Search

The EXPADES (EXotic PArticle DEtection System) detector array consists of 16 Double Side Silicon Strip Detectors (DSSSD) with active areas of 64 × 64 mm 2 , arranged in 8 ΔE (40/50 μm)–E (300 μm) telescopes. All detector faces are segmented into 32 × 2-mm wide strips, ensuring a 2 × 2 mm 2 pixel configuration. Eight ionization chambers can be alternatively used as ΔE stages or, if needed, as an additional third layer for more complex triple telescopes. The signals from silicon ΔE layers and from ionization chambers are read by standard electronics, while innovative 32-channel ASIC chips are employed for the readout of the E stages. The results of off-line tests with alpha sources and from the first in-beam experiment with a 17 O beam are presented.

Objective To evaluate the effects of methadone, administered alone or in combination with acepromazine or xylazine, on sedation and on physiologic values in dogs. Study design Randomized cross-over design. Animals Six adult healthy mixed-breed dogs weighing 13.5 ± 4.9 kg. Methods Dogs were injected intramuscularly with physiologic saline (Control), or methadone (0.5mg kg−1) or acepromazine (0.1 mg kg−1) or xylazine (1.0 mg kg−1), or acepromazine (0.05 mg kg−1) plus methadone (0.5 mg kg−1) or xylazine (0.5 mg kg−1) plus methadone (0.5 mg kg−1) in a randomized cross-over design, with at least 1-week intervals. Sedation, pulse rate, indirect systolic arterial pressure, respiratory rate (RR), body temperature and pedal withdrawal reflex were evaluated before and at 15-minute intervals for 90 minutes after treatment. Results Sedation was greater in dogs receiving xylazine alone, xylazine plus methadone and acepromazine plus methadone. Peak sedative effect occurred within 30 minutes of treatment administration. Pulse rate was lower in dogs that received xylazine either alone or with methadone during most of the study. Systolic arterial pressure decreased only in dogs receiving acepromazine alone. When methadone was administered alone, RR was higher than in other treatments during most of the study and a high prevalence of panting was observed. In all treatments body temperature decreased, this effect being more pronounced in dogs receiving methadone alone or in combination with acepromazine. Pedal withdrawal reflex was absent in four dogs receiving methadone plus xylazine but not in any dog in the remaining treatments. Conclusions and clinical relevance Methadone alone produces mild sedation and a high prevalence of panting. Greater sedation was achieved when methadone was used in combination with acepromazine or xylazine. The combination xylazine–methadone appears to result in better analgesia than xylazine administered alone. Both combinations of methadone/sedative were considered effective for premedication in dogs.

The Silicon Vertex Trigger (SVT) is a processor developed at CDF experiment to perform online fast and precise track reconstruction. SVT is made of two pipelined processors, the Associative Memory, finding low precision tracks, and the Track Fitter, refining the track quality whith high precision fits. We will describe the architecture and the performances of a next generation track fitter, the GigaFitter, developed to reduce the degradation of the SVT efficiency due to the increasing instantaneous luminosity. The GigaFitter reduces the track parameter reconstruction to a few clock cycles and can perform many fits in parallel, thus allowing high resolution tracking at very high rate. The core of the GigaFitter is implemented in a modern Xilinx Virtex-5 FPGA chip, rich in powerful DSP arrays. The FPGA is housed on a mezzanine board which receives the data from a subset of the tracking detector and transfers the fitted tracks to a Pulsar motherboard for the final corrections. Instead of the current 12 boards, one per sector of the detector, the final system will be much more compact, consisting of a single GigaFitter Pulsar board equipped with four mezzanine cards receiving the data from the entire tracking detector. Moreover, the GigaFitter modular structure is adequate to scale for much better performances and is general enough to be easily adapted to future High Energy Physics (HEP) experiments and applications outside HEP.

XPS and LEED measurements of the oxidation in air and thermal desorption on PbTe, SnTe and Pb 0.8 Sn 0.2 Te surfaces are presented. The initial cleaning of the surface for the oxidation experiments by Ar sputtering (3 kV) yields immediately a perfect, unreconstructed Pb 1− x -Sn x Te surface. The oxidation process is determined by the preferential oxidation of Sri. The surface is strongly depleted of tellurium and enriched with lead and especially tin. During thermal desorption tellurium oxide is lost first from the surface. Lead and tin oxide are too stable to become thermally desorbed during our heat treatment (350°C, 30 min). The oxidation and thermal desorption can be understood as a competing chemical reaction between the stable SnO 2 and the unstable TeO 2 .

The Gruneisen parameters γ τ of the most prominent τ phonons in CdSiP 2 , CuAlS 2 are presented. Concerning the sign and magnitude of γ τ , a separation into three groups of phonons can be observed. This result is compared with the γ values of the corresponding phonon branches of the analogue binaries in the zincblende structure. In addition, the τ phonon spectrum of CuGaS 2 is given.

The reflectance spectra of the A and B exciton in β-AgI were measured on different crystallographic planes. The n = 2 state of the A exciton and the longitudinal-transverse mixed modes of the A and B exciton ground states could be identified. Magnetic circular reflectance measurement (MCR) yielded the exciton g -values.

The p-InP/n-CdS heterodiode has reached Air Mass 2 solar conversion efficiencies of 15.0% in single crystal and 5.7% in polycrystalline thin film form. After a brief description of the physical principles of this solar cell we give an account of its preparation and characterization. Key results are included on photocurrent, photovoltage, quantum efficiency, as well as on stability and operation at high temperature.

The reflection, absorption and luminescence spectra of the lowest excitons in AgGaS2 are measured in magnetic fields. The results can be explained by the quasicubic model. The exchange splittings of the Γ4, Γ5 and Γ3 exciton state are evaluated. The Zeeman splittings of the Γ5 and Γ5-Γ3 states yield g-values of + 3.8 and 3.7, respectively. They are determined mainly by the contributions of the hole and conduction electron spins.

A new method of investigating band gaps in birefringent materials by means of polarization modulation in reflection is described. Measurements at the E0-gap of the I-III-VI2 compounds CuAlS2, CuGaS2, CuInS2 give results similar to those found by other methods.2,5 The energy of the lowest exciton of CuAlSe2 is 2.715 eV at T = 78K.

We have measured in photoluminescence the energy shift of free, weakly and tightly bound excitons in high purity GaAs in magnetic fields up to 12T. In the weak binding limit we find a surprising result: the mass obtained from the magnetic shift is the electron-heavy hole reduced mass in contrast to the results obtained from k · p calculation in zincblende type semiconductors in zero magnetic field. In the tight binding limit the mass deduced from the magnetic shift is the effective electron mass.