Proposal to build a neutrino observatory in Sudbury, Canada

Summary The proposal to build a heavy-water Čerenkov detector deep underground is discussed. The main physics objectives are to measure the⁸B solar neutrino flux, to identify neutrino oscillations and to watch for gravitational collapse. The measurements of the sources of background and the optical properties of heavy water, which are necessary to prove the feasibility of the detector, are reported. The present status of the project is indicated.

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Riassunto Si discute il progetto di costruire un rivelatore Čerenkov ad acqua pesante a grande profondità. Gli obiettivi fisici principali sono quelli di misurare il flusso di neutrini solati di⁸B, d'identificare le oscillazioni neutriniche e di osservare il collasso gravitazionale. Si riportano le misure delle sorgenti di background e le proprietà ottiche dell'acqua pesante, che sono necessarie per provare la fattibilità del rivelatore. Si indica lo stato attuale del progetto.

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Резюме Обсуждается преложение о строительстве черенковского детектора на тяжелойводе. Основные физические задачи—измерение потока⁸B солнечных нейтрино, идентификация нейтринных осцилляций и наблюдение гравитационного коллапса Сообщаются результаты измерений источников фона и оптических свойств тяжелой воды, необходимые для вьшолнения этого детектора. Описывается состояние проекта в настоящее время.

     

Desert terrain characterization of landforms and surface materials within vehicle test courses at U.S. Army Yuma Proving Ground, USA

The U.S. Army Yuma Proving Ground is the Department of Defense desert environment test center within the Sonoran Desert of Arizona. The Yuma Proving Ground has ∼320 km of unpaved vehicle test courses that cross a variety of landforms of diverse geologic age and characteristics. The surface materials of the courses ranges from bedrock to silt and their topography varies from steep and rolling to flat. Research presented here aims to provide a systematic characterization of the terrain of eight vehicle endurance and three dust courses so that their comparability with other desert areas of the World may be assessed. Landform and surface cover (upper 1 m) characterization was accomplished by geomorphic mapping based on 1-m resolution IKONOS satellite imagery, 10-m digital elevation models, field verification, and by assimilating pre-existing soil surveys and geologic maps, as well as site-specific investigations. Results provide an assessment of each test course, including information on the landform, geology, surface materials, soil type, degree of desert pavement development, dust content, and percent slope. Data is presented both on individual terrain property maps for each course and in the form of tabulated data for each official milepost marker along the courses. The results for one course area and an example of how they may be used to assess comparability with another desert of interest are presented here with the objective to improve the fidelity of desert testing during material research, development, testing and evaluation prior to deployment in the field.     

Adsorption and reaction of hydrogen sulfide on thin-film cerium oxide

The adsorption and reaction of hydrogen sulfide, H₂S, have been studied on cerium oxide thin films that were vapor deposited on Ru(0 0 0 1). The behavior of the H₂S was examined as a function of Ce oxidation state. H₂S weakly chemisorbs on fully oxidized CeO₂ desorbing near 155 K. Hydrogen from the H₂S reacts with the surface O to desorb as water between 200 K and 450 K. When ca. 20% of the Ce⁴⁺ is reduced to Ce³⁺ more H₂S dissociates to -OH and -SH and water is produced near 580 K. When the ceria is ca. 70% reduced, water formation is suppressed and H₂ desorbs near 580 K. S 2p photoelectron spectroscopy indicates the decomposition of H₂S into -SH and then -S as the sample is annealed from 100 K to 600 K. O 1s photoemission indicated the presence of H₂O and -OH.     

Paradox in Wave-Particle Duality

We report on the simultaneous determination of complementary wave and particle aspects of light in a double-slit type “welcher-weg” experiment beyond the limitations set by Bohr’s Principle of Complementarity. Applying classical logic, we verify the presence of sharp interference in the single photon regime, while reliably maintaining the information about the particular pinhole through which each individual photon had passed. This experiment poses interesting questions on the validity of Complementarity in cases where measurements techniques that avoid Heisenberg’s uncertainty principle and quantum entanglement are employed. We further argue that the application of classical concepts of waves and particles as embodied in Complementarity leads to a logical inconsistency in the interpretation of this experiment. A Preliminary version of this paper was presented by S.S.A. at a Seminar titled “Waving Copenhagen Good-bye: Were the Founders of Quantum Mechanics Wrong?,” Department of Physics, Harvard University, Cambridge, MA 02138, 23 March, 2004.     

Optimisation of solvent desorption conditions for chemical warfare agent and simulant compounds from Porapak Q using experimental design. Part 2: Extraction of sulphur mustard from steel and glass Porapak tubes

The ion-pair solid-phase extraction (SPE) of 4-alkylphenols followed by derivatization with pentafluoropyridine is demonstrated. Under alkaline conditions, the 4-alkylphenols could be efficiently adsorbed on a C18 SPE cartridge conditioned with an ion-pair reagent, tetra-n-hexylammonium bromide. The ion pairs, ammonium phenolates, formed on the C18 solid phase, were eluted with a solvent containing the derivatizing reagent, pentafluoropyridine, and completely derivatized during the elution. After optimization of the adsorption and derivatization, we established a method for the determination of the 4-alkylphenols in water samples. The method showed good linearity between 20 and 1000 ng (200-10,000 ng for nonylphenol). By processing 20-ml samples, the method detection limits (MDL) were in the range of 5.2-8.9 ng/l for the 4-alkylphenols (76 ng/l for nonylphenol). To evaluate its applicability to a real aqueous matrix, several river water samples were analyzed.     

Dynamics of the pi(-)p-->pi(0)pi(0)n reaction for p(pi(-))<750 MeV/c

Data are presented for the reaction pi(-)p-->pi(0)pi(0)n in the range from threshold to p(pi(-))=750 MeV/c. The systematics of the data and multipole analyses are examined for sensitivity to a f(0)(600) ("sigma") meson. A one-pion-exchange mechanism is found to be very weak, or absent. The reaction appears to become dominated by sequential pi(0) decays through the Delta(1232) resonance as the beam momentum increases, along with substantial interference effects from several competing mechanisms.     

Laser-polarized 129Xe NMR at 1.88 T and 8.5 mT: a signal-to-noise ratio comparison

The signal-to-noise ratio of nuclear magnetic resonance signals from laser-polarized 129Xe gas was investigated at 8.5 mT and compared to that of signals acquired at 1.88 T. A dedicated 8.5 mT resistive magnet was constructed and used to acquire the signals. The SNR for 1 atm of xenon gas with a polarization of 1% was measured to be 1900 at a field of 1.88 T. Under identical acquisition conditions, the SNR at 8.5 mT was about 60 (or 32 times lower). After measuring and including all of the electrical factors of the detection systems at each field strength, theory indicates the SNR value measured at 8.5m T should be about 36 times lower. Considering the widely differing frequencies and completely different detection systems the agreement is quite good and indicates that extrapolating the frequency dependence of the SNR down to very low fields does work as long as the detection system parameters are carefully accounted for. This work suggests that magnetic resonance (MR) imaging is achievable on ideal gas samples at 8.5 mT using laser-polarized 129Xe gas down to the practical resolution limit of about 0.5mm, although the SNR will be very low (approximately 1.4). The feasibility of imaging small animals at 8.5 mT is discussed and it is suggested that a field of about 50 mT is required.     

Arsinophosphonium cations from arsenium-phosphine and -bisphosphine coordination chemistry

A new 14pi-electron tricyclic organoarsenium cation (5-hydrophenarsazinium, AN, C12H9AsN+) has been prepared in situ and used as a Lewis acceptor with trimethylphosphine, triphenylphosphine, bis(diphenylphosphino)methane (dppm), bis(dimethylphosphino)methane (dmpm), and 1,4-bis(diphenylphosphino)benzene (dppb) ligands. Solid-state structures and spectroscopic characterization data are reported for complexes of the general formula [AN-PMe3]+, [AN-PPh3]+, [AN-dppm]+, [AN-dppm-AN]2+, [AN-dmpm-AN]2+, and [AN-dppb-AN]2+ as tetrachlorogallate salts. Depending on reaction stoichiometry, dppm forms adducts at one or both of the donor sites. Structural comparisons with analogous complexes of phosphenium cations provide interesting similarities and differences.     

Brønsted acid-catalyzed allylboration: short and stereodivergent synthesis of all four eupomatilone diastereomers with crystallographic assignments

This study describes a novel Br?nsted acid-catalyzed allylboration method suitable for the most difficult, electronically deactivated allylboronate and aldehyde substrates. This method circumvents the use of metal ions, and rather employs a simple and cheap catalyst, triflic acid. Its usefulness as a complementary allylboration variant was demonstrated with a four-step, stereodivergent synthesis of all four diastereomers of eupomatilone-6 from a single allylboronate. A thorough proof of stereochemistry supported by as many as five X-ray crystallographic structures brings an end to the ambiguity of the original stereochemical assignments. Further to the TfOH-catalyzed allylboration, the synthetic route featured a number of remarkable observations: the surprising reactivity of 2-bromo-3,4,5-trimethoxybenzaldehyde, the subtle reagent control observed in the hydrogenation of an alpha-exo-methylene lactone intermediate, and the success of a difficult case of Suzuki biaryl coupling using Buchwald's conditions.     

Unprecedented coordination modes and demetalation pathways for unbridged polyenyl ligands. Ruthenium eta1,eta4-cycloheptadienyl complexes from allyl/alkyne cycloaddition

Cationic (eta6-hexamethylbenzene)ruthenium(II) mediates the [3 + 2 + 2] cycloaddition of allyl and alkyne ligands, leading to the unexpected isolation of eta1,eta4-cycloheptadienyl complexes, an unprecedented coordination mode for transition metal complexes of simple organic rings. The nonconjugated, eta1,eta4-coordinated complex is obtained as the kinetic reaction product from treatment of the unsubstituted allyl complex with excess ethyne; this complex rearranges slowly at 80 degrees C to the thermodynamically more stable conjugated eta5-cycloheptadienyl isomer. The eta1,eta4-coordinated isomer is fluxional at room temperature, undergoing rapid and reversible equilibration with a cycloheptatriene hydride intermediate via facile beta-hydride elimination/reinsertion. The reinsertion process is remarkably regioselective, returning the nonconjugated eta1,eta4-cycloheptadienyl isomer exclusively at room temperature. For reactions incorporating dimethylacetylene dicarboxylate (DMAD) as one or both of the alkyne components, eta1,eta4-coordination appears to be both kinetically and thermodynamically favored, despite undergoing equilibration among all possible eta1,eta4-cycloheptadienyl and cycloheptatriene hydride isomers prior to arriving at one observed eta1,eta4-isomer. For this series, no isomerization to eta5-coordination is observed even upon prolonged heating. In contrast, the cyclization incorporating both DMAD and phenylacetylene proceeds directly to the eta5-cycloheptadienyl isomer at or below room temperature, indicating that eta5-coordination remains energetically accessible to this system. The DMAD-based cyclization reactions produce structurally diverse minor byproducts, including both eta1,eta4-methanocyclohexadiene and acyclic eta3,eta2-heptadienyl isomers, which have been isolated and rigorously characterized. The unusual eta1,eta4-coordination of the seven-membered ring leads to unique new organic products upon oxidative demetalation by iodinolysis. Thus, reactions with excess iodine afford bridged tricyclic cyclopropane-containing lactones or substituted cycloheptatrienes in good but sometimes variable yields, depending on the substrate and specific reaction conditions. The ruthenium in these reactions is returned in high yield as the interesting cationic mu-triiodo pseudodimer of (eta6-hexamethylbenzene)ruthenium, which is obtained as a triiodide salt. This Ru(III) complex, along with several representative Ru(II) cyclization products, has been characterized in the solid state by X-ray crystallography.