577 research outputs found
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Report of Foreign Travel of F. Plasil. August 1990
No full textThe traveler spent eleven intense days at CERN, Switzerland. His time was divided between daytime, when he worked mainly on L* issues, and evenings/nights, when he performed shift work during the current run of the WA80 collaboration. It was decided to reduce the size and cost of the proposed L* experiment. Strategy for SSC subsystem proposals was discussed, and several relevant decisions were made
Fluorpyromorphite, Pb5(PO4)3F, a new apatite-group mineral from Sukhovyaz Mountain, Southern Urals, and Tolbachik volcano, Kamchatka
No full textFluorpyromorphite, ideally Pb5(PO4)3F, a new apatite-group member, an F-dominant analog of pyromorphite and hydrox-ylpyromorphite. It is a supergene mineral found at two localities: Sukhovyaz Mountain, Ufaley District, Southern Urals (holotype) and Mountain 1004, Tolbachik volcano, Kamchatka (co-type), both in Russia. At Sukhovyaz, fluorpyromorphite forms anhedral grains up to 0.2 mm across (usually much smaller), filling cavities in quartz and sometimes partially replacing fluorapatite. Associated supergene minerals include pyromorphite, hydroxylpyromorphite, fluorphosphohedy-phane, mimetite, and nickeltsumcorite. At Tolbachik, fluorpyromorphite occurs in the oxidation zone of paleo-fumarolic deposits in close association with pyromorphite, fluorphosphohedyphane, wulfenite, cerussite, munakataite, vanadinite, chrysocolla, and opal. It forms crude long-prismatic to acicular crystals up to 0.1 mm long and up to 5 mu m thick com-bined in bunches and spherulites up to 0.2 mm. Fluorpyromorphite is colorless (Sukhovyaz) or yellow (Tolbachik), translucent to transparent and has a vitreous luster. It is brittle, with an uneven fracture and poor cleavage on (001). The calculated density values are 7.382 (holotype) and 6.831 (cotype) g/cm3. Fluorpyromorphite is optically uniaxial (-). In reflected light, it is light-grey, weakly anisotropic. The reflectance values (Rmin/Rmax, %) are: 15.8/16.6 (470 nm), 16.2/17.2 (546 nm), 15.9/16.9 (589 nm), 15.4/16.2 (650 nm). The chemical composition is (electron microprobe, wt. %; holotype/co-type): CaO 0.10/3.16, SrO 0.17/0.00, PbO 83.51/77.39, P2O516.13/16.35, CrO3 0.00/0.49, SeO3 0.00/0.98, F 1.00/1.35, Cl 0.29/0.40, H2Ocalc 0.13/0.00, -O=(F,Cl) -0.49/-0.66, total 100.84/99.46. The empirical formulae based on 13 anions (O +F + Cl+OH)pfu are Pb4.95Ca0.02Sr0.02P3.00O12F0.70(OH)0.19Cl0.11 (holotype) and Pb4.26Ca0.69P2.83Se6+0.09Cr6+0.06 O11.99F0.87Cl0.14 (co-type). Fluorpyromorphite is hexagonal, space group P63/m, unit-cell parameters (from powder X-ray diffraction data; holotype / co-type) are: a = 9.779(5) / 9.732(1), c = 7.241(9) / 7.242(1) angstrom, V = 599.6(7) / 594.0(2) angstrom 3, and Z = 2. The crystal structure was refined using the Rietveld method to Rp= 0.1764 (holotype). Fluorpyromorphite is isostructural with other members of the apatite group, a subdivision of the apatite supergroup
Tolstykhite, Au3S4Te6, a new mineral from Maletoyvayam deposit, Kamchatka peninsula, Russia
No full textTolstykhite, ideally Au3S4Te6, is a new mineral from the Gaching ore occurrence of the Maletoyvayam deposit, Kamchatka peninsula, Russia. It occurs as individual anhedral grains up to 0.05 mm or as intergrowths with native Se, native Te and tripuhyite. Other associated minerals include calaverite, fischesserite, Cu-Te-rich 'fahlores' [stibiogoldfieldite, 'arsenogoldfieldite', tennantite-(Cu), tetrahedrite-(Zn)], galena, gold, maletoyvayamite, minerals of famatinite-luzonite series, pyrite, baryte, ilmenite, magnetite, quartz and V-bearing rutile. Tolstykhite is bluish-grey, opaque with metallic lustre and grey streak. It is brittle and has an uneven fracture. Cleavage is good on {010} and {001}. D-calc = 7.347 g/cm(3). In reflected light, tolstykhite is grey with a bluish shade. No bireflectance, pleochroism and internal reflections are observed. In crossed polars, it is weakly anisotropic with bluish to brownish rotation tints. The reflectance values for wavelengths recommended by the Commission on Ore Mineralogy of the International Mineralogical Association are (R-min/R-max, %): 32.6/34.3 (470 nm), 32.4/34.1 (546 nm), 32.6/34.5 (589 nm) and 33.0/35.0 (650 nm). The Raman spectrum of tolstykhite contains the main bands at 297, 203, 181, 151 and 127 cm(-1). The empirical formula calculated on the basis of 13 atoms per formula unit is (Au2.98Ag0.01)(sigma 2.99)(S3.59Se0.41)(sigma 4.00)Te-6.01. Tolstykhite is triclinic, space group P(sic)1, a = 8.977(5), b = 9.023(2), c = 9.342(6) angstrom, alpha = 94.03(3), beta = 110.03(3), gamma = 104.27(4)& DEG;, V = 679.0(3) angstrom(3) and Z = 2. The strongest lines of the powder X-ray diffraction (XRD) pattern [d, angstrom (I, %) (hkl)] are: 8.59 (18) (010); 2.90 (100) ; 1.89 (21) (13(sic)4). Tolstykhite is the S-analogue of maletoyvayamite, Au3Se4Te6. The structural identity between them is confirmed by powder XRD and Raman spectroscopy. The mineral honours Russian mineralogist Dr. Nadezhda Dmitrievna Tolstykh for her contributions to the mineralogy of gold and platinum-group elements and the study of ore deposits
Maletoyvayamite, Au3Se4Te6, a new mineral from Maletoyvayam deposit, Kamchatka peninsula, Russia
No full textMaletoyvayamite, Au3Se4Te6, is a new mineral discovered in a heavy-mineral concentrate from the Gaching occurrence of the Maletoyvayam deposit, Kamchatka, Russia (60°19′51.87′′N, 164°46′25.65′′E). It forms anhedral grains (10 to 50 μm in size) and is found in intergrowths with native gold (Au-Ag), Au tellurides (calaverite), unnamed phases (AuSe, Au2TeSe and Au oxide), native tellurium, sulfosalts (tennantite, tetrahedrite, goldfieldite and watanabeite) and supergene tripuhyite. Maletoyvayamite has a good cleavage on {010} and {001}. In plane-polarised light, maletoyvayamite is grey, has strong bireflectance (grey to bluish grey), and strong anisotropy; it exhibits no internal reflections. Reflectance values for maletoyvayamite in air (Rmin,Rmax in %) are: 38.9, 39.1 at 470 nm; 39.3, 39.5 at 546 nm; 39.3, 39.6 at 589 nm; and 39.4, 39.7 at 650 nm. Sixteen electron-microprobe analyses of maletoyvayamite gave an average composition: Au 34.46, Se 16.76, Te 47.23 and S 0.84, total 99.29 wt.%, corresponding to the formula Au2.90(Se3.52S0.44)Σ3.96Te6.14 based on 13 atoms; the average of eleven analyses on synthetic analogue is: Au 34.20, Se 19.68 and Te 45.42, total 99.30 wt.%, corresponding to Au2.90Se4.16Te5.94. The calculated density is 7.98 g/cm3. The mineral is triclinic, space group P1, with a = 8.901(2), b = 9.0451(14), c = 9.265(4) Å, α = 97.66(3), β = 106.70(2), γ = 101.399(14)°, V = 685.9(4) Å3 and Z = 2. The crystal structure of maletoyvayamite represents a unique structure type resembling a molecular structure. There are cube-like [Au6Se8Te12] clusters linked via van der Waals interactions. The structural identity of maletoyvayamite with the synthetic Au3Se4Te6 was confirmed by powder X-ray diffraction and Raman spectroscopy
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Nucleus-nucleus collisions at ultra-relativistic energies: Status and prospects
No full textThis paper is based on three lectures presented at the Prague Seminar on Relativistic Heavy-Ion Physics in September 1994. The first lecture, following a general introduction, focuses on three different aspects of the CERN experiment WA80. The author first presents results on global event characteristics deduced primarily from measured distributions of transverse energy and of forward energy. The purpose is to introduce the main general features of nucleus-nucleus reactions at the highest energies currently available. He highlights the role of projectile-target geometry, discusses the degree of nuclear stopping, and estimates the energy densities attained in these reactions. This discussion is followed by a presentation of one of two topics that are unique to the WA80 experiment and which are not addressed by any of the other CERN collaborations that study nucleus-nucleus reactions: direct measurements of photons. The second topic unique to WA80, measurements of proton-proton correlations in the target-fragmentation region, is covered in the first part of the second lecture. The remainder of the second lecture is devoted to a selective overview of results obtained at the AGS accelerator of Brookhaven National Laboratory (BNL). The third lecture is devoted to a discussion of the two main experiments, STAR and PHENIX, planned for the Relativistic Heavy Ion Collider, RHIC, under construction at BNL
High energy nuclear collisions
No full textThis presentation covers three broad topics: a brief introduction to the field of nucleus-nucleus collisions at relativistic energies; a discussion of several topics illustrating what`s been learned after more than a decade of fixed target experiments; and an indication of what the future may bring at the Relativistic Heavy Ion Collider (RHIC) under construction at the Brookhaven National Laboratory (BNL) and at the Large Hadron Collider (LHC) planned at CERN
Gladkovskyite, MnTlAs3 S6, a new thallium sulfosalt from the vorontsovskoe gold deposit, Northern Urals, Russia
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Research highlights from the Holifield Heavy Ion Research Facility
No full textThe purpose of this paper is to present the scope of research carried out at the new Holifield Heavy Ion Research Facility (HHIRF) at Oak Ridge. This will be accomplished with reference to several research projects currently underway. The areas of research represented are microscopic and macroscopic aspects of nuclear reactions and nuclear structure. In view of the scope of this conference, emphasis will be placed on nuclear reactions. A brief description of HHIRF is given, together with its current status. Microscopic aspects of reactions between nuclei are discussed with reference to the prospects for the study of giant resonances by means of heavy ions, and to studies of elastic and inelastic scattering of /sup 60/Ni nuclei. Macroscopic aspects of nuclear reactions are illustrated by means of the study of collisions between /sup 58/Ni nuclei at 15.1 MeV/u and by means of Spin Spectrometer (crystal ball) studies of the /sup 19/F + /sup 159/Tb reaction. Results are presented for lifetime measurements of high-spin states in ytterbium nuclei. (WHK
Sharing the Architectural Knowledge of Quantitative Analysis
No full textSharing the architectural knowledge of architectural analysis among stakeholders proves to be troublesome. This causes problems in and with architectural analysis, which can have serious consequences for the quality of a system being developed, as this quality might be incompletely or wrongly assessed. This paper presents a domain model, which can be used as a common ground among analysts and architects to capture and explicitly share such knowledge. This enables a way to overcome some of the obstacles imposed by the multi-disciplinary context in which architectural analysis takes place. To apply the domain model in practice, we have created a tool implementing (part of) this domain model for capturing and using explicit architectural knowledge during analysis. We validate the tool and domain model in the context of an industrial case study.</p
Sharing the Architectural Knowledge of Quantitative Analysis
No full textSharing the architectural knowledge of architectural analysis among stakeholders proves to be troublesome. This causes problems in and with architectural analysis, which can have serious consequences for the quality of a system being developed, as this quality might be incompletely or wrongly assessed. This paper presents a domain model, which can be used as a common ground among analysts and architects to capture and explicitly share such knowledge. This enables a way to overcome some of the obstacles imposed by the multi-disciplinary context in which architectural analysis takes place. To apply the domain model in practice, we have created a tool implementing (part of) this domain model for capturing and using explicit architectural knowledge during analysis. We validate the tool and domain model in the context of an industrial case study.
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