26 research outputs found
Parameters of the crystalline undulator and its radiation for particular experimental conditions
We report the results of theoretical and numerical analysis of the
crystalline undulators planned to be used in the experiments which are the part
of the ongoing PECU project [1]. The goal of such an analysis was to define the
parameters (different from those pre-set by the experimental setup) of the
undulators which ensure the highest yield of photons of specified energies. The
calculations were performed for 0.6 and 10 GeV positrons channeling through
periodically bent Si and SiGe crystals.Comment: 13 pages, 8 figures, submitted to SPI
Total energy losses due to the radiation in an acoustically based undulator: the undulator and the channeling radiation included
This paper is devoted to the investigation of the radiation energy losses of
an ultra-relativistic charged particle channeling along a crystal plane which
is periodically bent by a transverse acoustic wave. In such a system there are
two essential mechanisms leading to the photon emission. The first one is the
ordinary channeling radiation. This radiation is generated as a result of the
transverse oscillatory motion of the particle in the channel. The second one is
the acoustically induced radiation. This radiation is emitted because of the
periodic bending of the particle's trajectory created by the acoustic wave. The
general formalism described in our work is applicable for the calculation of
the total radiative losses accounting for the contributions of both radiation
mechanisms. We analyze the relative importance of the two mechanisms at various
amplitudes and lengths of the acoustic wave and the energy of the projectile
particle. We establish the ranges of projectile particle energies, in which
total energy loss is small for the LiH, C, Si, Ge, Fe and W crystals. This
result is important for the determination of the projectile particle energy
region, in which acoustically induced radiation of the undulator type and also
the stimulated photon emission can be effectively generated. The latter effects
have been described in our previous works
Channeling of Charged Particles Through Periodically Bent Crystals: on the Possibility of a Gamma Laser
We discuss radiation generated by positrons channeling in a crystalline
undulator. The undulator is produced by periodically bending a single crystal
with an amplitude much larger than the interplanar spacing. Different
approaches for bending the crystal are described and the restrictions on the
parameters of the bending are established. We present the results of numeric
calculations of the spectral distributions of the spontaneous emitted radiation
and estimate the conditions for stimulated emission. Our investigations show
that the proposed mechanism provides an efficient source for high energy
photons, which is worth to be studied experimentally.Comment: contributed to the conference ``Fundamental and Applied Aspects of
Modern Physics'' in Luederitz, Namibia, 200
Simulation of Ultra-Relativistic Electrons and Positrons Channeling in Crystals with MBN Explorer
A newly developed code, implemented as a part of the \MBNExplorer package
\cite{MBN_ExplorerPaper,MBN_ExplorerSite} to simulate trajectories of an
ultra-relativistic projectile in a crystalline medium, is presented. The motion
of a projectile is treated classically by integrating the relativistic
equations of motion with account for the interaction between the projectile and
crystal atoms. The probabilistic element is introduced by a random choice of
transverse coordinates and velocities of the projectile at the crystal entrance
as well as by accounting for the random positions of the atoms due to thermal
vibrations. The simulated trajectories are used for numerical analysis of the
emitted radiation. Initial approbation and verification of the code have been
carried out by simulating the trajectories and calculating the radiation
emitted by \E=6.7 GeV and \E=855 MeV electrons and positrons in oriented
Si(110) crystal and in amorphous silicon. The calculated spectra are compared
with the experimental data and with predictions of the Bethe-Heitler theory for
the amorphous environment.Comment: 41 pages, 11 figures. Initially submitted on Dec 29, 2012 to Phys.
Rev.