It is shown that both the oscillation amplitude and the The spectralĭistributions of radiation and energy of radiation are derived. Planar channeled positrons at arbitrary incidence angle and transverse coordinate is constructed. Radiation by planar channeled positrons, taking into account the medium polarization, is considered. When the oscillatorĮnergy gets over this value, the spectrum of the radiated photons number modifies. Threshold there is another special value for the oscillator energy (equals to the double of threshold). Theory of one-dimensional relativistic oscillator in dispersive medium is developed.
The efficiency of positron production by a photon beam from a thick diamond target was estimated and possibility to achieve the efficiency about one accelerated positron per each initial electron with energy ~ 10 GeV was shown. Our estimations show that for electron with energy 4.5 GeV passing through 10mm diamond target along axis, the photon multiplicity may achieve 10 photons per each electron. The comparison of existing experimental results with developed approach has been performed. The model for estimation of radiation losses, mean photon energy and photon multiplicity in coherent bremsstrahlung processes is described in the report. For axial orientation of such thick crystal only initial part of a crystal forms channeling radiation (around 0.5 mm for 10 GeV electrons) electrons emit coherent bremsstrahlung (CBS) in the remained part of a crystal. Properties of a diamond crystal such as a high thermal conductivity ( 660 W/m.K versus 170 W/m.K for tungsten), high Debye temperature (1860K versus 379K tungsten) and the shortest lattice constant allow us to consider a thick diamond crystal (> 10mm) as a best candidate for a photon source. The promising scheme to design the intense positron source is based on using of oriented crystal to generate an intense photon beam and amorphous converter for shower producing. (2003) 1053]: the low-energy spiked radiation can be deflected towards the patient, while the higher energy incoherent background continues forward, avoiding the patient who is placed several This problem can be solved with the use of Kumakhov's capillary optics [see Inadmissible overexposure of the patient. The large, broad incoherent bremsstrahlung background underlying the monochromatic spike would lead to Which can be obtained by many larger hospitals, eliminating the scheduling problems present at synchrotrons. Which is inherently monochromatic, furnishing a flux of 10 12 photon/sec. Propose instead the use of coherent bremsstrahlung Monochromatization of the synchrotron radiation causes a loss of intensity of 10 -3. The radiation mustīe monochromatized and is applied above and below the K-edge of iodine (33.16 keV), with a subsequent digital The imaging of coronaryĪrteries is carried out with an iodine-based contrast agent which need not be injected into the heart.
Hofstadter) and was subsequently taken over at the Brookhaven Synchrotron and Digital subtraction angiography (DSA), also known as Dichromography, using synchrotron radiation beams has beenĭeveloped at Stanford University (R.
0 kommentar(er)
