The energy-depth-dose profile is a curve starting with a surface dose, ascending to the maximum dose in a certain depth dm (usually normalized as 100% dose), then descends slowly through depths of 90% dose (d90) and 80% dose (d80), then falls off linearly and relatively sharply though depth of 50% dose (d50). The extrapolation of this linear part of the curve to zero defines the maximum electron range, Rp. In practice, there is a long tail of weaker but deep dose, called "bremsstrahlung tail", attributable to bremsstrahlung. The penetration depth depends also on beam shape, narrower beam tend to have less penetration. In water, broad electron beams, as is the case in homogeneous surface contamination of skin, have d80 about E/3 cm and Rp about E/2 cm, where E is the beta particle energy in MeV.The penetration depth of lower-energy beta in water (and soft tissues) is about 2 mm/MeV. For a 2.3 MeV beta the maximum depth in water is 11 mm, for 1.1 MeV it is 4.6 mm. The depth where maximum of the energy is deposited is significantly lower.The energy and penetration depth of several isotopes is as follows:
For a wide beam, the depth-energy relation for dose ranges is as follows, for energies in megaelectronvolts and depths in millimeters. The dependence of surface dose and penetration depth on beam energy is clearly visible. Causes
Radiation burns are caused by exposure to high levels of radiation.
Twenty-three U.S. radar servicemen of the 28-member weather station on Rongerik were affected, experiencing discrete 1–4 mm skin lesions which healed quickly, and ridging of fingernails several months later. Sixteen crew members of the aircraft carrier USS Bairoko received beta burns, and there was an increased cancer rate.During the Zebra test of the Operation Sandstone in 1948, three men had beta burns on their hands when removing sample collection filters from drones flying through the mushroom cloud; their estimated skin surface dose was 28 to 149 Gy, and their disfigured hands required skin grafts. A fourth man showed weaker burns after the earlier Yoke test.The Upshot–Knothole Harry test at the Frenchman Flat site released a large amount of fallout. A significant number of sheep died after grazing on contaminated areas. The AEC however had a policy to compensate farmers only for animals showing external beta burns, so many claims were denied. Other tests on the Nevada Test Site also caused fallout and corresponding beta burns to sheep, horses and cattle. During the Operation Upshot–Knothole, sheep as far as 50 miles (80 km) from the test site developed beta burns to their backs and nostrils.During underground nuclear testing in Nevada, several workers developed burns and skin ulcers, in part attributed to exposure to tritium.