Design of an electrochemically assisted radiation sensor for α-spectrometry of actinides traces in water.

We describe a new approach for the detection and identification of actinides at low activity levels directly in aqueous solution. The measurement consists initially, in immobilizing alpha emitters in the form of insoluble hydroxides onto the entrance window of an immersed alpha particles detector. For this, a boron doped diamond detector window is negatively polarized to produce a basic layer on its surface by water decomposition.

Context and dating of Aurignacian vulvar representations from Abri Castanet, France.

We report here on the 2007 discovery, in perfect archaeological context, of part of the engraved and ocre-stained undersurface of the collapsed rockshelter ceiling from Abri Castanet, Dordogne, France. The decorated surface of the 1.5-t roof-collapse block was in direct contact with the exposed archaeological surface onto which it fell.

Freeze-drying applied to radioactive source preparation.

In the framework of R&D studies for the improvement of radioactive source efficiencies prepared on thin films for 4pibeta-gamma coincidence counting, a comparative study on two drying methods has been undertaken in our laboratory (BNM-Laboratoire National Henri Becquerel, France). The standard method of evaporation at atmospheric pressure and a method based on freeze-drying using commercial equipment are compared. The preliminary results of this study obtained with 65Zn sources are presented and a significant improvement of the detection efficiencies to the electron emission for freeze-dried sources is shown.

A new design of 238Pu activity sources for use in intercomparison exercises.

In the framework of a BIPM 238Pu comparison exercise, a new design for a-radiation counting sources was developed. These sources are constructed with a gold-coated Vyns film stretched over a stainless-steel disk. To improve the crystallization of the radioactive salt, the physical properties of the gold-coated polymer surface which receives the radioactivity deposit is modified.

Intercomparison of efficiency transfer software for gamma-ray spectrometry.

The EUROMET project 428 examines efficiency transfer results for Ge gamma-ray spectrometers when the efficiency is known for a reference point source geometry. For this, different methods are used, such as Monte Carlo simulation or semi-empirical computation. The exercise compares the application of these methods to the same selected experimental cases to determine the usage limitations versus the requested accuracy.

Application of rotating disk electrode technique for the preparation of Np, Pu and Am alpha-sources.

Method of electrodeposition on rotating disk cathode (RDE) is applied for preparation of Np, Pu and Am alpha-standards. Phenomenon of critical current density is experimentally observed which is in perfect accord with Hansen's theory of electrodeposition. Influence of deposit calcination regime on quality of alpha-sources is studied, and comparison is made of uniformity of deposits obtained in various deposition systems.