Planar channelling of relativistic electrons in half-wave silicon crystal and corresponding radiation

New experimental data on planar channeling of 255 MeV electrons in a 0.74 µm Si Half-Wave Crystal (HWC) obtained at SAGA-LS facility are presented. The computer simulation showed that the angular distribution of electrons after penetration through the HWC revealed the number of unknown before peculiarities is connected with specific electron trajectories in HWC. These specific trajectories lead to specific radiation, the properties of which are analyzed

Computer simulation of electron-positron pair production by channeling radiation in amorphous converter

We consider the radiator-converter approach at 200 MeV channeled electrons (the SPARC_LAB LNF facility energies) for the case of using W crystalline radiator and W amorphous converter. A comparison of the positron production by the axial channeling radiation and the bremsstrahlung is performed. The positron stopping in the convertor is studied by means of computer simulations. It is shown that for the maximum yield of positrons the thickness of the W amorphous converter should be taken 0.35 cm in the case of using the axial channeling radiation resulting to total yield of positrons 5 10-3 e+/e- and 0.71 cm in the case of using the bremsstrahlung resulting to total yield of positrons 3.3 10-3 e+/e-

Channeling of Relativistic Electrons in Half-Wave Silicon Crystal and Corresponding Radiation

The new experiments on channeling of 255 MeV in a 0.7 ?m silicon half-wavelength crystal were performed at SAGA LS facility. Both experimental and simulated electron angular distribution after the crystal and corresponding radiation spectra reveal the number of peculiarities

Angular distributions of relativistic electrons under channeling in half – wavelength crystal and corresponding radiation

New experiments on channeling of 255 MeV electrons in a half-wavelength crystals (HWC) were performed at SAGA Light Source facilities. The simulations of trajectories for (2 2 0) and (1 1 1) planar channeling in Si were performed using the computer code BCM-1.0. Comparison of experimental and theoretical results shows a good agreement. The results of calculations of spectral distribution of radiation in forward direction (h = 0) from 255 MeV electrons at (2 2 0) channeling in HWC silicon are presented. Qualitative comparison with radiation spectrum from an electron moving in an arc is performed

Planar channelling of relativistic electrons in half-wave silicon crystal and corresponding radiation

New experimental data on planar channeling of 255 MeV electrons in a 0.74 µm Si Half-Wave Crystal (HWC) obtained at SAGA-LS facility are presented. The computer simulation showed that the angular distribution of electrons after penetration through the HWC revealed the number of unknown before peculiarities is connected with specific electron trajectories in HWC. These specific trajectories lead to specific radiation, the properties of which are analyzed

Orbital angular momentum of channeling radiation from relativistic electrons in thin Si crystal

We propose to use channeling radiation (CR) from relativistic electrons as a source of high energy twisted photons in the MeV range. We calculate numerically the orbital angular momentum (OAM) of radiation produced by electrons with the energies 155:2500 MeV for the axial and planar channeling in the thin Si crystal. We obtain that the average OAM of CR in this case is approximately 1:6h per photon with the photon energies about 1:2 MeV

Orientation effect in the neutron yield in deuterated Pd target bombarded by deuterium ion beam

At the ion accelerator HELIS at the LPI, the neutron yield is investigated from a deuteron-deuteron (DD) reaction in a deuterated Pd target, during an irradiation of its surface by a 20 keV deuterium (D) ion beam. The measurements of the neutron flux in the D beam direction are performed in dependence on the target angle β with respect to the D beam axis using a multichannel detector based on He^{3} counters. A significant anisotropy in the neutron yield is observed, and it was higher by a factor of 2 at β=0 compared to that at β=±30°. The possible reasons for the anisotropy, including D ion channeling, are discussed. The orientation effect of increasing the relative probability of the DD reaction in Pd due to channeling was investigated by computer simulations using the bcm-2.0 code. The numerically obtained 20 keV D trajectories allow calculating the flux density of channeled D in dependence on the penetration depth and angle of incidence. The enhanced D flux density between crystal planes at a zero incident angle with respect to (200) Pd planes allows a qualitative explanation of the increase of the neutron yield in the DD reaction

Hybrid scheme of positron source at SPARC_LAB LNF facility

The hybrid scheme of the positron source for SPARC_LAB LNF facility (Frascati, Italy) is proposed. The comparison of the positron yield in a thin amorphous W converter of 0.1 mm thickness produced by bremsstrahlung, by axial 〈1 0 0〉 and planar (1 1 0) channeling radiations in a W crystal is performed for the positron energy range of 1 ÷ 3 MeV. It is shown that the radiation from 200 MeV electrons (parameters of SPARC_LAB LNF Frascati) in a 10 μm W crystal can produce positrons in the radiator of 0.1 mm thickness with the rate of 10–102 s−1 at planar channeling, of 102–103 s−1 at bremsstrahlung and of 103–104 s−1 at axial channeling

Hybrid scheme of positron source at SPARC_LAB LNF facility

The hybrid scheme of the positron source for SPARC_LAB LNF facility (Frascati, Italy) is proposed. The comparison of the positron yield in a thin amorphous W converter of 0.1 mm thickness produced by bremsstrahlung, by axial 〈1 0 0〉 and planar (1 1 0) channeling radiations in a W crystal is performed for the positron energy range of 1 ÷ 3 MeV. It is shown that the radiation from 200 MeV electrons (parameters of SPARC_LAB LNF Frascati) in a 10 μm W crystal can produce positrons in the radiator of 0.1 mm thickness with the rate of 10–102 s−1 at planar channeling, of 102–103 s−1 at bremsstrahlung and of 103–104 s−1 at axial channeling