V. K. Grishin

POLARIZATION BREMSSTRAHLUNG OF RELATIVISTIC ELECTRONS IN ALUMINIUM

Abstract The spectral-angular distribution of the polarization bremsstrahlung of relativistic electrons crossing a thin aluminium foil is measured. The earlier predicted strong difference between polarization bremsstrahlung properties for amorphous and polycrystalline targets is observed for the first time.

SUPPRESSION OF POLARIZATION BREMSSTRAHLUNG OF RELATIVISTIC ELECTRONS MOVING THROUGH AN AMORPHOUS CARBON FOIL

Abstract The suppression effect of relativistic polarization bremsstrahlung in an amorphous carbon foil is observed for the first time. A theoretical explanation for this effect is discussed.

Diagnostics of atoms encapsulated into fullerenes by the polarization bremsstrahlung from accelerated electrons

It is shown that the polarization bremsstrahlung (PB), which arises during scattering of coherent electromagnetic fields of fast charged particles by atomic electrons and resonantly reacts to changes of the density of a substance, allows one to diagnose the states of atoms that are encapsulated in fullerene. As a result of modeling, by comparing the spectra of an empty fullerene and fullerene with an encapsulated atom and using difference fitting, it is possible to detect compressions or expansions of an electron shell of the atom that is encapsulated in a fullerene. The calculations are fulfilled for the model approximation of the P@C60 endohedral compound.

Coherent radiation diagnostics of parameters of nanostructures at electron accelerators

The possibility of observing and diagnosing parameters of nanoobjects in a substance by using coherent X-ray radiation arising from the direct interaction of accelerated electrons with the object of interest is discussed. It is analytically shown that analysis of the generated radiation allows the microstructural features of the nanoobject to be studied. To illustrate the main conclusions, coherent radiation generated by relativistic electron scattering on fullerene is considered.

High efficiency x-ray bremsstrahlung sources

We propose to generate X-rays by having an electron beam in a magnetic field cross thin foil radiators multiple times. We report that our simulation and analytic results agree and indicate that the X-ray yield will be at least doubled over that from a single, equivalently thick, target.

Free electron laser-FEL-study in Institute of Nuclear Physics of MSU

The possibility of creation of a source of coherent shortwave radiation on the basis of the RM of Moscow State University (MSU) facility was considered. The RM is designed to obtain accelerated electrons with a variable energy of 7-180 MeV at high quality of beam: the homogeneity of energy is 0.0001, the beam emittance is not higher than 0.01 mm.mrad. The beam current is a continuous sequence of electron pulses with the duration of 3-4 ps following at a frequency of 2.45 GHz and the average current of 100 mA. A special operation mode of the acceleration is provided for duty cycle decreasing by 100-300 times and the amplitude of current pulses 1-10 A. Two operation regimes of the FEL are possible. At the standard undulator parameters (length and number of periods are 2.5 cm and 100, B=5 kG, undulator factor is K=0.5-1, optical length is 3-5 m) positive gain in the single-particle regime is realised in the 5-170 mkm band. Low emittance permits to provide the collective amplification regime of FEL with channelling radiation. In this case the positive gain may be achieved in the wavelength region of /spl lambda/s< 1 mkm.

Configurational splitting of electron radiation on atoms and its discovery on accelerators

New effects in the coherent polarization bremsstrahlung radiation (PB) of relativistic electrons on light element atoms with clearly expressed atomic shell structures are discussed. The coherent PB acquires a special structure which is split into low and high frequency regions. This phenomenon is most noticeable in media with atomic numbers of Z<10. The coherent PB spectrum in the low frequency region contrasts with earlier predictions. There are real possibilities for splitting discoveries using electron accelerators. A special computer code is designed for empirical data processing.

Spectral structure of polarization radiation from relativistic electrons in aluminum

Collective effects in polarization bremsstrahlung generated by relativistic electrons in a polycrystalline aluminum foil are studied experimentally on the basis of the 2.4-MeV electron accelerator installed at the Institute of Nuclear Physics (Moscow State University, Moscow). A peak structure found in this polarization bremsstrahlung for the first time is in agreement with theoretical predictions.

Collective effects in polarization X-ray bremsstrahlung of relativistic electrons and microstructure analysis of media

The peculiarities of collective effects in polarization X-ray bremsstrahlung (PB) which occur due to the coherent interaction of fast charged particles with atomic electrons are discussed. Results of an experimental study performed with a 2.4 MeV electron CW linear accelerator from MSU are reported. The predicted strong difference between polarization bremsstrahlung properties for amorphous and polycrystalline targets is important for different application regions of X-ray radiation (photon energies 1-10 keV) is observed for the first time manifesting clearly the polycrystalline structure of the used Al target. The possibility of development of a method to test the structure of different substances with PB is indicated.