An important radiative process, used in several astrophysical contexts to generate high energy photons, is the inverse compton scattering. In this process, relativistic electrons transfer part of their kinetic energy to low energy photons thereby creating high energy photons. Conventional text book derivation (Rybicki & Lightman 1979) of this process uses the photon picture, kinematics of elect...

We present results from design studies carried out to investigate measurements of the flux, spectrum and polarization of undulator photons for SLAC Proposal E166. A transmission Compton polarimeter is considered for measuring the photon circular polarization. We also present results for measuring the flux and spectrum of positrons produced by the undulator photons in an 0.5X0 Titanium target. A...

Hard photons well above 100GeV have to be generated in a future photon collider which essentially will be based on the infrastructure of the planned International Linear Collider (ILC). The energy of near-infrared laser photons will be boosted by Compton backscattering against a high-energy relativistic electron beam. For high effectiveness, a very powerful laser system is required that exceeds...

Virtual Compton Scattering off the proton: γ∗p → γp is a new field of investigation of nucleon structure. Several dedicated experiments have been performed at low c.m. energy and various momentum transfers, yielding specific information on the proton. This talk reviews the concept of nucleon Generalized Polarizabilities and the present experimental status. Virtual Compton Scattering (VCS) off t...

We present the handbag contribution to Wide Angle Compton Scattering (WACS) at moderately large momentum transfer obtained with a proton distribution amplitude close to the asymptotic form. In comparison it is found to be significantly larger than results from the hard scattering (pQCD) approach.

A large population of heavily obscured, Compton-thick AGN is predicted by AGN synthesis models for the cosmic X-ray background and by the “relic” super-massive black-hole mass function measured from local bulges. However, even the deepest X-ray surveys are inefficient to search for these elusive AGN. Alternative selection criteria, combining mid-infrared with near-infrared and optical photometr...

A more detailed analysis is made of the energy spectrum of the diffuse component of extragalactic gamma rays over the range of 0.3- 10 GeV, obtained fromthe EGRET instrument at the Compton Gamma Ray Observatory. The derived excess energy spectrum of high galactic latitude, b > 60°, using intercept method shows that it is correlated with Virgo cluster (over lsr) and average Virgo intensity i...