Search

A new type of tracking device using large area nuclear emulsion sheets was developed for the short baseline neutrino oscillation experiment, CERN-WA95/CHORUS. The emulsion tracker is made of three layers, each 25 mm thick including support, and covering an area of about 5 m 2 . Two layers were installed upstream and one downstream of the hexagonal magnet of the CHORUS hadron spectrometer. The achieved position resolution over the whole area is 25 μm, which keeps the momentum resolution of the spectrometer below 30% up to momenta of about 15 GeV/ c .

A scintillating fiber tracker system consisting of more than one million fibers has been successfully constructed and made operational for the CERN WA95/CHORUS experiment. The design and construction of the tracker system as well as its opto-electronic readout are described. The performance of the detector with high-energy muons is presented.

The CERN WA95/CHORUS collaboration has been constructing a hybrid detector to search for ( ν μ - ν τ )-oscillations. An essential component of the detector is a scintillating fiber tracking system for precise track reconstruction of particles. The physics motivation is explained, and the detector layout, the tracker design, its optoelectronic readout and test beam results are presented.

Analytical equations are formulated to describe the influence of climatic conditions on moisture loss and temperature of hatching eggs. The equations are based on physical properties and are used to calculate moisture loss and temperature of eggs in different situations. Temperature development during cooling of eggs, moisture loss of eggs during cooling or heating and at constant temperature, and temperature in the egg during development of the embryo is described. For every characteristic, analytical equations are formulated and practical impacts are discussed.

Scalding of pig carcasses (n = 34) at 60°C for a period of at least 5·5 to 7·5 min gave satisfactory dehairing results, with the exception of autumn hair for which a longer period (9 mins) was required. Temperature curves were recorded for a subcutaneous position in the ham (n = 26) between the rind and the underlying fat layer. These showed a curve starting at about 30·8°C and increasing to an asymptotic value of 53°C during scalding. Results of calculations with a finite element model of a flat layer of muscle covered with a layer of 1·0 cm fat broadly showed the same temperature increase at about 0·5 cm below the surface as the actual values measured. Immediately after dehairing, about 1·5 mins after finishing scalding, the subcutaneous temperature had already dropped to 46·1 ± 3·0°C, which was considerably higher than the muscle temperature at the same position at a depth of 5 cm under the skin (40·6°C). The heat removal and temperatures during the cooling period after scalding were also calculated. It can be concluded that the increase in temperature due to scalding has only a minor influence on muscle temperature and that meat quality (pH, FOP) is not affected.

The layout and construction of the muon drift chambers equipping the end caps of the DELPHI detector are described. The performance of this forward muon detection system, determined from cosmic ray tests and data collected during the first year of LEP operation, is presented.

A set of two cylindrical multiwire proportional chambers, 2.2 meter long and 1 meter in diameter, are being built as part of the central tracking detector of the H1 experiment, at HERA. The chamber bodies are of sandwich type; the cathodes are segmented in pads. The transmission line, which is part of the sandwich, has an impedance matched to the preamplifiers. The electronic readout has been tested on a flat prototype chamber; the time resolution is well below the 96 ns bunch crossing time at HERA.

Successful operation of a drift chamber with 10 cm drift in the limited streamer mode is demonstrated. Good results were obtained with a 50-50 argon-isobutane gas mixture. A preliminary search for alternative gas mixtures avoiding the hydrocarbon quencher component is described.

This report presents the performance of drift chambers operated in the limited streamer mode with 9.4 cm maximum drift distance and position sensing along the 4.35 m long anode wire through delay line timing. Using only three timing channels a position resolution of 1×3 mm2 is obtained over a detector surface of 19×435 cm2. In this contribution, the emphasis is mainly put on the performance of the delay line and on the drift behaviour in streamer mode using safe gas mixtures.

We present a description of the Brussels scanning and measuring system for holographic bubble chamber or streamer chamber images. Conclusions are drawn from six months of operation of the system.

Results of a systematic study of operating conditions for holographic image recording in a heavy liquid rapid cycling bubble chamber are presented. We find that the limiting phenomenon is the turbulences generated by the growth and recompression of the bubbles. To minimize this effect it is necessary to operate the chamber at high temperature where the bubble growth is slow. A total of 40 000 useful holograms were recorded in the NA25 experiment at CERN. Typical running conditions were 10 Hz cycling rate, 80 beam tracks per expansion and a bubble density of 95 bubbles per cm. The bubble diameter was 12 μ.

The construction of the BCD-ring system of C 19 -diterpene alkaloids was initiated by development of a ring expansion reaction of cyclic enamino-esters with propiolic acid esters, leading from the 5-membered ring ketone 3 to the 7-membered ring ketone 10. Epoxidation and stereospecific reductive epoxide ring opening to give hydroxy ester 18 were subsequent key-steps which eventually furnished cyclic β-keto ester 22. This versatile intermediate has a full potential of functional groups suited for further elaboration into the A-, E- and F-rings and substituents of a variety of C 19 -diterpene alkaloids.