Range beta particle

Figure 2.4. Beta-particle range-energy curve (log/log) in aluminum and polystyrene. (Data from ICRU 1984.)...

By locating the anode entirely upstream from the ionized gas volume, collection of long range beta particles is minimized in the displaced coaxial cylinder design, and the direction of gas flow minimizes diffusion and convection of electrons to the collector electrode. However, the free electrons are sufficiently mobile that modest pulse voltages (e.g., 50 V) are adequate to cause the electrons to move against the gas flow and be collected during. this time. 

TABLE 3-3. Percent Occurrence and the Energies of the Major Alpha and Beta Particles Emitted by Thorium Isotopes With Atomic Masses Ranging from 223 to 234 ... 

What is the significance of la, 2a, and 3a deviations reported with a numerical value For the beta-particle standard solution counted repeatedly, what percentage of the values is in the range of +la to -la ... 

The formula for the self-absorption factor is exact for gamma rays (see Experiment 3) but approximate for beta particles. That it is applicable at all is due to the near-linear decrease of the logarithm of the count rate with absorber thickness of a beta-particle group (see Figure 2.6 in the Radioanalytical Chemistry textbook). The obvious deviation is that this relation ends at the range of the maximum-energy beta particle, whereas it continues indefinitely for gamma rays. 

The simplest and most direct reliable way to characterize the self-absorption of beta particles in a sample is to obtain a self-absorption curve by counting the same radionuclide in aliquots of a solid sample over a range of sample thickness. Aliquots can be prepared with the same specific activity (activity per unit mass) but with different masses, in identical planchets. The sample aliquots are counted and the results are presented in graphic form for interpolating the self-absorption factor for the sample mass of interest. 

Since alpha particles have a smaller range than beta particles, by using them the radiation is delivered to cancer cells without damaging surrounding healthy tissue. The successful use of alpha-emitters for cancer therapy depends on the identification of a homing material for each type of cancer to be treated. Chemical processes that can attach an alpha-emitter to the desired homing material must also be found. If this therapy proves successful, specific alpha-emitters must be produced at a large rate that allows for full-scale treatment of affected populations. 

About lO becquerels of iodine-131 were released in the accident. Iodine is mainly absorbed by a person s thyroid gland after inhalation or after consumption of contaminated foodstuffs such as milk products its short-range beta particles irradiate the gland from the inside. Uptake of iodine by the thyroid is very easy to prevent, for example by banning consumption of contaminated food for a few weeks until the iodine-131 decays sufficiently or by administering small amounts of non-radioactive iodine prophylactic-ally to block the thyroid gland. 

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