This work examines the processes of steel corrosion initiation and arrest in chloride contaminated concrete. It is noted that the local production of acid is an essential feature in chloride induced corrosion damage. An acidification-realkalisation model of chloride induced corrosion has been developed to improve the explanation of some experimental observations. A simplified electrochemical treatment consisting of a hybrid of a pit re-alkalisation process to arrest corrosion followed by supplementary galvanic protection to maintain a high pH and steel passivity has been applied to concrete structures. Both the pit-realkalisation and supplementary galvanic treatments are delivered from a permanently installed sacrificial anode system. Risk management includes monitoring and a strategy to deal with any future risk of corrosion. An identified risk may be treated using a 2 week pit re-alkalisation treatment from a permanently installed sacrificial anode system with an impressed current connection.

Current standards on the safety of small portable gas cylinders only define the pressures at temperatures of up to 50°C and therefore have limited applicability in situations where cylinders are close to fires. Cylinders containing a pressurised liquid butane–propane mixture were heated in a small barbecue. The cylinders underwent a boiling liquid expanding gas explosion (BLEVE) at a liquid temperature of 90–100°C. Failure was at the rolled seam where gas could escape thus provoking the BLEVE. Previous hydrostatic pressure testing of the cylinders showed that collapse of the spherical cap base occurred at a pressure of 1.8MPa and that this was followed by failure of the rolled seam at a pressure of 2.0MPa. These pressures were lower than that required to produce longitudinal cracks in the cylinder wall. Analysis of the pressure created as the temperature is raised by means of the Clausius–Clapeyron equation indicated the temperature for failure of the seam to be about 100°C. After the BLEVE the cylinder broke into two fragments, an end cap and a tub rocket. The velocity of the tub rocket was estimated to be 65ms−1, giving a kinetic energy of 309J. By comparison with the ballistics of rubber bullets it is believed that any injuries will be non-penetrating blunt trauma injuries and be less likely to cause severe injuries than those created by rubber bullets. The range over which the kinetic energy is likely to be capable of creating injuries is estimated to be less than 30m.

This paper examines steel corrosion initiation and arrest in chloride-contaminated concrete. Corrosion damage is, at least in part, attributed to the production of acid at sites of corrosion initiation. Solid phase inhibitors provide a reservoir of hydroxyl ions to inhibit damage. Pit re-alkalisation is identified as an important protective effect in electrochemical treatments used to arrest corrosion. An acidification–pit-re-alkalisation model is used to explain the lateral spread of chloride-induced corrosion across a steel surface, the time required to arrest corrosion in cathodic protection and the potential shifts observed as protection is achieved. The process of pit re-alkalisation may be achieved using a relatively small electric charge that is readily impressed off sacrificial anodes using a power supply. A simple but powerful electrochemical treatment comprises a hybrid of a brief pit-re-alkalisation process to arrest corrosion followed by low maintenance galvanic protection to prevent local acidification. Methods of monitoring the steel corrosion rate in electrochemically treated concrete have been developed and used to assess corrosion risk. The brief pit-re-alkalisation process may be applied at any time using the existing anode system to manage future corrosion risk.

The parity-violating longitudinal analyzing power, A(z), has been measured in pvectorp elastic scattering at an incident proton energy of 221 MeV. The result obtained is A(z) = [0.84+/-0.29(stat)+/-0.17(syst)]x10(-7). This experiment is unique in that it selects a single parity violating transition amplitude (3P2 - 1D2) and consequently directly constrains the weak meson-nucleon coupling constant h(pp)(rho). When this result is taken together with the existing pvectorp parity violation data, the weak meson-nucleon coupling constants h(pp)(rho) and h(pp)(omega) can, for the first time, both be determined.

We have measured the relative differential cross section and spin observables for the reaction np\ensuremath{\rightarrow}pp${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$ at 443 MeV. Our measurements have been compared with predictions of the model of Kloet and Lomon. Some of the variables show marked disagreement with predictions; for other variables there is surprisingly good agreement.

We measured the relative differential cross section and analyzing powers A SO, A NO and A LO for the reaction np→ppπ− at an incident neutron energy of 443 MeV. The geometry of our detector allowed us to sample almost all the available phase-space. We reconstructed the full kinematics of each event from the measured trajectories of at least two of the three final state particles. Cuts based on the vertex reconstruction and kinematic χ2 allowed us to remove most background, primarily nn→npπ− from the target walls and other materials. These cuts gave a signal-to-noise ratio of 22:1, but fewer than 3% of the total data survived the cuts. The resulting ~400,000 np→ppπ− were binned against p-p invariant mass and angles which are most suited to partial waves analysis. Comparisons are made to predictions of the model of Kloet and Lomon. These observables represent the first measurements of their kind at this energy and it is hoped that their determination will allow us to extract the role of isospin-0 amplitudes in the process of pion production.

Proton total reaction cross sections (sigma(R)) have been measured for the nuclei Ca-42, Ca-44, and 48Ca at seven energies each between 20.8 and 48.0 MeV. The experimental results plus our previously Measured sigma(R) values for Ca-40 are compared to the results of optical model analyses, both nonrelativistic and relativistic, of an extensive set of elastic scattering data for the same calcium isotopes in this energy range. The experimental results are also compared to global optical model predications. In general, the theoretical values are in good agreement with the experimental results, with a slight preference for the relativistic analysis. In addition, our results are used in nuclear transparency calculations, which show that over the range of energies studied, the average nuclear transparency decreases by almost 15%.

A stable, phase restricted tune has been developed for the TRIUMF cyclotron. By use of a radially adjustable foil or skimmer on the first turn and a slit on the tenth turn of the machine, the phase acceptance may be reduced from its normal value of approximately 35° to typically 3.7°, corresponding to a beam burst duration of 450 ps FWHM. The beam intensity is reduced by a factor of ten. The time structure of the beam is measured by a time pickoff near the experimental target location. Timing information is derived from protons elastically scattered in a thin in-beam target. The timing pickoff was found to have an intrinsic resolution of 50 ps rms.

An outline is given of an experiment to measure parity violation in p-p scattering at 230 MeV at TRIUMF. The parity-violating longitudinal analysing power Az will be measured to a precision of 2×10−8 and will isolate the parity-violating 3P2−1D2 partial wave amplitude.

Differential cross section measurements for the radiative capture reaction p(n,d)γ at 0°–3° laboratory angle and neutron energies of 360, 410 and 460 MeV (corresponding to photon lab energies of 182.5, 207.7 and 232.5 MeV for the inverse reaction) have been made using the TRIUMF medium resolution spectrometer. These data complement measured photo-disintegration differential cross sections at forward angles in this energy range and are the first capture cross sections at 0° above the pion-production energy threshold. The results are in qualitative agreement with three recent theoretical treatments of this reaction.

This paper describes the recently completed study of the np→ppπ− reaction carried out at TRIUMF using a neutron beam of 440 MeV. The apparatus and beam characteristics are described and early results discussed.

A recent experiment, measuring the spin correlation parameter Ann in neutron-proton elastic scattering to a precision of ±0.03 at several energies in the range 200 to 500 MeV, required the polarization of the proton frozen-spin target used in the experiment to be known to an accuracy of ±2%. The calibration of the polarization of the frozen-spin target was accomplished through an experiment interleaved with the Ann experiment. An unpolarized proton beam, of an intensity comparable to the intensity of the neutron beam in the Ann experiment, was scattered at 24° (lab.) from the frozen-spin target at energies of 468 and 501 MeV. From the measured left-right asymmetries and knowledge of the proton-proton analyzing powers, Ay(24°, 468 MeV) = 0.4087±0.0060 and Ay(24°, 501 MeV) = 0.4204±0.0059, the target polarizations could be deduced. The weighted average of the ratios of the target polarization deduced in the scattering experiment and obtained from nuclear magnetic resonance measurements was found to be Pt(scattering)/Pt(NMR) = 0.962±0.008(stat)±0.021(sys)±0.014(sys) at 468 MeV and 0.950±0.005(stat)±0.020(sys)±0.013(sys) at 501 MeV. By dividing the target cell holding the butanol beads, as illuminated by the incident proton beam, in three parts (top, middle, and bottom), a determination of the average polarization for each of the three parts was made. A clear decrease of the polarization going from the top to the bottom of the target cell was found.

The validity of charge symmetry has long been of fundamental interest and much circumstantial evidence has accumulated over the years favoring charge symmetry breaking (CSB) on the order of a fraction of a percent. Although low energy nucleon-nucleon scattering studies have shown a slight inequality of the nn and pp scattering lengths[1], it has proved very difficult to remove experimental and theoretical uncertainties to isolate charge symmetry breaking interactions unequivocally. Evidence of CSB is present in π scattering from 3 H and 3 He and in π — d total and differential cross section measurements[2],[3],[4],[5]. The π — d results have been interpreted in terms of mass splittings in the Δ system. Differences in the binding energies of mirror nuclei (the Nolen-Schiffer effect) hint at the presence of charge symmetry breaking terms in the interaction but, again, the isolation and removal of electromagnetic (EM) effects has proved difficult[6],[7].

Two dual function intensity profile monitors have been designed for a measurement of parity violation in p-p scattering at about 230 MeV using longitudinally polarized protons. Each device contains a set of split secondary electron emission (SEM) foils to determine the median of the beam current distribution (in x and y). The split foils, coupled through servoamplifiers and operational amplifiers to upstream aircore steering magnets, have demonstrated the ability to hold the beam position stable to ±5 μm for beam position fluctuations up to 1000 Hz. These monitors also contain a set of foil strip planes giving information on the intensity distribution projected onto the two orthogonal axes, x and y. Data were acquired using 0.008 mm thick, 0.90 mm wide aluminum foil strips at 1.00 mm centers. The foil strip planes were able to determine the beam centroid to within ±3 μm after one hour of data taking with a 100 nA, 15 mm FWHM Gaussian beam.

We have measured np\ensuremath{\rightarrow}d${\ensuremath{\pi}}^{0}$ cross sections at eleven beam energies within 16 MeV of threshold. Total cross sections are only 0.67\ifmmode\pm\else\textpm\fi{}0.10 of the value which has been generally accepted for s-wave pion production strength near threshold. The differential cross sections are anisotropic at only 1 MeV (c.m.) above threshold. Our results are compared to ${\ensuremath{\pi}}^{+}$d\ensuremath{\rightarrow}pp data and to predictions of two models.