Gamma Ray Cherenkov-Transition Radiation

The production of gamma-ray Cherenkov-transition radiation (GCTR) by charged particles in the photon energy region 0.8 - 2 MeV is studied theoretically using the results of the recent discovery that in the above mentioned region the dielectric constant or the refraction index of some materials is greater than 1 due to Delbruck scattering on Coulomb field of nuclei. Using the results of the carried out numerical calculations, the possibility of observing GCTR and some of its applications are discussed

Use of single carbon nanotubes and graphene in particle detectors and beam monitors

After a short review of some physical properties of single carbon nanotubes and graphene layers it is discussed the possibility of construction of new beam particle monitors (BPM), ionization and proportional counters and time projection chambers (TPC). It is shown that in spite of the tested laser and wire BMPs the proposed single nanotube BPMs can provide better measurement of the profile of future electron-positron colliders with very high beam density. The use of single nanotubes as anode wires in proportional counters allows their operation at lower electric fields and to construct multiwire proportional counters (MPC) with better space resolution. It is proposed to construct TPCs using nanotubes and graphene ribbons based on the sharp variation of graphene electrical conduction under the influence of electrostatic potential resulting from the charge deposited by the ionizing particles

Some new processes in the collisions of high energy ions and electrons with amorphous or crystalline target atoms

It is shown that taking into account the energy levels of the ions and/or of the crystalline atoms, some energy transfer and excitation processes with consequences similar to the Kossel and Okorokov effects can take place when some additional resonance conditions are satisfied. Such resonance processes can be expected also when microbunched electron beams interact with ions. Since these processes have significant cross-sections and the interaction of projectile ions with atoms of crystals has not been almost studied, it is proposed to begin their study in Kossel- and Okorokov-type experiments

Coherent Pair Production by Photons in the 20-170 GeV Energy Range Incident on Crystals and Birefringence

The cross section for coherent pair production by linearly polarised photons in the 20-170 GeV energy range was measured for photon aligned incidence on ultra-high quality diamond and germanium crystals. The theoretical description of coherent bremsstrahlung and coherent pair production phenomena is an area of active theoretical debate and development. However, under our experimental conditions, the theory predicted the combined cross section and polarisation experimental observables very well indeed. In macroscopic terms, our experiment measured a birefringence effect in pair production in a crystal. This study of this effect also constituted a measurement of the energy dependent linear polarisation of photons produced by coherent bremsstrahlung in aligned crystals. New technologies for manipulating high energy photon beams can be realised based on an improved understanding of QED phenomena at these energies. In particular, this experiment demonstrates an efficient new polarimetry technique. The pair production measurements were done using two independent methods simultaneously. The more complex method using a magnet spectrometer showed that the simpler method using a multiplicity detector was also viable.Comment: 10 pages, 13 figures, 1 table, REVTeX4 two column, Version for publicatio