G. Fanourakis

DLTS and PL studies of proton radiation defects in tin-doped FZ silicon

Abstract In this paper, deep level transient spectroscopy (DLTS) is applied to study the deep levels in tin-doped and high-energy proton irradiated n-type float-zone (FZ) silicon. The results will be compared with irradiated tin-free FZ reference material, in order to evaluate the hardening potential. It will be shown that in Sn-doped silicon (FZ:Sn), a number of additional deep levels can be observed, two of which have been identified as acceptors associated with Sn–V. Furthermore, optically active recombination centres have been probed by photoluminescence (PL) spectroscopy. The PL results confirm the reduction of electrically active radiation-defect formation in FZ:Sn. At the same time, no Sn-related optically active centres have been found so far.

Axion searches at CERN with the CAST telescope

The CERN Axion Solar Telescope (CAST) searches for axions coming from photon to axion conversion in the suns core, as stated by the Primakoff effect. Axions arise in particle physics as a consequence of the breaking of Peccei-Quinn symmetry which has been introduced as a solution to the strong CP problem. As cosmological axions they are candidates for at least some part of cold Dark Matter.They are also expected to be produced copiously in stellar interiors with energies as high as the thermal photons undergoing photon to axion conversion. In our sun the axion energy spectrum peaks at about 4.4 keV, extending up to 10 keV. CAST collected preliminary data in 2002 and data taking with its full capability will start in the beginning of 2003.The CERN Axion Solar Telescope (CAST) searches for axions coming from photon to axion conversion in the suns core, as stated by the Primakoff effect. Axions arise in particle physics as a consequence of the breaking of Peccei-Quinn symmetry which has been introduced as a solution to the strong CP problem. As cosmological axions they are candidates for at least some part of cold Dark Matter.They are also expected to be produced copiously in stellar interiors with energies as high as the thermal photons undergoing photon to axion conversion. In our sun the axion energy spectrum peaks at about 4.4 keV, extending up to 10 keV. CAST collected preliminary data in 2002 and data taking with its full capability will start in the beginning of 2003.

CAST - A CERN Experiment to Search for Solar Axions

The CAST experiment at CERN is the only running solar axion telescope. The first results obtained so far with CAST — PHASE I is presented, which compete with the best astrophysically derived limits of the axion‐to‐photon coupling. The ongoing PHASE II of the experiment as well as the scheduled upgrades, which improve the axion discovery potential of CAST, are discussed.