525 research outputs found
Relativistic Stern-Gerlach Interaction in an RF Cavity
The general expression of the Stern-Gerlach force is deduced for a
relativistic spin-1/2 particle which travels inside a time varying magnetic
field. This result was obtained either by means of two Lorentz boosts or
starting from Dirac's equation. Then, the utilization of this interaction for
attaining the spin states separation is reconsidered in a new example using a
new radio-frequency arrangement.Comment: 12 pages, 4 figure
Numerical Spin Tracking in a Synchrotron Computer Code SPINK - Examples (RHIC)
In the course of acceleration of polarized protons in a synchrotron, many depolarizing resonances are encountered. They are classified in two categories: Intrinsic resonances that depend on the lattice structure of the ring and arise from the coupling of betatron oscillations with horizontal magnetic fields, and imperfection resonances caused by orbit distortions due to field errors. In general, the spectrum of resonances vs spin tune G{gamma}(G = 1.7928, the proton gyromagnetic anomaly, and y the proton relativistic energy ratio) for a given lattice tune {nu}, or vs {nu} for a given G{gamma}, contains a multitude of lines with various amplitudes or resonance strengths. The depolarization due to the resonance lines can be studied by numerically tracking protons with spin in a model accelerator. Tracking will allow one to check the strength of resonances, to study the effects of devices like Siberian Snakes, to find safe lattice tune regions where to operate, and finally to study in detail the operation of special devices such as Spin Flippers. A few computer codes exist that calculate resonance strengths E{sub k} and perform tracking, for proton and electron machines. Most relevant to our work for the AGS and RHIC machines are the programs Depol and Snake. Depol, calculates the E{sub k}`s by Fourier analysis. The input to Depol is the output of a machine model code, such as Synch or Mad, containing all details of the lattice. Snake, does the tracking, starting from a synthetic machine, that contains a certain number of periods, of FODO cells, of Siberian snakes, etc. We believed the complexities of machines like the AGS or RHIC could not be adequately represented by Snake. Then, we decided to write a new code, Spink, that combines some of the features of Depol and Snake. I.E., Spink reads a Mad output like Depol and tracks as Snake does. The structure of the code and examples for RHIC are described in the following
Elementary seismological analysis applied to the April 6, 2009 L'Aquila mainshock and its larger aftershock
To understand the source complexity of the April 6, 2009 L’Aquila earthquake (MW =
6.3), a quick seismological analysis is done on the waveforms of the mainshock and
the larger aftershock that occurred on April 7, 2009. We prove that a simple waveform
analysis gives useful insights into the source complexity, as soon as the seismograms
are available after the earthquake occurrence, whereas the reconstruction of the
rupture dynamics through the application of sophisticated techniques requires a
definitely longer time. We analyzed the seismograms recorded at broadband and
strong motion stations and provided firm constraints on rupture kinematics, slip
distribution, and static surface deformation, also discriminating the actual fault plane.
We found that two distinct rupture patches associated with different fracture
propagation directions and possibly occurring on distinct rupture planes, characterized
the source kinematics of the April 6 events. An initial updip propagation successively
proceeds toward SE, possibly on a different plane. We also show that the same
processing, applied to the April 7, 2009 aftershock (MW = 5.6), allows us to obtain
useful information also in the case of lower magnitude events. Smaller events with
similar location and source mechanism as the mainshock, to be used as Green’s
empirical function, occur in the days before or within tens of minutes to a few hours
after the mainshock. These quick, preliminary analyses can provide useful constraints
for more refined studies, such as inversion of data for imaging the rupture evolution
and the slip distribution on the fault plane. We suggest implementing these analyses
for real, automatic or semi-automatic, investigations
Coherence in Compton scattering at large angles
Compton scattering of laser light by an electron beam at large angles, in particular at 90°, produces coherent hard radiation if the density of the electron beam is high enough. In this case, the intensity of the scattered radiation is greatly enhanced in a small cone around the forward direction of propagation of the electron beam. As an example, the production of 1-KeV coherent X rays is discussed
Державна грошова допомога як одна із форм соціального захисту дітей-сиріт та дітей, позбавлених батьківського піклування
В статті аналізуються види державної грошової допомоги, які передбачені чинним законодавством України щодо дітей-сиріт та дітей, позбавлених батьківського піклування, а також осіб з їх числа. Сформульовані пропозиції по удосконаленню законодавства про державну соціальну допомогу, застосуванню нових підходів у забезпеченні такою допомогою зазначених осіб.В статье анализируются виды государственной денежной помощи, предусмотренные действующим законодательством Украины по отношению к детям-сиротам и детям, лишенным родительского попечения, а также лицам из их числа. Сформулированы предложения по усовершенствованию законодательства о государственной социальной помощи, применению новых подходов в обеспечении такой помощью вышеуказанных лиц.The article is devoted to the analysis of types of the state monetary (financial) aid, foreseen by the current Ukrainian legislation for children-orphans and children who lost the parental care, as well as persons with the same status. The elaborated proposals on improvement of the legislation concerning the state social aid, as well as introducing new approaches of its granting to the mentioned persons
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