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Results for “GAMMA RAYS”

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At least 37 records · Page 2Linked to original sources
PubMed1976

Comparison of X-ray and gamma-ray dose-response curves for pink somatic mutations in Tradescantia clone 02.

Microdosimetric data indicate that the mean specific energy, eta, produced by individual charged particles from X-rays and gamma rays is different for the two radiation qualities by nearly a factor of two. In order to test whether this influences the initial, linear component in the dose-effect relations, a comparison was made between dose-response curves for pink somatic mutations in Tradescantia clone 02 stamen hairs following X and gamma irradiations. Absorbed doses ranged from 2.66 to 300 rad.The results are in agreement with predictions made on the basis of microdosimetric data. At low doses gamma rays are substantially less effective than X-rays. The RBE of gamma rays vs. X-rays at low doses was approximately 0.6, a value lower than those usually reported in other experimental systems.

Cesium Radioisotopes↗
PubMed2003

Polarization of the prompt gamma-ray emission from the gamma-ray burst of 6 December 2002.

Observations of the afterglows of gamma-ray bursts (GRBs) have revealed that they lie at cosmological distances, and so correspond to the release of an enormous amount of energy. The nature of the central engine that powers these events and the prompt gamma-ray emission mechanism itself remain enigmatic because, once a relativistic fireball is created, the physics of the afterglow is insensitive to the nature of the progenitor. Here we report the discovery of linear polarization in the prompt gamma-ray emission from GRB021206, which indicates that it is synchrotron emission from relativistic electrons in a strong magnetic field. The polarization is at the theoretical maximum, which requires a uniform, large-scale magnetic field over the gamma-ray emission region. A large-scale magnetic field constrains possible progenitors to those either having or producing organized fields. We suggest that the large magnetic energy densities in the progenitor environment (comparable to the kinetic energy densities of the fireball), combined with the large-scale structure of the field, indicate that magnetic fields drive the GRB explosion.

Journal Article↗