Search for large-rapidity-gap events in e+e− annihilation

We investigate the cross section for the production of a low-mass colour-singlet cluster ine ⁺ e ^? annihilation with a large rapidity gap between the colour-singlet cluster and the other jets. It is argued that such events are the cross-channel analogue of large-rapidity-gap events in deep-inelastic scattering, and therefore could in principle be used to investigate the analytic continuation of the BFKL pomeron to the positive-t kinematic regime, where one would expect the trajectory to pass through glueball states. The cross section can be calculated in perturbative QCD, so that the infrared scale arising from non-perturbative effects, which prevents an exponential fall-off with rapidity gap in the case of deep-inelastic scattering, is absent ine ⁺ e ^? annihilation. Correspondingly, the cross section for such events decreases rapidly with increasing rapidity gap.     

Experiments on the active control of transformer noise

This paper describes an experiment which demonstrates how a useful degree of active noise control can be achieved with ordinary sound amplification and reproduction equipment. A loudspeaker positioned next to a large pair of noisy electricity transformers was made to mimic their noise but in antiphase. The aim of the study was to investigate the degree to which the “antisound” would cancel a disturbing noise heard in a nearby office. Some 20 decibels of control was achieved very easily for the 100 Hz component of the noise but the higher frequency sound could only be controlled in localized patches. The experiment suggests that sounds of discrete frequencies of less than 100 Hz are relatively easily controlled with unsophisticated audio equipment, but that useful control of higher frequency elements is much more difficult.     

Site location and requirements for the installation of a nuclear magnetic resonance scanning unit

The installation of a nuclear magnetic resonance unit in any diagnostic facility involves certain location and environmental requirements. Based on our experience with the FONAR QED 80 system, we have delineated the major factors which must be considered when planning for such an installation. The major requirements are location and space. Suggested layouts for the suite and the control room are included. Certain environmental specifications will vary depending on the location of the facility and the type of unit installed.     

On the time to first failure in multicomponent exponential reliability systems

Consider an n-component reliability system having the property that at any time each of its components is either up (i.e., working) or down (i.e., being repaired). Each component acts independently and we suppose that each time the i^th component goes up it remains up for an exponentially distributed time having mean μ_i, and each time it goes down it remains down for an exponentially distributed time having mean υ_i. We further suppose that whether or not the system itself is up at any time depends only on which components are up at that time. We are interested in the distribution of the time of first system failure when all components are initially up at time zero. In section 2 we show that this distribution has the NBU (i.e., new better than used) property, and in Section 3 we make use of this and other results to obtain a lower bound to the mean time until first system failure.     

Purely hadronic weak interactions in unified field theories of the weak and electromagnetic interactions

Non-leptonic weak interactions are investigated in unified gauge theories. A large enhancement of parity violation in nuclei relative to conventional Cabibbo theory is indicated.     

A demonstration of active control of broadband sound

This paper describes a short experiment undertaken to demonstrate how easily broad-band active control of sound can be used to tackle real industrial problems. Ten decibles of the low frequency sound entering an anechoic chamber through a lobby was blocked by using a single degree of freedom system. The experiment was set up, tested and demonstrated in a day.     

Modification of the chemical properties of silicon by ion implantation with high doses of Ar and P

The behaviour of Si implanted with high doses of P and Ar (5·10¹⁴ to 10¹⁷ cm⁻²) in HF solutions was investigated using radioactive isotopes. The reaction products were analyzed by ion exchange and electrochemical polarization. An increased dissolution was found and a possible reaction mechanism given.     

Flavour symmetry breaking in antiquark distributions

We show that knowledge of the valence quark distribution of a proton at one value of q², enables one to calculate a contribution to the difference between the distribution of anti-up quarks $\text{(}\text{u}{}_{\mathrm{<mtext>p</mtext>}}\text{)}$ and anti-down quarks $\text{(}\text{d}{}_{\mathrm{<mtext>p</mtext>}}\text{)}$ in the sea of the proton at higher values of q². This difference can be expressed as a linear combination of the structure functions F₁, for νp → νX and e^?p → e^?p (for which one knows the q² behaviour of the moments) and for $\text{ν}\text{p}\text{→ μ}{}^{\mathrm{?}}\text{X}\text{and}\text{ν}\text{p}\text{→ μ}{}^{\mathrm{+}}\text{X}$ (for which one knows the q² behaviour of the odd moments). The calculable contribution involves a non-trivial continuation of the even (odd) moments of the neutral (charged) current structure functions to odd (even) moments. We calculate this contribution and although we find that its sign is negative we point out that this cannot be interpreted as a consequences of the Pauli exclusion principle. We discuss the constraints our results impose on antiquark distributions.