Measurements of Radioactivity |
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absorbed absorption alpha particles alpha rays amount amplifier approximately atomic number beta particles beta rays beta-ray spectra bombardment calibrated capture centimeter circuit constant conversion electrons counting rate cross section crystals curie curve decay deflection detected determined deuteron diagram disintegration rate disintegration scheme duced ejected elec electric field electrometer electroscope elements emission g of radium gamma radiation gamma rays Geiger-Müller counter grid half-period half-value periods helium hydrogen increase ionization chamber magnetic field maximum energy measured ment mesotrons metal method nuclear charge nucleus number of atoms number of particles observed obtained ohms plate positron potential produced proportional counter protons pulses radio radioactive isotopes radioisotope radium radon range reaction relatively represented result roentgen sample scattering sensitive shown in figure slow neutrons spectrum standards substances thickness thyratron ticles tion total number tracer trons tube unit uranium various velocity voltage zero λι
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Page 77 - The unit of exposure dose of x- or gamma-radiation is the roentgen (r). One roentgen is an exposure dose of x- or gamma-radiation such that the associated corpuscular emission per 0.001293 g of air produces, in air, ions carrying 1 electrostatic unit of quantity of electricity of either sign.
Page 21 - The metal support is mounted on a small insulator. It may be charged by a battery through pressing the charging key. A small piece of quartz fiber mounted across the end of the metallized fiber serves as an index that is viewed through a microscope equipped with an eyepiece scale. Upon being charged, the metallized fiber is deflected from the support; it returns toward the position of zero charge when the gas in the chamber is ionized. A window is provided for illuminating the fiber. Approximately...
Page 61 - This electromotive force may be resolved into two components, one parallel and the other perpendicular to I, as shown, for example, in Fig.
Page ii - Standards, and brief descriptions of the methods currently available for the absolute measurement of resistance and of current, which will be used in the future as a check on the maintenance of the units. June 30, 1949. 38 p. C476. Measurements of radioactivity Leon F. Curtiss This publication is a compilation of information intended to be useful to those starting out in research on problems in radioactivity and nuclear physics. An effort has been made to provide, in brief form, most of the essential...
Page 61 - ... origin. This mass is shown by the elementary laws of electromagnetism to be constant for small velocities of the electron. M. Abraham2 has developed an electro-dynamic theory of moving electrons by which he accounts for the falling off of the ratio e/m for electrons moving with high velocities. If...
Page 29 - E = mc2, where E is the energy in ergs, m the mass in grams and c the velocity of light (that is, 3 X 1o10 cm.
Page 26 - In terms of the constituents of the nucleus (neutrons and protons) and of the atomic number Z (equal to the number of protons in the nucleus), we may tabulate the primary processes as in table 1 (overleaf).
Page 10 - They are taken up by neutral atoms in most gases to form negative ions of a mass comparable to that of the positive ions formed in the ionization process. Pure nitrogen and the noble gases are exceptions to this rule.
Page 71 - Statistical Error in Counting Experiments The best approximation to the life time T is the arithmetic mean of the individual times at which particles have been observed and the mean relative error is where N is the total number of counts (in this case, N = m). This result has to be compared with those of 4b and 4c. If T is finite, the connection between s and T is more complicated. The condition...
Page 60 - The incident radiation loses all its energy, and an orbital electron is ejected with an energy equal to the energy of the gamma ray minus the binding energy of the electron.