Characterisation of optical components of the COMPASS RICH1 detector

The COMPASS RICH1 detector is under construction at CERN. We participated to the preparation of its optical system by characterising its spherical mirrors. In the article, the experimental set-up for mirror characterisation is described together with the obtained results. (5 refs)

Chemical nucleation, a new concept applied to the mechanism of action of organic acid salts on the crystallization of polyethylene terephthalate and bisphenol-A polycarbonate

Bisphenol-A-polycarbonate (PC) and polyethylene terephthalate (PETP) systems containing different concentrations of sodium /b o/-chlorobenzoate (SOCB) as crystallization promoters have been studied by DSC, IR and GPC. It is shown that the time and temperature of mixing of the salt with the polymer considerably affects the crystallization rates. GPC and IR show that a chemical reaction occurs during the mixing process between the salt and the ester links of the macromolecules. This reaction produces ionic end-groups which are responsible for the acceleration of the crystallization rate. This phenomenon is called `chemical nucleation'. The same behaviour is observed also with other alkali metal salts derived from aromatic carboxylic acids.Anglai

Partial-array test results in IFSMTF

Preliminary performance tests of two large superconducting magnets have been carried out in the International Fusion Superconducting Magnet Test Facility (IFSMTF). Each of the Japanese (JA) and General Dynamics/Convair (GD) coils was operated up to its full design current of 10.2 kA with the other serving as an adjacent background coil at 40% of design current. Cryostatic stability was demonstrated for both coils by noting recovery from a full half-turn (5 m) driven normal. A new pick-up coil compensation scheme was successfully used for the quench detection system. Each coil remained superconducting when the other was dumped. Unique instrumentation was used to measure changes in bore dimensions and displacement of the winding from the coil case. Agreement between structural analysis and measurement of bore dimension changes resulting from magnetic loads is good. The Swiss (CH) coil underwent only a cryogenic test. The forced cooling worked well and an inlet temperature of 3.8 K was demonstrated