Natural and man-made sources of ionizing radiation have made and continue to make invaluable contributions to society and to individuals. Radiation is part of nature. Natural sources of radiation including radon gas from the earth’s crust and cosmic radiation from outer space account for 80-90 percent of the radiation to which the public is exposed every year. Man-made sources provide hundreds ...

The electromagnetic wave ranging from the millimeter wave to gamma ray is radiated from plasmas produced by irradiating solid and gas targets with high intensity optical pulses. Recently, several theoretical works have pointed out the possibility that laser produced plasmas radiate intense THz wave [1]. The laser produced plasma is one of the promising candidates for an efficient generator of t...

introduction today, there is a growing interest in the use of hadrontherapy as an advanced radiotherapy technique. hadrontherapy is considered a promising tool for cancer treatment, given its high radiobiological effectiveness and high accuracy of dose deposition due to the physical properties of hadrons. however, new radiation modalities of dose delivery and on-line beam monitoring play crucia...

iran is one of several countries that has regions of high dose natural ionizing radiation. two wellknown villages in the suburb of ramsar town in the caspian sea strip, taleshmahaleh and chaparsar, have background radiation that is 13 times higher than normal. this radiation is the result of radium 226 and radon gas both of which are highly water soluble. while people living in these regions do...

I consider the physics of gravitational instabilities in the presence of dynamically important radiation pressure and gray radiative diffusion, governed by a constant opacity κ. For any non-zero radiation diffusion rate on an optically-thick scale k−1, the medium is unstable unless the classical gas-only isothermal Jeans criterion is satisfied. If the radiation acoustic sound crossing timescale...

We use cosmological simulations to study the origin of primordial star-forming clouds in a CDM universe, by following the formation of dark matter halos and the cooling of gas within them. To model the physics of chemically pristine gas, we employ a nonequilibrium treatment of the chemistry of nine species (e , H, H+, He, He+, He++, H2, H þ 2 , H ) and include cooling by molecular hydrogen. By ...