3,617 research outputs found
A Two-Layer Model of Venus' Atmosphere /Interpretations of Radar Observations/
Two-layer atmosphere model of Venu
Longitudinal Hadronic Shower Development in a Combined Calorimeter
This work is devoted to the experimental study of the longitudinal hadronic
shower development in the ATLAS barrel combined prototype calorimeter
consisting of the lead-liquid argon electromagnetic part and the
iron-scintillator hadronic part. The results have been obtained on the basis of
the 1996 combined test beam data which have been taken on the H8 beam of the
CERN SPS, with the pion beams of 10, 20, 40, 50, 80, 100, 150 and 300 GeV/c.
The degree of description of generally accepted Bock parameterization of the
longitudinal shower development has been investigated. It is shown that this
parameterization does not give satisfactory description for this combined
calorimeter. Some modification of this parameterization, in which the e/h
ratios of the compartments of the combined calorimeter are used, is suggested
and compared with the experimental data. The agreement between such
parameterization and the experimental data is demonstrated.Comment: Latex, 21 pages, 10 figure
Non-compensation of an Electromagnetic Compartment of a Combined Calorimeter
The method of extraction of the ratio, the degree of non-compensation,
of the electromagnetic compartment of the combined calorimeter is suggested.
The ratio of has been determined on the basis of the 1996
combined calorimeter test beam data. This value agrees with the prediction that
for this electromagnetic calorimeter.Comment: LATEX, 17 pages, 7 figure
Short-Baseline Active-Sterile Neutrino Oscillations?
We suggest the possibility that the anomalies observed in the LSND experiment
and the Gallium radioactive source experiments may be due to neutrino
oscillations generated by a large squared-mass difference of about 20 - 30
eV^2. We consider the simplest 3+1 four-neutrino scheme that can accommodate
also the observed solar and atmospheric neutrino oscillations. We show that, in
this framework, the disappearance of nu_e and nu_mu in short-baseline neutrino
oscillation experiments is mainly due to active-sterile transitions. The
implications of the first MiniBooNE results, appeared after the completion of
this paper, are discussed in an addendum.Comment: 12 pages. The implications of the first MiniBooNE results are
discussed in an addendu
Enhancement of superconductivity in NbN nanowires by negative electron-beam lithography with positive resist
We performed comparative experimental investigation of superconducting NbN
nanowires which were prepared by means of positive-and negative electron-beam
lithography with the same positive tone Poly-methyl-methacrylate (PMMA) resist.
We show that nanowires with a thickness 4.9 nm and widths less than 100 nm
demonstrate at 4.2 K higher critical temperature and higher density of critical
and retrapping currents when they are prepared by negative lithography. Also
the ratio of the experimental critical-current to the depairing critical
current is larger for nanowires prepared by negative lithography. We associate
the observed enhancement of superconducting properties with the difference in
the degree of damage that nanowire edges sustain in the lithographic process. A
whole range of advantages which is offered by the negative lithography with
positive PMMA resist ensures high potential of this technology for improving
performance metrics of superconducting nanowire singe-photon detectors
On q-tensor products of Cuntz algebras
We consider the Câ-algebra Eqn, m, which is a q-twist of two Cuntz-Toeplitz algebras. For the case |q| < 1, we give an explicit formula which untwists the q-deformation showing that the isomorphism class of Eqn, mdoes not depend on q. For the case |q| = 1, we give an explicit description of all ideals in Eqn, m. In particular, we show that Eqn, mcontains a unique largest ideal Mq. We identify Eqn, m/Mq with the Rieffel deformation of On âOm and use a K-theoretical argument to show that the isomorphism class does not depend on q. The latter result holds true in a more general setting of multiparameter deformations
Towards single-electron metrology
We review the status of the understanding of single-electron transport (SET)
devices with respect to their applicability in metrology. Their envisioned role
as the basis of a high-precision electrical standard is outlined and is
discussed in the context of other standards. The operation principles of single
electron transistors, turnstiles and pumps are explained and the fundamental
limits of these devices are discussed in detail. We describe the various
physical mechanisms that influence the device uncertainty and review the
analytical and numerical methods needed to calculate the intrinsic uncertainty
and to optimise the fabrication and operation parameters. Recent experimental
results are evaluated and compared with theoretical predictions. Although there
are discrepancies between theory and experiments, the intrinsic uncertainty is
already small enough to start preparing for the first SET-based metrological
applications.Comment: 39 pages, 14 figures. Review paper to be published in International
Journal of Modern Physics
Light Lepton Number Violating Sneutrinos and the Baryon Number of the Universe
Recent results of neutrino oscillation experiments point to a nonvanishing
neutrino mass. Neutrino mass models favour Majorana-type neutrinos. In such
circumstances it is natural that the supersymmetric counterpart of the
neutrino, the sneutrino, bears also lepton number violating properties. On the
other hand, the fact that the universe exhibits an asymmetry in the baryon and
antibaryon numbers poses constraints on the extent of lepton number violation
in the light sneutrino sector if the electroweak phase transition is second or
weak first order. From the requirement that the Baryon Asymmetry of the
Universe should not be washed out by sneutrino induced lepton number violating
interactions and sphalerons below the critical temperature of the electroweak
phase transition we find that the mass splitting of the light sneutrino mass
states is compatible with the sneutrino Cold Dark Matter hypothesis only for
heavy gauginos and opposite sign gaugino mass parameters.Comment: 13 pages, 4 figure
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