Experimental limits on the production of fractionally charged particles in proton-nucleus and neutrino-nucleus collisions

A search for fractionally chargedQ=1/3 (2/3) particles of different properties of interaction produced in (anti)neutrino-nucleus and in protonnucleus collisions was performed using the scintillator system of the CHARM neutrino detector at the CERN SPS. No events of the cases considered were found. In (anti)neutrino beams production was found to be less than a few times 10^?5 per interaction of a beam particle. In a proton beam an upper limit on the production cross section of ～10^?40 cm² was obtained.     

A facile one‐pot synthesis of tetrahydropyrimidines part 3 Synthesis of [alkanediylbis(3‐alkyl/aralkyl/aryl‐3,6‐dihydropyrimidine‐1,5(2H)‐diyl)bis(arylmethanones) and [1,4‐phenylenebis(3‐phenyl‐3,6‐dihydropyrimidine‐1,5(2H)‐diyl)]bis(phenylmethanone)

A facile one‐pot synthetic strategy has been developed for novel [alkanediylbis(3‐alkyl/aralkyl/ aryl‐3,6‐dihydropyrimidine‐1,5(2H)‐diyl)]bis(arylmethanones) 2a‐c, 2e‐m and [1,4‐phenylenebis(3‐phenyl‐3,6‐dihydropyrimidine‐1,5(2H)‐diyl)]bis(phenylmethanone) 2d by refluxing enaminones 1a‐f in methanol with diamines and formaldehyde.     

Crystallization kinetics study on higher homologues of benzylidene aniline compounds: impact of phase variant on nucleation process

A systematic kinetic study leading to the crystallization process from the kinetophases (which occur prior to crystal phase) smectic B, crystal G and smectic F is performed on representative compounds of the homologous series p -phenylbenzylidene-p′-alkylanilines (PBnA) and p-n -alkoxybenzylidene-p′-alkylanilines (nO.m) these compounds are p-phenylbenzylidene-p′-nonylaniline (PB9A), p -phenylbenzylidene-p′-tetradecylaniline (PB14A), p-n -pentadecyloxybenzylidene p′-tetradecylaniline (15O.14) and p-n -octadecyloxybenzylidene-p′-nonylaniline (18O.9). The molecular mechanism and dimensionality in crystal growth from the kineto phases are computed from the Avrami equation, while the characteristic crystalline time (t ^*) at each crystallization temperature is deduced from the individual plots of log t vs. Δ H. The low magnitudes of the dimensionality parameter n infers the occurrence of diffusion-controlled transformations leading to the formation of plates or needles of finite size possessing impinged edges. The degree of variation in the value of n at each crystallization temperature also reveals the existence of an independent nucleation mechanism for any individual member of the series. The influence of the terminal alkyl chain lengths on the rate of crystallization is determined from a comparative study with the reported analogous compounds.     

The Influence of the Dispersion and Vertical Divergence on the Reflection Curve of a Double-crystal Arrangement

The influence of the dispersion and vertical divergence on the half width of the reflection curves was investigated using a double-crystal arrangement where the second crystal could be rotated about an axis parallel to the beam reflected by the first crystal. The experimentally measured dependence of the half width of the reflection curves on the angle of rotation φ is accurately confirmed by geometrical considerations.     

Technical Reports: A Single-photon Counting Pixel Detector for Surface Diffraction Experiments

The intense flux delivered by third-generation synchrotron sources has opened up exciting new possibilities in surface diffraction (SD) studies [1–3]. Nonetheless, practical SD experiments are plagued by several technical problems. Because the crystalline surface is typically probed down to a depth of approximately 1 or 2 nm when using subcritical-angle incident X-ray beams, the scattering volume is only about 10^-12 cm³. This is further exacerbated by the fact that the most interesting information on the surface structure is generally obtained from those regions of diffraction features known as crystal truncation rods (CTRs) where scattering is weakest, i.e., in between Bragg peaks.     

Investigation of the quantitative properties of the quadrupole orthogonal acceleration time-of-flight mass spectrometer with electrospray ionisation using 3,4-methylenedioxymethamphetamine

This paper describes the investigation of the potential of a quadrupole orthogonal acceleration time-of-flight mass spectrometer (Q-TOF) equipped with an atmospheric pressure ionisation interface for quantitative measurements of small molecules separated by reversed phase liquid chromatography. To this end, the detection limits and linear dynamic range in particular were studied in an LC/MS/MS experiment using 3,4-methylenedioxymethamphetamine standards and 3,4-methylenedioxyethylamphetamine for internal standardisation. In a second phase, the experiment was repeated with real biological extracts (whole blood, serum, and vitreous humour). A calibration for 3,4-methylenedioxymethamphetamine and its metabolite 3,4-methylenedioxyamphetamine was prepared in each of these matrices again using 3,4-methylenedioxyethylamphetamine as internal standard. The resulting quantitative data were compared with those obtained by liquid chromatography with fluorescence detection for the same extracts. The Q-TOF results revealed excellent sensitivity and a linear dynamic range of nearly four decades (2-10 000 pg on-column, r(2) = 0.9998, 1/x weighting). Furthermore, all the calibration curves prepared in biological material were superimposable, LC/MS/MS and LC-fluorescence, and the quantitative results for actual samples compared very favourably. It was concluded that the Q-TOF achieves a linear dynamic range for quantitative LC/MS/MS work exceeding that of fluorescence detection and at much better absolute sensitivity. Copyright 1999 John Wiley & Sons, Ltd.     

Ion equilibria in THF solutions of models of “living” methacrylonitrile oligomers with Li+ counterion

The electro-chemical characteristics of isobutyronitrile lithium (P₁Li) and 2-lithio-4-cyano-2,4-dimethylpentanenitrile (P₂Li) are studied. The dissociation constants K of P₁Li and P₂Li are of the order of 10^?11M and show that in THF mainly contact ion pairs exist. The lower value of K for P²Li is an indication for intramolecular complexation between the counterion and the cyano group, next to the active center. Both compounds tend to form ion triples. The results obtained show that in THF the nitrile group of the second monomer unit participates both in intra- and intermolecular interactions with the counterion.     

Analyse multielementaire instrumentale des phosphates marocains par photoactivation nucleaire

Photonuclear activation and high resolution gamma-ray spectrometry have been used to determine non-destructively the concentrations of 25 trace elements in Maroccan phosphate rock. The activation was simultaneously performed for phosphate samples and multielement standards in the bremsstrahlung beam of a linear electron accelerator at 18 and 30 MeV maximum energies. Gamma-ray spectra were recorded with a 79 cm³ Ge(Li) detector and a programmable analyzer IN 96. A detailed study of interferences was carried out. Limits of detection between 0.5 and 125 μg·g^?1 were obtained.