|MENTOR||STUDENT||2016 PROJECT (click on link to see abstract)|
|David Rubin||Trickle, Tanner Presentation Final Report||
Abstract: A Dark-Photon search with electron beam from Cornell's synchrotron has been proposed. It is aimed at detecting the possible existence of a massive gauge boson through invisible decays. Beam parameters of the synchrotron would allow a search for this particle where no other experiment has searched before. In order to make this a reality, the experiment needs to be able to slowly and uniformly extract positrons from the synchrotron, which can be done through third integer resonant extraction. This project will examine the Hamiltonian dynamics of a simplified extraction process to show how this resonant extraction can be set up for the synchrotron. BMAD will be used as simulation code.
|Jim Crittenden||San Soucie, John Presentation Final Report||
Abstract: The buildup of low-energy electron densities has been shown to limit the performance of storage rings such as the B-meson factories KEK-B in Japan and PEP-II at the SLAC National Laboratory. In 2008, the Cornell Electron Storage Ring (CESR) was reconfigured as a test accelerator in order to study cloud buildup. In 2013 we obtained the first-ever measurements of electron cloud trapping in a quadrupole magnet in a positron storage ring. It had long been surmised that cloud electrons may become trapped in the quadrupole field, but no measurements of the effect were available to validate modeling codes. Owing to its potential for imposing operational limitations on the SuperKEKB e+e- collider to be commissioned this year in Japan, as well as on the positron damping ring for the proposed International Linear Collider, plans are underway to install an additional quadrupole magnet and detector in the CESR ring to make possible an expanded measurement program. This REU project will concentrate on the continued analysis of the available data sets and on modeling the performance of the new detector design. Installation of the new detector is foreseen for the summer of 2016.
|James Maniscalco||Jeffas, Sean Presentation Final Report||
Abstract: Recent theoretical work suggests that a constant (DC) magnetic field applied to a superconducting RF surface can, under certain circumstances, lower the BCS surface resistance of the superconductor. In this project, the REU student will use RF simulation software and mechanical modeling software to design an SRF cavity to test this phenomenon. If the design process is successful, the cavity will be manufactured and the student will commence initial DC field testing
|Matthias Liepe, Dan Hall||Wikner, Alexander Presentation Final Report||
Abstract: The ultra-high frequency (UHF) surface impedance of superconductors strongly depends on temperature and also shows an unexpected, strong dependence on applied surface magnetic field. As part of this project, you will perform advanced data analysis of UHF performance data from pulsed and continuous measurements of niobium and Nb3Sn superconducting RF cavities. You will develop complex data fitting algorithms to reliably extract key material parameters and their field dependence. You will analyze sloppiness in the data fitting model used, and apply this information to further improve your data analysis routines.
|Dan Hall||Kline, Adam Presentation Final Report||
Abstract: Nb3Sn is an alternative superconductor that shows great potential to replace niobium in SRF cavities, allowing operation at temperatures and fields that would greatly reduce the size and maintenance cost of future accelerators. Cornell's Nb3Sn program stands solidly at the forefront of the development of this material, producing record-breaking SRF cavities that show highly promising RF performance. The emphasis of this project will be to better understand, and effectively simulate, the growth of the Nb3Sn film during the coating process. Techniques will include image processing of surface analysis data taken from samples and numerical simulations of the evaporation-deposition process. The outcome of this work will be used to alter the fabrication process of the cavities, with the aim of further improving their performance.
|Ralf Eichhorn||Parkes, James Presentation Final Report||
Abstract: Second sound is a property of helium cooled below the lambda point. It describes the propagation of an entropy/ temperature wave through the helium which is used in diagnosing quench location in superconducting cavity R&D. Second sound has quite some interesting features which are not yet well understood: for short distances, the wave seems to have a larger speed than expected and several theories exist on that. In this project, you will extensively study the physics of second sound, compare and eventually modify existing theoretical models. This will lead to designing and conducting an experiment to measure the second sound propagation systematically to confirm or falsify your model.
|Jacob Ruff||Akorede, Rufai Presentation Final Report||
Abstract: There is an ongoing technological revolution at synchrotron x-ray sources, driven by the advent of exquisite quality digital detectors based on crystalline silicon bump-bonded to ASIC hardware (Pilatus, MMPAD, Merlin, etc). These devices allow x-ray users to generate images with very high dynamic range, simultaneously resolving both weak and strong signals and drastically improving performance for a number of techniques. However, there is a fundamental limitation in using silicon-based technology with very "hard" (high-energy) photons. A secondary Compton scattering signal within the sensor chip generates a "halo" of unwanted signal around pixels which are brightly illuminated, which can mask the very weakest signals on other nearby regions of the detector. An REU student with interests in numerical physics and digital image processing is sought to develop an iterative routine to automatically remove the unwanted Compton component from x-ray data. The basic methodology to perform this has been worked out, but a fast, robust, and general solution has never been implemented at a synchrotron beamline. The results of this REU project, if successful, would potentially lead to a scholarly publication and a software solution that would be in demand at many x-ray sources around the globe. This work will involve significant coding in python and/or c.
|Michael Billing, James Shanks||Runburg, Elliott Presentation Final Report||
Abstract: Cornell's electron/positron storage ring (CESR) has been utilized for the study of electron clouds (ECs), generated by photoemission, which come from synchrotron radiation from the circulating trains of stored positron bunches striking the walls of the vacuum chamber. During the passage of a train through each section of CESR's vacuum system, the density of the EC grows along the length of the train with electromagnetic fields from the EC becoming sufficiently strong to affect the motion of later bunches in the train. We have made measurements, where we have excited single bunches in the positron train for a short length of time and observed their motion damps. The motion of the excited bunch drives oscillations in the EC, which in turn excite subsequent bunches within the train. This project will analyze the data taken by beam position monitors (BPMs), which measure the position of the center of each bunch within the train turn-by-turn at several places around CESR's circumference. From these results we would like to develop a model describing the coupling of the motion from bunch to bunch within the train. The work will entail developing computer analysis software for the BPM data to determine the oscillatory motion of the excited bunch and how this motion couples to subsequent bunches via the EC. This project will also develop a formal method to describe the coupling of motion between different bunches within the train. If time permits, this study will also attempt to understand the mechanism, by which an oscillating bunch excites the EC and in turn the EC excites a subsequent bunch.
|Yulin Li||Mershon, Jack Presentation Final Report||
Abstract: While detailed information on residual gas pressure distribution in complex vacuum system is important to the operations of advanced particle accelerators, it is often impractical for direct measurement of the pressure distribution, due to very limited access to the vacuum system to commercially available vacuum instrument. 3D tracking program is employed to simulate the pressure distribution. In this project, the student will construct a 3D model of vacuum system of the Cornell prototype photo-emission electron inject using Inventor (a 3D CAD program), and simulate vacuum pressure distribution along the electron beam transport beamline using a 3D tracking program, MolFlow+ (http://test-molflow.web.cern.ch/). The goal for this project is to establish a tool not only for calculating steady-state pressure distributions, but also for simulating impulse responses of the photon-cathode system.
|Hyeri Lee||Schiller-Weiss, Ilana Presentation Final Report||
Abstract: Photoemission electron sources have grown in their importance tremendously in accelerator physics community as they have enabled novel applications such as Energy Recovery Linacs and Free Electron Lasers. If the transverse electron temperature of the beam can be further reduced to below the room temperature, such beams produced by photoemission acquire long coherence length and can transform ultrafast electron diffraction or microscopy applications by allowing unprecedented space and time resolution in imaging. In this project, you will participate in operating a new high voltage cryogenically cooled photoemission source designed and built at Cornell, which will reach sub liquid nitrogen temperatures of the cathode at a high voltage (~250kV) and will test this system for beam production with various photocathodes also developed at Cornell. This project will provide various hands-on training opportunities with laser optics, ultra high vacuum, high voltage, cryogenics, accelerator operation as well as beam dynamics simulations using modern particle tracking codes.
|Steven Full||Smith, Kristina Presentation Final Report||
Abstract: The residual gas in an accelerator beam pipe is readily ionized by collisions with an electron beam. The resulting ions can become trapped inside of high intensity beams, such as those found in Cornell's ERL photoinjector. Once they are trapped, these ions cause a variety of detrimental effects including beam charge neutralization, particle losses, or even beam instabilities. Recent experiments designed to measure the trapped ion density in the photoinjector have produced some exciting, unexpected results. Our goal over the summer is to extend these experiments with state of the art measurement techniques, as well as analyze our data using simulations.
|Ira Wasserman||Starkman, Nathaniel Presentation Final Report||
Abstract: Radio pulsars are highly magnetic, rotating neutron stars. Their magnetospheres feature current flows and large voltages; they are excellent particle accelerators. Radio radiation has enormous antenna temperature hence is due to some sort of coherent process, probably coherent curvature radiation from relativistic electrons streaming along curved magnetic field lines. The recently observed fast radio bursts, which emit tremendous amounts of radio radiation over very short time periods (milliseconds or less) may represent the extreme amount of radiation that can be emitted. An important question is: what is the maximum amount of energy available for producing such bursts? The answer depends on the extent of the region in the magnetosphere that can radiate coherently, and this depends on where the radiation originates from, and the structure of the magnetosphere. This important quantity has only been computed for a dipole magnetic field so far. There are numerical and analytic solutions for a magnetosphere where the magnetic and spin axes of the neutron star are aligned. The project would be to compute the largest possible coherently radiating region in such models, and the energy reservoir available for the radiation