|SULI Student||Mentor||Project Title||Project Description|
|Cole Adams||Travis Brooks||INSPIRE and SPIRES Log File Analysis||SPIRES, an aging high-energy physics publication data base, is in the process of being replaced by INSPIRE. In order to ease the transition from SPIRES to INSPIRE it is important to understand user behavior and the drivers for adoption. The goal of this project was to address some questions in regards to the presumed two-thirds of the users still using SPIRES. These questions are answered through analysis of the log files from both websites. A series of scripts were developed to collect and interpret the data contained in the log files. The common search patterns and usage comparisons are made between INSPIRE and SPIRES, and a method for detecting user frustration is presented. The analysis reveals a more even split than originally thought as well as the expected trend of user transition to INSPIRE.|
|Peter Bolgert||Yijin Liu||A Comparison of Image Quality Evaluation Techniques for Transmission X-Ray Microscopy||Beamline 6-2c at Stanford Synchrotron Radiation Lightsource (SSRL) is capable of Transmission X-ray Microscopy (TXM) at 30 nm resolution. Since typical data sets normally contain thousands of images, it is necessary to automate the image processing workflow as much as possible, particularly for the aligning and averaging of similar images. In our research we explored two image sharpness metrics, the variance method and the frequency threshold method. These metrics were tested on a variety of test images, containing both real and artificial noise. To apply these sharpness metrics, we designed and built a MATLAB graphical user interface (GUI) called “Blur Master.” We found that it is possible for blurry images to have a large variance if they contain high amounts of noise. On the other hand, we found the frequency method to be quite reliable, although it is necessary to manually choose suitable limits for the frequency band. Further research must be performed to design an algorithm which automatically selects these parameters.|
|Keaton Burns||Jeff Oishi||Investigating the Magnetorotational Instability with Dedalus, an Open-Source Hydrodynamics Code||The magnetorotational instability is a uid instability that causes the onset of turbulence in discs with poloidal magnetic fields. It is believed to be an important mechanism in the physics of accretion discs, namely in its ability to transport angular momentum outward. A similar instability arising in systems with a helical magnetic field may be easier to produce in laboratory experiments using liquid sodium, but the applicability of this phenomenon to astrophysical discs is unclear. To explore and compare the properties of these standard and helical magnetorotational instabilities (MRI and HRMI, respectively), magnetohydrody-namic (MHD) capabilities were added to Dedalus, an open-source hydrodynamics simulator. Dedalus is a Python-based pseudospectral code that uses external libraries and parallelization with the goal of achieving speeds competitive with codes implemented in lower-level languages. This paper will outline the MHD equations as implemented in Dedalus, the steps taken to improve the performance of the code, and the status of MRI investigations using Dedalus.|
|Julie Cass||Joe Frisch||Simulations and Analysis of an Infrared Prism Spectrometer for Ultra-short Bunch Length Diagnostics at the Linac Coherent Light Source||We require a means of determining the minimum achievable bunch length at the Linac Coherent Light Source (LCLS) at SLAC National Accelerator Laboratory. Current methods of measurement in the time domain do not have the resolution to measure ultra-short bunch lengths below 10 fs. An alternative method has been designed, using a single-shot near- to mid-infrared prism spectrometer for bunch length diagnosis in the frequency domain. This design requires the precision alignment of sensitive optical equipment and complete understanding of the spectrum reaching the spectrometer’s detector surface. This paper provides information on preliminary simulations designed to model beam behavior in the optical set-up and at the detector surface for comparison to measured values as an indication of the current achievable optical alignment and the study of optimal detector orientation. The results of these simulations indicate the necessity for a method of greater precision in optical alignment and further study of achievable spectrometer range.|
|Gilles Dongmo-Momo||Joe Frisch||Infrared Spectroscope for Electron Bunch-length Measurement: Heat Sensor parameters Analysis||The LCLS Linac Coherent Light Source (LCLS) is used for many experiments. Taking advantage of the free electron laser (FEL) process, scientists of various fields perform experiments of all kind. Some for example study protein folding; other experiments are more interested in the way electrons interact with the molecules before they are destroyed. These experiments among many others have very little information about the time profile of the electrons’ x-ray produced by the FEL, except that the FEL is using bunches less than 10 femtoseconds long. To be able to interpret the data collected from those experiments, more accurate information is needed about the electron bunch-length. Existing bunch length measurement techniques are not suitable for the measurement of such small time scales. Hence the need to design a device that will provide more precise information about the electron bunches. This project investigates the use of pyreoelectric heat sensor that has a sensitivity of about 1.34 micro amps per watt for the single cell detector. Such sensitivity, added to the fact that the detector is an array sensor, makes the detector studied the primary candidate to be integrated to an infrared spectrometer designed to better measure the LCLS’ electron bunch length.|
|Jennifer Felder||Chris Kenney||Design & Fabrication of a High-Voltage Photovoltaic Cell||Silicon photovoltaic (PV) cells are alternative energy sources that are important in sustainable power generation. Currently, applications of PV cells are limited by the low output voltage and somewhat low efficiency of such devices. In light of this fact, this project investigates the possibility of fabricating high-voltage PV cells on oat-zone silicon wafers having output voltages ranging from 50 V to 2000 V. Three designs with different geometries of diffusion layers were simulated and compared in terms of metal coverage, recombination, built-in potential, and conduction current density. One design was then chosen and optimized to be implemented in the final device design. The results of the simulation serve as a feasibility test for the design concept and provide supportive evidence of the effectiveness of silicon PV cells as high-voltage power supplies.|
|Ross Greenwood||Arafat Mokhtar Gabareen||Dark Photon Search at BABAR||Presented is the current progress of a search for the signature of a dark photon or new particle using the BaBar data set. We implement ROOT’s Toolkit for Multivariate Analysis (TMVA), a machine learning tool that allows us to evaluate the signal character of events based on many of discriminating variables. TMVA training is conducted with samples of Monte Carlo as signal and a small portion of Run 6 as background. The multivariate analysis produces additional cuts to separate signal and background. The signal efficiency and sensitivity are calculated. The analysis will move forward to fit the background and scan the residuals for the narrow resonance peak of a new particle.|
|Allison Hume||Marvin Weinstein & Apurva Mehta||Using Dynamic Quantum Clustering to Analyze Hierarchically Heterogeneous Samples on the Nanoscale||Dynamic Quantum Clustering (DQC) is an unsupervised, high visual data mining technique.DQC was tested as an analysis method for X-ray Absorption Near Edge Structure (XANES) data from the Transmission X-ray Microscopy (TXM) group. The TXM group images hierarchically heterogeneous materials with nanoscale resolution and large field of view. XANES data consists of energy spectra for each pixel of an image. It was determined that DQC successfully identifies structure in data of this type without prior knowledge of the components in the sample. Clusters and sub-clusters clearly reflected features of the spectra that identified chemical component, chemical environment, and density in the image. DQC can also be used in conjunction with the established data analysis technique, which does require knowledge of components present.|
|Forrest Iandola||Joseph Perl||Representing Range Compensators with Computational Geometry in TOPAS||In a proton therapy beamline, the range compensator modulates the beam energy, which subsequently controls the depth at which protons deposit energy. In this paper, we introduce two computational representations of range compensator. One of our compensator representations, which we refer to as a subtraction solid-based range compensator, precisely represents the compensator. Our other representation, the 3D hexagon-based range compensator, closely approximates the compensator geometry. We have implemented both of these compensator models in a proton therapy Monte Carlo simulation called TOPAS (Tool for Particle Simulation). In the future, we will present a detailed study of the accuracy and runtime performance trade-offs between our two range compensator representations.|
|Lisa Lee||Rolf Buehler||The Search for Gamma-Rays from Galaxy Clusters||These theories of gamma-ray production have been tested with gamma-ray telescopes, but as of now, no gamma-ray detection has been reported among galaxy clusters. This could be due to the energy range of gamma-rays studied thus far, specifically in the GeV energies. Although the Fermi Large Area Telescope (LAT) collects gamma-rays in the energy range of 20 MeV-300 GeV, the precision of the instrument is ideal above 200 MeV, which is why so far only energies above 200 MeV have been studied. However, new data-processing programs have been released which now allow lower energy ranges to be studied in greater accuracy. Thus, this study utilizes gamma-rays below MeV in hopes of detecting the anticipated gamma-ray emission from galaxy clusters. In search for these gamma-rays, we hope to also decipher the nature of the NT activity, as well as the emission and acceleration mechanisms of the energetic particles in the ICM.|
|Stephanie Mack||Uli Wienands||Channeling through Bent Crystals||Bent crystals have demonstrated potential for use in beam collimation. There are several different effects that are observed during channeling including dechanneling and feed-in mechanisms. Experiments have demonstrated channeling by varying the incident angle of a beam and detecting the deflection. As the crystal is rotated, the particle beam can enter the axial planes and channel through the bent crystal and be deflected by up to millirads.
Different codes and methods for calculations will be compared. The reliability of the results as compared to experiments and their relative accuracy will be examined. As well, the existing code may be modified to model electron beam channeling. The crystal parameters will then be optimized for a beam collimation experiment at the FACET facility at SLAC. The crystal would be placed within the accelerator on the side in order to intercept the halo electrons and redirect them to a target where they can be removed from propagating further. This research will allow optimizing the layout of an experiment, to be proposed for FACET in the fall.
|Daniel Marley||James Welch||Magnet Lattice Design for the Transmission of Power Using Particle Beams||As the amount of electricity generated by renewable energy sources continues to increase, the current method of power transmission will not serve as an adequate method for transmitting power over very long distances. A new method for transmitting power is proposed using particle beams in a storage ring. Particle beams offer an incredibly energy efficient alternative to transmission lines in transmitting power over very long distances. A thorough investigation of the magnet lattice design for this storage ring is presented. The design demonstrates the ability to design a ring with stable orbits over a 381.733 km circumference. Double bend achromats and FODO cells are implemented to achieve appropriate β functions and dispersion functions for 9-11 GeV electron beams.|
|Mitch Miller||Alan Fisher||Bunch Profiling Using a Rotating Mask||The current method for measuring profiles of proton bunches in accelerators is severely lacking. One must dedicate a great deal of time and expensive equipment to achieve meaningful results. A new method to complete this task uses a rotating mask with slots of three different orientations to collect this data. By scanning over the beam in three different directions, a complete profile for each bunch is built in just seconds, compared to the hours necessary for the previous method. This design was successfully tested using synchrotron radiation emitted by SPEAR3. The profile of the beam was measured in each of the three desired directions. Due to scheduled beam maintenance, only one set of data was completed and more are necessary to solve any remaining issues. The data collected was processed and all of the RMS sizes along the major and minor axes, as well as the tilt of the beam ellipse were measured.|
|Blythe Moreland||Risa Wechsler||Risa Wechsler||When is a dark matter halo “relaxed”? In our efforts to understand the structure of the universe, dark matter simulations have provided essential grounds for theoretical predictions. These simulations provide a wealth of ways of parameterizing and measuring the features of astronomical objects. It’s these measurements on which we base comparisons of our world and our attempts to re-create it. One of the essential questions dark matter simulations help address is how dark matter halos evolve. How does one characterize different states of that evolution? The focus o f this project is identifying cluster relaxedness and how it relates to the internal structure of the halo.|
|Ashley Parker||Debbie Bard||An Improved Technique for Increasing the Accuracy of Photometrically Determined Redshifts for ‘Blended’ Galaxies||The goal of this project is to utilize Sloan Digital Sky Survey’s (SDSS) data along with machine learning techniques to ultimately increase the reliability of photometric redshift analysis for “blended” galaxies. Currently in SDSS database, self-adjusting algorithms are used to determine photometric redshifts for all objects as a set, although none of these algorithms are optimized for galaxies. This summer research aims to separate “blended” from not “blended” galaxies, to determine if more accurate photometric redshift measurements will result from looking at only galaxy data and separating “blended” from not “blended.”|
|Chris Payne||Apurva Mehta||Characterizing the Nanoscale Layers of Tomorrow’s Electronics An Application of Fourier Analysis||Thin film applications are of great interest to the semiconductor industry due to the important role they play in cutting edge technology such as thin film solar cells. X-Ray Reflectivity (XRR) characterizes thin films in a non-destructive and efficient manner yet complications exist in extracting these characteristics from raw XRR data. This study developed and tested two different algorithms to extract quantity of layers and thickness information on the nanometer scale from XRR data. It was concluded that an algorithm involving a local averaging technique revealed this information clearly in Fourier space.|
|Veronica Policht||Johanna Nelson||Research and Design of a Sample Heater for Beam Line 6-2c Transmission X-ray Microscope||There exists a need for environmental control of samples to be imaged by the Transmission X-Ray Microscope (TXM) at the SSRLs Beam Line 6-2c. In order to observe heat-driven chemical or morphological changes that normally occur in situ, microscopes require an additional component that effectively heats a given sample without heating any of the microscope elements. The confinement of the heat and other concerns about the heaters integrity limit which type of heater is appropriate for the TXM. The bulk of this research project entails researching different heating methods used previously in microscopes, but also in other industrial applications, with the goal of determining the best-fitting method, and finally in designing a preliminary sample heater.|
|W. Clarke Smith||Tim Barklow||Extracting bb Higgs Decay Signals Using Multivariate Techniques||A Toroidal LHC ApparatuS (ATLAS), one of the six experiments at the Large Hadron Collider (LHC), is currently attempting to confirm the empirical existence of the Higgs mechanism by observing its scalar remnant: h0, the Higgs boson. Teams within ATLAS are attempting to do this by detecting the particles that characteristically result when these bosons decay.
In order to successfully detect the Higgs boson, we seek to exploit its intrinsic narrow mass width of several MeV. Theoretically, this will manifest itself as a sharp, narrow spike at mh in the bb-dijet mass (mbb) plot, allowing for the Higgs boson to be easily observed. However, reconstructing mbb from event information proves difficult due to the so-called `jet combinatorics problem,' that is, our inability to identify jets accurately. To solve this problem, there have been many mass-reconstruction algorithms developed to isolate such FSR-jets, but their inability leads to a reconstructed mbb plot with a dull, essentially nonexistent bump at mh. The goal of this project is to specifically construct an improved mh-reconstruction algorithm.
|Katherine Spoth||Dennis Nordlund||X-Ray Emission Spectrometer Design with Single-Shot Pump-Probe and Resonant Excitation Capabilities||Core-level spectroscopy in the soft X-ray regime is a powerful tool for the study of chemical bonding processes. The ultrafast, ultrabright X-ray pulses generated by the Linac Coherent Light Source (LCLS) allow these reactions to be studied in greater detail than ever before. In this study, we investigated a conceptual design of a spectrometer for the LCLS with imaging in the non-dispersive direction. This would allow single-shot collection of X-ray emission spectroscopy (XES) measurements with varying laser pump X-ray probe delay or a variation of incoming X-ray energy over the illuminated area of the sample. Ray-tracing simulations were used to demonstrate how the components of the spectrometer affect its performance, allowing a determination of the optimal final design. These simulations showed that the spectrometer's non-dispersive focusing is extremely sensitive to the size of the sample footprint; the spectrometer is not able to image a footprint width larger than one millimeter with the required resolution. This is compatible with a single shot scheme that maps out the laser pump X-ray probe delay in the non-dispersive direction as well as resonant XES applications at normal incidence. However, the current capabilities of the Soft X-Ray (SXR) beamline at the LCLS do not produce the required energy range in a small enough sample footprint, hindering the single shot resonant XES application at SXR for chemical dynamics studies at surfaces. If an upgraded or future beamline at LCLS is developed with lower monochromator energy dispersion the width can be made small enough at the required energy range to be imaged by this spectrometer design.|
|Colleen Treado||Cecile Limborg||Space Charge Correction on Emittance Measurement of Low Energy Electron Beams||The goal of any particle accelerator is to optimize the transport of a charged particle beam along a set path by confining the beam to a small region close to the design trajectory and directing it accurately along the beamline. To do so in the simplest fashion, accelerators use a system of magnets that exert approximately linear electromagnetic forces on the charged beam. These electromagnets bend the beam along the desired path, in the case of bending magnets, and constrain the beam to the desired area through alternating focusing and defocusing effects, in the case of quadrupole magnets. We can model the transport of such a beam through transfer matrices representing the actions of the various beamline elements. However, space charge effects, produced from self electric fields within the beam, defocus the beam and must be accounted for in the calculation of beam emittance. We present below the preliminary results of a MATLAB code built to model the transport of a charged particle beam through an accelerator and measure the emittance under the influence of space charge effects. We demonstrate the method of correctly calculating the emittance of a beam under space charge effects using a least square fit to determine the initial properties of the beam given the beam size measured at a specific point after transport.|
|Jack Wang||Jeff Corbett||Longitudinal Bunch Pattern Measurements through Single Photon Counting at SPEAR3||The SSRL is a synchrotron light source that provides x-rays for experimental use. As electrons are bent in the storage ring, they emit electromagnetic radiation. There are 372 different buckets which electrons can be loaded into. Different filling patterns produce different types of x-rays. What is the bunch pattern at a given time? Which filling pattern is better? Are there any flaws to the current injection system? These questions can be answered with this single photon counting experiment.|
|Kiel Williams||Joe Frisch||Optical Design of a Broadband Infrared Spectrometer for Bunch Length Measurement at the Linac Coherent Light Source||The electron pulses generated by the Linac Coherent Light Source at the SLAC National Accelerator Laboratory occur on the order of tens of femtoseconds and cannot be directly measured by conventional means. The length of the pulses can instead be reconstructed by measuring the spectrum of optical transition radiation emitted by the electrons as they move toward a conducting foil. Because the emitted radiation occurs in the mid-infrared from 0.6 to 30 microns a novel optical layout is required. Using a helium-neon laser with wavelength 633 nm, a series of gold-coated off-axis parabolic mirrors were positioned to direct a beam through a zinc selenide prism and to a focus at a CCD camera for imaging. Constructing this layout revealed a number of novel techniques for reducing the aberrations introduced into the system by the off—axis parabolic mirrors. The beam had a recorded radius of less than a millimeter at its final focus on the CCD imager. This preliminary setup serves as a model for the spectrometer that will ultimately measure the LCLS electron pulse duration.|