Photon Activation Analysis

Abstract

In photon activation analysis (PAA), nuclides of the analyte elements in the material sample under study are converted to radioactive nuclides through exposure to high‐energy photons. Characteristic radiation upon disintegration of these radionuclides (preferably γ quanta) is then measured with appropriate spectrometers. PAA is not an “absolute” method; hence, the samples under investigation have to be irradiated together with a comparative material sample (calibration material) with well‐known chemical composition. After spectroscopic measurement of both samples, the quantitative evaluation is performed by comparison of the two resulting element spectra, basically following the same procedure as in most instrumental methods, e.g. ICP, AAS, etc. The particular advantages of this method are freedom from blank values; reduced danger of contamination; and, since frequent investigations can be carried out “nondestructively”, easy handling of materials that are difficult to treat chemically, e.g. certain refractory metals, dusts, ashes, etc. Another advantage is the option to study very small samples (a few milligrams) as well as very large ones (up to kilogram amounts). Basically, there are no limitations concerning the nature of material studied but matrices like lead or other heavy elements raise the limit of detection considerably, and separation techniques have to be used.

A new equation for activity calculation in pulse irradiation: derivation, simulation, and experimental validation

“…Equation (27) is the general activity equation for pulse irradiation. If = , or in other word, the irradiation is continuous, then (27) changes its form back to (2), which is the general activity equation for continuous irradiation.…”

“…Nowadays, due to the development of accelerator technology, more and more radioisotopes are produced by pulse irradiation [1]. Traditionally, to calculate the activity from pulse irradiation, scientists usually expand the usage of continuous irradiation Equations (1) and (2) into applications of pulse irradiation without too much consideration of details in pulses. Instead of peak flux in the pulse width, they use average particle flux during the whole irradiation period to calculate the final radioactivity [2][3][4][5].…”

“…Traditionally, to calculate the activity from pulse irradiation, scientists usually expand the usage of continuous irradiation Equations (1) and (2) into applications of pulse irradiation without too much consideration of details in pulses. Instead of peak flux in the pulse width, they use average particle flux during the whole irradiation period to calculate the final radioactivity [2][3][4][5]. This practice does make sense at the first thought: the repetition rate of pulses is usually relatively high, the irradiation can be regarded as continuous from the point of whole irradiation period, and the half-life of the product nuclides of interest are usually long even comparable to the whole irradiation time.…”

Photonuclear Reaction Cross Sections for Gallium Isotopes

“…Photonuclear reactions have been used in basic and applied sciences in nuclear and radiation physics related fields [1][2][3][4]. When a gamma-ray is incident upon a nucleus, the excited nucleus behaves like any compound nucleus with an excitation energy.…”

“…After this, (γ,2n), (γ,1p) and (γ,2p) reactions take part. Nuclear level and half-life identifications, nucleon binding energy determinations, material analysis, radiation protection applications, dosimetry, absorbed dose assessment, activation analysis, radiation transport analyses, physics of fission and fusion reactors, nuclear waste transmutations, and understanding element creations by astrophysical processes can be given as examples to such studies [2,4]. The experimental studies on these reactions have begun in 1934 [5] but there are still lack of existing data.…”