• A. V. Tyukhtin, S. N. Galyamin
  Saint-Petersburg State University, Saint-Petersburg

The possibility of using an active medium to amplify the generated wakefield of an electron beam and employing the amplified wakefield to accelerate a second beam has been recognized recently*. This acceleration scheme is one of several related methods referred to as the Particle Acceleration by Stimulated Emission of Radiation (PASER). However, only the case of an active medium with a single resonant frequency has been analyzed until now. In this paper we present the results of analytical and numerical studies of Cherenkov radiation (CR) in an active medium with two resonant frequencies. We show that this medium can amplify CR even in the case of a purely real refractive index. In contrast to a medium with a single resonant frequency the amplification effect takes place in the absence of metal boundaries but only for sufficiently strong restrictions on the parameters of the medium. The amplification can be effective even for a medium with a relatively small inversion. Examples of CR amplification are given for several active materials. The effect may be useful both for wakefield accelerators and Cherenkov detectors.

*L. Schachter, Phys. Rev., E, 62, 1252 (2000); N. V.Ivanov, A. V.Tyukhtin, Tech. Phys. Lett., 32, 449 (2006).

• A. V. Tyukhtin
  Saint-Petersburg State University, Saint-Petersburg
• S. P. Antipov
  ANL, Argonne, Illinois
• A. Kanareykin, P. Schoessow
  Euclid TechLabs, LLC, Solon, Ohio

Cherenkov radiation (CR) is extensively used for detection of charged particles. The prompt nature of the radiation is one major advantage for diagnostics that measure temporal properties of the beam. However, low signal levels and small angles of radiation with respect to the particle trajectory present limitations on the use of traditional detector media. Using modern artificial metamaterials as Cherenkov radiators can provide essential advantages. As a rule metamaterials are characterized by strong dispersion and anisotropy that can be engineered to the requirements of the detector. We present theoretical and numerical analyses of CR in bulk anisotropic and dispersive media and in waveguides. The properties exhibited by these materials (large angles of radiation, two maxima in the angular distributions, etc.) allow the design of detectors with unusual characteristics, like a detector that registers almost all moving particles, and simultaneously only particles with velocity exceeding a predetermined threshold. We consider the case of a material that is approximately equivalent to an isotropic left-handed medium that also presents advantages as a Cherenkov medium.

• P. Schoessow, A. Kanareykin
  Euclid TechLabs, LLC, Solon, Ohio
• S. P. Antipov, M. E. Conde, W. Gai, J. G. Power
  ANL, Argonne, Illinois
• E. Bagryanskaya
  International Tomography Center, SB RAS, Novosibirsk
• V. Gorelik, A. Kovshik, A. V. Tyukhtin, N. Yevlampieva
  Saint-Petersburg State University, Saint-Petersburg
• L. Schachter
  Technion, Haifa

The PASER is a new method for particle acceleration, in which energy from an active medium is transferred to a charged particle beam. The effect is similar to the action of a maser or laser with the stimulated emission of radiation being produced by the virtual photons in the electromagnetic field of the beam. We are developing a demonstration PASER device operating at X-band, based on the availability of a new class of active materials that exhibit photoinduced electron spin polarization. We will report on the status of active material development and measurements, numerical simulations, and preparations for microwave PASER experiments at the Argonne Wakefield Accelerator facility.