Theses (Physics and Astronomy)

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An odyssey in exploring nuclei: High-precision mass measurements of exotic tin isotopes and progress toward implementing a phase-based measurement technique
(2024) Czihaly, Annabelle Isabella; Kwiatkowski, A. A.; Lefebvre, Michel
Precision mass measurements are integral in advancing our understanding of nuclear physics. Since mass is a fundamental property of nuclei. TRIUMF’s Ion Trap for Atomic and Nuclear science (TITAN) facility houses two high-precision mass spectrometers designed for mass measurements of radioactive isotopes: a Multiple-Reflection Time-of-Flight Mass Spectrometer (MR-TOF MS) and a Measurement Penning Trap (MPET). This thesis presents the results from a MR-TOF MS campaign focused on the measurement of doubly magic 100Sn where we successfully measured isotopes with mass numbers 104 through 107 to a precision of δm/m ≈ 10−7. Additionally, the most precise TITAN trap, MPET, is undergoing a major upgrade aimed at achieving precisions below δm/m ≈ 10−10. As part of this upgrade, a new phase-based measurement technique called Phase-Imaging Ion-Cyclotron-Resonance (PI-ICR) is being implemented. To support this implementation, the Phase-Imaging Analysis Tool (PhIAT) was upgraded to assist in system tuning and to perform mass measurements with PI-ICR.
Searching for long-lived supersymmetric particles using displaced vertices and missing transverse energy with the ATLAS detector
(2024) Carlson, Evan Michael; Trigger, Isabel; Kowalewski, Robert V.
The Standard Model of particle physics has been extremely successful in its predictive power and has withstood a wide array of precision tests designed to expose any flaws in its description of fundamental particles. However, the Standard Model is unable to explain several phenomena observed in the universe, such as the nature of the dark matter which makes up more than 80% of the gravitationally interacting matter in the universe. Theories that extend the Standard Model with new fundamental particles have been postulated to address the questions left unanswered by the Standard Model. Many supersymmetric theories provide viable dark matter candidates. In order to more precisely test the Standard Model and its possible extensions, the ATLAS experiment at the Large Hadron Collider has been constructed to measure high energy proton-proton collisions. Long-lived particles (LLPs) are commonly predicted by extensions to the Standard Model. The decay of a LLP to charged particles within the ATLAS Inner Detector would produce tracks that are displaced from the interaction point, which could be reconstructed as a displaced vertex. This dissertation presents a search for displaced vertices with high invariant mass and high track multiplicity in events with significant missing transverse energy in the 2016-2018 data set collected by the ATLAS experiment. The observed number of events is consistent with the number expected from background processes. The results are interpreted in the context of a split-supersymmetry model with long-lived gluinos decaying to neutralinos and Standard Model quarks, and exclusion limits are set at 95% confidence level.
The search for young planets with JWST/NIRCam
(2024) Mullin, Camryn; Dong, Ruobing
As part of the James Webb Space Telescope (JWST) Guaranteed Time Observation (GTO) program “Direct Imaging of YSOs” (program ID 1179), I used JWST NIRCam’s direct imaging mode with filters F187N, F200W, F405N, and F410M to perform high contrast observations of the circumstellar structures surrounding the protostar HL Tau. The data reveal the known stellar envelope, outflow cavity, and streamers, but do not detect any companion candidates. I detect scattered light from an in-flowing spiral streamer previously detected in HCO+ by the Atacama Large Millimeter/submillimeter Array, and part of the structure connected to the c-shaped outflow cavity. For detection limits in planet mass, I use BEX evolutionary tracks when Mp < 2MJ and AMES-COND evolutionary tracks otherwise, assuming a planet age of 1 Myr (youngest available age). Inside the disk region, due to extended envelope emission, the point-source sensitivities are ∼5 mJy (37 MJ) at 40 au in F187N, and ∼0.37 mJy (5.2 MJ) at 140 au in F405N. Outside the disk region, the deepest limits I can reach are ∼0.01 mJy (0.75 MJ) at a projected separation of ∼525 au.
Development and demonstration of an on-detector technique to limit the impact of atmospheric emission lines on near-infrared spectra
(2024) Grosson, Theodore; McConnachie, Alan; Venn, Kimberley Ann
Observations in the near-infrared using large ground-based telescopes are limited by bright atmospheric emission lines, particularly the OH Meinel bands. These lines can saturate a spectrograph on the order of minutes, resulting in the loss of information at wavelengths containing the lines. OH lines also vary on the scale of minutes, so observations longer than this timescale cannot capture this variability. Both of these properties necessitate the use of short exposure times in order to perform accurate sky subtraction. To observe faint science targets, several short exposures must be coadded instead of taking a single long exposure. Because each exposure includes its own independent read noise, this results in an increase in the total noise of the coadded image. In this thesis I present a new method to achieve longer exposure times in near-infrared spectra without the saturation of these lines, while still preserving information about their variability so that sky subtraction can still be applied. This is accomplished by periodically resetting the pixels on an H2RG detector that contain bright lines while the rest of the detector continues integrating. This method is demonstrated on the McKellar Spectrograph, where we reset the emission lines from an arc lamp while still recording their flux. I show that, when comparing the resulting spectrum and its signal-to-noise to a more conventional observing mode, the only measurable systematic difference is a result of our imperfect setup and can be removed with a standard nonlinearity correction. This method does not have the drawbacks of other measures to mitigate the effects of OH lines, such as short exposure times or completely removing the information at the relevant wavelengths, and as such shows promise for potential future use at observatories. We advocate demonstrating this method on sky spectra at existing high-quality facilities in order to test its feasibility for use in sky subtraction schemes for premier modern spectrographs.
Deep learning-enabled studies of galaxy mergers and supermassive black hole evolution
(2024) Bickley, Robert W.; Ellison, Sara L.
When the smooth evolution of an isolated galaxy is punctuated by a merger event with a companion of similar mass, theory and observations indicate that a metamorphosis will begin. Dramatic changes in the morphologies and kinematics of merging galaxies are thought to funnel gas towards their centres, leading to elevated star formation rates and supermassive black hole (SMBH) accretion rates. The transformation brought about by mergers appears to be the missing link between the two main types of galaxies – blue star-forming spiral galaxies, and red quiescent elliptical galaxies – observed in the Universe. Simulations predict that galaxies are experiencing the most rapid changes immediately after coalescence (when the merging companions are no longer distinct objects), but observational samples of post-merger galaxies predating this work are generally incomplete (small, and possibly not representative of the post-merger class) or contaminated. In this work, I present the methodological details of an updated post-merger identification effort using a simulation-trained convolutional neural network (CNN a type of automated machine vision tool) to flag galaxies that are very likely to be post-mergers. I present a proof-of-concept feasibility study using mock observations of simulated galaxies (Chapter 2) before applying the CNN to classify real images of galaxies in the low-redshift Universe (Chapter 3). The CNN classification effort is followed by a manual quality control exercise, which finally leads to the identification of large (with some 100s of galaxies each), pure, and defensible post-merger samples from two different imaging surveys: the Canada France Imaging Survey (CFIS), and the Dark Energy Camera Legacy Survey (DECaLS). With the post-merger samples in hand, I also present on the demographics and evolutionary characteristics of post-merger galaxies using multiple astronomical surveys for multi-wavelength characterization. I find that star-forming post-mergers are elevated by a factor of ∼ 2 in their star formation rates relative to star-forming non-merger galaxies (Chapter 4). I also find that active galactic nuclei (AGN; the observable phenomena associated with SMBH accretion) are more common by a factor of 2–4 in post-mergers compared to non-mergers, and that those AGN appear to be about twice as luminous as AGN in non-mergers (Chapter 5). Finally, I use new X-ray observations from the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) space mission to verify that AGN are unusually common in post-mergers, and to characterize the strength of the connection between mergers, SMBH, and AGN obscuration (Chapter 6). In each result, I also compare the characteristics of the new post-merger samples to statistically identified groups of galaxy pairs that are presumed pre-mergers. Close galaxy pairs are somewhat more likely to experience elevated star formation, SMBH accretion, and obscuration than their isolated peers, but the results for galaxy pairs are generally weaker than for post-mergers. Together, the results of my studies indicate that the amplitude of transformation seen in post- mergers is unique in the low-redshift Universe. Looking forward, I project the viability of future astronomical surveys for post-merger identification, and find something rather unexpected: while next-generation observatories will offer an opportunity for marginal improvement in identifying the remnants of major galaxy mergers, imaging that is already available (CFIS, DECaLS) is well suited to the task (Chapter 7). I therefore posit that the present generation of astronomers studying galaxy mergers can use forthcoming surveys like Euclid and the Legacy Survey of Space and Time (LSST) to answer more difficult and granular questions about the impact of mergers on galaxy evolution.
Dosimetry and radiobiology of ultrahigh dose-rate radiotherapy delivered with low-energy x-rays and very high-energy electrons
(2024) Hart, Alexander; Bazalova-Carter, Magdalena
Radiotherapy is a powerful tool in oncology, from curative treatments to pain relief in palliative care. However, the efficacy of radiotherapy is limited by side effects caused by damage to healthy tissues. Ultrahigh dose-rate radiotherapy (UHDR-RT) has emerged as a possible method of reducing damage to normal tissues while maintaining the ability to control the progression of cancer. UHDR treatments are delivered three orders of magnitude faster than conventional dose-rate radiotherapy (CDR-RT). To reach the dose rates associated with UHDR-RT, novel radiation sources have been developed, spanning a wide range of radiation types, energies, and time structures of delivery. These include kilovoltage x-rays produced by a shutter-controlled x-ray tube, and very high energy electrons (VHEE) accelerated to 200 MeV at high energy physics laboratories. Testing the capability of these sources requires specialized dosimeters and radiobiological models which are not commonly used in traditional radiotherapy. In this work, plastic scintillation detectors (PSDs) of various compositions were used to measure dose from both 120 kVp x-rays and 200 MeV electrons. Experiments with the shutter-controlled x-ray tube demonstrated that lead-doped polystyrene PSDs can be used as accurate dosimeters for dose-rates of up to 40.1 Gy/s and for pulse widths of 1 - 100 ms. At the CERN linear electron accelerator for research (CLEAR) the ability of PSDs to respond linearly with dose and independent of dose rate with 200 MeV electrons was assessed as well as the radiation hardness of the probes. Polystyrene-based PSDs maintained linear light output with dose up to 125.2 Gy per pulse. After receiving tens of kGy within one day, PSDs showed reduced light output. However, they exhibited dose-dependent recovery, and maintained linearity of output with dose per pulse. To explore the radiobiological effects of the same radiation sources, Drosophila melanogaster were irradiated as larvae and were monitored for effects on their development. It was shown that UHDR 120 kVp x-rays are capable of reducing normal tissue damage in flies compared to CDR treatments. At 22 Gy, the UHDR irradiated flies had a longer median lifespan, while at 24 Gy they survived to adulthood at higher rates than the corresponding CDR groups. Irradiations of D. melanogaster with 200 MeV and 9-20 MeV over a range of doses from 10 - 45 Gy at both UHDR and CDR were also performed. The dose response curves allowed for an in vivo determination of the relative biological effectiveness (RBE) of VHEE beams, cal- culated to be between 0.97 and 1.01. This work establishes that PSDs and D. melanogaster are useful platforms for characterizing the physical and radiobiological properties of novel UHDR-RT sources.
An examination of the use of the chemotherapy drug doxorubicin, gold nanoparticles, and radiation in combined cancer therapy
(2024) Eaton, Sarah; Chithrani, Devika
The chemotherapy drug doxorubicin (DOX) is a widespread and effective treatment for many different types of cancer. However, it is known for causing significant and dangerous side effects due to high cardiotoxicity. Gold nanoparticles (GNPs) are a promising field of nanomedicine due to their stability, customizability, and radiosensitization properties as demonstrated using in vitro and mice models. They accumulate preferentially in tumours due to the enhanced permeability and retention effect. The combination of GNP mediated radiotherapy and DOX has the potential to deliver highly targeted and effective therapeutics while sparing surrounding healthy tissue. This work used GNPs conjugated with PEG and RGD, DOX, and radiotherapy in combination to investigate possible synergistic cancer therapeutics. MDA-MB-231 cells were dosed for 48 hours with GNPs at a clinically relevant concentration of 7.5 μg/mL. DOX was dosed at the measured IC50 concentration of 144.4 nM for a 48 hour exposure. Radiation doses of 2 Gy and 5 Gy were used, as 2 Gy is commonly used for fractionated radiotherapy and recent clinical trials have also shown 5 Gy to be an effective fractionated radiation dose. A cytotoxicity assay was conducted to determine the IC50 of DOX which was used as the dosing concentration for all other assays. Live cell images were taken to demonstrate the internalization of DOX and GNPs in the cells. To quantify if DOX affected the uptake of GNPs into the cells, a cellular uptake study was conducted. As previous research has indicated that DOX causes cell cycle arrest, a cell cycle assay was conducted. To assess the cytotoxicity and radiosensitization properties of GNPs and DOX, a cellular proliferation study and a clonogenic assay were conducted. Additionally, a DNA double strand break assay was conducted to assess the amount of DNA damage caused. The cellular uptake study revealed that DOX caused an increase in GNP uptake, with (1.27±0.16)×10^6 GNPs per cell when treated with DOX, and (0.76±0.05)×10^6 GNPs per cell when untreated. DOX showed evidence of radiosensitization in the proliferation assay with the combination of DOX and radiation causing a (54±2)% reduction in cell growth when 2 Gy was administered, and a (69±8)% reduction in cell growth when 5 Gy was administered. However, this effect was not synergistic. In the other assays conducted, DOX caused cell cycle arrest, extensive DNA damage, and no clonogenic growth. It was concluded that DOX was inducing senescence at the given dose. GNPs showed some radiosensitization in the proliferation assay at 2 Gy, with (24±2)% reduction in growth after 3 days in the 2 Gy GNP sampled compared to (15±2)% reduction in growth in the 2 Gy control sample. No other significant differences in growth due to GNPs were seen in the proliferation assay. The clonogenic assay showed that 2 Gy radiation caused a (67±5)% decrease and 5 Gy caused a (97.9±0.6)% decrease in clonogenic survival of cells treated with radiation only when compared to the unirradiated control. The GNP incubated sample demonstrated some radiosensitivity in the clonogenic assay as it had a (78±3)% lower surviving fraction when irradiated with 2 Gy then the unirradiated control. The GNPs also showed toxicity in the unirradiated sample, with (30±11)% lower surviving fraction than the control in the clonogenic assay. A Bliss independence test found the GNPs and 2 Gy radiation to have independent effects. There was no significant difference between the GNP and control cells in the clonogenic assay when irradiated with 5 Gy. The DNA double strand break assay showed that 2 Gy radiation caused an increase in DNA damage foci from 2.0±0.2 to 5.1±0.5 foci per cell. No significant difference in foci was seen between the control and the GNP incubated cells. While the results from this work did not demonstrate a conclusive benefit from the combined therapy of doxorubicin, GNPs, and radiation, the system is still of interest. Future experiments could be performed using a reduced doxorubicin concentration such as the IC20, to reduce the toxicity while still causing an effect. If a synergistic effect can be observed, it could be exploited to significantly reduce normal tissue toxicity in cancer patients while still delivering a lethal dose of chemotherapy and radiotherapy to the tumour.
Expedition unknown: Characterizing and modelling perturbed debris disks in search for elusive planets
(2024) Crotts, Katie; Matthews, Brenda C.; Dong, Ruobing
Debris disks, which are defined as optically thin, dusty disks around main sequence stars, are intimately connected with planets in their systems. Not only does the mere existence of a debris disk suggest the presence of planets, as they efficiently stir the orbits of planetesimals leading to collisional evolution, but they can also easily shape the morphologies of their disk. To better understand planet-disk interactions, one crucial step is to uncover the variation in disk morphologies that are present in currently resolved disks. Further studies can then be done to understand how these disk morphologies are related to known or unknown planets. In my thesis, I conducted a uniform, empirical analysis of 23 debris disks imaged with the Gemini Planet Imager (GPI) in polarized intensity. For this study, I characterized each disk through multi-wavelength, near-IR data to identify any asymmetries present. I find that the majority of disks (19/23) present a significant asymmetry in either geometry, surface brightness, disk color, or a combination of the three. These findings suggest that perturbations in our sample, as seen in scattered light, are common. Some of these perturbations are consistent with planet-disk interactions, including surface brightness asymmetries, eccentric disks, and warps. Additionally, I identified several possible trends between disk properties and stellar properties that may give further insight into debris disk evolution. This includes a trend between disk color and stellar temperature, and trends between the disk vertical aspect ratio and stellar temperature in tandem with the disk radius. Within the GPI disk sample, I identify one of the most asymmetric disks, HD 111520. In another empirical analysis, I take a closer look at the HD 111520 debris disk to better understand its complex morphology. Using both polarized and total intensity multi-wavelength GPI observations, alongside observations taken with the Hubble Space Telescope (HST), I confirm that the disk hosts a variety of asymmetrical features and structures. This includes the strong 2 to 1 brightness asymmetry observed in previous studies, as well as a significant disk color asymmetry, a distinct 4 degree warp from the disk midplane past ∼180 au, and a bifurcation or “fork”-like structure on the NW side. While the color asymmetry and extreme brightness asymmetry suggests that the disk may have undergone a recent giant collision, the warp and fork structures strongly suggests the presence of an unseen planet. Once these complex disk structures/features are identified, the disk morphology can effectively be used to probe unseen planets. In the final part of my thesis, I used the n-body code REBOUND to simulate the features of the highly asymmetrical disk around HD 111520 via planet-disk interactions. I find that a planet with a mass of ~1 Mjup, that is on an eccentric and inclined orbit outside of the warp location, can create a similar radial asymmetry, warp, and “fork”-like structure in the disk as seen in observations. This work demonstrates how disk morphologies can be used to constrain the mass and orbit of a hidden planet in a perturbed debris disk system.
Evaluation of an acoustic Doppler profiler with application to stratified flow in a fjord
(1985) Zedel, Leonard James
In this thesis, the incoherent Doppler profiling technique for remote current measurement in the ocean is evaluated. The fundamentals of Doppler profiling are analyzed in detail and the practical application of the technique is discussed. The single beam Institute of Ocean Sciences (IOS) prototype Doppler profiler is investigated, both with theoretical models of its signal processing circuit and with laboratory and field tests of its operational characteristics. Some time series analysis techniques useful in evaluating the Doppler signal are discussed. The performance of three mean frequency estimators are compared: it is found that the complex covariance method and the scalar phase change method produced accurate estimates, but the vector phase change method yields standard deviations 1.4 times higher than the other methods. The standard deviation of the complex covariance method is shown to depend on the choice of time lag. In agreement with a previous theoretical study (Miller and Rochwarger 1972), it is found that the use of small time lags does not provide the smallest standard deviations. Several data averaging schemes are compared, and, based on the results of this comparison an acceptable scheme for use in coastal waters is selected. As an example of the application of the Doppler profiler, tidal flows occurring over Observatory Inlet sill are investigated. The observations demonstrate the detail with which such a flow can be studied using acoustic remote sensing techniques. The observations are compared to a time-dependent, layered hydraulic model of flow over a sill. The agreement between flow simulated by the model and the Doppler observations indicates that the hydraulic analysis of such a flow accounts for many of the observed characteristics. This comparison serves to illustrate the value of the Doppler measurement approach in highly variable flows.
Structure beneath Queen Charlotte Sound from seismic refraction and gravity interpretations
(1990) Yuan, Tianson
The Queen Charlotte Islands region is located on the Canadian western margin near the triple junction between the Juan de Fuca ridge system, the Cascadia subduction zone, and the Queen Charlotte transform fault. The evolution and interactions of the continental and oceanic plates have played an important role in the structural development of the region. A combined multichannel seismic reflection and refraction survey was carried out in July 1988 to study the Tertiary sedimentary basin architecture and formation, and to define the crustal structure and associated plate interactions in the region. Simultaneously with the collection of the multi-channel reflection data, refractions and wide-angle reflections from airgun array shots were recorded on single channel seismographs distributed on land around Hecate Strait and Queen Charlotte Sound. For this thesis a subset of the resulting data set was chosen to study the crustal structure in Queen Charlotte Sound and the adjacent subduction zone. Two-dimensional raytracing and synthetic seismogram modelling produced a well constrained velocity structure model across Queen Charlotte Sound. Moho depth is modelled at 27 km off southern Moresby Island but only 23 km north of Vancouver Island. Excluding the approximately 3 km of the Tertiary sediments, the crust in the latter area is less than 20 km thick, indicating substantial crustal thinning in Queen Charlotte Sound. Such thinning of the crust suggests an extensional mechanism for the origin of the sedimentary basin. On a margin-parallel line, in the southern portion of Queen Charlotte Sound a mid-crustal event with apparent velocity of more than 7.2 km/s was modelled as a high velocity sliver at a depth of about 17 km. On an unreversed refraction line normal to the continental margin, an upper crust layer with velocity more than 7 km/s also was interpreted at depths above about 13 km. The interpretation of these high velocity layers is uncertain, but they could represent high velocity material imbedded in the crust from earlier subduction episodes or mafic underplating associated with the Masset volcanics. Refraction velocities of both sediment and upper crust layers are lower in the southern part of Queen Charlotte Sound than in the region near Moresby Island. Well velocity logs and multichannel reflection velocity analyses indicate a similar velocity contrast. Gravity models along the reflection line require lower sediment and upper crust densities, consistent with the crustal thinning implied by refraction data. The low velocity/low density sediments correspond to high porosity marine sediments found in wells in the southern part of the region, and contrast with lower porosity non-marine sediments in wells further north. The contrast in upper crust velocity and density from north to south can be explained if the Mesozoic or Tertiary volcanics that appear to floor the basin are underlain by thick and dense volcanic sequences in the north, and by a predominantly sedimentary sequence in the south.
Radiative muon capture and the pseudoscalar coupling constant
(1992) Welsh, Mark S.
Radiative and ordinary muon capture rates are studied in medium-heavy nuclei, with all relativistic effects considered. To model the nucleus, a Fermi gas of nucleons acting under mean scalar and vector fields is considered. The calculation is performed first for a uniform density nucleus and then, using the local density approximation, for a more realistic nuclear density distribution obtained from electron scattering data. These calculated rates a.re compared with experimental data, the goal being to extract a value for the induced pseudoscalar coupling constant of the weak nucleonic interaction.
Curve-of-growth analyses of Arcturus and 31 Cygni A
(1971) Vanden Berg, Don Allan
Radiation reaction and classical models of the electron
(1988) Vollick, Daniel Nelson
In this thesis the classical theories concerning the structure and self interaction of the electron are examined. The infamous 1 problem in the transformation of the electromagnetic field momentum is discussed and elucidated in chapter two. The Lorentz-Dirac equation and its non relativistic limit, the Abraham-Lorentz equation, are examined in chapters three and four. Phenomena such as runaway solutions and preacceleration are shown to be related to an unexpected form of internal energy which is known as the Schott energy. It is then shown that this Schott energy is part of the bound electromagnetic energy. Both mass renormalization and the renormalization of the energy momentum tensor are discussed in chapter four. Other possible equations of motion for point particles are looked at in chapter five. In this chapter the exact equation of motion for an extended charge distribution is examined and it is found that for a spherical shell of charge both preacceleration and runaway solutions are absent if the radius of the shell is greater than its classical radius. It is also found that if the radius of the shell is smaller than this radius preacceleration and runaway solutions are present. In chapter six, general relativistic electron models are discussed. The remainder of the thesis deals with classical models which are based on modifications of either Maxwell's or Einstein's theory.
A measurement of the [equation] branching ratio using the opal detector at LEP
(1993) Towers, Sherry Meleah Jean
Radiative tail for the process pp - [pi+d] near threshold
(1973) Tanaka, Seiichi
A calculation of the radiative tail for the process proton + proton → pion + deuteron (pp → πd) is presented. A soft-photon technique is applied in which the radiative amplitude is expressed in terms of the elastic amplitude. Numerical calculations are carried out for incident proton energies of 300 - 400 MeV and pion angles of 1°, 20° and 40°. These values are relevant to proposed experiments which will examine the process proton + proton → pion + neutron + proton with very high resolution. This process might be smeared out by the radiative tail of the reaction proton + proton → pion + deuteron ( pp → πd), and therefore it is important to estimate the contribution from the radiative tail to the pion spectrum. It is found that the radiative tail is very small at the experimental parameters of interest, and therefore one need not worry about this contamination when performing the experiments.
A computer program for beam transport calculations
(1968) Tautz, Maurice Francis
A computer program TRIUMF for the solution of beam transport problems is described. This program tracks, to first order, particle trajectories and phase space ellipses through any combination of up to 30 drift spaces, quadrupole magnets, and constant field bending magnets with rotated pole faces. Particle trajectories or the beam envelope may be plotted for points every 20 cm. along the optic axis. The phase space ellipse at the exit of any beam element may also be plotted. The program does trajectory matching and ellipse matching to a waist or to a specified ellipse. It will also attempt to create an 'identity system'. The matching routines are based on a method for finding the minimum of a function of N variables without calculating first derivatives due to Powell. The program has been written in Fortran II and will run without modification on the IBM/360 digital computer.
19F NMR investigation of CF3 motion in solid zinc trifluoromethylsulfonate
(1987) Sun, Jiankang
Electromagnetic induction in a stratified conducting half-space
(1971) Summers, David McNeil
A luminosity classification of northern Sb galaxies
(1977) Stenning, Mark Cheveley
The DDO system of luminosity classification has been applied to 670 Sb galaxies listed in the Uppsala General Catalogue. UGC diameter and magnitude information, which was found to correlate well with similar information in the Second Reference Catalogue of Bright Galaxies, was corrected for absorption effects in accordance with methods outlined in the RCBG2. These modified data were then used to examine the luminosity function and velocity-magnitude-diameter relationships. Absolute magnitude calibration was accomplished using recent estimates of the distance moduli of M31 and M81. Magnitude-diameter relationships were found to agree well with both theoretical and other observational results; in particular, the absolute luminosity-diameter relation L = D².⁶⁷±.¹⁴ was obtained. The luminosity function for Sb galaxies , based on a total spatial density of 3.5 x 10⁻³ Mpc⁻³, increases exponentially from the supergiant to the normal giant class beyond which it abruptly terminates, although some evidence for a fainter (III+) class is discussed. The Malmquist effect was prominent on the initial Hubble diagrams and when it was accounted for following the precepts of Sandage and Tammann, a value of H =70km sec⁻¹ Mpc⁻¹ was obtained. The Malmquist effect was then rediscussed in terms of an implication of the luminosity function and a Malmquist correction based on individual class absolute magnitude-diameter relationships was made. The revised Hubble diagrams showed little dispersion and had slopes consistent with the theoretical value over the velocity range of the data (Vₒ≤ 10⁴km s⁻¹). From the revised Sb I-II diagram a Hubble constant of 95(+18,-14) was obtained. Supportive evidence was found f or the Rubin-Ford effect although the present study lacks the southern galaxies necessary to make a rigourous investigation of this phenomenon. Finally, luminosity classifications were used to help ascertain group and pair memberships.
Analysis of the 1978 Brooks Peninsula, Vancouver Island earthquakes
(1991) Spindler, Christopher William Leonard
Two earthquakes occurred on the Brooks Peninsula on June 2nd and July 25th, 1978. They were the largest events to have been recorded in the region. Both were followed by extensive aftershock sequences and a field program was mounted to monitor part of the first sequence. Using the field program data for reference, the main shock epicentres were relocated and the teleseismic and regional location biases identified. The main shock epicentres were coincident within location uncertainties and located on the NW shore of the peninsula at a depth of between 10 and 20 km. Teleseismic epicentre solutions, using the Jeffreys Bullen model and all available data, misplaced the epicentres to the NE by 12 km. This was corrected by using only data from Delta greater or equal to 20°. The regional bias was on the order of 4-6 km to the east or west, depending on whether the Canadian Shield or Georgia Straits model was being used. The focal mechanisms, determined using a combination of first-motion and surface wave data, were found to be essentially identical. The preferred fault plane displayed sinistral, normal strike-slip faulting along a NE striking fault, dipping 30°-45° northwest. The other plane displayed dextral motion on a steeply dipping, north striking fault. There was no strong evidence to favour either plane as the fault plane. The pressure axes of the mechanisms were oriented NE-SW, consistent with present convergence vector of the Explorer plate with North America. Using the surface wave data, the seismic moments were found to be 1. 60 X 10^24 dyne·cm for June and 1.19 X 10^24 dyne·cm for July. The surface wave magnitudes were redetermined using additional data (June: 5.2, July 5.1) and agreed with the I.S.C. values. The stress drops were calculated from the far field displacement spectra and averaged 16 bars for both events. The rupture surface radii for June and July were found to be 3.5 km and 3.2 km respectively. Other earthquakes in the Brooks Peninsula region, spanning the period from 1978 to 1987, were relocated using the corrections developed from the aftershock data. The events were found to be concentrated off the NW shore of the peninsula and not spread over the entire region, as the original G.S.C. data indicated. The orientations of the pressure axes of the focal mechanisms suggest that the Brooks Peninsula earthquakes are directly related to the relative motions of the Explorer and North American plates. If this is also true of the regional seismicity, then the data imply that there is coupling between between the plates in the region, possibly due to the subsidence of the peninsula. The placement of the events in the overlying plate further implies that the plates are locked at the interface and that the stress across the interface has been transmitted into the interior of that plate. The relatively low stress drops indicate that the earthquakes did not take place on a new or well cemented fault and that motion on this fault is not uncommon.

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