A description of the nuclear microprobe under construction by the CEA and the CNRS in an air-conditioned building is given. The installation consists of a 3.5 MV Vivitron-type single-stage Van de Graaff accelerator specially designed for microprobe purposes, two beam lines and an exploitation equipment including a high-performance image mapping and analysing system.One of these lines (45-degrees) is extended to the high activity area of the "Pierre Sue" Laboratory. It will be mainly used for examinations of very high activity nuclear materials (irradiated fuel, cladding materials, etc.). The corresponding analysis chamber is surrounded by special equipment including two lead-shielded hot cells and a sophisticated device allowing the transfer and the positioning of the samples. The other line (90-degrees) is provided with an analysis chamber enabling analytical examinations under ultrahigh-vacuum conditions.The various analytical possibilities and the potential performances of this particularly powerful new generation nuclear microprobe are indicated.

The various possibilities of the nuclear interaction methods are discussed. The advantages of their utilization in conjunction with PIXE is emphasized. Typical application examples are briefly described. A comparative table of the main instrumental microanalysis techniques is given.

After a brief description of different research topics which have been explored between 1983 and 1988, we show several original results obtained using the Bruyères le Châtel nuclear microprobe facility. Then we discuss the instrumental improvements carried on in the middle of 1988, by presenting recent works conducted in the new analysis chamber. Finally, looking forward to the starting of the second-generation French nuclear microprobe (beginning of 1991) at Laboratoire Pierre Süe in Saclay, we mention the 1989–1990 research projects of our Nuclear Microanalysis Group.

The principle of the nuclear microprobe, the atomic and nuclear interactions used for analytical purposes, are presented. The various possibilities and the performances authorized are exposed. Application possibilities and some typical examples are given. The main advantages of the nuclear microprobe over the other punctual analysis techniques are emphasized. Es werden die Grundlagen der nuklearen Mikrosonde vorgestellt, wie sie für analytische Zweeke verwendet wird, wobei die atomaren und nuklearen Wechselwirkungen ebenfalls dargeslellt werden. Die unterschiedlichen Möglichkeiten und befugten Ausführungen werden behandelt und an einigen typischen Beispielen die Anwendungen vorgestellt. Es werden dabei die wichtigsten Vorteile der nuklearen Mikrosonde im Vergleich mit anderen punktuellen Analysentechniken hervorgehoben.

The determination of2 3 7Np by activation analysis2 3 7Np(n,γ)2 3 8Np (2. 2. d). Main gamma ray 984.4 keV is disturbed either by highly activable elements or by uranium giving interference. Therefore, a pre-irradiation chemical separation step is used.2 3 7Np determination has been performed in irradiated experimental fuels, waste solutions, nuclear fuel zircaloy sheats and in studies of distribution in sea-water and submarine fauna and flora from disposal sites. The detection limit is 5·10−13 g of2 3 7Np corresponding to 2.5·10−9 mg/kg for 200 ml sea-water sample.

The CEA nuclear microprobe, set on one of the beam lines of a 4 MV Van de Graaff accelerator, is briefly described. Its possibilities and performances are recalled. It is used to study healthy teeth sections irradiated by a laser beam. The major elements (P, Ca) and other heavier elements of the mineral part are determined by PIXE, light elements (C, N) are determined by direct observation of (d, p) and (d, α) nuclear reactions.

The main resonant nuclear reactions which permit hydrogen determination in the near-surface region of solids, and particularly to determine its concentration depth profile by a non-destructive procedure, are presented and compared. More specifications are given about the three reactions we have studied:1H(15N,αγ)12C;1H(7Li,γ)8Be;1H(13O,α)15N; which seem to be the most interesting for the above purpose.

The physico-chemical characteristics of the pigments used in oil paintings supply valuable informations concerning the age of the work and sometimes even the geographic origin of the ores used.

Thick targets (mica) and thin hydrogen layers obtained by ionic implantation of protons in silica are used to establish the excitation function of the nuclear resonant reaction1H (15N, α γ)12C. Two main resonances in the energy gap explored were observed. Their FWHM and the cross section at ER are specified. The experimental conditions required and the performances allowed, using this reaction to determine hydrogen depth profiles in the near surface region of solids, are presented. Examples concerning borosilicates, leached in aqueous medium, are given.

Photonuclear activation with 18 and 35 MeV bremsstrahlung beams and gamma ray spectrometry has been used to determine the concentrations of 14 elements in human hair. A careful study of interferences made possible a nondestructive analysis with practical limits of detection between 0.1 and 100 μg·g.

The principle of the method based in the use of boron anhydride (B2O3) and lead oxide (PbO)melting agents are described. The effect of the reacting mixture on the main chemical forms of carbon and nitrogen encountered in sodium is examined. The results obtained on the efficiency of the process, as determined with radioactive tracers and sodium cyanide doped samples, are presented.

An apparatus ensuring identitical irradiation conditions for three samples and a standard of large volumes is reported. The interference caused by the protons originating from the16O(γ, p)15N reaction is determined. Results show that the secondary rection18O(p, n)18F induced by the protons of the former reaction gives an apparent fluorine content in natural waters of 0.015 μg/g for a maximum gamma photon beam energy of 21 MeV.

The method used is briefly described. It is based on direct observation of the following resonant nuclear reactions: 1H(15N, αγ)12C, 23Na(p, αγ)20Ne and 27Al(p, γ)28Si. The possible performances of these techniques, in the non-destructive exploration of the first few microns of the glass surface, are presented. The choice of appropriate experimental conditions required for the investigation of concentration profiles without secondary effects is discussed. A few examples, showing the profiles obtained after aqueous leaching of glasses with different temperature and time conditions, are given.

The determination of carbon and nitrogen in molybdenum and of carbon, nitrogen and oxygen in tungsten, is described. The analytical techniques applied were charged-particle activation (carbon, nitrogen and oxygen), photon activation (carbon and oxygen), combustion (carbon) and vacuum-fusion extraction (nitrogen and oxygen). Chemical methods yielded upper limits in the 2-5 mug/g range. Activation analysis yielded 100 and 8 ng/g for carbon in molybdenum and tungsten respectively, 500 and 74 ng/g for nitrogen in molybdenum and tungsten respectively and 70 ng/g for oxygen in tungsten. The results obtained by charged-particle and photon activation agreed satisfactorily.