Gamma ray

Gamma radiation (sometimes called gamma ray), denoted by the lower-case Greek letter gamma (γ), is extremely high-frequency electromagnetic radiation and therefore consists of high-energy photons. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation gamma rays. Rutherford had previously discovered two other types of radioactive decay, which he named alpha and beta rays.

Gamma rays are ionizing radiation, and are thus biologically hazardous. Decay of an atomic nucleus from a high energy state to a lower energy state, a process called gamma decay, produces gamma radiation. This is what Villard had observed.

Natural sources of gamma rays on Earth include gamma decay of radionuclides and secondary radiation from atmospheric interactions with cosmic ray particles. Rare terrestrial natural sources produce gamma rays that are not of a nuclear origin, such as lightning strikes and terrestrial gamma-ray flashes. Additionally, gamma rays are produced by a number of astronomical processes in which very high-energy electrons are produced, that in turn cause secondary gamma rays via bremsstrahlung, inverse Compton scattering, and synchrotron radiation. However, a large fraction of such astronomical gamma rays are screened by Earth's atmosphere and can only be detected by spacecraft. Gamma rays are produced by nuclear fusion in stars including the Sun (such as the CNO cycle), but are absorbed or inelastically scattered by the stellar material before escaping and are not observable from Earth.

Gamma ray (disambiguation)

Gamma rays are a form of electromagnetic radiation.

Gamma Ray may also refer to:

Gamma Ray (band)

Gamma Ray is a power metal band from Hamburg, northern Germany, founded and fronted by Kai Hansen after his departure from the German power metal band Helloween. Hansen is the current lead vocalist, guitarist as well as the chief songwriter of Gamma Ray. The band is known as one of the most prominent bands of the German heavy metal scene.

Biography

Formation

In 1988, after four years with the German power metal band Helloween, guitarist and songwriter Kai Hansen decided, for reasons that are still the subject of much debate, to leave the group. Hansen claimed that Helloween had become too big for him to handle, although the group's troubles with financial issues and their record company, Noise Records, most likely played a part as well. He proceeded to do some studio work with German power metal band Blind Guardian and in 1989 decided to form his own project with long-time friend Ralf Scheepers, former vocalist of the band Tyran Pace. This two-man project grew into a four-man band with the addition of Uwe Wessel on bass and Mathias Burchardt on drums. This was the first line-up of Gamma Ray, bearing a sound understandably close to that of Helloween of that period.