The experimental data was acquired for eight chlorine prompt gamma rays
and minimum detectable concentration (MDC) for each gamma-ray line was estimated.
(8) Unlike gamma rays
, neutrons do not have a characteristic energy spectrum by which an isotope can be identified.
originating from this high-activity area provide for subsequent background noise that is detected as real, recorded [gamma]-rays, but not indicative of SLN's.
Another astonishing finding of CGRO's seven years in orbit has been the discovery of distant beacons in the universe, termed gamma-ray blazars, that send out particularly high-energy gamma rays
in beams resembling those from a tight spotlight.
Another class of effects leads to gamma ray
asymmetries from beta decays of polarized nuclei produced by interactions of the beam with materials upstream of the hydrogen target.
Other discoveries in the Milky Way detailed in the special edition include the sharpest image yet of a gamma ray
source -- a nearby supernova remnant -- which will enable researchers to study this object at finer scale than before -- and three new 'gamma ray
shells' that are possibly examples of a new type of supernova remnant.
The error is due to the accuracy to which we know the detector efficiency ([approximately equal to]5%), the estimate on the accuracy in the number of neutrons capturing in the target ([approximately equal to]5%), but mostly due to an error estimate on the number of gamma rays
that will deposit all of their energy in the detector ([approximately equal to]20%).
Through a still poorly understood mechanism, they attain very high energies, made visible by the emission of gamma rays
. When these gamma rays
reach the Earth's atmosphere they are absorbed, producing a short-lived shower of secondary particles that emit weak flashes of bluish light known as Cherenkov radiation, lasting just a few billionths of a second.
These clouds emit gamma rays
when struck by high-speed particles escaping the remnants.
As GLAST project scientist Steven Ritz of NASA/Goddard explains, "Gamma rays
tell us about physics we can't explore on Earth."
Occasionally, a gamma ray
collides with starlight and transforms into a pair of particles-an electron and its antimatter counterpart, a positron.
Gamma-ray astronomy got a big boost in 1991 with the launch of the NASA's now-defunct Compton Gamma Ray