Physics Commons^™

Gain Of A Single Gas Electron Multiplier, Mythra Varun Nemallapudi

Graduate Theses and Dissertations

Gas Electron Multiplier (GEM) is a gaseous detector used in particle detection and is

known for its high rate capability. Ever since its invention in 1997, GEM was applied in

many areas and recently has been proposed to be installed in the CMS high η regions for

upgrade at LHC, CERN. A complete understanding of the working and gain behaviour does

not exist. GEM gain is influenced by charging up and this has been variedly interpreted

in literature lacking consensus. I have attempted in this work through simulations and

measurements to achieve a better understanding of single GEM gain and …

Development Of A Pyrotechnic Shock Simulation Apparatus For Spacecraft Applications, Joseph Binder, Matthew Mccarty, Chris Rasmussen

Aerospace Engineering

This report details the research, design, construction, and testing of a pyrotechnic shock simulation apparatus for spacecraft applications. The apparatus was developed to be used in the Space Environments Lab at California Polytechnic State University. It will be used for testing spacecraft components with dimensions up to 24”x12”x12” as well as CubeSats. Additionally, it may be used as an instructional or demonstrational tool in the Aerospace Department’s space environments course. The apparatus functions by way of mechanical impact of an approximately 20 lb stainless steel swinging hammer. Tests were performed to verify the simulator’s functionality. Suggestions for improvement and further …

Point-Spread Function Assessment Of Sg-Dbr Based Swept Source For Oct Imaging, David Wilkey Gilbert

Master's Theses

Swept Source Optical Coherence Tomography (SS-OCT) is a medical imaging technique that requires high repetition rate, widely-tunable coherent laser sources. Sampled grating distributed Bragg reflector (SG-DBR) lasers are proven in telecom applications and are expected to fulfill the requirements for SS-OCT at a significantly lower cost than alternative solutions.

Constructed entirely on a semiconductor substrate, SG-DBR lasers require four synchronized waveforms to modulate the output wavelength and intensity. Because of this unique tuning mechanism, there are a number of systematic and noise sources that can affect the quality of the OCT point-spread function (PSF). Based on these noise sources, software …

Parallel Diffusion-Limited Aggregation, H Kaufman, A Vespignani, B B. Mandelbrot, L Woog

Alessandro Vespignani

We present methods for simulating very large diffusion-limited aggregation (DLA) clusters using parallel processing (PDLA). With our techniques, we have been able to simulate clusters of up to 130 million particles. The time required for generating a 100 million particle PDLA is approximately 13 h. The fractal behavior of these ''parallel'' clusters changes from a multiparticle aggregation dynamics to the usual DLA dynamics. The transition is described by simple scaling assumptions that define a characteristic cluster size separating the two dynamical regimes. We also use DLA clusters as seeds for parallel processing. In this case, the transient regime disappears and …

Simulation Chamber For Space Environment Survivability Testing, Lisa Montierth, Robert H. Johnson, John R. Dennison, James Dyer

All Physics Faculty Presentations

A vacuum chamber was designed and built that simulates the space environment making possible the testing of material modification due to exposure of solar radiation. Critical environmental components required include an ultra high vacuum (10-9 Torr), a UV/VIS/NIR solar spectrum source, an electron gun and charge plasma, temperature extremes, and long exposure duration. To simulate the solar spectrum, a solar simulator was attached to the chamber with a range of 200nm to 2000nm. The exposure time can be accelerated by scaling the solar intensity up to four suns. A Krypton lamp imitates the 120 nm ultraviolet hydrogen Lymann alpha emission …

The Inexorable Resistance Of Inertia Determines The Initial Regime Of Drop Coalescence, Joseph Paulsen, Justin C. Burton, Sidney R. Nagel, Santosh Appathurai, Michael T. Harris, Osman A. Basaran

Physics - All Scholarship

Drop coalescence is central to diverse processes involving dispersions of drops in industrial, engineering, and scientific realms. During coalescence, two drops first touch and then merge as the liquid neck connecting them grows from initially microscopic scales to a size comparable to the drop diameters. The curvature of the interface is infinite at the point where the drops first make contact, and the flows that ensue as the two drops coalesce are intimately coupled to this singularity in the dynamics. Conventionally, this process has been thought to have just two dynamical regimes: a viscous and an inertial regime with a …

Simulation And Phases Of Macroscopic Particles In Vortex Flow, Heath Eric Rice

Electronic Theses and Dissertations

Granular materials are an interesting class of media in that they exhibit many disparate characteristics depending on conditions. The same set of particles may behave like a solid, liquid, gas, something in-between, or something completely unique depending on the conditions. Practically speaking, granular materials are used in many aspects of manufacturing, therefore any new information gleaned about them may help refine these techniques. For example, learning of a possible instability may help avoid it in practical application, saving machinery, money, and even personnel. To that end, we intend to simulate a granular medium under tornado-like vortex airflow by varying particle …

Small Scale Simulation Chamber For Space Environment Survivability Testing, Robert H. Johnson, Lisa D. Montierth, John R. Dennison, James S. Dyer, Ethan Lindstrom, Alex Chanson

All Physics Faculty Publications

A versatile vacuum system for long duration testing of materials modifications due to exposure to simulated space environment conditions has been designed and built. The chamber is particularly well suited for cost-effective tests of multiple small scale materials samples over prolonged exposure. Critical environmental components simulated include neutral gas [ultrahigh vacuum (10-7 Pa) to ambient], FUV/UV/VIS/NIR solar spectrum, electron plasma fluxes, and temperature. The UV/VIS/NIR solar spectrum is simulated using an external, normally incidence and collimated class AAA Solar Simulator source, with standard Air Mass Zero (AM0) filters to shape the incident radiation spectrum. This Xe arc discharge tube source …