A collaboration into research on nanoparticles (ACORN)

This paper describes the operation and outcome of one of the United Kingdom's largest multi-partner research activities in nanoparticles.The research covers the discovery and development of organic and inorganic crystals/nanoparticles,nanoparticle properties towards specific product applications,The research also encompassed bespoke measurement technology for nanoparticles and structure interactions.Significant research outcomes are summarised.The paper illustrates the advantages from industrially motivated research and value of collective action between a broad group of researchers in a nation.     

Bose-Einstein correlations in neutrino and antineutrino interactions in deuterium

Bose-Einstein correlations between pions of equal charge have been observed in Charged Current and Neutral Current (anti)neutrino-deuterium interactions in the BEBC bubble chamber exposed to the SPS wide band beam. The pion emission region is found to be essentially spherical with a mean radius of (0.48±0.07) fm; the chaoticity parameter is 0.36±0.04.     

Cyclic polytopes, hyperplanes, and Gray codes

We consider cyclic d-polytopes P that are realizable with vertices on the moment curve $M_d:t\longrightarrow (t,t^2,\ldots,t^d)$ of order $d\geq 3$. A hyperplane H bisects a j-face of P if H meets its relative interior. For $\ell\geq 1$, we investigate the maximum number of vertices that P can have so that for some $\ell$ hyperplanes, each j-face of P is bisected by one of the hyperplanes. For $\ell > 1$, the problem translates to the existence of certain codes, or equivalently, certain paths on the cube $\{0,1\}^\ell$.     

High transverse momentumη production in π− p, π+ p,andpp interactions at 280 GeV/c

The inclusive cross sections for η production by the interactions of 280 GeV/c momentum π^?, π⁺, and proton beams in hydrogen have been measured. The kinematical range covered is ?0.45<x _F <0.45, and 4.0<P _T <7.0 GeV/c for Feynmanx _F and transverse momentum respectively. The η to π⁰ cross section ratios are given for the three reactions. The ratio of π^? p to π⁺ p cross sections for η production in the above kinematic ranges is 1.22±0.08±0.11.     

A study of the centrally producedK *0 K^{*0} \bar K^{*0} final state in the reactionpp→p f (K + K -π+π-)p s at 300 GeV/c

The reactionpp→p _f (K ⁺ K ^-π⁺π^-)p _s , where theK ⁺ K ^? π⁺π^- system is centrally produced, has been studied at 300 GeV/c. TheK ^*0 \(K^{*0} \bar K^{*0} \) final state has been observed and the cross sections for its central production are found to be the same at 300 and 85 GeV/c. TheK ^*0 \(K^{*0} \bar K^{*0} \) final state appears to be produced as a non-resonant threshold enhancement.     

Measurement of the structure functionsF 2 andxF 3 and comparison with QCD predictions including kinematical and dynamical higher twist effects

The isoscalar nucleon structure functionsF ₂(x, Q ²) andxF ₃(x, Q ²) are measured in the range 0<Q ²<64 GeV², 1.7<W ²<250 GeV²,x<0.7 using ν and \(\bar v\) interactions on neon in BEBC. The data are used to evaluate possible higher twist contributions and to determine their impact on the evaluation of the QCD parameter Λ. In contrast to previous analyses reaching to such lowW ² values, it is found that a low \(\Lambda _{\overline {MS} } \) value in the neighbourhood of 100 MeV describes the data adequately and that the contribution of dynamical higher twist effects is small and negative.     

A measurement of $K^{*\pm}$ production in the hyperon beam experiment at CERN

We report on a measurement of the differential cross sections of inclusive production in and neutron beams. A strong leading particle effect was observed for production by . The measured –distributions are compared with calculations based on the Lund model (PYTHIA) and the quark-gluon string model. Received: 6 August 2001 / Revised version: 3 September 2001 / Published online: 5 October 2001     

Production of π0 mesons and charged hadrons in\bar v neon and ν neon charged current interactions

The average multiplicities of charged hadrons and of π⁺, π^? and π⁰ mesons, produced in \(\bar v\) Ne and νNe charged current interactions in the forward and backward hemispheres of theW ^±-nucleon center of mass system, are studied with data from BEBC. The dependence of the multiplicities on the hadronic mass (W) and on the laboratory rapidity (y _Lab) and the energy fraction (z) of the pion is also investigated. Special care is taken to determine the π⁰ multiplicity accurately. The ratio of average π multiplicities \(\frac{{2\left\langle {n_{\pi ^O } } \right\rangle }}{{[\left\langle {n_{\pi ^ + } } \right\rangle + \left\langle {n_{\pi ^ - } } \right\rangle ]}}\) is consistent with 1. In the backward hemisphere \(\left\langle {n_{\pi ^O } } \right\rangle \) is positively correlated with the charged multiplicity. This correlation, as well as differences in multiplicities between \(\mathop v\limits^{( - )} \) and \(\mathop v\limits^{( - )} \) , \(\mathop v\limits^{( - )} \) scattering, is attributed to reinteractions inside the neon nucleus of the hadrons produced in the initial \(\mathop v\limits^{( - )} \) interaction.     

Heme-heme interactions in the cytochrome b6f complex: EPR spectroscopy and correlation with structure

Cytochrome b6f of oxygenic photosynthesis was studied using multifrequency, multimode EPR Spectroscopy. Frequency dependent signals above g = 4.3, and the observation of parallel-mode signals, are indicative of spin interactions in the complex. We demonstrate the presence of an exchange interaction between the unique high-spin heme cn and a nearby low-spin heme bn, and show that a quinone analog NQNO binds at or near to heme cn. The two hemes remain spin coupled upon the binding of NQNO, though strength of interaction decreases significantly. The electronic coupling implies that the heme bn/cn pair could function as a unit to facilitate 2-electron reduction of plastoquionone without generation of an energetically unfavorable semiquinone intermediate.     

Electrodermal arousal between participants in a conversation: nonlinear dynamics and linkage effects

Physiological linkages between two people in conversation were investigated from a nonlinear dynamical systems theory perspective. Thirty-seven pairs of college students engaged in a 20-minute discussion while connected to electrodes that measured their electrodermal response (ED). Greater incidents of linkage were detected through the nonlinear regression analysis compared to linear models. The nonlinear models were exponential structures that determined positive Lyapunov exponents (and thus the presence of chaos) for 73 out of 74 participants. Results support the use of nonlinear models for interpersonal linkage effects of this type. For each participant, Social Sensitivity from the Social Skills Inventory was correlated with the nonlinear model R(2) coefficient, but not with the size of the Lyapunov exponent. The latter results supported the conclusion that empathy acted as a moderator of the nonlinear process that underlies changes in ED levels over time.