X-ray Production Efficiency Research Articles

Thick-Target X-Ray Production in the Range from 1250 to 2350 Kilovolts

An experimental investigation has been made of the thick-target production of x-rays by electrons from an electrostatic accelerator. Measurements were made with an ionization chamber for targets of beryllium, aluminum, copper, silver, tungsten, and gold. Various voltages from 1250 to 2350 kilovolts were used, and the angular range covered was from 0 to 140 degrees. The total radiation intensity, integrated over all angles, is found to be accurately linear with atomic number in this energy range. From these measurements, the efficiency of x-ray production has been calculated. For the case of 2.35-million-volt electrons on gold, a value of 7.4 percent is obtained. This is in adequate agreement with theoretical predictions.

Measurements on X-Ray Production and Absorption in the Range 0.7 to 2.5 Mv

In the voltage range from 0.7 to 2.5 Mv, the intensity and the total mass absorption coefficient of the heterogeneous radiation produced in a thick gold target have been measured as a function of tube voltage, angle with respect to the electron beam, and thickness and material of the filter. Curves giving the dependence of absorption coefficient on voltage are presented for lead, tin, copper, aluminum, carbon, and water as absorbers. A method is described for calculating the absorption coefficient of the heterogeneous radiation produced at a given tube voltage and subjected to a given amount of filtration, utilizing accepted values for the absorption coefficient of homogeneous radiation. Measured and calculated values of the absorption coefficients for heterogeneous radiation are in good agreement. Curves giving the dependence of intensity on angle are in qualitative agreement with approximate theory. Curves giving the dependence of absorption coefficient on angle and the dependence of intensity in the forward direction on voltage are presented. A method for calculating the efficiency of x-ray production from these data is described and used to obtain results in satisfactory agreement with theory in the voltage range from 0.90 to 2.35 Mv.

The Heat Energy of X-rays

Efficiency of a tungsten-target Coolidge x-ray tube operated at peak voltages from 100 to 200 kv.---The efficiency of x-ray production was experimentally determined for voltages between one and two hundred kilovolts. The high voltage energy input into the x-ray tube was measured by means of an absorption calorimeter. The intensity of the x-rays was measured by means of the temperature rise of a lead absorption cup arranged so that the effects due to scattering and fluorescence of the x-rays as well as effects due to external temperature conditions were eliminated. Elaborate precautions were also taken to suppress electrostatic and electromagnetic induced effects from the high voltage circuits. The efficiency was found to be proportional to the peak voltage. The factor of proportionality was 0.0032 when the efficiency is expressed in percent and the peak voltage in kilovolts.