[en] A measuring technique for hydrogen determination in liquids flowing through pipelines based on neutron thermalization is described. With a fast neutron source emitting 5 x 10⁵ neutrons/s and 200 s counting time, the relative standard deviation of hydrogen determination in liquid hydrocarbons by this technique is less than 0,5%. The usability of the technique for measuring the concentration of sulphuric acid is shown. 23 refs., 4 figs. (author)

[en] Short communication

[en] An improved isotopic neutron source technique for measuring Σ_a of rocks is presented. A ²⁵²Cf source emitting roughly 4.10⁶ n/s and a miniature BF₃-filled detector are inserted in an annular sample placed in a large polyethylene block. Only one calibration sample is needed. No sample preparation, except grinding, is required. The attainable relative standard deviation on the measured value is about 10% for 25 cm³ samples and about 3% for 300 cm³ samples, respectively, both for 1 h counting times. (author)

[en] Interpretation of neutron porosity logs requires that the neutron slowing-down properties of rock matrices under investigation be known. A neutron thermalization technique is described for measuring the mass slowing-down power, ξΣ_s/ρ, of rocks using 291 cm³ samples. Using a ²⁵²Cf source emitting approx. 4.10⁶ n/s, an accuracy (1 SD) in the ξΣ_s/ρ determination of 0.001 cm²/g can be achieved, assuming a 2 h counting time. Measurements of ξΣ₂/ρ form the basis for deriving other related slowing-down characteristics of rocks. (author)

[en] A steady-state neutron source technique for determining the thermal neutron absorption cross section of geological samples is presented. It needs for analysis about 340 cm³ of crushed material. No sample saturation is required. Variations of scattering properties of samples are monitored and taken into account in the interpretation procedure. Calibration of the system is achieved using a few calibration samples prepared from pure reactor graphite and boric acid. A total time of analysis is well below 2 h per sample. Uncertainty of the cross section determination with this technique has been estimated at less than 5%. Measured cross sections for several kinds of rocks have been compared with values obtained with other methods. (author)

No abstract available

No abstract available

[en] A question of graphite purity testing is discussed in the context of the Nuclear Non Proliferation Treaty. A method for determining the boron equivalent for graphite impurity via measuring the thermal neutron absorption cross section is described. With the use of 300 cm³ ground graphite sample the boron equivalent can be determined to the precision of 0,75 ppm. Computer simulations showed a potential for improvements of the experimental assembly. (author)

No abstract available

[en] Suggestions about determining the concentration of ¹⁰B in blood via the thermal neutron flux depression measurement (NFDM) are made. The use of a measuring set-up consisting of a ²⁵²Cf neutron source, polyethylene moderator and a slim BF₃ counter surrounded by an annular sample is examined. It is shown experimentally that using 6 ml samples and the source emitting 1.4 x 10⁷ neutrons s^-1, one can determine the concentration of ¹⁰B in water at the level of 10 ppm with a statistical precision of 10% in about 20 min. Monte Carlo simulations performed with the use of MCNP-4C code revealed a potential for further improvements of the NFDM technique both in respect of the sample volume and counting period. (letter to the editor)