A lower bound for the number of Reidemeister moves of type III

We study the number of Reidemeister type III moves using Fox n-colorings of knot diagrams.     

80–360 GHz very wide band millimeter wave network analyzer

An extension to a 20 GHz HP8510C Network Analyzer has been built for wideband measurements between 80 and 360 GHz. Improvements relative to the first version [1], [2] include new harmonic mixers, and an active doubler. Dynamic ranges up to 60 dB in transmission and 50 dB in reflection are obtained up to 280 GHz, with more than 50 GHz instantaneous bandwidth using waveguide calibration. Detection with a 30 dB dynamic range is obtained at 320 – 360 GHz. Time domain measurements give spatial resolution down to 2 mm.     

Nuclear moments of the neutron-deficient thallium isotopes

The nuclear moments of the neutron-deficient^187,188Tl isotopes were determined by measuring the hyperfine structure splittings of the λ=535 nm line in neutral thallium. An optical efficiency of 2×10⁻⁴ photons per radioactive ion was achieved using collinear fast beam laser spectroscopy with a large solid angle fiber optical array detector. Most of the moments can be interpreted fairly well in the single particle model.     

Evidence for a contribution to the extrinsic photoconductive signal by hopping through excited states of the donors in silicon and CdTe

The intensities of the bound to bound transitions of the shallow donors in silicon and CdTe are found to be strongly electric field dependent when observed by photoconductivity techniques at low temperatures. Under these conditions significant differences can be detected between the photoconductive spectrum and the same transitions observed in absorption. The photoconductive peaks are shifted consistently to lower frequency compared with the absorption spectrum and additional peaks appear which are not significant features in absorption. These additional peaks are believed to result from the formation of molecular complexes of donors. The strong electric field dependence of the bound transitions observed in photoconductivity, the shift to lower frequency of the peaks and the enhancement of the additional lines can all be explained qualitatively on the assumption that the mechanism responsible for the generation of the photosignal involves hopping between the excited states of the molecular complexes     

Diffraction and resonance production in exclusive pp interactions at 100 GeV/c

We have investigated the reactions $\text{p}\text{p}\text{π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{a}\text{?}\text{and}\text{p}\text{p}\text{a}\text{?}\text{p}\text{p}\text{2π}{}^{\mathrm{+}}\text{2π}{}^{\mathrm{?}}\text{at}\text{100}\text{GeV}\text{/c}$. The $\text{p}\text{p}\text{π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}$ final state is dominated by diffractive production of a $\text{p}\text{π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{(}\text{or}\text{p}\text{π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{)}$ system which shows a strong tendency to form $\text{Δ}{}^{\mathrm{++}}\text{π}{}^{\mathrm{?}}\text{(}\text{or}\text{Δ}{}^{\mathrm{++}}\text{π}{}^{\mathrm{+}}\text{)}$. The process $\text{p}\text{p}\text{a}\text{?}\text{Δ}{}^{\mathrm{++}}\text{Δ}{}^{\mathrm{++}}$ is also observed in this reaction, indicating an energy dependence of s^?1.5±0.1. The $\text{p}\text{p}\text{2π}{}^{\mathrm{+}}\text{2π}{}^{\mathrm{?}}$ channel shows less single diffraction, and has a doubly diffractive component consistent with pomeron factorization. Strong Δ⁺⁺(Δ⁺⁺) production is agoain seen, but in contrast to the $\text{p}\text{p}\text{π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}$ channel we also observe considerable ?⁰ production.     

Measurement of the inclusive forward neutron spectrum produced in proton-copper interactions at 24 GeV/c

We present data on the inclusive neutron spectra produced in the forward direction by the interactions of 23.85 GeV/c protons in a copper target. The results are in good agreement with the predictions of the triple-Regge model.     

Reactions of π-allyl with atomic oxygen and hydroxyl on Ag(110)

The oxidation of the adsorbed π-allyl (η³-C₃H₅), prepared on atomic oxygen- and hydroxyl-covered Ag(110) by dissociation of allyl chloride (C₃H₅Cl), is investigated with temperature-programmed desorption and high-resolution electron energy loss spectroscopy. Allyl chloride adsorbs molecularly on oxygen-covered Ag(110) at 110 K. Upon heating to 180 K, some allyl chloride dissociates to form π-allyl and atomic chlorine, and the remainder desorbs molecularly. The π-allyl undergoes combustion to form hydroxyl or carbonate until all of the free oxygen is consumed by 200 K. Migratory insertion of hydroxyl into excess π-allyl commences near 220 and finishes by 250 K, forming adsorbed allyl alcohol (C₃H₅OH), which reacts either with excess hydroxyl near 240 K to form allyl alkoxy (η¹(O)-C₃H₅O) and water, or with π-allyl at 250 K to form allyl alkoxy and propylene (C₃H₆). Th allyl alkoxy evolves acrolein (C₃H₄O) by β-hydrogen elimination near 285 K, and propylene is evolved concurrently as the hydrogen released by this reaction rapidly scavenges π-allyl. Finally, the remaining π-allyl dimerizes to form 1,5-hexadiene (C₆H₁₀), which desorbs at 315 K. The gross observations of reaction pathways and temperatures are used to evaluate important aspects of the thermochemistry of these reactions.     

A new upper limit for the branching ratio (Ξ− → nπ−)(Ξ− → Λπ−)

From a sample of 735 000 Ξ^? decays, we have obtained a new upper limit for the branching ratio $\text{(Ξ}{}^{\mathrm{?}}\text{→}\text{n}\text{π}{}^{\mathrm{?}}\text{)}\text{(Ξ}{}^{\mathrm{?}}\text{→ Λπ}{}^{\mathrm{?}}\text{)}$. The result is 1.9 × 10^?5 at the 90% confidence level.