton-proton collisions at an unprecedented center of mass energy of 13 TeV and at extremely high intensities. As of 2018 a data volume that is more than 10 times larger than what was used in the discovery of the Higgs Boson is available for analysis. Over the next few years, this huge dataset will be searched for signs of new physics. Traditionally, new physics searches at the LHC have looked for the direct production of undiscovered particles in the collisions, and this remains the dominant approach. The current lack of any evidence of new particles has however led to a new approach. The presence of new physics might manifest itself as modified standard model (SM) interactions or couplings, which can be observed through precise measurements of SM processes.
Our group is involved in several direct searches for production of undiscovered particles, as well as precision measurements of the standard model in the top-quark sector. The subjects we are currently working on are direct searches for heavy sterile neutrinos and supersymmetric particles, and the precise measurement of top-quark production in association with electroweak gauge bosons, which can then be used to probe the presence of new physics.
High Energy Cosmic Radiation and Neutrinos: IceCube
The IceCube collaboration installed and operates the largest neutrino-observatory in the world at the geographic South-Pole. Signals created by high-energy neutrinos in the Antarctic ice are detected by several thousand optical sensors in a volume of about 1 km3. A small fraction of the highest energetic neutrinos originate from extraterrestrial sources, such as Active Galactic Nuclei. We are mostly interested in the particle physics aspects that can be probed with this astroparticle physics facility.
Our group is active in the IceTop component of the IceCube detector: a 1km2 array of detectors placed on the surface of the icesheet over IceCube, capable of observing charged cosmic rays in the energy range between the knee and the ankle of the cosmic ray spectrum. We use these high energy particles to study e.g. particle interactions at energies beyond those reached with the most powerful accelerators on Earth.
In addition, our group uses the IceCube detector to search for particles with anomalous charge (e.g. 1/3 of the electron charge).
Low Energy Neutrino Physics: SoLid
The SoLid collaboration aims to contribute to the understanding of the reactor anomaly, where the flux of (anti-)neutrinos coming from nuclear reactors is observed to be lower than expected from calculations. A possible reason for this deficit is an oscillation of the electon-antineutrino into a new fundamental particle, the sterile neutrino. By deploying a segmented detector close to a nuclear reactor core, the SoLid experiment will be able to detect or rule out such a neutrino oscillation.
The SoLid detector was constructed at Ghent during 2016-2017 and is now taking data at the BR2 research reactor at the Belgian center for nuclear research SCK.
Instrumentation: gaseous detectors
Gaseous detectors exploit the ionizing effect of a charged particle passing through a gas-filled container. Many different types of such detectors exist and they have a multitude of different applications in and outside of particle physics. Among the more advanced, modern gaseous detectors are the so-called Resistive Plate Chambers (RPCs) and the general class of Micro-Pattern Gaseous Detectors (MPGDs), with Gas Electron Multipliers (GEMs) as an example of one of the primary MPGD technologies.
Our group focuses on generic R&D and construction of MPGDs and RPCs for applications in different experiments. In CMS we are involved in the operation and upgrade of the muon system that is in part based on RPCs and GEMs. For the Phase-1 upgrade of the CMS Muon system many RPCs have been produced at Ghent University, and we are currently constructing chambers for several new RPC and GEM stations for the CMS Phase-2 upgrade. Within CALICE we are performing R&D on RPC-based hadron calorimetry for experiments at future accelerator facilities such as the International Linear Collider. In addition, we recently started working on the development of a gaseous detector based telescope for applications in muon transmission radiography.