BIJEENKOMSTEN KONINKLIJK GENOOTSCHAP PHYSICA

Elke eerste maandag van de maanden oktober tot en met april organiseert het Genootschap een lezing op wetenschappelijk niveau.  De lezingen vinden steeds plaats in het Wijkcentrum "Thuis in Overdie", Van Maerlantstraat 8-10, 1813 BH Alkmaar.

 

Op 13 april 2015 sprak:

prof. dr. J.F.J. (Jo) van den Brand

hoogleraar astro- & deeltjesfysica aan de Vrije Universiteit Amsterdam(Fac. Rechts-geleerdheid Leiden) over:

Gravitatie en dynamische ruimtetijd

Einsteins algemene relativiteitstheorie voorspelt het bestaan van gravitatiegolven. Als massieve objecten in het heelal bewegen, dan veroorzaken ze rimpels in het Universum, die in werkelijkheid verstoringen zijn in het weefsel van ruimtetijd. De detectoren LIGO en Virgo speuren naar deze gravitatiegolven. Deze instrumenten zijn Michelson interferometers met 3 tot 4 km lange optische resonatoren in hun armen. In de lezing wordt een overzicht van het Virgo experiment gegeven, alsook een schets van toekomstige ontwikkelingen, zoals Einstein Telescope, een derde generatie observatorium voor gravitatiegolven en het ruimtevaartproject eLISA.

Prof.dr. Jo van den Brand is director of the Subatomic Physics group at VU University Amsterdam (since 1996) and specializes in particle and astroparticle physics. In the early 1990s he was active in electron scattering experiments at SLAC that addressed color transparency and virtual Compton scattering. He was spokesman of BLAST at MIT-Bates (with Prof. Milner, MIT), and carried out the world’s first fully polarized internal target experiment (CE25) at the Indiana University Cooler Facility. In the 1990s he was involved in the HERMES collaboration at DESY, an experiment at HERA to determine the contribution of the various quark flavors and gluons to the nucleon spin. He was the leader of the Dutch participation and he was spokesman of HERMES during start-up and first measurements (1994-1995).

Until 2000 he directed the nuclear spin-physics program at the Amsterdam Pulse Stretcher (AmPS) facility at Nikhef. AmPS was the first storage ring where longitudinal polarization of electrons was maintained by a Siberian snake and the stored electrons were scattered from polarized targets. He realized polarized hydrogen, deuterium and Helium-3 internal targets. The measurement of the charge form factor of the neutron is the best cited work carried out with Nikhef’s local accelerator.

From 2000 (until 2012) he was member of the LHCb experiment at CERN to study CP violation in the decay of B mesons, and to determine elements of the CKM matrix (relation between mass and electroweak eigenstates). As leader of the LHCb/FOM program he was the driving force of the Dutch contributions to the collaboration. He was LHCb project leader of the VELO detector (2001–2005), one of the most advanced silicon vertex detectors. His present research focuses on gravitational physics. He coordinates all activities in the Netherlands for the Virgo experiment near Pisa, and has made substantial contributions to Einstein Telescope, a third generation gravitational observatory in the design stage. He leads the effort on the development of instrumentation for Advanced Virgo, a European project that should lead to the first detection of gravitational waves after commissioning in 2016. His group has made a systematic study in a Bayesian framework of model independent tests of the validity of General Relativity by using gravitational-wave events. In this field, his group is the leading one in the world.