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Old Dominion University

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Articles 181 - 210 of 395

Full-Text Articles in Engineering Physics

Bandgap Profiling In Cigs Solar Cells Via Valence Electron Energy-Loss Spectroscopy, Julia I. Deitz, Shankar Karki, Sylvain X. Marsillac, Tyler J. Grassman Mar 2018

Bandgap Profiling In Cigs Solar Cells Via Valence Electron Energy-Loss Spectroscopy, Julia I. Deitz, Shankar Karki, Sylvain X. Marsillac, Tyler J. Grassman

Electrical & Computer Engineering Faculty Publications

A robust, reproducible method for the extraction of relative bandgap trends from scanning transmission electron microscopy (STEM) based electron energy-loss spectroscopy (EELS) is described. The effectiveness of the approach is demonstrated by profiling the bandgap through a CuIn1-xGaxSe2 solar cell that possesses intentional Ga/(In + Ga) composition variation. The EELS-determined bandgap profile is compared to the nominal profile calculated from compositional data collected via STEM-based energy dispersive X-ray spectroscopy. The EELS based profile is found to closely track the calculated bandgap trends, with only a small, fixed offset difference. This method, which is particularly advantageous …

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Cryogenic Test Results Of The Sps Prototype Rf-Dipole Crabbing Cavity With Higher Order Mode Couplers, Subashini De Silva, H. Park, Jean R. Delayen, Z. Li Jan 2018

Cryogenic Test Results Of The Sps Prototype Rf-Dipole Crabbing Cavity With Higher Order Mode Couplers, Subashini De Silva, H. Park, Jean R. Delayen, Z. Li

Physics Faculty Publications

The rf-dipole crabbing cavity planned for the LHC High Luminosity Upgrade is designed to deliver a transverse kick of 3.34 MV; crabbing the proton beam in the horizontal plane. The proton beams of the LHC machine operating at 7 TeV each sets high impedance thresholds on the crabbing cavity systems. The rf-dipole crabbing cavity is designed with a two higher order mode couplers to suppress those HOMs. The first prototype of the HOM couplers are fabricated at Jefferson Lab. This paper reports the cryogenic test results of the HOM couplers with the SPS prototype rf-dipole cavity.

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Room Temperature Measurements Of Higher Order Modes For The Sps Prototype Rf Dipole Crabbing Cavity, Subashini De Silva, P. Berrutti, Jean R. Delayen, N. A. Huque, Hyekyoung Park Jan 2018

Room Temperature Measurements Of Higher Order Modes For The Sps Prototype Rf Dipole Crabbing Cavity, Subashini De Silva, P. Berrutti, Jean R. Delayen, N. A. Huque, Hyekyoung Park

Physics Faculty Publications

LHC High Luminosity Upgrade will be developing two local crabbing systems to increase the luminosity of the colliding bunches at the ATLAS and CMS experiments. One of the crabbing systems uses the rf-dipole cavity design that will be crabbing the beam in the horizontal plane. The fully integrated crabbing cavity has two higher order mode couplers in damping those excited modes. Currently two sets of HOM couplers have been fabricated at Jefferson Lab for prototyping and testing with the LARP crabbing cavities. This paper presents the measurements of the higher order modes with the prototype HOM couplers carried out at …

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Lessons Learned From Rf-Dipole Prototype Cavities For Lhc High Luminosity Upgrade, Subashini De Silva, Jean R. Delayen, Z. Li, H. Park Jan 2018

Lessons Learned From Rf-Dipole Prototype Cavities For Lhc High Luminosity Upgrade, Subashini De Silva, Jean R. Delayen, Z. Li, H. Park

Physics Faculty Publications

The RF-Dipole Crabbing Cavity designed for the LHC High Luminosity Upgrade includes two higher order mode (HOM) couplers. One of the HOM couplers is an rf filter, which is a high pass filter designed to couple to the horizontal dipole modes and accelerating modes up to 2 GHz, while rejecting the fundamental operating mode at 400 MHz. The coupler consists of a high pass filter circuit where the rejection of the operating mode and transmission of HOMs are sensitive to dimensional deviations. An rf test box has been designed to measure the transmission of the rf filter in order to …

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Measurements Of Frequency, Temperature, Rf Field Dependent Surface Resistance Using Superconducting Half-Wave Cavity, Hyekyoung Park, Subashini De Silva, Jean R. Delayen Jan 2018

Measurements Of Frequency, Temperature, Rf Field Dependent Surface Resistance Using Superconducting Half-Wave Cavity, Hyekyoung Park, Subashini De Silva, Jean R. Delayen

Physics Faculty Publications

A theory of surface resistance of superconductor was rigorously formulated by Bardeen, Cooper, Schrieffer more than 50 years ago. Since then the accelerator community has been used the theory as a guideline to improve the surface resistance of the superconducting cavity. It has been observed that the surface resistance is dependent on frequency, temperature and rf field strength, and surface preparation. To verify these dependences, a well-controlled study is required. Although many different types of cavities have been tested, the typical superconducting cavities are built for specific frequencies of their application. They do not provide data other than at its …

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Coupled Bunch Instability From Jleic Crab Cavity Higher Order Modules, S. I. Sosa, R. Li, H. Park, S. De Silva, V. S. Morozov, J. R. Delayen Jan 2018

Coupled Bunch Instability From Jleic Crab Cavity Higher Order Modules, S. I. Sosa, R. Li, H. Park, S. De Silva, V. S. Morozov, J. R. Delayen

Physics Faculty Publications

Particle bunches traveling in a ring can excite wakefields inside any radio-frequency element present. These electromagnetic modes can resonate long enough and interact with subsequent passing bunches. A coherent oscillation between bunches can quickly become an instability and needs to be addressed. The Jefferson Lab electron ion collider has a large 50 mrad crossing angle and thus relies on bunch crabbing to achieve high luminosity. Bunch crabbing is done with compact superconducting rf dipole cavities. We study coupled bunch oscillations driven by the higher order modes of multicell RFD crab cavities under study for JLEIC, we calculate the instability growth …

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Production Of Magnetized Electron Beam From A Dc High Voltage Photogun, M.A. Mamun, P.A. Adderly, J. Benesch, B. Bullard, J. Delayen, J. Grames, J. Guo, F. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, Geoffrey Krafft, M. Poelker, R. Suleiman, M. Tiefenback, Y. Wang, Sajini Wijethunga, S. Zhang Jan 2018

Production Of Magnetized Electron Beam From A Dc High Voltage Photogun, M.A. Mamun, P.A. Adderly, J. Benesch, B. Bullard, J. Delayen, J. Grames, J. Guo, F. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, Geoffrey Krafft, M. Poelker, R. Suleiman, M. Tiefenback, Y. Wang, Sajini Wijethunga, S. Zhang

Physics Faculty Publications

Bunched-beam electron cooling is a key feature of all proposed designs of the future electron-ion collider, and a requirement for achieving the highest promised collision luminosity. At the Jefferson Lab Electron Ion Collider (JLEIC), fast cooling of ion beams will be accomplished via so-called 'magnetized cooling' implemented using a recirculator ring that employs an energy recovery linac. In this contribution, we describe the production of magnetized electron beam using a compact 300 kV DC high voltage photogun with an inverted insulator geometry, and using alkali-antimonide photocathodes. Beam magnetization was assessed using a modest diagnostic beamline that includes YAG view screens …

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Mobile Free-Electron Laser For Remote Atmospheric Survey, S. Johnson, Balša Terzić, Geoffrey A. Krafft Jan 2018

Mobile Free-Electron Laser For Remote Atmospheric Survey, S. Johnson, Balša Terzić, Geoffrey A. Krafft

Physics Faculty Publications

Reliable atmospheric surveys for carbon distributions will be essential to building an understanding of the Earth's carbon cycle and the role it plays in climate change. One of the core needs of NASA 's Active Sensing of CO2 Over Nights, Days and Seasons (ASCENDS) Mission is to advance the range and precision of current remote atmospheric survey techniques. The feasibility of using accelerator-based sources of infrared light to improve current airborne lidar systems has been explored. A literary review has been conducted to asses the needs of ASCENDS versus the current capabilities of modern atmospheric survey technology, and the parameters …

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300 Kv Dc High Voltage Photogun With Inverted Insulator Geometry And Csk₂Sb Photocathode, Y.W. Wang, P.A. Adderley, J. F. Benesch, D.B. Bullard, J.M. Grames, F. E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, Geoffrey A. Krafft, M. A. Mamun, G. G. Palacios Serrano, M. Poelker, R. Suleiman, M. G. Tiefenback, S.A.K. Wijethunga Jan 2018

300 Kv Dc High Voltage Photogun With Inverted Insulator Geometry And Csk₂Sb Photocathode, Y.W. Wang, P.A. Adderley, J. F. Benesch, D.B. Bullard, J.M. Grames, F. E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, Geoffrey A. Krafft, M. A. Mamun, G. G. Palacios Serrano, M. Poelker, R. Suleiman, M. G. Tiefenback, S.A.K. Wijethunga

Physics Faculty Publications

A compact DC high voltage photogun with inverted-insulator geometry was designed, built and operated reliably at 300 kV bias voltage using alkali-antimonide photocathodes. This presentation describes key electrostatic design features of the photogun with accompanying emittance measurements obtained across the entire photocathode surface that speak to field non-uniformity within the cathode/anode gap. A summary of initial photocathode lifetime measurements at beam currents up to 4.5 mA is also presented.

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Geometry Tagging For Heavy Ions At Jleic, V. S. Morozov, A. Accardi, A. Sy, G. H. Wei, M. D. Baker, R. Dupré, M. Ehrhart, C. Fogler, C. E. Hyde, P. Nadel-Turonski, J. Stukes, T. Toll, L. Zheng Jan 2018

Geometry Tagging For Heavy Ions At Jleic, V. S. Morozov, A. Accardi, A. Sy, G. H. Wei, M. D. Baker, R. Dupré, M. Ehrhart, C. Fogler, C. E. Hyde, P. Nadel-Turonski, J. Stukes, T. Toll, L. Zheng

Physics Faculty Publications

Geometry tagging is an experimental technique for selecting event samples where one can, on a statistical basis, control the geometry of the collision in order to make more incisive physics measurements. Several physics measurements at the EIC would benefit significantly from the use of this technique, including studies of gluon anti-shadowing, studies of parton propagation, attenuation and hadronization in the nucleus, and ultimately the search for parton saturation. The JLEIC full-acceptance detector, with full acceptance to forward-going neutrons, protons and nuclear fragments and a high data-taking rate is ideally suited to such geometry tagging. We improve, tune, and apply existing …

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First Test Results Of Superconducting Twin Axis Cavity For Erl Applications, Hyekyoung Park, Subashini De Silva, Jean R. Delayen, Andrew Hutton, Frank Marhauser Jan 2018

First Test Results Of Superconducting Twin Axis Cavity For Erl Applications, Hyekyoung Park, Subashini De Silva, Jean R. Delayen, Andrew Hutton, Frank Marhauser

Physics Faculty Publications

RF superconducting (SRF) cavities with two beam pipes have been proposed in the past for energy recovery linac applications. The relatively complex geometry of those cavities presented a serious challenge for fabrication and surface processing. The main concerns have now been overcome with the fabrication and successful RF testing of a new elliptical twin-axis cavity proposed by Jefferson Lab (JLab) and optimized by the Center for Accelerator Science (CAS) at Old Dominion University (ODU) in the framework of a DoE accelerator stewardship program. The cavity design provides uniform accelerating or decelerating fields for both beams. This paper describes the cavity …

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Cryogenic Probe Station At Old Dominion University Center For Accelerator Science, Junki Makita, Jean R. Delayen, Alex Gurevich, Gianluigi Ciovati Jan 2018

Cryogenic Probe Station At Old Dominion University Center For Accelerator Science, Junki Makita, Jean R. Delayen, Alex Gurevich, Gianluigi Ciovati

Physics Faculty Publications

With a growing effort in research and development of an alternative material to bulk Nb for a superconducting radiofrequency (SRF) cavity, it is important to have a cost effective method to benchmark new materials of choice. At Old Dominion University's Center for Accelerator Science, a cryogenic probe station (CPS) will be used to measure the response of superconductor samples under RF fields. The setup consists of a closed-cycle refrigerator for cooling a sample wafer to a cryogenic temperature, a superconducting magnet providing a field parallel to the sample, and DC probes in addition to RF probes. The RF probes will …

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Determination Of The Field-Dependence Of The Surface Resistance Of Superconductors From Cavity Tests, Jean R. Delayen, Subashini De Silva, Hyekyoung Park Jan 2018

Determination Of The Field-Dependence Of The Surface Resistance Of Superconductors From Cavity Tests, Jean R. Delayen, Subashini De Silva, Hyekyoung Park

Physics Faculty Publications

Cryogenic tests of superconducting cavities yield an average surface resistance as a function of the peak surface magnetic field. An analytical formalism has been developed to extract the actual field dependence of the surface resistance from cavity tests and is applied to coaxial cavities and cavities of more complex geometries.

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Rf Tests Of Rf-Dipole Prototype Crabbing Cavities For Lhc High Luminosity Upgrade, Subashini De Silva, Hyekyoung Park, Jean R. Delayen, Zi Li Jan 2018

Rf Tests Of Rf-Dipole Prototype Crabbing Cavities For Lhc High Luminosity Upgrade, Subashini De Silva, Hyekyoung Park, Jean R. Delayen, Zi Li

Physics Faculty Publications

The superconducting rf-dipole crabbing cavity is one of the two crabbing cavity designs proposed for the LHC high luminosity upgrade. The proof-of-principle (P-o-P) rf-dipole cavity operating at 400 MHz has demonstrated performance exceeding the design specifications. The prototype cavity for SPS beam test has been designed to include the fundamental power coupler, HOM couplers, and all the ancillary components intended to meet the design requirements. The crab cavities will be installed in the SPS beam line prior to the installation in LHC; this will be the first crabbing cavity operation on a proton beam. The fabrication of two prototype rf-dipole …

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Investigation Of The Surface Resistance Of Niobium Between 325 Mhz And 1300 Mhz Using A Coaxial Half-Wave Cavity, Hyekyoung Park, Jean R. Delayen, Subashini De Silva Jan 2018

Investigation Of The Surface Resistance Of Niobium Between 325 Mhz And 1300 Mhz Using A Coaxial Half-Wave Cavity, Hyekyoung Park, Jean R. Delayen, Subashini De Silva

Physics Faculty Publications

The Center for Accelerator Science at Old Dominion University has built a half-wave coaxial cavity (*) to measure the surface resistance of niobium as a function of frequency, temperature, rf field, preparation techniques, over a wide range of frequencies of interest for particle accelerators. The characteristics of the half-wave coaxial cavity provide these information on a same surface. The preliminary results showed clearly the frequency dependence of residual surface resistance (**). After establishing baseline, we have conducted a study of low temperature baking effect on the surface resistance under controlled environment. This paper will describe the details of the test …

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Simulation Study Of The Magnetized Electron Beam, S.A.K. Wijethunga, J.F. Benesch, Jean R. Delayen, F. E. Hannon, Geoffrey A. Krafft, M. A. Poelker, R. Suleiman Jan 2018

Simulation Study Of The Magnetized Electron Beam, S.A.K. Wijethunga, J.F. Benesch, Jean R. Delayen, F. E. Hannon, Geoffrey A. Krafft, M. A. Poelker, R. Suleiman

Physics Faculty Publications

Electron cooling of the ion beam plays an important role in electron ion colliders to obtain the required high luminosity. This cooling efficiency can be enhanced by using a magnetized electron beam, where the cooling process occurs inside a solenoid field. This paper compares the predictions of ASTRA and GPT simulations to measurements made using a DC high voltage photogun producing magnetized electron beam, related to beam size and rotation angles as a function of the photogun magnetizing solenoid and other parameters.

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Magnetron Sputtering Of Nb3Sn For Srf Cavities, Md. N. Sayeed, H. Elsayed-Ali, G. V. Eremeev, M. J. Kelley, U. Pudasaini, C. E. Reece Jan 2018

Magnetron Sputtering Of Nb3Sn For Srf Cavities, Md. N. Sayeed, H. Elsayed-Ali, G. V. Eremeev, M. J. Kelley, U. Pudasaini, C. E. Reece

Electrical & Computer Engineering Faculty Publications

Nb3Sn is a potential candidate for surface material of SRF cavities since it can enable the cavity to operate at higher temperatures with high quality factor and at an increased accelerating gradient. Nb-Sn films were deposited using magnetron sputtering of individual Nb and Sn targets onto Nb and sapphire substrates. The as-deposited films were annealed at 1200 °C for 3 hours. The films were characterized for their structure by X-ray Diffraction (XRD), morphology by Field Emission Scanning Electron Microscopy (FESEM), and composition by Energy Dispersive X-ray Spectroscopy (EDS) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The …

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Real Time Spectroscopic Ellipsometry Analysis Of First Stage Cuin1-Xgaxse2 Growth: Indium-Gallium Selenide Co-Evaporation, Puja Pradhan, Puruswottam Aryal, Dinesh Attygalle, Abdel-Rahman Ibdah, Prakash Koirala, Jian Li, Khagendra P. Bhandari, Geethika K. Liyanage, Randy J. Ellingson, Michael J. Heben, Sylvain Marsillac, Robert W. Collins, Nikolas J. Podraza Jan 2018

Real Time Spectroscopic Ellipsometry Analysis Of First Stage Cuin1-Xgaxse2 Growth: Indium-Gallium Selenide Co-Evaporation, Puja Pradhan, Puruswottam Aryal, Dinesh Attygalle, Abdel-Rahman Ibdah, Prakash Koirala, Jian Li, Khagendra P. Bhandari, Geethika K. Liyanage, Randy J. Ellingson, Michael J. Heben, Sylvain Marsillac, Robert W. Collins, Nikolas J. Podraza

Electrical & Computer Engineering Faculty Publications

Real time spectroscopic ellipsometry (RTSE) has been applied for in-situ monitoring of the first stage of copper indium-gallium diselenide (CIGS) thin film deposition by the three-stage co-evaporation process used for fabrication of high efficiency thin film photovoltaic (PV) devices. The first stage entails the growth of indium-gallium selenide (In1-xGax)₂Se₃ (IGS) on a substrate of Mo-coated soda lime glass maintained at a temperature of 400 °C. This is a critical stage of CIGS deposition because a large fraction of the final film thickness is deposited, and as a result precise compositional control is desired in order to …

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Characterization Of Laser-Generated Aluminum Plasma Using Ion Time-Of-Flight And Optical Emission Spectroscopy, Md. Haider A. Shaim, Hani E. Elsayed-Ali Nov 2017

Characterization Of Laser-Generated Aluminum Plasma Using Ion Time-Of-Flight And Optical Emission Spectroscopy, Md. Haider A. Shaim, Hani E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

Laser plasma generated by ablation of an Al target in vacuum is characterized by ion time-of-flight combined with optical emission spectroscopy. A Q-switched Nd:YAG laser (wavelength λ = 1064 nm, pulse width τ ∼ 7 ns, and fluence F ≤ 38 J/cm2) is used to ablate the Al target. Ion yield and energy distribution of each charge state are measured. Ions are accelerated according to their charge state by the double-layer potential developed at the plasma-vacuum interface. The ion energy distribution follows a shifted Coulomb-Boltzmann distribution. Optical emission spectroscopy of the Al plasma gives significantly lower plasma temperature …

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Nanostructure Evolution Of Magnetron Sputtered Hydrogenated Silicon Thin Films, Dipendra Adhikari, Maxwell M. Junda, Sylvain X. Marsillac, Robert W. Collins, Nikolas J. Podraza Aug 2017

Nanostructure Evolution Of Magnetron Sputtered Hydrogenated Silicon Thin Films, Dipendra Adhikari, Maxwell M. Junda, Sylvain X. Marsillac, Robert W. Collins, Nikolas J. Podraza

Electrical & Computer Engineering Faculty Publications

Hydrogenated silicon (Si:H) thin films have been prepared by radio frequency (RF) magnetron sputtering. The effect of hydrogen gas concentration during sputtering on the resultant film structural and optical properties has been investigated by real time spectroscopic ellipsometry (RTSE) and grazing incidence x-ray diffraction (GIXRD). The analysis of in-situ RTSE data collected during sputter deposition tracks the evolution of surface roughness and film bulk layer thickness with time. Growth evolution diagrams depicting amorphous, nanocrystalline and mixed-phase regions for low and high deposition rate Si:H are constructed and the effects of process parameter (hydrogen gas concentration, total pressure and RF power) …

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Perspective: The Physics, Diagnostics, And Applications Of Atmospheric Pressure Low Temperature Plasma Sources Used In Plasma Medicine, M. Laroussi Jul 2017

Perspective: The Physics, Diagnostics, And Applications Of Atmospheric Pressure Low Temperature Plasma Sources Used In Plasma Medicine, M. Laroussi

Electrical & Computer Engineering Faculty Publications

Low temperature plasmas have been used in various plasma processing applications for several decades. But it is only in the last thirty years or so that sources generating such plasmas at atmospheric pressure in reliable and stable ways have become more prevalent. First, in the late 1980s, the dielectric barrier discharge was used to generate relatively large volume diffuse plasmas at atmospheric pressure. Then, in the early 2000s, plasma jets that can launch cold plasma plumes in ambient air were developed. Extensive experimental and modeling work was carried out on both methods and much of the physics governing such sources …

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Instrument Design Optimization With Computational Methods, Michael H. Moore Jul 2017

Instrument Design Optimization With Computational Methods, Michael H. Moore

Physics Theses & Dissertations

Using Finite Element Analysis to approximate the solution of differential equations, two different instruments in experimental Hall C at the Thomas Jefferson National Accelerator Facility are analyzed. The time dependence of density fluctuations from the liquid hydrogen (LH2) target used in the Qweak experiment (2011-2012) are studied with Computational Fluid Dynamics (CFD) and the simulation results compared to data from the experiment. The 2.5 kW liquid hydrogen target was the highest power LH2 target in the world and the first to be designed with CFD at Jefferson Lab. The first complete magnetic field simulation of the Super High Momentum …

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Aluminum Multicharged Ion Generation From Femtosecond Laser Plasma, Md. Haider A. Shaim, Frederick Guy Wilson, Hani E. Elsayed-Ali May 2017

Aluminum Multicharged Ion Generation From Femtosecond Laser Plasma, Md. Haider A. Shaim, Frederick Guy Wilson, Hani E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

Aluminum multicharged ion generation from femtosecond laser ablation is studied. A Ti:sapphire laser (wavelength 800 nm, pulse width ∼100 fs, and maximum laser fluence of 7.6 J/cm2) is used. Ion yield and energy distribution of each charge state are measured. A linear relationship between the ion charge state and the equivalent acceleration energy of the individual ion species is observed and is attributed to the presence of an electric field within the plasma-vacuum boundary that accelerates the ions. The ion energy distribution follows a shifted Coulomb-Boltzmann distribution. For Al1+ and Al2+, the ion energy distributions …

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Fire, Ice, Water, And Dirt: A Simple Climate Model, John Kroll Jan 2017

Fire, Ice, Water, And Dirt: A Simple Climate Model, John Kroll

Mathematics & Statistics Faculty Publications

A simple paleoclimate model was developed as a modeling exercise. The model is a lumped parameter system consisting of an ocean (water), land (dirt), glacier, and sea ice (ice) and driven by the sun (fire). In comparison with other such models, its uniqueness lies in its relative simplicity yet yielding good results. For nominal values of parameters, the system is very sensitive to small changes in the parameters, yielding equilibrium, steady oscillations, and catastrophes such as freezing or boiling oceans. However, stable solutions can be found, especially naturally oscillating solutions. For nominally realistic conditions, natural periods of order 100kyrs are …

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Unification Of Gravity And Quantum Theory, Adam Daniels Jan 2017

Unification Of Gravity And Quantum Theory, Adam Daniels

Faculty-Sponsored Student Research & Capstones

An overview of the four fundamental forces of physics as described by the Standard Model (SM) and prevalent unifying theories beyond it is provided. Background knowledge of the particles governing the fundamental forces is provided, as it will be useful in understanding the way in which the unification efforts of particle physics has evolved, either from the SM, or apart from it. It is shown that efforts to provide a quantum theory of gravity have allowed supersymmetry (SUSY) and M-Theory to become two of the prevailing theories for unifying gravity with the remaining non-gravitational forces.

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Rf Superconductivity, Jean R. Delayen Jan 2017

Rf Superconductivity, Jean R. Delayen

Physics Faculty Publications

Tutorial, based on the "RF Superconductivity" course taught by J. Delayen at the US PAS.

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Status Of The Bonus12 Radial Time Projection Chamber, Gabriel Charles, Stephen Bueltmann, Gail Dodge, Nathan Dzbenski, Mathieu Ehrhardt, Sebastian E. Kuhn, David Payette, Jiwan Poudel, Keith A. Griffioen, Pascal Baron, Irakli Mandjavidze, Eric Christy, I. Hakki Albayrak, Aruni Nadeeshani, Howard Fenker, Narbe Kalantarians, Jixie Zhang, Carlos Ayerbe Gayoso Jan 2017

Status Of The Bonus12 Radial Time Projection Chamber, Gabriel Charles, Stephen Bueltmann, Gail Dodge, Nathan Dzbenski, Mathieu Ehrhardt, Sebastian E. Kuhn, David Payette, Jiwan Poudel, Keith A. Griffioen, Pascal Baron, Irakli Mandjavidze, Eric Christy, I. Hakki Albayrak, Aruni Nadeeshani, Howard Fenker, Narbe Kalantarians, Jixie Zhang, Carlos Ayerbe Gayoso

Physics Faculty Publications

Part of the experimental program in Hall B of the Jefferson Lab, Virginia, USA is dedicated to studying neutron structure functions using deep inelastic scattering on nuclei. For this purpose, the BONuS12 experiment will detect low momentum recoil protons in coincidence with scattered electrons. The protons will be detected by a second-generation Radial Time Projection Chamber (RTPC) using triple Gas Electron Multiplier foils for amplification while the scattered electrons will be detected by the CLAS12 spectrometer installed in Hall B. The following article presents the status of the BONuS12 RTPC detector that will take data within the next 2 years. …

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High Average Brilliance Compact Inverse Compton Light Source, K. Deitrick, J. R. Delayen, G. A. Krafft Jan 2017

High Average Brilliance Compact Inverse Compton Light Source, K. Deitrick, J. R. Delayen, G. A. Krafft

Physics Faculty Publications

There exists an increasing demand for compact Inverse Compton Light Sources (ICLS) capable of producing substantial fluxes of narrow-band X-rays. While multiple design proposals have been made, compared to typical bremsstrahlung sources, most of these have comparable fluxes and improve on the brilliance within a 0.1% bandwidth by only a few orders of magnitude. By applying cw superconducting rf beam acceleration and rf focusing to produce a beam of small emittance and magnetic focusing to produce a small spot size on the order of a few microns at collision, the source presented here provides a 12 keV X-ray beam which …

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Optimization Of The Rf Cavity Heat Load And Trip Rates For Cebaf At 12 Gev, H. Zhang, Y. Roblin, A. Freyberger, G. Krafft, B. Terzić Jan 2017

Optimization Of The Rf Cavity Heat Load And Trip Rates For Cebaf At 12 Gev, H. Zhang, Y. Roblin, A. Freyberger, G. Krafft, B. Terzić

Physics Faculty Publications

The Continuous Electron Beam Accelerator Facility at JLab has 200 RF cavities in the north linac and the south linac respectively after the 12 GeV upgrade. The purpose of this work is to simultaneously optimize the heat load and the trip rate for the cavities and to reconstruct the pareto-optimal front in a timely manner when some of the cavities are turned down. By choosing an efficient optimizer and strategically creating the initial gradients, the pareto-optimal front for no more than 15 cavities down can be re-established within 20 seconds.

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Compact Crabbing Cavity Systems For Particle Colliders, Subashini De Silva Jan 2017

Compact Crabbing Cavity Systems For Particle Colliders, Subashini De Silva

Physics Faculty Publications

In circular or ring-based particle colliders, crabbing cavities are used to increase the luminosity. The first superconducting crabbing cavity system was successfully implemented at KEKB electron-positron collider that have demonstrated the luminosity increase with overlapping bunches. Crabbing systems are an essential component in the future colliders with intense beams, such as the LHC high luminosity upgrade and proposed electron-ion colliders. Novel compact superconducting cavity designs with improved rf properties, at low operating frequencies have been prototyped successfully that can deliver high operating voltages. We present single cavity and multi-cell crabbing cavities proposed for future particle colliders and addresses the challenges …

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