Nuclear and Particle Physics coming seminars
Academic year 2008-2009

As a new seminar organizer, I will open the season with a somewhat special seminar, presenting what I do best when not dealing with physics: travel photography.

I will present an overview of the indirect constraints from flavor physics and cosmology on supersymmetric models. During the past few years flavor data, and in particular b -> s gamma transitions, have been extensively used in order to constrain supersymmetric parameter spaces. I will briefly illustrate the constraints obtained by a collection of low energy observables including FCNC transitions, rare decays and leptonic and semileptonic decays of B and K mesons. In a second part I will discuss the relevance of cosmological constraints on supersymmetric models.

With the commissioning of LHC progressing some minds are already busy with the design of a future collider. Such a collider will be a linear electron-positron machine with a centre-of-mass energy of at least 1 TeV. It requires an ultra-high accelerating gradient and efficient RF power generation. Two paths are being investigated: ILC with superconducting acceleration technology and CLIC based on normal conducting technology. The brand-new Two-beam Test Stand at the CTF3 facility, CERN, is a unique facility to test the accelerating equipment required for such a future collider.

RF breakdown in room temperature accelerating structures is one of the main obstacles for stable high gradient operation in accelerators. For future high energy accelerators, like the CLIC project, it is essential to master these RF breakdowns. In order to improve the limited understanding of the different stages of a breakdown event, a research program has been launched at CERN. I present measurements, performed as a part of this program, of ions ejected from the accelerating cavities after a breakdown, resulting in estimates for parameters of the plasma formed during a breakdown event, such as temperature and composition. The measurement took place at the 30 GHz test-stand in the CLIC test facility CTF3 at CERN. Furthermore I investigated the impact of RF breakdown on the beam in CLIC. Breakdown prevents stable operation of accelerating cavities due to damage of the cavities, and interactions between the breakdown ions and electrons and the beam, a so-called kick. This interaction might steer the beam to hit equipment along the beam line, or cause oscillations which make the colliding electron-positron beams miss each other at the interaction point. I present a proposed measurement of the kick magnitude, and give the accuracy with which the kick can be measured. The experiment will be performed at the two-beam test-stand in CTF3 at CERN.

The PAMELA satellite experiment was launched into low earth orbit on June 15th 2006 for a 3 year mission. The combination of a permanent magnet silicon strip spectrometer, and a silicon - tungsten imaging calorimeter allows precision studies of the charged cosmic radiation to be conducted over a wide energy range (~100 MeV - ~200 GeV) with high statistics. The primary scientific goal is to measure the cosmic ray antiparticle energy spectra, allowing a search for exotic sources such as dark matter particle annihilations. The status of the PAMELA experiment will be reviewed with a particular focus on recent results concerning antiprotons and positrons.