June 03, 2015

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Welcome to my homepage!

On these web pages you find information about my research, the courses I teach as well as some fun after work.


I work in the Dutch Institute for Particle Physics: Nikhef.
My current research focusses on the matter-antimatter asymmetry: Why is there almost no antimatter present in our universe?
I coordinate a FOM research program in which we study this mystery by comparing the decays of particles and antiparticles that contain bottom quarks using the LHCb experiment at the Large Hadron Collider at CERN in Geneva.

The LHCb Experiment

For an overview of exciting physics results of the LHCb experiment click here.

Have a look at the online event display and the LHCb movie.
Wednesday 30 Mar 2010: LHC collisions at high energy! The LHC experiments have observed the first collisions at the record breaking energy of 7 TeV. A long video report can be found here, and a shorter, LHCb specific youtube clip is here. To see pictures of the first events click on the icons below to see images from: LHCb, Atlas, Alice and CMS:

April 5, 2010: The first Beauty particle has been seen by LHCb. Click on the following links to see an overview of the event as well as the x-y and y-z sideviews.
May 7, 2010: A first Beauty Strange (the "Bs" meson) particle decay has been captured by LHCb. The Strange Beauty particle is seen to decay into a Charmed particle (the "Ds") and a muon and a neutrino. A picture of the reconstructed event can be seen here. In the picture "PV" is the collision point of the LHC beam particles where the Bs is produced, "SV" is the location where it decays into a Ds, a muon and an invisible neutrino, and "TV" is the position where the Ds decays into two kaons and a pion.
August, 2010: Click here to see recordings of LHCb event displays.
November 12, 2012: The Standard Model passes stringent quantum test as LHCb sees evidence for the most rare B-decay ever. For more information see the Nikhef news article and the CERN quantum diaries.
Feb 14, 2013: End of Run-1 of the LHC. The accelerator and experiment worked like a charm. Start to prepare the LHC for highest beam energy.
March 3, 2013: Presentation of the measurement "matter to antimatter" transitions of Bs mesons at the La Thuile conference. A Bs meson turns into an anti Bs meson and back again with a speed of 3 million million times per second. The red and blue curves are the measurements of the "mixed" and "unmixed" existence of the Bs particles (click to enlarge).
April 24, 2013: The Collaboration publishes a paper announcing the discovery of a difference between decays of matter and antimatter Bs particles.
March 20, 2015: Puzzling results of the decay of Bs particles into a so-called K* particle and two muons are discussed at the conference in Moriond. Perhaps the data are not in agreement with the Standard Model theory and scientists speculate on the existance of a new particle called Z' ("Z-prime").
May 13, 2015: Discovery of the almost forbidden decay of a Bs meson to two muons published in Nature, together with a tentalizing hint of similar decays of the the Bd meson. These rare decays offer the deepest view in the quantum world where unknown particles can spontaneously exist for a very short time and affect these rare B meson decays, and as such put the Standard Model under stringent test.
June 03, 2015: Start of LHC physics run-2: the first collisions at record energy of 13 TeV have been recorded by the experiments. A first spectacular LHCb event:

The live status of the LHCb experiment can be followed on the status and the event display. Will nature reveil new physics?


At the Vrije Universiteit in Amsterdam I hold a chair on the research topic: "Discrete Symmetries in Elementary Particle Physics"
I teach topical courses to graduate students (quark flavour physics) as well as a Particle Physics course to master students of Amsterdam and Utrecht universities.

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I am married to Esther and have two children: Didier and Helene.
One of my favorite activities in my free time is to visit Mestreech.