No abstract available

[en] The activation neutron detector for measuring integral fluxes of fast or thermal neutrons consists of a material which can be activated by neutrons and is distributed in the volume of a heat-hardenable neutron-inert polycondensation resin. The material is a mixture of at least two elements each of which is capable of forming radioactive isotopes with different decay energies under neutron irradiation. Suitable materials are mixtures of the salts of the metals cobalt, nickel, iron, indium, mercury or lutetium and a neutron-inert acid radical in a polycondensation resin or a copolymerisation product of phenol formaldehyde-resol resin with m-chlorophenol formaldehyde resin. These substances are mixed with aluminum oxide, magnesium oxide, the oxides of aluminium, nickel, iron and thallium, nickel oxide and aluminum oxide, mercury sulfide, iron sulfide or red phosphorus. An integral neutron flux of 10²⁰ n/cm² can be detected. (DG/RF)

[en] Multileaf Collimators (MLCs) have become an important technological advance as part of clinical linear accelerators (linacs) for radiotherapy. Treatment planning and delivery were substantially modified after these devices. However, it was needed to develop Quality Assurance (QA) methodologies related to the performance of these developments. The most common methods for QA of MLC are made in basic conditions that hardly cover all possible difficulties in clinical practice. Diaz et. el. developed a methodology based upon volumetric detectors bidimensional arrays that can be extended to more demanding situations. In this work, the Auril methodology of Diaz et. al. was implemented to the irradiation with the linac gantry in horizontal position. A mathematical procedure was developed to ease the dosimetric centering of the device with the Auril centering tool. System calibration was made as in the typical Auril methodology. Patterns with leaf misplacements in known positions were irradiated. the method allowed the detection of leafs' misplacements with a minimum number of false positives. We concluded that Auril methodology can be applied in clinical conditions. (Author)

[en] The aim of this invention is to be able to determine the emerging or effective activity of the α radiation emitted by a source, by a simple and reliable method in an activity range extending from a fraction of a mCi to several Curies, by means of an electric microphone. The process and device described in the invention permit absolute as well as relative determinations of the activity of the α rays emitted by the source and also permit a measurement of the local emission of this source. Further, when the microphone includes a substance which is the seat of a reaction (n, α), the process and device under the invention allow the neutron radiation emitted by a neutron source to be determined. Specifically, the characteristic of the process is that near the source there is a microphone comprising two metal plates. The first plate of the microphone (sometimes called armature) is placed opposite the α radiation source and is of sufficiently small thickness for the α radiation emitted by the source to cross it without apprecialbe attenuation. Between these two plates, as with the usual capacitive microphone, a difference of continuous potential is established and the intensity of the α radiation emitted by the source is determined by measuring, after amplification, the potential developed between the two plates of the microphone, (this potential being created by the charges collected on these plates and which are created by the α radiation in the ionisable gas included in the volume thus delimited)

[en] A detecting material capable of being activated by neutrons is mixed with a liquid polycondensation resin capable of thermal hardening. The obtained mixture is heated until the resin is transformed into a fusible product that is then cooled to room temperature. This hardened mixture is ground into powder suitable for pressing into tablets

[en] Method of neutron activation weighing used for certification of neutron activation detectors is described. It is shown that for its realization the fund of initial specimens (FIS) including sets of initial specimens of different types together with necessary normative technical documentation is required. Basic requirements to FIS and its separate specimens are given, fabricating methods of the initial specimens decreasing considerably their certification error are considered. A concrete certification procedure of serial neutron activation detectors by means of the FIS initial specimens is described as well. It is noted that FIS is included in a special state standard of units of neutron flux and neutron fluence for nuclear physical devices

[en] The activation detector technique is very widely used in dosimetry of materials irradiations. The ⁹³Nb(n,n')sup(93m)Nb reaction is the most suitable. In this paper, the causes of this selection are summarized: high melting point and good compatibility of the metal with usual environments, long half-life and mainly low threshold cross-section comparable with radiation damage cross-sections. The selected solutions for its practical utilization are: irradiation of rolled metallic high purity niobium, (bare or under various jackets); measurement of the X ray Ksub(α) Nb activity with a Si-Li detector (cooled preamp.) and analysis of the X ray spectrum

No abstract available

[en] The optimum lead thickness for lead-activation detectors has been studied in this paper. First existence of the optimum lead thickness is explained theoretically. Then the optimum lead thickness is obtained by two methods, MCNP5 calculation and mathematical estimation. At last factors which affect the optimum lead thickness are discussed. It turns out that the optimum lead thickness is irrelevant to incident neutron energies. It is recommended 2.5 cm generally.

[en] The activation neutron detector presents a formed and hardened mixture whose material is a conglomerate of powder of element and a solid solution of salts of the elements that can be activated in a polymer mixture. Phenol formaldehyde resol and phenol benzaldehyde novolak resin are suitable amongst others as polymer mixture. Integral neutron fluxes of 10²⁰ neutrons/cm² are measurable. Many examples are given for the elements and salts to be activated. (DG)