The synchrotron self-Compton (SSC) emission from Gamma-ray Burst (GRB) forward shock can extend to the very-high-energy (VHE; Eγ >100 GeV) range. Such high energy photons are rare and are attenuated by the cosmic infrared background before reaching us. In this work, we discuss the prospect to detect these VHE photons using the current ground-based Cherenkov detectors. Our calculated results are...

The feasibility of an experimental determination of the parton distributions of virtual photons at high energy ep colliders is studied in the context of the DESY-HERA collider. Recently proposed parton densities of virtual photons are utilized to evaluate the appropriate production processes and their relevant kinematical regions. It is demonstrated that high E T jet production with E T ≃ 5−7 G...

A measurement of the longitudinal polarization of the electron beam at HERA utilizing coherent interactions of high energy photons in crystals is described. Modification of existing facilities would allow an independent polarization measurement and a verification of birefringence phenomena in crystals for 20–30 GeV photons. Relevant experimental issues and systematic uncertainties are also pres...

PLEIADES is a compact, tunable, high-brightness, ultra-short-pulse, Thomson-scattering X-ray source. Picosecond pulses of hard X-rays (10–200 keV) are created by colliding an ultra-relativistic (20–100 MeV), picosecond-duration electron beam with a high-intensity, sub-picosecond, 800-nm laser pulse. Initial operation of this source has produced 78-keV X-rays with 106 photons per pulse using a 5...

Following our previously proposed technique, we have used the recent-ray observations of Mkr421 to place theoretically signiicant constraints on and possible estimates of the intergalactic infrared radiation eld (IIRF). Our 2 upper limits and estimates are consistent with normal galactic IR production by stars and dust. They rule out exotic mechanisms proposed to produce a larger IIRF. We nd po...

objective(s): the energy resolution of a cadmium-zinc-telluride (czt) solid-state semiconductor detector is about 5%, and is superior to the resolution of the conventional anger type detector which is 10%. also, the window width of the high-energy part and of the low-energy part of a photo peak window can be changed separately. in this study, we used a semiconductor detector and examined the ef...