A comparative study is done on the Mini Drift Chamber (MDC) and the Scintillating Electromagnetic Calorimeter (SEC), two main components of the WASA detector. The purpose of the study is to determine the most effective way to calculate the mass of the η−meson by determining the invariant mass of the final products in the η → e+e− decay. When calculating the invariant mass of the lepton pair the distribution from the MDC had a standard deviation of σMDC = (4.212 ± 0.080) · 10−2 GeV/c2 and from the SEC σSEC = (3.563±0.011)·10−2 GeV/c2. To get a precise measurement, events with a lepton scattering at a polar angle below 30◦ have to be rejected, and to achieve highest precision, it is favorable to use the SEC for momenta above 0.28 GeV/c and the MDC below, respectively. In this study, a combined method is developed which results in an invariant mass resolution of σMix = (3.341±0.012)·10−2 GeV/c2. Thus, the combined method gives a small improvement compared to using the SEC alone, but a considerable improvement compared to using only the MDC.

In this report the neutron-gamma discrimination capabilities of the new type of solid organic scintillator, EJ-299-33, was investigated using several pulse-shape discrimination (PSD) techniques. Among others, the analog zero-crossing method andthe digital charge-comparison and integrated-rise-time method were tested. The parameters of the digital PSD methods were optimised individually and the figure-of-merit was measured for each method and compared in different energy windows. The photoelectron yield of the setup was measured using two different photomultiplier tubes (PMT), a 3 inch diameter ET 9821 and a 5 inch diameter ET 9390KB. The highest photoelectron yield was measured with the ET 9390KB, which was the PMT used for the neutron-gamma discrimination capability measurements. In this work, four decay constants were found for the scintillator decay times. These were found by fitting average neutron and gamma-ray waveforms with the convolution of severeal exponential functions, that describes the light emission intensity of the scintillator, with an approximation of the PMT response function. Thebest agreement was found for the assumption that the scintillator light emission intensity is governed by four decay constants. The intensity of the two slowest components contain information about the incident particle.

In this work, we study the statistical properties of deterministic and stochastic dynamical systems. We are particularly interested in extreme values and recurrence. We prove the existence of Extreme Value Laws (EVLs) and Hitting Time Statistics (HTS)/ ReturnTime Statistics (RTS) for systems with decay of correlations against L1 observables. We also carry out the study of the convergence of Rare Event Point Processes (REPP). In the first part, we investigate the problem for deterministic dynamics and completely characterise the extremal behaviour of expanding systems by giving a dichotomy relying on the existence of an Extremal Index (EI). Namely, we show that the EI is strictly less than 1 for periodic centres and is equal to 1 for non-periodic ones. In a more general setting, we prove that the REPP converges to a standard Poisson if the centre is non-periodic, and to a compound Poisson with a geometric multiplicity distribution for the periodic case. Moreover, we perform an analysis of the convergence of the REPP at discontinuity points which gives the convergence to a compound Poisson with a multiplicity distribution different than the usual geometric one.In the second part, we consider stochastic dynamics by randomly perturbing a deterministic system with additive noise. We present two complementary methods which allow us to obtain EVLs and statistics of recurrence in the presence of noise. The first approach is more probabilistically oriented while the second one uses spectral theory. We conclude that, regardless of the centre chosen, the EI is always equal to 1 and the REPP converges to the standard Poisson.

No description available.

This thesis describes an analysis of the process e⁺e^— → l⁺l^- (where l = e, μ,, τ) at centre-of-mass energies between 88 GeV and 94 GeV, using the data collected by the DELPHI detector between the years 1991 and 1993. The leptonic decays of the Z° boson are selected without attempting to separate the three lepton types, thus making it an inclusive lepton analysis. The theory behind lepton pair production is introduced and the extraction of various electroweak parameters from the experimental observables is discussed. The LEP collider and the DELPHI detector are described, with special emphasis being given to the sub-detectors used in the analysis. The criteria used to select a high purity leptonic sample are described along with calculations of various backgrounds and efficiencies. The sample of selected leptonic events is then used to measure the cross-sections and forward-backward asymmetries. Finally, a fit to these cross-sections and asymmetries, together with the hadronic (e⁺e^- → qq̄) cross-sections, is carried out. Various Z° parameters are obtained: the mass and total width Mz-91.1876 ± 0.0052 GeV/c², Γ_z = 2.4971 ± 0.0061 GeV, the ratio of the hadronic to leptonic partial widths R_l = 20.73 ± 0.09, and the pole leptonic asymmetry (A°_FB)¹ = 0.0195 ± 0.0042. Using these results and the value of the strong coupling constant (α_s), determined by the DELPHI collaboration, the number of light neutrino species is determined to be N_ν = 3.045 ± 0.035. The leptonic partial width is found to be: Γ_l = 83.82 ± 0.29 MeV. Using the measured leptonic forward-backward asymmetries, the squared vector and axial-vector couplings of the Z° to charged leptons are found to be (ĝ_v¹)^{2</sup = (1.65 ± 0.36) x 10^-3 and (ĝ_a¹)}2</sup> = 0.2505 ± 0.0009. These values can be used to determine the effective rho parameter and the effective weak mixing angle: p̂ = 1.0020 ± 0.0036, and sin² θ^eff_lept = 0.2297 ± 0.0024. A full Standard Model fit to the data gives the values of the strong coupling constant, α_s, and the mass of the top quark, m_top, as being: α_s = 0.123 ± 0.010, m_top = 178⁺²²_-25 (expt)<sup>+18<sup>_-16(Higg s)GeV/c², where 60 < m_Higgs (GeV/c²) < 1000 with a central value of 300 GeV/c². All the results obtained agree with the results from the lepton-identified analyses (analyses in which leptonic events are selected on the basis of their individual flavour) and with the predictions of the Standard Model.

Harvest-related decreases of downed woody debris (DWD) in forests may have important ecological implications; however, patterns of nutrient release from decaying DWD are poorly understood. The importance of DWD was investigated relative to biomass and nutrient pools in six, second-growth boreal mixedwood forest stands, differing by harvest regime near Kapuskasing, Ontario. Nutrient concentrations and mineralization trends using ion exchange resins at three proximities during the decay of Abies balsamea and Populus tremuloides were also examined. Concentrations of N, P, Ca, and Mg increased with decay, whereas K decreased. DWD was a minor contributor to biomass and nutrient pools. Inorganic N, P, Ca, and Mn were significant between harvest types with decay class interaction for N, Ca, and Mn. Species and proximity effects were found for Al, Fe, and K. These results suggest DWD may be a minor contributor to biomass and nutrient pools, but highlights its dynamic nature.

Harvest-related decreases of downed woody debris (DWD) in forests may have important ecological implications; however, patterns of nutrient release from decaying DWD are poorly understood. The importance of DWD was investigated relative to biomass and nutrient pools in six, second-growth boreal mixedwood forest stands, differing by harvest regime near Kapuskasing, Ontario. Nutrient concentrations and mineralization trends using ion exchange resins at three proximities during the decay of Abies balsamea and Populus tremuloides were also examined. Concentrations of N, P, Ca, and Mg increased with decay, whereas K decreased. DWD was a minor contributor to biomass and nutrient pools. Inorganic N, P, Ca, and Mn were significant between harvest types with decay class interaction for N, Ca, and Mn. Species and proximity effects were found for Al, Fe, and K. These results suggest DWD may be a minor contributor to biomass and nutrient pools, but highlights its dynamic nature.

Characterization of semi-permeable films promotes the systematic selection of membranes and process design. When acquiring the diffusive and sorption properties of gas transport in non-porous membranes, the time lag method is considered the conventional method of characterization. The time lag method involves monitoring the transient accumulation of species due to permeation on a fixed volume present in a downstream reservoir. In the thesis at hand, an alternative approach to the time lag technique is proposed, termed as the short cut method. The short cut method appoints the use of a two reservoir system, where the species decay in the upstream face of the membrane is monitored, in combination with the accumulation on the downstream end. The early and short time determination of membrane properties is done by monitoring the inflow and outflow flux profiles, including their respective analytical formulas. The newly proposed method was revealed to have estimated the properties at 1/10 the required time it takes for the classical time lag method, which also includes a better abidance to the required boundary conditions. A novel design of the upstream reservoir, consisting of a reference and working volume, is revealed, which includes instructional use, and the mechanics involved with its operation. Transient pressure decay profiles are successfully obtained when the reference and working volumes consisted of only tubing. However when tanks were included in the volumes, large errors in the decay were observed, in particular due to a non-instantaneous equilibration of the pressure during the start up. This hypothesis was further re-enforced by examining different upstream tank-based configurations. iii In the end, a validated numerical model was constructed for the purpose of simulating the two reservoir gas permeation system. A modified form of the finite differences scheme is utilized, in order to account for a concentration-dependent diffusivity of penetrants within the membrane. Permeation behavior in a composite membrane system was disclosed, which provided a new perspective in analyzing the errors associated with the practical aspect of the system.

In many regions of North America, Europe, and Australia, wood utility poles are used as main and secondary structural members for the support of electrical distribution and transmission lines. In the province of Ontario alone there are over 40000 H-frame, 6000 Gulfport, and thousands of single pole structures constructed of over 2 million wood utility poles (Pandey et al. 2010b). Currently, utility companies report an increasing number of woodpecker damage incidents on in-service utility poles (HONI 2010). In addition, many aging poles have woodpecker damage in combination with wood decay. Both these forms of degradation cause strength reductions in utility poles, making their structural integrity questionable. This has raised concerns regarding the safety of utility maintenance workers and the public, and the dependability of the electrical network. In response to these concerns, Hydro One Networks Incorporated (HONI) initiated a research project on the effect of woodpecker damage and wood decay on wood utility pole strength. The objective of the research was to develop methods of quantifying the strength reduction caused by woodpecker damage and wood decay. This information was then used to develop in-service assessment methods for determination of whether pole replacement is necessary when specific levels of woodpecker damage and wood decay are present. By developing better assessment methods, in-service utility poles will not be unnecessarily replaced, reducing maintenance costs. In this study, three analytical models were developed that predicted the theoretical cross-sectional strength reduction caused by the presence of woodpecker damage. A bending failure model was developed since, in the structural design of utility poles, bending moment stresses are known to be the critical design parameter. It was decided that the significance of shear stress in a cross-section should also be considered since the presence of woodpecker damage could cause shear stresses to be a significant parameter. As a result, a shear-bending and a shear failure model was developed to determine the significance of shear stress on cross-section behaviour. These models were developed for analysis purposes and were verified by the subsequent experimental program. A total of 28 new and in-service utility poles were received from HONI for experimental testing. The new poles were received in as-new condition, while the in-service poles received had varying levels of woodpecker damage and wood decay. The poles received were cut into 4.25 m lengths for beam testing. A single new pole and in-service specimen from each pole was tested as a control specimen without woodpecker damage to obtain reference utility pole bending strengths. The remainder of the new pole specimens were mechanically introduced with woodpecker damage, while the remainder of the in-service specimens were tested with natural woodpecker damage. The tested specimens were analyzed and the results were compared with the woodpecker damage analytical model predictions. Results indicated that the effect of woodpecker damage is well modelled by the woodpecker damage analytical models. Overall, the bending failure analytical model was preferable for cross-section analysis due to the accuracy of the model predictions and the simplicity of required calculations. It was evident from the experimental program that the presence of woodpecker damage can severely reduce the strength of utility poles, making replacement necessary according to CSA C22.3 No. 1 Cl. 8.3.1.3 (2006a). In-service specimen experimental results indicated that if wood decay is detected in wood utility poles, severe reduction in wood strength has occurred and the utility pole should be replaced. Analytical and experimental results were used to develop three application methods for determining whether utility pole replacement is necessary due to the presence of woodpecker damage. These three methods include the simplified method, the chart method, and the case-specific method. The simplified method allows determination of whether a utility pole should be replaced based only on knowledge of the most severe level of woodpecker damage present in a pole. The chart method takes into account additional factors such as the diameter of the pole at the location of the woodpecker damage and the width of the hole opening. The case-specific method is advantageous since it accounts for the parameters used in the chart method and allows the location of woodpecker damage along the length of a pole to be accounted for. The simplified and chart methods are preferable since they are relatively simple and easy to implement in the field. The case-specific method requires a full structural analysis of the utility pole in question to be undertaken and is useful for more accurately assessing whether replacement is necessary. These three methods show how the research completed can be used for improved assessment of in-service utility poles resulting in reduced unnecessary pole replacement and maintenance costs.

With global freshwater supplies under pressure, viable water reuse methods are being examined to assist in improving water supplies. Municipal effluent is an ideal source for water reclamation as it is consistent in quality and quantity. The health aspects of water reuse have been identified as an issue of concern, in particular the potential presence of enteric viruses. Managed Aquifer Recharge (MAR) is a method that can aid water reclamation by recharging water such as treated effluent into a suitable aquifer. Research into the removal of pathogenic contaminants by natural processes within aquifers, namely the action of autochthonous bacteria, has led to the consideration that MAR could be used to assist in the removal of microbial pathogens. Pathogens have been demonstrated to be removed during residence in groundwater, but the presence of active autochthonous groundwater bacteria are required for significant removal rates to occur. The aim of this research was to investigate the interaction between autochthonous groundwater bacteria (AGB) and the enteroviruses Poliovirus type 1, Coxsackievirus B3 and Adenovirus B41. It was established that these viruses decrease in number in the presence of AGB but the mechanisms causing this decrease are poorly understood. Experiments were designed to examine how the individual AGB caused decay of the viruses. In this study AGB were isolated and tested for their ability in increase the decay of the viruses. It was determined that 27 % (17/63) of the isolated AGB influenced viral decay. The AGB isolates varied in their influence with only 3 out of 17 isolates being able to cause of the decay of both poliovirus and coxsackievirus. Similar variations in decay were observed for adenovirus. Decay times for all three viruses varied amongst the AGB and between the viruses. Experiments were undertaken to characterise the mechanism causing the antiviral activity of four groundwater isolates (1G, 3A, 4B and 9G) under varying conditions and treatments to give insight into the compounds or mechanisms responsible for viral decay. This would indicate whether compounds produced by the AGB responsible for viral decay were closely associated to bacterial cells (perhaps membrane bound), independent of metabolic activity, heat labile or were enzymatic in nature. The influence of enzyme inhibiters and heat treatment indicated that viral degradation is caused by compounds that are enzymatic in nature. As viral numbers were monitored by nucleic acid copy numbers rather than via infectivity assays, the viral protein coats must be the first step in degradation followed by the removal of the viral nucleic acid. This two step process would require both protease and nuclease enzymes to result in loss of viral numbers as measured by RT-PCR/PCR. Further characterisation and identification of these four bacterial isolates was also carried out. Three out of the four isolates were sequenced and analysed using partial 16S rRNA gene sequences to determine their phylogenetic relationships compared to related organisms. Isolate 3A was placed in the order Burkholderiales. Isolate 4B was placed in the family Xanthomonadaceae. Isolate 9G was placed in the family Rhizobiaceae. Isolate 1G was only partially sequenced and preliminary identification placed it in the phylum Bacteriodetes. Understanding of the processes carried out by AGB within an aquifer during MAR using reclaimed waters will aid in increasing the viability of this water reuse process. If important natural processes could be utilised to remediate any potential pathogens, the health concerns with reclaimed waters could be addressed and solved simply through prescribed retention times within the aquifer. Key species of AGB may even be utilised as markers to assess the suitability of an aquifer for MAR.