Calorimetric Determination of the Energy Flux of 22.5-Mev X-Rays

Abstract

A sensitive method of calorimetrically measuring the energy flux of an x-ray beam is described. Thermistors are employed as the temperature-sensitive elements and are embedded in the irradiated material in a calorimeter. Details and results of the application of this technique to a betatron x-ray beam are described. This method can be applied to x-ray beams of other energies and does not require high intensities.

Determination of total x-ray beam energy with a calibrated ionization chamber

“…The alloy densities listed indicate that the alloy compositions of these chambers are approximately the same. It can be seen from this table that the predicted / T /s agree with the measured values to within a few tenths of one percent, which is within the uncertainties inherent in the measurements of Fcy X, and T. ir /(l} t t (4], and £(10) should be measured near the centers of the corre sponding pieces .since their faces are seldom flat.…”

“…In the X-ray tube experiments, measurements of roentgens/min were made with a free-air ionization chamber [13], and the beam intensities w^ere calculated from the equation watts/cm 2 roe nt gen/mi n 6 r ,/n R(E) (4) w^here I(E,EmtL*) is the differential intensity spec trum in units proportional to watts/cm2/Mev, and R(E) is the conversion factor ergs/crn2/roentgen for photons of energy E. I(E,EmtaL) was calculated by assuming that at these low energies, the unfiltered intensity spectra are proportional to (E^^ E) [1], and correcting for filtration with published total attenuation coefficients [14]. The filtered spectra are shown in figure 8.…”

“…The method is based upon results obtained in a series of experiments [3], performed with two instruments which determine the total beam energy in absolute units, a refined version of the lead calorimeter described by Laughlin and Seattle [4], and a large scintillation crystal [5].…”

Physical aspects of irradiation: recommendations of the International Commission on Radiological Units and Measurements (ICRU) report 10B 1962

“…Methods oj measurement. There are several techniques which have been used to determine the TBE in absolute units; the most direct of which is calorimetry (Laughlin and Beattie, 1951). The usefulness of calorimeter measurements of TBE is limited by low sensitivity and by the need to correct for energy escaping from the calorimeter in the form of neutrons, secondary electrons, and scattered and transmitted photons.…”

Calorimetric calibration of an ionization chamber for determination of x-ray total beam energy

“…Hig h energy X-ray calonme ter m easuremen ts h ave b een r eported by several authors [2][3][4][5], and some of' t hese measurements have b ee n used to calibrate ion iza lion chamb ers for routin e determin aLion of' t he LotfLl b eam e ner gy [3][4][5]. T~is p ap er is a descrip t ion of an X-ray calonme ter and Its use lI1 two experiments to calibrate an al uminum ionization cham ber.…”