Pulse height counter

Fig. 2-4. Mean pulse height versus quantum energy, to illustrate pulse-height selection of characteristic lines. Side window tube, 3-in. diameter 0.005-in. wire operating at 1275 v filled with argon plus 10% ethylene total pressure, 15 cm of mercury (proportional counter) gain, 3.5 X 104. (After Friedman, Birks, and Brooks, A STM Spec. Tech. Publ., No. 157, page 3. Copyright 1954. American Society for Testing Materials.)...

When a proportional counter is. used in conjunction with a pulse-height selector, the occurrence of an escape peak may vitiate the results. Assume that the counter filling contains argon, whose K edge is at 3.87 A, and suppose that the pulse-height selector is set to select an x-ray line 3f shorter wavelength the intensity of which is to be measured. This line will excite the K lines of argon. To the extent that these lines are... 

The apparatus as modified for x-ray emission spectrograph is also shown in Figure 11-1. The proportional counter may be used alone (pulse-height analysis Section 2.13) or a curved-crystal spectrometer can be employed to achieve better resolution. Analytical results were comparable to those quoted above, but localization of the area analyzed was considerably less sharp than the micron-diameter spot achieved in differential absorptiometry. 

Discrimination by adjustable path length in gas-flow Geiger Counters, 258 Discriminators, see Pulse-height discriminator Pulse-height selection Distribution of sample in spot test, 228 Divergence of x-ray beam in slit system, 111, 112... 

Excitation of sample by bombardment with electrons, radioactive particles or white X-rays. Dispersive crystal analysers dispersing radiation at angles dependent upon energy (wavelength), detection of radiation with gas ionization or scintillation counters. Non-dispersive semiconductor detectors used in conjunction with multichannel pulse height analysers. Electron beam excitation together with scanning electron microscopes. 

A single channel pulse height analyser utilizes an electronic gate typically 0.1 V wide, which only accepts pulses between the preset upper and lower limits. Scintillation counters frequently employ such devices to remove small noise pulses and large pulses initiated by cosmic rays, as well... 

Radioactivity of uranium can be measured by alpha counters. The metal is digested in nitric acid. Alpha activity is measured by a counting instrument, such as an alpha scintillation counter or gas-flow proportional counter. Uranium may be separated from the other radioactive substances by radiochemical methods. The metal or its compound(s) is first dissolved. Uranium is coprecipitated with ferric hydroxide. Precipitate is dissolved in an acid and the solution passed through an anion exchange column. Uranium is eluted with dilute hydrochloric acid. The solution is evaporated to near dryness. Uranium is converted to its nitrate and alpha activity is counted. Alternatively, uranium is separated and electrodeposited onto a stainless steel disk and alpha particles counted by alpha pulse height analysis using a silicon surface barrier detector, a semiconductor particle-type detector. 

Saros, M. T., R. J. Weber, J. J. Marti, and P. H. McMurry, Ultrafine Aerosol Measurement Using a Condensation Nucleus Counter with Pulse Height Analysis, Aerosol Sci. Techno , 25, 200-213 (1996). 

Weber, R. J M. R. Stolzenburg, S. N. Pandis, and P. H. McMurry, Inversion of Ultrafine Condensation Nucleus Counter Pulse Height Distributions to Obtain Nanoparticle (— 3—10 nm) Size Distributions, J. Aerosol Sci, 29, 601-615 (1998). 

Proportional Spectra of the Counter. The proportional pulses resulting from ionization of electrons and x-rays in the counter have been measured using a pulse height analyzer. Argon-37 and krypton-83m have been found to be excellent calibration gases. Argon-37, with a... 

In the absence of a calibrated standard, the radioactivity in an argon-37 sample, supplied by Oak Ridge National Laboratory, has been approximated, using calibration data foar tritium and a pulse height analyzer to observe the peak. In the counter set up, a long line connects the counter to the fill system. The volume of the line is about 310 cm.3,... 

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