prof. dr. ir. C.J.G. (Gerco) Onderwater

LHCb -- Lepton Flavour Violation & Lepton Universality

Lepton flavour distringuishes the electron, muon, and tau leptons. For reasons currently unknown, lepton flavour seems to be conserved in all known interactions. Furthermore all leptons are thought to interact identically, esp. for the weak interaction, so called Lepton Universality. Deviations from these strong predictions are a clear sign for the existence of New Physics.

Search for Lepton Flavour Violation in the B0(s) → e±μ∓ reaction -- Maarten van Veghel (PhD; 2019)

LHCb -- Flavour Changing Neutral Currents

The weak interaction may change the quark flavour via the charged current interaction, i.e. via the exchange of a W-boson. On the other hand, neutral current interactions, i.e. Z0-exchange, conserve quark flavour. Observation of flavour changing neutral current reactions, beyond those expected from Standard Model loop contributions, may point to the existence of New Physics. 

Measurement of the B0(s) → μ±μ∓ branching fraction -- Mick Mulder (PhD; 2021)

JPARC -- Muon g-2 & EDM

The discrepancy between the measured and predicted anomalous magnetic moment of the muon is among the most troubling discrepancies in current-day particle physics and is by many regarded as a manifestation of the existinence of new physics not yet contained in the Standard Model of Particle Physics.

A new measurement at FermiLab (USA), conceptually similar and in many respects identical to the precious measurement at Brookhaven Lab (USA), is about to improve the experimental precision.

At JPARC (Japan) a new concept has been proposed for measuring the anomalous magnetic and the electric dipole moments of the muon. We assist in identifying possible sources of systematic errors.

Current and Past Master Projects

• Groundwork for a Taylor Model for Fast Charged Particle Tracking in LHCb -- Davey Karsseboom (2021)
• Modeling Electron Track Reconstruction at LHCb -- Jasper Somsen (2021)
• b-Meson Tracking at LHCb: a Feasibility Study-- Jan Rol (2021)
• Improving upstream electron identification with bremsstrahlung information -- Nicolas Kruse (2020)
• Systematic errors in the magnetic field measurement in the JPARC g-2/EDM experiment -- Jowzick Karunanity (2019)
• Systematic errors in the reconstructed spin precession frequency in the JPARC g-2/EDM experiment -- Sietse Buijsman (2019)
• Branching fraction of Λb -> Λ0 J/psi(->mumu) -- Koen Lambrechts (2019)
• Study of muon selections at upgrade conditions -- Hilbrand Kuindersma (2018)
• A fast tool to predict peaking and semi-peaking backgrounds in two body decay processes -- Michiel Veen (2017)
• A fast simulation model for mass spectrum shapes of particle decays in high-energy physics experiments -- Jim Baarslag (2017)
• Using the B0 → K± π∓ channel as normalization in the
  search for the charged lepton flavor violating B0 →e±μ∓ decay -- Garbrand Wiersema (2017) 
• Exploring GPU-Computing to Accelerate Vertex Finding in Particle Physics -- Joren Heit (2017)
• Experimental tests of Everettian quantum mechanics -- Lammert Wiersma (2017)
• Electron identification efficiency in B0(s) → e±μ∓  -- Rosa Kappert (2016)
• Modelling of collective spin behaviour in NMR experiments -- Herre Kamsma (2015)
• Exploration of Lorentz Violation in neutral hyperon decay -- Christiaan Douma (2014)
• Production and Polarization of Radioactive Rubidium for Testing Lorentz Invariance -- Elwin Dijck (2012)
• A Model Independent Method To Look For CPT And Lorentz Violating Signals -- Wim Ottjes (2008) (second advisor)
• Implementation of elastic scattering of polarised deuterons of 12Carbon for Monte Carlo simulations using Geant-4 -- Klaas Brantjes (2008)

Current and Past Bachelor Projects

• Polynomial approximation for precise and fast charged-particle tracking through a digitized magnetic field -- Teddy Milkova (2022)
• Track Reconstruction for the KEK muon g-2/EDM Experiment -- Josie van Driel (2022)
• Exploring the Possibility for Fast and Accurate Particle State Mapping Using Julia-- Iulia Dumitru (2021)
• Parallel Evaluation of Taylor Models -- Marcel vd Broek (2019)
• RETINA Algorithm for Track Finding -- Mariko Kami (2019)
• Lepton Universality -- Kseniya Prakhova (2019) 
• Exploring Taylor Methods for Fast Particle Tracking -- Ibai Ceberio Basanez (2019) 
• Deformation Measurement of a Glass Dome Undergoing Hydrostatic Pressure -- Paul Werker (2018) (Applied Physics)
• Using Taylor series for fast and precise charged particle tracking in the LHCb magnet -- Maurice Dekker (2018) (Physics/Mathematics)
• Maxwellian Interpolation of Magnetic Fields on a Grid -- Jose Luis Rodrigo Ramon (2018) (Applied Physics)
• Quark Stars -- Leander van Beek (2018) (Physics/Astronomy)
• Exploration of an Origin of Anisotropy and its Effect upon Invariant Mass Reconstruction in a Two-Body Decay -- Jan de Boer (2017)
• Track finding in Physics – a review of existing methods and an exploration of two new methods -- Martine Schut (2017)
• Diagrammatic analysis of approximate relations between existing and proposed (c)LFV limits -- Jowzick Karunanithy (2017)
• Trigger Efficiencies at LHCb in the Search for Bs0 → eμ -- Hilbrand Kuindersma (2016)
• Antigravity in positronium -- Marick Manrho (2016) (second advisor)
• Disappearance of positronium into extra dimensions -- Guus Avis (2016) (2nd advisor)
• Overview of the experimental status of cLFV -- Elianna Kraan (2016)
• Effect of the Earth’s rotation and relativistic effects in spin precession -- Thomas Meesters (2016)
• Overview of the theoretical status of cLFV -- Chris Vos (2015)
• Searching for Lorentz Invariance Violation in Λ decay -- Ivar Dijck (2016) (2nd advisor)
• Investigating Lorentz Invariance Violation in Muon Decay -- Joren Vermijs (2014)
• The limitations of the precision and accuracy of X-ray imaging -- Maarten Degen (2014)
• Temperature effects on test of Lorentz invariance -- Willem Elbers (2014)
• Effect of earth's motion on measurements of Lorentz invariance -- Daniel Chernowitz (2013)
• Simulation of systematic errors for the 129Xe Permanent Electric Dipole Moment experiment -- Henri Mussche (2013)
• Application of Taylor Models to Tracking of Charged Particles in Magnetic Fields -- Herre Kamsma (2013)
• Polarization of 20Na in a Neon-environment -- Jacob vd Eijnden (2013)
• Reconstruction of objects in 3D by means of photogrammetry – Positioning of the setup of the Lorentz Invariance Experiment – Jean Grivaux (2013) (internship ENSIAME Engeneering School) 
• Data-acquisition for ultra-precise time-measurement -- Mathieu Santin (2013)(internship ENSIAME Engeneering School)
• Design of a gas cell for the production and extraction of radioactive Rubidium-80 -- Florent Andrieu (2012) (internship ENSIAME Engeneering School)
• Design and construction of a laser setup for the Lorentz- Invariance Test experiment --  Florent Boulay (2012)  (internship ENSIAME Engeneering School)
• β-detector calibration and design -- Stéphane Michel (2010) (internship ENSIAME Engeneering School)

Current and Past Honours College Projects

• State of the art of the electron and muon mass parameters and their impact on the SM and WED tests -- Lucas van der Horst (2021)
• Exploring Machine Learning Methods For Elementary Particle Track Identification -- Nithesh Balasubramanian (2021)
• Implementation of Computing in the Physics Curriculum -- Floris Westerman (2018)
• Track finding on a GPU using the “Retina” algorithm -- Frank Westers (2016)
• Spin dynamics in an electromagnetic storage ring and evaluating systematic errors for the muon g-2 experiment -- Thomas Hoeksema (2015)
• Analysis of GPU acceleration in Physic Simulations -- Rik Schaafs & Thomas Hoeksema (2014)
• Report on the simulation of the LIV experiment -- Mart Salverda (2013)