[en] Uncertainty in nondestructive elemental or isotopic assay arises from two distinct factors. Unknown spatial distribution of the assayed analyte in the matrix of the sample gives rise to spatial uncertainty. Limitation of the duration of measurement and randomness of the pulse-counting process give rise to statistical uncertainty. These two types of uncertainty occur in the assay of nuclear waste, in mineral prospecting, in in vivo radionuclide assay, and in other applications. In all cases, proper design of the assay system is essential for reliable and accurate assay. The designer of a nondestructive assay system confronts numerous design decisions. He must choose the type and number of detectors to be employed and their arrangement around the sample, the type of radiation to be measured, whether the assay is to be passive or active, and the duration of the measurement. Sometimes the designer is free to specify the shape and size of the sample or the density or composition of the matrix material. A concise, quantitative, computerizable performance criterion is described in detail, which enables the designer to choose from among the wide range of possible assay-system designs. Realistic calculations are presented to illustrate the type of information obtained from the performance criterion

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[en] Non-destructive assay is a nuclear technique with wide applications e.g. in medicine, archaeology, geology and nuclear engineering. The main factor complicating non-destructive assay is the random or unknown spatial distribution of the analyte in the sample. Other factors are non-uniformity of the matrix and statistical uncertainties in the measurements. The performance of a non-destructive assay system can be expressed by the relative mass resolution and this paper presents a procedure for evaluating relative mass resolution. (author)

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[en] An investigation has been made of the possible improvement in resolution employing the rise time method, if the filter bandwidth is increased beyond that required for position linearity. To this end, the computed resolution and linearity of position information have been plotted as a function of the filter time-constant for RC and double-delay line shaping. High and low capacitance detectors have been considered. The plots yield an estimate of the improvement in resolution obtainable, if position linearity is disregarded. Preamplifier noise was assumed to be negligible. (Auth.)

[en] The interpretational model correlates the instrument readings with the actinides content in the waste item. A transparent model is essential for parameter study, calibration procedure design and uncertainty assessment. The paper summarizes a study on modelling for passive gamma and neutron assay techniques. A model is presented for one-shot high resolution gamma monitor based on multilines information. The model includes the leakage of scattered radiation. The nonhomogeneity of waste matrix and the non-uniformity of the gamma emitter distributions within the item volume are dealt by the probability methodology. Response functions for passive neutron assay based on Feynman's variance method and on covariance method are discussed

[en] The reaction π^- p → ωπ^- p, ω → π⁺ π^- π⁰ has been studied at 18 GeV/c. The ωπ^- mass spectrum is found to be dominated by the b₁(1235). Partial Wave Analysis shows that b₁ production is dominated by natural parity exchange. The S-wave and D-wave amplitudes for b₁(1235) → ωπ have been determined, and it is found that the amplitude ratio, |D/S| = 0.269 ± (0.009)_stat ± (0.01)_sys and the phase difference, φ(D-S) = 10.54^o ± (2.4^o)_stat ± (3.9)_sys