Towards the european strategy for particle physics: The briefing book

This document was prepared as part of the briefing material for the Workshop of the CERN Council Strategy Group, held in DESY Zeuthen from 2nd to 6th May 2006. It gives an overview of the physics issues and of the technological challenges that will shape the future of the field, and incorporates material presented and discussed during the Symposium on the European Strategy for Particle Physics, held in Orsay from 30th January to 2nd February 2006, reflecting the various opinions of the European community as recorded in written submissions to the Strategy Group and in the discussions at the Symposium.     

Experimental tests of fundamental symmetries

PANDA is a universal modular 4 π detector for both charged particles and photons that will study antiproton-proton and antiproton-nucleus collisions using the high-quality internal antiproton beam of the HESR storage ring at the international FAIR facility. With beam momenta between 1.5 GeV/c and 15 GeV/c a wide range of physics topics is accessible. An overview of the physics program of the PANDA experiment is given.     

Atomic parity violation in a single trapped radium ion

Atomic parity violation (APV) experiments are sensitive probes of the electroweak interaction at low energy. These experiments are competitive with and complementary to high-energy collider experiments. The APV signal is strongly enhanced in heavy atoms and it is measurable by exciting suppressed (M1, E2) transitions. The status of APV experiments and theory are reviewed as well as the prospects of an APV experiment using one single trapped Ra^?+? ion. The predicted enhancement factor of the APV effect in Ra^?+? is about 50 times larger than in Cs atoms. However, certain spectroscopic information on Ra^?+? needed to constrain the required atomic many-body theory, was lacking. Using the AGOR cyclotron and the TRI??P facility at KVI in Groningen, short-lived ^212???214Ra^?+? ions were produced and trapped. First ever excited-state laser spectroscopy was performed on the trapped ions. These measurements provide a benchmark for the atomic theory required to extract the electroweak mixing angle to sub-1% accuracy and are an important step towards an APV experiment in a single trapped Ra^?+? ion.     

Construction and timing system of the EPOS beam system

The Forschungszentrum Dresden-Rossendorf provides an intense pulsed 40 MeV electron beam with high brilliance and low emittance (ELBE). The pulse has a length of 1-10 ps and a repetition time of 77 ns, or in slow mode 616 ns. The EPOS system (ELBE Positron Source) generates by pair production on a tungsten converter and a tungsten moderator an intense pulsed beam of mono-energetic positrons. To transport the positrons to the laboratory (12 m) we constructed a magnetic beam guidance system with a longitudinal magnetic field of 75 G. In the laboratory outside the cave, the positron beam is chopped and bunched according to the time structure, because the very sharp bunch structure of the electron pulses is broadened for the positron beam due to transport and moderation.     

<Emphasis Type="Italic">β</Emphasis>-Decay and the electric dipole moment: Searches for time-reversal violation in radioactive nuclei and atoms

One of the greatest successes of the Standard Model of particle physics is the explanation of time-reversal violation (TRV) in heavy mesons. It also implies that TRV is immeasurably small in normal nuclear matter. However, unifying models beyond the Standard Model predict TRV to be within reach of measurement in nuclei and atoms, thus opening an important window to search for new physics. We will discuss two complementary experiments sensitive to TRV: Correlations in the β-decay of ²¹Na and the search for an electric dipole moment (EDM) in radium.