The polarised beam asymmetry in photoproduction of eta mesons from protons at 2.5 GeV and 3.0 GeV

Measurements of the polarised beam asymmetry parameter Σ for eta photoproduction from protons, have been carried out at incident energies of 2.5 GeV and 3.0 GeV, and for various t-values between ?0.2 (GeV/c)² and ?1.2 (GeV/c)². The values of Σ are close to +1 for values of |t| less than 0.7 (GeV/c)², showing that there can be little contribution from unnatural parity exchange in any Regge exchange model of the process, in disagreement with present theories. Differential cross sections for the process werre also measured, and are consistent with those from other experiments.     

An update on the start-up of the double-beta-decay experiment Nemo 3

The NEMO collaboration is in the final stages of completing a detector to search for neutrinoless double-beta decay. The experiment is called NEMO 3 and came on line at the beginning of 2002. Located in the Fréjus Underground Laboratory, the detector holds 10 kg of double-beta-decay isotopes, allowing one to study the effective neutrino mass down to approximately 0.1 eV. Thus, the detector has the potential to confirm physics beyond the Standard Model. Three of the detector’s sectors have been operating since June 2000 to perform diagnostic tests on the track recognition, the calorimeter, and the software. The results of these diagnostic tests are presented with a discussion of the detector and source backgrounds.     

A traversing pulsed-wire probe for velocity measurements near a wall

A pulsed-wire-anemometer probe which is capable of velocity measurements in the near-wall regions of turbulent separated flows is described. Measurements made with the probe in an attached flow are shown to compare favorably with those made using a hot-wire anemometer. Measurements made in a separated flow are also presented.     

Investigations of the origins of estrogenic A-ring aromatic steroids in UK sewage treatment works effluents

The present preliminary study describes an investigation of a putative aromatisation pathway in sewage from cholesterol through the corresponding A-ring aromatic steroid, norcholest-1,3,5(10)-trienol (NCT) to estrone. The synthesis and analytical characterisation of NCT and of the trimethyl silyl ether by gas chromatography-mass spectrometry, is described. The analytical properties of synthetic NCT were used to direct a search for the compound over several months in 1998 in the effluents of two sewage treatment works (STW; Deephams and Harpenden, north London). The study was prompted by the earlier findings that increased vitellogenin concentrations in the plasma of caged male rainbow trout held in the STW effluents (so-called fish 'feminisation') could be attributed to the presence of A-ring steroids such as estrone. Until now it has been assumed that these steroids originate from the STW influents and it is not clear to what extent, if at all, aromatisation of steroids might occur during STW operation. NCT was only detected in the solid particles associated with the effluents on one occasion in 8 months. This suggests that the hypothesised pathway is not a major one. Confirmation of previous reports of estrone and 17 beta-estradiol was also obtained using a published analytical method and by a simple modification of the method these reports were extended to include a regular occurrence of the weaker estrogen, 16 alpha-estriol in the case of Harpenden STW effluents in 1998.     

Kinetic study of N2(B3Πg, υ) quenching by laser-induced fluorescence

The quenching kinetics of N₂(B³Π_g, υ) have been determined in a low-pressure flow system in the absence of N atoms. Individual vibrational levels of the B state were populated by laser pumping (first-positive bands) of N₂(A³Σ_u⁺) molecules. The latter were created upstream by energy transfer from Ar metastable atoms.