Showing papers by "Peter Fischer published in 1988"
TL;DR: In this article, a new route for the synthesis of monoclinic AgO has been developed, yielding, for the first time, coarse crystalline samples which apparently do not show deviations from the ideal composition.
Abstract: A new route for the synthesis of monoclinic AgO has been developed, yielding, for the first time, coarse crystalline samples which apparently do not show deviations from the ideal composition. On electrolysis of aqueous AgF solutions, (cAg+ = 0.03 M, platinum electrodes, 0.65–0.70 V, current density of 100–200 A m−2, 96 °C) AgO forms at the anode as crystals of 1.0 × 0.2 × 0.05 mm in size. The crystal structure has been refined using single-crystal diffractometer data (P21/c; a = 5.8592(19), b = 3.4842(10), c = 5.4995(13) A, β = 107.506(24)°; Z = 4; 739 independent reflections, R = 0.04) and confirmed to have the empirical formula Ag+Ag3+O2. The thermal stability recorded by differential thermal and thermogravimetric analysis techniques is improved over samples prepared previously by chemical oxidation.
41 citations
15 Dec 1988-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, a Cherenkov radiator was used to detect visible light emitted from single photoelectron avalanches using a CCD camera coupled with an image intensifier system.
Abstract: UV photons from a Cherenkov radiator are multiplied in a multistep avalanche chamber operating in a gated mode at low gas pressure (40 Torr). The gas mixture is C 2 H 6 -argon ( 80 20 ) and TMAE at 34°C. Visible light emitted from single photoelectron avalanches is detected by a CCD camera coupled to an image intensifier system. The detector was tested with 5 GeV c electrons, using a CH 4 radiator gas at 1 atm. Cherenkov rings essentially free of particle background and of secondary photon feedback were obtained in this mode of operation with a mean number n ≅ 11.5 ( N 0 ≅ 76 cm −1 ). We present this new method and discuss its performance.
29 citations
CERN1, Lund University2, University College London3, University of Bari4, Université de Montréal5, Heidelberg University6, Tel Aviv University7, University of Turin8, Weizmann Institute of Science9, University of Pittsburgh10, McGill University11, Sapienza University of Rome12, Los Alamos National Laboratory13, Stockholm University14, Brookhaven National Laboratory15, Rutherford Appleton Laboratory16, University of Salerno17
TL;DR: In this article, the authors measured the transverse energy distributions of the 32 S nucleus with Al, Ag, W, Pt, Pb, and U target nuclei, at an incident energy of 200 GeV per nucleon.
26 citations
CERN1, Lund University2, University College London3, University of Bari4, Université de Montréal5, Heidelberg University6, Vienna University of Technology7, Tel Aviv University8, University of Turin9, Weizmann Institute of Science10, Niels Bohr Institute11, University of Pittsburgh12, McGill University13, Sapienza University of Rome14, University of Oxford15, Los Alamos National Laboratory16, Stockholm University17, Brookhaven National Laboratory18, Rutherford Appleton Laboratory19, University of Salerno20, Carnegie Mellon University21
TL;DR: In this article, the authors measured the transverse energy distributions in the pseudorapidity region −0.1<ηγγγη ≥ 2.9 for oxygen-nucleus collisions at incident energies of 60 and 200 GeV per nucleon for Al, Ag, and W targets.
Abstract: Transverse-energy distributions have been measured in the pseudorapidity region −0.1<η
lab<2.9 for oxygen-nucleus collisions at incident energies of 60 and 200 GeV per nucleon for Al, Ag, and W target nuclei. The cross-section for the heaviest target nuclei at the highest incident energy is measured over 5 orders of magnitude and out to a maximumE
T
of 200 GeV. Measurements of the differential densitydE
T/dη
lab as a function ofη
lab are presented. In the pseudorapidity region −0.1<η
lab<2.9 the transverse energy for an average central collision is proportional to ≈A
0.5, while the fraction of the total transverse energy measured in an extended region ofη
lab>2.9 decreases with increasingA. The distributions are compared with the predictions of a dual parton model. Finally the question of the energy density is addressed.
15 citations
TL;DR: A low-pressure multistep, TMAE-filled, UV-sensitive detector has been developed for Cerenkov ring imaging for ultrarelativistic heavy-ion experiments (HELIOS-CERN).
Abstract: A low-pressure multistep, TMAE-filled, UV-sensitive detector has been developed for Cerenkov ring imaging for ultrarelativistic heavy-ion experiments (HELIOS-CERN). A description is given of the detector structure and its basic properties, and the experimental setup and the detector performance in tests with high-energy electrons are presented. Three modes of readout are used: three-wire coordinates and flash analog-to-digital converters; pad readout; and optical recording of the avalanches. Single photons can be localized with an accuracy of sigma approximately=2 mm, mainly due to single-photoelectron diffusion and to chromatic dispersion in the radiator gas. The experimental N/sub 0/ values obtained by the three methods are close to those expected, taking into account the various losses due to the test conditions. >
14 citations
McGill University1, CERN2, Lund University3, University College London4, University of Bari5, Université de Montréal6, Heidelberg University7, Tel Aviv University8, University of Turin9, Weizmann Institute of Science10, University of Pittsburgh11, Sapienza University of Rome12, University of Oxford13, Los Alamos National Laboratory14, Stockholm University15, Brookhaven National Laboratory16, Rutherford Appleton Laboratory17
TL;DR: In this paper, the transverse energy distributions have been measured in the pseudo-rapidity region −0.1 > ηlab <2.9 for oxygen-nucleus collisions of incident energies of 60 and 200 GeV per nucleon for Al, Ag, and W target nuclei.
Abstract: Transverse-energy distributions have been measured in the pseudo-rapidity region −0.1 >ηlab <2.9 for oxygen-nucleus collisions of incident energies of 60 and 200 GeV per nucleon for Al, Ag, and W target nuclei. We present a summary of the results and a comparison to theoretical model descriptions.
9 citations
15 Dec 1988-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the application of low-pressure two-step gas detectors to the ring-imaging Cherenkov (RICH) technique is demonstrated, and the advantages of using this method in high background experiments, such as in relativistic heavy ion collisions, are discussed.
Abstract: The application of low-pressure two-step gas detectors to the ring-imaging Cherenkov (RICH) technique is demonstrated. A RICH prototype with a UV-photon detector of 20×20 cm2, filled with 53 mbar of C2H6 + TMAE at 30°C, was exposed to 3 GeV c electrons. Photoelectrons were localized with a FADC system with a spatial resolution of 2 mm rms. The ring reconstruction technique is presented. The advantages of using this method in high background experiments, such as in relativistic heavy ion collisions, are discussed.
7 citations
01 Jan 1988
TL;DR: Alzheimer’s disease affects 1% of the population of the Western world and 100% of aged individuals with Down's syndrome and it is characterized by neuronal dysfunction and depositions of amyloid A4 in the form of intracellular neurofibrillary tangles, extracellular plaques and cerebrovascular amyloids.
Abstract: Alzheimer’s disease affects 1% of the population of the Western world and 100% of aged individuals with Down’s syndrome. It is characterized by neuronal dysfunction and depositions of. amyloid A4 protein (β-protein) in the form of intracellular neurofibrillary tangles, extracellular plaques and cerebrovascular amyloid. Amyloid A4 is a self-aggregating protein that consists of 42–43 residues. “Reverse genetics” based on the sequence of amyloid A4 protein has indicated that the amyloid protein is encoded as part of a larger protein by a gene on chromosome 21. Recent cloning studies have indicated that the amyloid precursor gene encodes at least three alternatively spliced products.
2 citations
01 Jan 1988
TL;DR: The major protein subunit of the amyloid fibril in Alzheimer's disease is a small molecule of 42 residues (termed A4), which is derived from a larger precursor (PreA4), the gene for which is located on chromosome 21, in close proximity to the region involved in Down’s syndrome.
Abstract: The major protein subunit of the amyloid fibril in Alzheimer’s disease is a small molecule of 42 residues (termed A4). It is derived from a larger precursor (PreA4), the gene for which is located on chromosome 21, in close proximity to the region involved in Down’s syndrome. The predicted structure of PreA4 suggests that it is an integral membrane glycoprotein. Knowledge of the mechanisms by which PreA4 is degraded to A4 may contribute to a better understanding of the cause of Alzheimer’s disease. Similarly, the amyloid fibril in the unconventional virus diseases is composed of the PrP molecule, which in turn is derived from a neuronal membrane glycoprotein. An understanding of the process by which the PrP molecule is converted into an amyloidogenic molecule may shed some light on the nature of the infectious unit.
1 citations