462 research outputs found
Technical and economic analysis of the reconversion of an existing biogas plant to biomethane production: a case study.
The paper deals with the technical and economic analysis of a project aimed at transforming an existing plant, used for the anaerobic digestion of zoo-technical and agroforest biomass and including a CHP system of about 1 MW of electric capacity, into a facility producing bio-methane for automotive and/or stationary power applications.
A comparison of different biogas upgrading technologies is performed, aimed at selecting the technology most appropriate to the size and typology of application under evaluation. Similarly, an analysis is performed to evaluate the opportunity of installing a bio-methane liquefaction facility, to simplify the management and transportation of the fuel, to be used in vehicles. The economic analysis is performed by considering the incentives presently available in Italy for bio-methane producers.
Different scenarios are analyzed and discussed, and it was concluded that the conversion of the existing plant into a facility to produce bio-methane to be liquified and sold as fuel for vehicles represents at this moment a very attractive and profitable option
X-ray detection with a scintillating YAP-window hybrid photomultiplier tube
A YAP(YAlO/sub 3/:Ce)-scintillating window, coated on its inner surface with an S20-photocathode, seals a cross-focusing hybrid photomultiplier tube (HPMT) equipped with a small p-i-n anode of 2-mm diameter. This new radiation detector separates X-ray lines down to about 2-keV peak energy from the HPMT noise. Its detection efficiency for high gamma energies depends on the YAP-window thickness and amounts to about 18% attenuation at 400-keV energy in the present version. Competitive radiation detectors like Si photodiodes and Si drift chambers are discussed and compared to our prototype, with particular attention given to their energy resolution and noise performance, which limits their active area considerably. (19 refs)
Dedicated multichannel readout ASIC coupled with single crystal diamond for dosimeter application
This paper reports on the tests of a low-noise, multi-channel readout integrated circuit used as a readout electronic front-end for a diamond multi-pixel dosimeter. The system is developed for dose distribution measurement in radiotherapy applications. The first 10-channel prototype chip was designed and fabricated in a 0.18 um CMOS process. Every channel includes a charge integrator with a 10 pF capacitor and a double slope A/D converter. The diamond multi-pixel detector, based on CVD synthetic single crystal diamond Schottky diodes, is made by a 3 Ă— 3 sensor matrix. The overall device has been tested under irradiation with 6 MeV radio therapeutic photon beams at the Policlinico ``Tor Vergata'' (PTV) hospital. Measurements show a 20 fA RMS leakage current from the front-end input stage and a negligible dark current from the diamond detector, a stable temporal response and a good linear behaviour as a function of both dose and dose rate. These characteristics were common to each tested channel
Study of Spin and Decay-Plane Correlations of W Bosons in the e+e- -> W+W- Process at LEP
Data collected at LEP at centre-of-mass energies \sqrt(s) = 189 - 209 GeV are
used to study correlations of the spin of W bosons using e+e- -> W+W- -> lnqq~
events. Spin correlations are favoured by data, and found to agree with the
Standard Model predictions. In addition, correlations between the W-boson decay
planes are studied in e+e- -> W+W- -> lnqq~ and e+e- -> W+W- -> qq~qq~ events.
Decay-plane correlations, consistent with zero and with the Standard Model
predictions, are measured
Ultrarelativistic sources in nonlinear electrodynamics
The fields of rapidly moving sources are studied within nonlinear
electrodynamics by boosting the fields of sources at rest. As a consequence of
the ultrarelativistic limit the delta-like electromagnetic shock waves are
found. The character of the field within the shock depends on the theory of
nonlinear electrodynamics considered. In particular, we obtain the field of an
ultrarelativistic charge in the Born-Infeld theory.Comment: 10 pages, 3 figure
Search for Charginos with a Small Mass Difference with the Lightest Supersymmetric Particle at \sqrt{s} = 189 GeV
A search for charginos nearly mass-degenerate with the lightest
supersymmetric particle is performed using the 176 pb^-1 of data collected at
189 GeV in 1998 with the L3 detector. Mass differences between the chargino and
the lightest supersymmetric particle below 4 GeV are considered. The presence
of a high transverse momentum photon is required to single out the signal from
the photon-photon interaction background. No evidence for charginos is found
and upper limits on the cross section for chargino pair production are set. For
the first time, in the case of heavy scalar leptons, chargino mass limits are
obtained for any \tilde{\chi}^{+-}_1 - \tilde{\chi}^0_1 mass difference
Measurement of the Cross Section for Open-Beauty Production in Photon-Photon Collisions at LEP
The cross section for open-beauty production in photon-photon collisions is
measured using the whole high-energy and high-luminosity data sample collected
by the L3 detector at LEP. This corresponds to 627/pb of integrated luminosity
for electron-positron centre-of-mass energies from 189GeV to 209GeV. Events
containing b quarks are identified through their semi-leptonic decay into
electrons or muons. The e+e- -> e+e-b b~X cross section is measured within our
fiducial volume and then extrapolated to the full phase space. These results
are found to be in significant excess with respect to Monte Carlo predictions
and next-to-leading order QCD calculations
Search for Charged Higgs Bosons in e+e- Collisions at \sqrt{s} = 189 GeV
A search for pair-produced charged Higgs bosons is performed with the L3
detector at LEP using data collected at a centre-of-mass energy of 188.6 GeV,
corresponding to an integrated luminosity of 176.4 pb^-1. Higgs decays into a
charm and a strange quark or into a tau lepton and its associated neutrino are
considered. The observed events are consistent with the expectations from
Standard Model background processes. A lower limit of 65.5 GeV on the charged
Higgs mass is derived at 95 % confidence level, independent of the decay
branching ratio Br(H^{+/-} -> tau nu)
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