A study of the energy performance of variable frequency drives sucker rod deep pump installations

The results of studies of power losses and specific energy costs in asynchronous frequency-controlled electric drive of rocking machines, obtained on the basis of a complete mathematical model, electric machine complex, are discussedОбсуждены результаты исследований потерь мощности и удельных затрат энергии в асинхронном частотно-регулируемом электроприводе станков-качалок, полученные на основе полной математической модели, электромашинного комплекс

Photodiode read-out of the ALICE photon spectrometer PbWO4PbWO_{4} crystals

Proposal of abstract for LEB99, Snowmass, Colorado, 20-24 September 1999The PHOton Spectrometer of the ALICE experiment is an electromagnetic calorimeter of high granularity consisting of 17280 lead-tungstate (PWO) crystals of dimensions 22x22x180 mm3, read out by large-area PIN-diodes with very low-noise front-end electronics. The crystal assembly is operated at -25C to increase the PWO light yield. A 16.1x17.1 mm2 photodiode, optimized for the PWO emissio spectrum at 400-500 nm, has been developed. The 20x20 mm2 preamplifier PCB is attached to the back side of the diode ceramic frame. The charge sensitive preamplifier is built in discrete logic with two input JFETs for optimum matching with the ~150pF PIN-diode. A prototype shaper has been designed and built in discrete logic. For a detector matrix of 64 units the measured ENCs are between 450-550e at -25C. Beam tests demonstrate that the required energy resolution is reached.Summary:The PHOton Spectrometer of the ALICE experiment is an electromagnetic calorimeter of high granularity consisting of 17280 lead-tungstate (PWO) crystals of dimensions 22x22x180 mm3, coupled to large-area PIN-diodes with matching low-noise preamplifiers. PHOS is optimized for measuring photons, pi0s and eta mesons in the momentum ranges 0.5-10, 1-10 and 2-10 GeV/c, respectively, and is designed for the expected large number of particles that will be produced in central Pb-Pb collisions. Lead tungstate (PWO) is a fast scintillating crystal with a rather complex emission spectrum, consisting of two components: a blue component peaking at 420 nm and a green component peaking at 480-520 nm. The light yield of PWO at room temperature is low compared with other heavy scintillating crystals, for instance BGO. However, the yield depends strongly on the temperature with a coefficient of ~-2 degree. At the selected operating temperature of -25C the yield is about a factor of 3 higher compared to room temperature. Still, in order to reach the required energy resolution for a PHOS channel, an ENC noise of less than 600e for the PIN-diode-preamplifier-shaper stage is required. This is a very low value taking into account the high capacitance of 150-200 pF of the large area PIN-diodes. In collaboration with the PHOS project, the company AME (Horten, Norway) has designed and produced a PIN-photodiode optimized for the cross-section and spectral responsivity of the PHOS PWO crystal. The photodiode has an active area of 17.1x16.1 mm2 and is fabricated on n-type silicon material of thickness 280 um. The wafer specific resistivity is between 3000 and 6000 ohm-cm, which corresponds to a depletion voltage of 70V. The photodiode response is optimized for the spectral region 400-500 nm in order to match the PWO emission spectrum. The PIN-diode is mounted on a ceramic substrate 0.65 mm thick. On this substrate the diode is surrounded by a ceramic frame. The preamplifier PCB of dimension 20x20 mm2 is attached to the back side of the frame. The PIN-diode and bondings to ground and preamplifier input are protected by an optically transparent epoxy layer. The front side of the PIN-diode is glued onto the endface of the PWO crystal with optically transparent glue (Melt-Mount Quick-Stick, Cargille Laboratories, USA). Each crystal is wrapped in White Tyvek to ensure maximum light collection efficiency and optical insulation between the crystals. The PHOS detector consists of four independent modules, each with 4320 channels. The crystal assembly with the photo detectors are operated at -25 +/- 0.3C. The power dissipation per module is ~1 kW. The charge sensitive preamplifier is an operational amplifier built in discrete logic and with two input JFETs (BF861A). Using two JFETs in parallel gives the lowest noise for detector capacitance >100 pF. A prototype shaper, comprising three amplification stages, has been designed and built in discrete logic. For a PIN-diode with capacitance ~150 pF and a leakage current <1 nA under cooling, calculations give optimum time differentiation and integration constants around 3 microsec. For a detector matrix of 64 units the measured ENCs are between 450-550 e at -25C. Beam tests of this matrix show that the required energy resolution for the PHOS is reached

State and prospects using hardware-software simulator electrical complex in educational process

The problems of the use of real-time simulation in the educational process in the study of subjects related to the development of electric systemsРассматриваются вопросы использования симуляторов реального времени в учебном процессе при изучении дисциплин, связанных с освоением систем электроприводо

Adrenoreactance of arteries of intestines and back finiteness at adaptation to a cold

At adaptation to a cold of rabbits for 1st, 5th, 10th, 30th day the quantity and sensitivity adrenoreceptors changes

Interferometry of Direct Photons in Central 280Pb+208Pb Collisions at 158A GeV

Two-particle correlations of direct photons were measured in central 208Pb+208Pb collisions at 158 AGeV. The invariant interferometric radii were extracted for 100<K_T<300 MeV/c and compared to radii extracted from charged pion correlations. The yield of soft direct photons, K_T<300 MeV/c, was extracted from the correlation strength and compared to theoretical calculations.Comment: 5 pages, 4 figure

Event-by-Event Fluctuations in Particle Multiplicities and Transverse Energy Produced in 158.A GeV Pb+Pb collisions

Event-by-event fluctuations in the multiplicities of charged particles and photons, and the total transverse energy in 158$\cdot A$ GeV Pb+Pb collisions are studied for a wide range of centralities. For narrow centrality bins the multiplicity and transverse energy distributions are found to be near perfect Gaussians. The effect of detector acceptance on the multiplicity fluctuations has been studied and demonstrated to follow statistical considerations. The centrality dependence of the charged particle multiplicity fluctuations in the measured data has been found to agree reasonably well with those obtained from a participant model. However for photons the multiplicity fluctuations has been found to be lower compared to those obtained from a participant model. The multiplicity and transverse energy fluctuations have also been compared to those obtained from the VENUS event generator.Comment: To appear in Physical Review C; changes : more detailed discussion on errors and few figures modifie

Multiplicity Distributions and Charged-neutral Fluctuations

Results from the multiplicity distributions of inclusive photons and charged particles, scaling of particle multiplicities, event-by-event multiplicity fluctuations, and charged-neutral fluctuations in 158$\cdot A$ GeV Pb+Pb collisions are presented and discussed. A scaling of charged particle multiplicity as $N_{part}^{1.07\pm 0.05}$ and photons as $N_{part}^{1.12\pm 0.03}$ have been observed, indicating violation of naive wounded nucleon model. The analysis of localized charged-neutral fluctuation indicates a model-independent demonstration of non-statistical fluctuations in both charged particles and photons in limited azimuthal regions. However, no correlated charged-neutral fluctuations are observed.Comment: Talk given at the International Symposium on Nuclear Physics (ISNP-2000), Mumbai, India, 18-22 Dec 2000, Proceedings to be published in Pramana, Journal of Physic

Scaling of Particle and Transverse Energy Production in 208Pb+208Pb collisions at 158 A GeV

Transverse energy, charged particle pseudorapidity distributions and photon transverse momentum spectra have been studied as a function of the number of participants (N_{part}) and the number of binary nucleon-nucleon collisions (N_{coll}) in 158 A GeV Pb+Pb collisions over a wide impact parameter range. A scaling of the transverse energy pseudorapidity density at midrapidity as N_{part}^{1.08 \pm 0.06} and N_{coll}^{0.83 \pm 0.05} is observed. For the charged particle pseudorapidity density at midrapidity we find a scaling as N_{part}^{1.07 \pm 0.04} and N_{coll}^{0.82 \pm 0.03}. This faster than linear scaling with N_{part} indicates a violation of the naive Wounded Nucleon Model.Comment: 13 pages, 16 figures, submitted to European Physical Journal C (revised results for scaling exponents