1,523 research outputs found
The Yellowstone Permutation
Define a sequence of positive integers by the rule that a(n) = n for 1 <= n
= 4, a(n) is the smallest number not already in the sequence
which has a common factor with a(n-2) and is relatively prime to a(n-1). We
show that this is a permutation of the positive integers. The remarkable graph
of this sequence consists of runs of alternating even and odd numbers,
interrupted by small downward spikes followed by large upward spikes,
suggesting the eruption of geysers in Yellowstone National Park. On a larger
scale the points appear to lie on infinitely many distinct curves. There are
several unanswered questions concerning the locations of these spikes and the
equations for these curves.Comment: 10 pages, 6 figures. Mar 7 2015: mostly stylistic change
Experimental Research of the Diffraction and Vavilov-Cherenkov Radiation Generation in a Teflon Target
Geometry of Vavilov-Cherekov (VChR) radiation when an electron moves close to
a dielectric target is in analogy to diffraction radiation (DR) geometry. In
this case we may expect DR generation from the upstream face of the target
besides that VChR. The joint observation of these booth types of radiation is
very interesting from the pseudo-photon viewpoint, which is applicable for
relativistic electrons. Unexpected results obtained in our experiment insist on
reflection about nature both DR and VChR. The experiment was performed on the
relativistic electron beam of the microtron of Tomsk Polytechnic University.Comment: This article will be published in Journal of Physic
Influence of metallic additives on manganese ferrites sintering
Influence of cuprum nanopowder additive received by electric explosion on the process of manganese ferrites MgFe2O4 consolidating at thermal sintering was researched by dilatometry method. Cuprum nanopowder at a rate of 5 mass % was added into the original commercial-grade powder of manganese ferrite MgFe2O4. Powder mixture was numerously blended with screening for better blending before pressing. Powder compacts were formed by cold one-axle static pressing. It was proved that introduction of cuprum additive caused shrinkage increase at final heating stage. There was abnormal compact enlarging at sintering in the air at isothermal stage; the specified process was not observed in vacuum. This difference can be explained by changes in conditions of gaseous discharge from volume of pores
Investigation of gas distributor for packed columns
The article deals with the construction of gas distributor for the mass-transfer columns, particularly for packed columns. Review and analysis of existing inlets of gas (steam) flow into the column were performed and methods of its even distribution on the cross section. The article presents the results of the uniform distribution of the gas flow along the cross section of the column and the hydraulic resistance for different gas distributors. It was established that the new design of the gas flow distributor has a low hydraulic resistance and distributes the gas flow along the cross section of the column
Experimental test of the shadowing effect in Smith-Purcell radiation
The observation of a shadowing effect of a relativistic electron Coulomb field for the Smith-Purcell radiation generation is presented in this paper. For this purpose the surface current from the closest surface of grating element
to the electron beam was measured for a downstream one shadowed by upstream element. The experimental results showed that shadowing effect for Smith-Purcell radiation depends on grating geometry
Electromagnetic field features at interaction of relativistic electron with matter
The features of electromagnetic field of relativistic electrons passing through a hole in an absorbing screen as a function of the distance from the screen in the range of radiation formation length were investigated for the transversal and longitudinal field components. The analysis of the obtained results allows approving the existence of a semi-bare electron with a particularly deprived Coulomb field, which turns into the stable state of the usual electron at the distance of radiation formation length
Using machine learning to speed up new and upgrade detector studies: a calorimeter case
In this paper, we discuss the way advanced machine learning techniques allow
physicists to perform in-depth studies of the realistic operating modes of the
detectors during the stage of their design. Proposed approach can be applied to
both design concept (CDR) and technical design (TDR) phases of future detectors
and existing detectors if upgraded. The machine learning approaches may speed
up the verification of the possible detector configurations and will automate
the entire detector R\&D, which is often accompanied by a large number of
scattered studies. We present the approach of using machine learning for
detector R\&D and its optimisation cycle with an emphasis on the project of the
electromagnetic calorimeter upgrade for the LHCb detector\cite{lhcls3}. The
spatial reconstruction and time of arrival properties for the electromagnetic
calorimeter were demonstrated.Comment: Talk presented on CHEP 2019 conferenc
“Shadowing” of the electromagnetic field of relativistic charged particles
VIII International Symposium Radiation from Relativistic Electrons in Periodic Structures (RREPS-09), Zvenigorod, Russia, Sept. 7-11, 2009International audienceIn radiation processes such as a transition radiation, diffraction radiation, etc. based on relativistic electrons passing through or near an opaque screen, the electron self-field is partly shadowed after the screen over a distance of the order of the formation length γ2λ. This effect has been investigated on coherent diffraction radiation (DR) by electron bunches. Absorbing and conductive half-plane screens were placed at various distances L before a standard DR source (inclined half-plane mirror). The radiation intensity was reduced when the screen was at small L and on the same side as the mirror. No reduction was observed when the screen was on the opposite side. It is worth noting that absorbing and conductive half-plane screens produce the same shadowing effect. The shadowing effect is responsible for a bound on the intensity of Smith-Purcell radiation
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