Physical Sciences and Mathematics Commons^™

Simulation And Measurements Of Hom Filter Of The Larp Prototype Rf-Dipole Crabbing Cavity Using An Rf Test Box, Subashini U. De Silva, Jean R. Delayen, Z. Li

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 …

High Current High Charge Magnetized And Bunched Electron Beam From A Dc Photogun For Jleic Cooler, S. Zhang, P. A. Adderley, J. F. Benesch, D. B. Bullard, Jean R. Delayen, J. M. Grames, J. Guo, F. E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, Geoffrey A. Krafft, M. A. Mamun, M. Poelker, R. Suleiman, M.G. Tiefenback, Y.W. Wang, S.A.K. Wijethunga

Physics Faculty Publications

A high current, high charge magnetized electron beamline that has been under development for fast and efficient cooling of ion beams for the proposed Jefferson Lab Electron Ion Collider (JLEIC). In this paper, we present the latest progress over the past year that include the generation of picosecond magnetized beam bunches at average currents up to 28 mA with exceptionally long photocathode lifetime, and the demonstrations of magnetized beam with high bunch charge up to 700 pC at 10s of kHz repetition rates. Detailed studies on a stable drive laser system, long lifetime photocathode, beam magnetization effect, beam diagnostics, and …

Announcement: In Memory Of Yong Ho Chin, Michael Thoennessen, Debbie Brodbar, Brant Johnson, Jean Delayen, Dan Kulp, Frank Zimmermann, Maria Poko

Physics Faculty Publications

No abstract provided.

Simulation Study Of The Emittance Measurements In Magnetized Electron Beam, S.A.K. Wijethunga, J. Benesch, Jean R. Delayen, F. E. Hannon, Geoffrey A. Krafft, M. A. Mamun, G. Palacios-Serrano, M. Poelker, R. Suleiman, S. Zhang

Physics Faculty Publications

Electron cooling of the ion beam is key to obtaining the required high luminosity of proposed electron-ion colliders. For the Jefferson Lab Electron Ion Collider, the expected luminosity of 10³⁴ 〖 cm〗⁻² s⁻¹ will be achieved through so-called ’magnetized electron cooling’, where the cooling process occurs inside a solenoid field, which will be part of the collider ring and facilitated using a circulator ring and Energy Recovery Linac (ERL). As an initial step, we generated magnetized electron beam using a new compact DC high voltage photogun biased at -300 kV employing an alkali-antimonide photocathode. This contribution presents the characterization of …

Measurement Of The Magnetic Field Penetration Into Superconducting Thin Films, Iresha Harshani Senevirathne, Gianluigi Ciovati, Jean R. Delayen

Physics Faculty Publications

The magnetic field at which first flux penetrates is a fundamental parameter characterizing superconducting materials for SRF cavities. Therefore, an accurate technique is needed to measure the penetration of the magnetic field directly. The conventional magnetometers are inconvenient for thin superconducting film measurements because these measurements are strongly influenced by orientation, edge and shape effects. In order to measure the onset of field penetration in bulk, thin films and multi-layered superconductors, we have designed, built and calibrated a system combining a small superconducting solenoid capable of generating surface magnetic field higher than 500 mT and Hall probe to detect the …

Magnetized Electron Source For Jleic Cooler, R. Suleiman, P.A. Adderley, J.F. Benesch, D.B. Bullard, J.R. Delayen, J.M. Grames, J. Guo, F.E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, G.A. Krafft, M.A. Mamun, M. Poelker, M.G. Tiefenback, Y.W. Wang, S.A.K. Wijethunga, J. T. Yoskowitz, S. Zhang

Physics Faculty Publications

Magnetized bunched-beam electron cooling is a critical part of the Jefferson Lab Electron Ion Collider (JLEIC). Strong cooling of ion beams will be accomplished inside a cooling solenoid where the ions co-propagate with an electron beam generated from a source immersed in magnetic field. This contribution describes the production and characterization of magnetized electron beam using a compact 300 kV DC high voltage photogun and bialkali-antimonide photocathodes. Beam magnetization was studied using a diagnostic beamline that includes viewer screens for measuring the shearing angle of the electron beamlet passing through a narrow upstream slit. Correlated beam emittance with magnetic field …

Compact Srf Linac For High Brilliance Inverse Compton Scattering Light Source, Kirsten E. Deitrick, Jean R. Delayen, Geoffrey A. Krafft, Balša Terzić

Physics Faculty Publications

New designs for compact SRF linacs can produce micron-size electron beams. These can can be used for inverse Compton scattering light sources of exceptional flux and brilliance.

Design And Commissioning Of A Magnetic Field Scanning System For Srf Cavities, Ishwari Prasad Parajuli, Gianluigi Ciovati, W. A. Clemens, Jean R. Delayen, J. Nice, Alex V. Gurevich

Physics Faculty Publications

Trapped magnetic vortices are one of the leading sources of residual losses in SRF cavities. Mechanisms of flux pinning depend on the materials treatment and cool-down conditions. A magnetic field scanning system using flux-gate magnetometers and Hall probes has been designed and built to allow measuring the local magnetic field of trapped vortices normal to the outer surface of 1.3 GHz single-cell SRF cavities at cryogenic temperatures. Such system will allow inferring the key information about the distribution and magnitude of trapped flux in the SRF cavities for different material, surface preparations and cool-down conditions.

Equilibria And Synchrotron Stability In Two Energy Storage Rings, B. Dhital, Jean R. Delayen, Y. S. Derbenev, D. Douglas, Geoffrey A. Krafft, F. Lin, B. Morozov, Y. Zhang

Physics Faculty Publications

In a dual energy storage ring, the electron beam passes through two loops at markedly different energies E_{L}, and E_{H}, i.e., energies for low energy loop and high energy loop respectively. These loops use a common beamline where a superconducting linac at first accelerates the beam from EL to EH and then decelerates the beam from EH to EL in the next pass. There are two basic solutions to the equilibrium problems possible, i.e., ’Storage Ring’ (SR) equilibrium and ’Energy Recovery Linac’ (ERL) equilibrium. SR equilibrium mode more resembles the usual single loop storage ring with strong synchrotron motion and …

Two-Energy Storage-Ring Electron Cooler For Relativistic Ion Beams, Bhawin Dhital, Jean R. Delayen, Y. S. Derbenev, D. Douglas, Geoffrey A. Krafft, F. Lin, V. S. Morozov, Y. Zhang

Physics Faculty Publications

An electron beam based cooling system for the ion beam is one of the commonly used approaches. The proposed two’energy storage-ring electron cooler consists of damping and cooling sections at markedly different energies connected by an energy recovering superconducting RF structure. The parameters in the cooling and damping sections are adjusted for optimum cooling of a stored ion beam and for optimum damping of the electron beam respectively. This paper briefly describes a two cavities model along with a third cavity model to accelerate and decelerate the electron beam in two energy storage ring. Based on our assumed value of …

Space Charge Study Of The Jefferson Lab Magnetized Electron Beam, Sajini A.K. Wijethunga, J. F. Benesch, Jean R. Delayen, F. E. Hannon, C. Hernandez-Garcia, Geoffrey A. Krafft, M. A. Mamun, M. Poelker, R. Suleiman, S. Zhang

Physics Faculty Publications

Magnetized electron cooling could result in high luminosity at the proposed Jefferson Lab Electron-Ion Collider (JLEIC). In order to increase the cooling efficiency, a bunched electron beam with high bunch charge and high repetition rate is required. We generated magnetized electron beams with high bunch charge using a new compact DC high voltage photo-gun biased at -300 kV with alkali-antimonide photocathode and a commercial ultrafast laser. This contribution explores how magnetization affects space charge dominated beams as a function of magnetic field strength, gun high voltage, laser pulse width, and laser spot size.

Electron-Ion Collider Performance Studies With Beam Synchronization Via Gear-Change, I. Neththikumara, Geoffrey A. Krafft, Y. Roblin, Balša Terzić

Physics Faculty Publications

Beam synchronization of the future electron-ion collider (EIC) is studied with introducing different bunch numbers in the two colliding beams. This allows non-pairwise collisions between the bunches of the two beams and is known as "gear-change", whereby one bunch of the first beam collides with all other bunches of the second beam, one at a time. Here we report on the study of how the beam dynamics of the Jefferson Lab Electron Ion collider concept is affected by the gear change. For this study, we use the new GPU-based code (GHOST). It features symplectic one-turn maps for particle tracking and …

Improving Performance Of Inverse Compton Sources Through Laser Chirping, Balsa Terzić, A. Brown, I. Drebot, T. Hagerman, E. Johnson, Geoffrey A. Krafft, C. Maroli, V. Petrillo, M. Ruijter

Physics Faculty Publications

We present a new method for computation of radiation spectra in the non-linear regime of operation of inverse Compton sources characterized by high laser intensities. The resulting simulations agree well with the experiments. Increasing the laser intensity changes the longitudinal velocity of the electrons during their collision, leading to considerable non-linear broadening in the scattered radiation spectra. The effects of such ponderomotive broadening are so deleterious that most inverse Compton sources either remain at low laser intensities or pay a steep price to operate at a small fraction of the physically possible peak spectral output. This ponderomotive broadening can be …

Beam-Beam Effect: Crab Dynamics Calculation In Jleic, He Huang, Vasiliy Morozov, Yves Roblin, Amy Sy, Fanglei Lin, Yuhong Zhang, Balša Terzić, Salvador Sosa, Isurumali Neththikumara

Physics Faculty Publications

The electron and ion beams of a future Electron Ion Collider (EIC) must collide at an angle for detection, machine and engineering design reasons. To avoid associated luminosity reduction, a local crabbing scheme is used where each beam is crabbed before collision and de-crabbed after collision. The crab crossing scheme then provides a head-on collision for beams with a non-zero crossing angle. We develop a framework for accurate simulation of crabbing dynamics with beam-beam effects by combining symplectic particle tracking codes with a beam-beam model based on the Bassetti-Erskine analytic solution. We present simulation results using our implementation of such …

Measurement Of Nuclear Transparency Ratios For Protons And Neutrons, M. Duer, O. Hen, E. Piasetzky, L. B. Weinstein, A. Schmidt, I. Korover, E. O. Cohen, H. Hakobyan, S. Adhikari, G. Angelini, H. Avakian, C. Ayerbe Gayoso, L. Barion, M. Battaglieri, A. Beck, I. Bedlinski, A. S. Biselli, S. Boiarinov, W. J. Briscoe, X. Zheng, Et Al., The Clas Collaboration

Physics Faculty Publications

This paper presents, for the first time, measurements of neutron transparency ratios for nuclei relative to C measured using the (e, e'n) reaction, spanning measured neutron momenta of 1.4 to 2.4 GeV/c. The transparency ratios were extracted in two kinematical regions, corresponding to knockout of mean-field nucleons and to the breakup of Short-Range Correlated nucleon pairs. The extracted neutron transparency ratios are consistent with each other for the two measured kinematical regions and agree with the proton transparencies extracted from new and previous (e, e'p) measurements, including those from neutron-rich nuclei such as lead. The data also agree with and …

Maximum Performance Of Cavities Affected By The High-Field Q-Slope (Hfqs), G. Ciovati, A.V. Gurevich, I. P. Parajuli

Physics Faculty Publications

The performance of high-purity, bulk niobium SRF cavities treated by chemical processes such as BCP or EP is limited by the so-called high-field Q-slope (HFQS). Several models and experimental studies have been proposed and performed over the years to understand the origin of these anomalous losses but a general consensus on what these origins are is yet to be established. In this contribution, we present the results from the RF tests of several 1.3 GHz single-cell cavities limited by the HFQS and tested using a variable input coupler. This allowed to maintain close to critical coupling even at high field …

Working Group 6 Summary: Spin And 3d Structure, Oleg Eyser, Bakur Parsamyan, Ted Rogers

Physics Faculty Publications

The spin and 3D structure session of the DIS2019 conference focused on recent efforts to understand nucleon structure using collinear factorization theorems, transverse momentum dependent correlation functions (TMDs), generalized parton distribution (GPDs) and similar objects. A large amount of progress in both theoretical and experimental directions was reported. We summarize some of the highlights here.

Modeling The Seasonal Cycle Of Iron And Carbon Fluxes In The Amundsen Sea Polynya, Antarctica, P. St-Laurent, P. L. Yager, R. M. Sherrell, H. Oliver, M. S. Dinniman, S. E. Stammerjohn

CCPO Publications

The Amundsen Sea Polynya (ASP) is distinguished by having the highest net primary production per unit area in the coastal Antarctic. Recent studies have related this high productivity to the presence of fast-melting ice shelves, but the mechanisms involved are not well understood. In this study we describe the first numerical model of the ASP to represent explicitly the ocean-ice interactions, nitrogen and iron cycles, and the coastal circulation at high resolution. The study focuses on the seasonal cycle of iron and carbon, and the results are broadly consistent with field observations collected during the summer of 2010–2011. The simulated …

Controlling For Confounding Via Propensity Score Methods Can Result In Biased Estimation Of The Conditional Auc: A Simulation Study, Hadiza I. Galadima, Donna K. Mcclish

Community & Environmental Health Faculty Publications

In the medical literature, there has been an increased interest in evaluating association between exposure and outcomes using nonrandomized observational studies. However, because assignments to exposure are not random in observational studies, comparisons of outcomes between exposed and nonexposed subjects must account for the effect of confounders. Propensity score methods have been widely used to control for confounding, when estimating exposure effect. Previous studies have shown that conditioning on the propensity score results in biased estimation of conditional odds ratio and hazard ratio. However, research is lacking on the performance of propensity score methods for covariate adjustment when estimating the …

Sec-Lib: Protecting Scholarly Digital Libraries From Infected Papers Using Active Machine Learning Framework, Nir Nissim, Aviad Cohen, Jian Wu, Andrea Lanzi, Lior Rokach, Yuval Elovici, Lee Giles

Computer Science Faculty Publications

Researchers from academia and the corporate-sector rely on scholarly digital libraries to access articles. Attackers take advantage of innocent users who consider the articles' files safe and thus open PDF-files with little concern. In addition, researchers consider scholarly libraries a reliable, trusted, and untainted corpus of papers. For these reasons, scholarly digital libraries are an attractive-target and inadvertently support the proliferation of cyber-attacks launched via malicious PDF-files. In this study, we present related vulnerabilities and malware distribution approaches that exploit the vulnerabilities of scholarly digital libraries. We evaluated over two-million scholarly papers in the CiteSeerX library and found the library …

Eeg-Based Processing And Classification Methodologies For Autism Spectrum Disorder: A Review, Gunavaran Brihadiswaran, Dilantha Haputhanthri, Sahan Gunathilaka, Dulani Meedeniya, Sampath Jayarathna

Computer Science Faculty Publications

Autism Spectrum Disorder is a lifelong neurodevelopmental condition which affects social interaction, communication and behaviour of an individual. The symptoms are diverse with different levels of severity. Recent studies have revealed that early intervention is highly effective for improving the condition. However, current ASD diagnostic criteria are subjective which makes early diagnosis challenging, due to the unavailability of well-defined medical tests to diagnose ASD. Over the years, several objective measures utilizing abnormalities found in EEG signals and statistical analysis have been proposed. Machine learning based approaches provide more flexibility and have produced better results in ASD classification. This paper presents …

Electroencephalogram (Eeg) For Delineating Objective Measure Of Autism Spectrum Disorder, Sampath Jayarathna, Yasith Jayawardana, Mark Jaime, Sashi Thapaliya

Computer Science Faculty Publications

Autism spectrum disorder (ASD) is a developmental disorder that often impairs a child's normal development of the brain. According to CDC, it is estimated that 1 in 6 children in the US suffer from development disorders, and 1 in 68 children in the US suffer from ASD. This condition has a negative impact on a person's ability to hear, socialize, and communicate. Subjective measures often take more time, resources, and have false positives or false negatives. There is a need for efficient objective measures that can help in diagnosing this disease early as possible with less effort. EEG measures the …

Regional Differences In Sea Level Rise Between The Mid-Atlantic Bight And The South Atlantic Bight: Is The Gulf Stream To Blame?, Tal Ezer

CCPO Publications

Recent studies appear to show that a "hot spot" for accelerated sea level rise (SLR) shifted around 2010 from the Mid-Atlantic Bight (MAB) to the South Atlantic Bight (SAB) and south Florida. The role of the Gulf Stream (GS) in this shift was thus investigated. The findings show that in the ~15–20 years before, SLR was accelerating in the MAB due to weakening and southward shifting of the GS. After 2010, however, SLR started slowing down in the MAB due to strengthening and northward shifting of the GS. Thermosteric effects seen in altimeter data indicate a warming trend south of …

Carbon Multicharged Ion Generation From Laser-Spark Ion Source, Md. Mahmudur Rahman, Oguzhan Balki, Hani E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

Multicharged carbon ions are generated by using a laser-assisted spark-discharge ion source. A Q-switched Nd:YAG laser pulse (1064 nm, 7 ns, ≤ 4.5 × 10⁹ W/cm²) focused onto the surface of a glassy carbon target results in its ablation. The spark-discharge (∼1.2 J energy, ∼1 µs duration) is initiated along the direction of the plume propagation between the target surface and a grounded mesh that is parallel to the target surface. Ions emitted from the laser-spark plasma are detected by their time-of-flight using a Faraday cup. The ion energy-to-charge ratio is analyzed by a three-mesh retarding field …

End-To-End Learning Via A Convolutional Neural Network For Cancer Cell Line Classification, Darlington A. Akogo, Xavier-Lewis Palmer

Electrical & Computer Engineering Faculty Publications

Purpose: Computer vision for automated analysis of cells and tissues usually include extracting features from images before analyzing such features via various machine learning and machine vision algorithms. The purpose of this work is to explore and demonstrate the ability of a Convolutional Neural Network (CNN) to classify cells pictured via brightfield microscopy without the need of any feature extraction, using a minimum of images, improving work-flows that involve cancer cell identification.

Design/methodology/approach: The methodology involved a quantitative measure of the performance of a Convolutional Neural Network in distinguishing between two cancer lines. In their approach, they trained, validated and …

Initial Implementation Of A Machine Learning System For Srf Cavity Fault Classification At Cebaf, A. Carpenter, K. M. Iftekharuddin, T. Powers, Y. Roblin, A. Solopava Shabalina, C. Tennant, L. Vidyaratne

Electrical & Computer Engineering Faculty Publications

The Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Laboratory is a high power Continuous Wave (CW) electron accelerator. It uses a mixture of of SRF cryomodules: older, lower energy C20/C50 modules and newer, higher energy C100 modules. The cryomodules are arrayed in two anti-parallel linear accelerators. Accurately classifying the type of cavity faults is essential to maintaining and improving accelerator performance. Each C100 cryomodule contains eight 7-cell cavities. When a cavity fault occurs within a cryomodule, all eight cavities generate 17 waveforms each containing 8192 points. This data is exported from the control system and saved for review. Analysis …

Functionality Of Membrane Proteins Overexpressed And Purified From E. Coli Is Highly Dependent Upon The Strain, Khadija Mathieu, Waqas Javed, Sylvain Vallet, Christian Lesterlin, Marie-Pierre Candusso, Feng Ding, Xiaohong Nancy Xu, Christine Ebel, Jean-Michel Jault, Cédric Orelle

Chemistry & Biochemistry Faculty Publications

Overexpression of correctly folded membrane proteins is a fundamental prerequisite for functional and structural studies. One of the most commonly used expression systems for the production of membrane proteins is Escherichia coli. While misfolded proteins typically aggregate and form inclusions bodies, membrane proteins that are addressed to the membrane and extractable by detergents are generally assumed to be properly folded. Accordingly, GFP fusion strategy is often used as a fluorescent proxy to monitor their expression and folding quality. Here we investigated the functionality of two different multidrug ABC transporters, the homodimer BmrA from Bacillus subtilis and the heterodimer PatA/PatB …

Phosgene In The Upper Troposphere And Lower Stratosphere: A Marker For Product Gas Injection Due To Chlorine-Containing Very Short Lived Substances, Jeremy J. Harrison, Martyn P. Chipperfield, Ryan Hossaini, Christopher D. Boone, Sandip Dhomse, Wuhu Feng, Peter F. Bernath

Chemistry & Biochemistry Faculty Publications

Abstract: Phosgene in the atmosphere is produced via the degradation of carbon tetrachloride, methyl chloroform, and a number of chlorine‐containing very short lived substances (VSLS). These VSLS are not regulated by the Montreal Protocol even though they contribute to stratospheric ozone depletion. While observations of VSLS can quantify direct stratospheric source gas injection, observations of phosgene in the upper troposphere/lower stratosphere can be used as a marker of product gas injection of chlorine‐containing VSLS. In this work we report upper troposphere/lower stratosphere measurements of phosgene made by the ACE‐FTS (Atmospheric Chemistry Experiment Fourier Transform Spectrometer) instrument and compare with results …

Exomol Line List - Xxxiv. A Rovibrational Line List For Phosphinidene (Ph) In Its X³Σ¯ And A¹Δ Electronic States, Jonathan Langleben, Jonathan Tennyson, Sergei N. Yurchenko, Peter Bernath

Chemistry & Biochemistry Faculty Publications

A rovibronic line list for the ground (X³Σ⁻) and first excited (a¹Δ) states of phosphinidene, ³¹PH, is computed. The line list is designed for studies of exoplanetary and cool stellar atmospheres with temperatures up to 4000 K. A combination of empirical and ab initio data is used to produce the line list: potential energy curves (PECs) are fitted using experimental transition frequencies; these transitions are reproduced with a root mean square error of 0.01 cm⁻¹. The nuclear Schrödinger equation is solved using these PECs plus Born–Oppenheimer and spin splitting correction terms. …

Molecular Level Comparison Of Water Extractives Of Maple And Oak With Negative And Positive Ion Esi Ft-Icr Mass Spectrometry, Zhongqi He, Rachel L. Sleighter, Patrick G. Hatcher, Shasha Liu, Fengchang Wu, Haixuan Zou, O. Modesto Olanya

Chemistry & Biochemistry Faculty Publications

Soluble extractives in wood function to protect living trees from destructive agents and also contribute to wood color and fragrance. Some extractive components have biological activities with medical applications. They also play important roles in wood processing and related applications. To increase the knowledge of wood chemistry, maple and oak were extracted by water. Ultraviolet/visible (UV/vis) spectroscopy indicated the presence of a phenolic compound, resorcinol, in maple extractives having higher molecular mass and more aromatic components than oak extractives. Negative and positive electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR-MS) identified thousands of formulas in the two …