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Samples For 3rd Harmonic Magnetometry Assessment Of Nbtin-Based Sis Structures, D.R. Beverstock, C.Z. Antoine, Jean R. Delayen, D. Manos, Iresha Harshani Senevirathne, J. K. Spradlin, A-M. Valente-Feliciano 2022 Old Dominion University

Samples For 3rd Harmonic Magnetometry Assessment Of Nbtin-Based Sis Structures, D.R. Beverstock, C.Z. Antoine, Jean R. Delayen, D. Manos, Iresha Harshani Senevirathne, J. K. Spradlin, A-M. Valente-Feliciano

Physics Faculty Publications

In the quest for alternative superconducting materials to bring accelerator cavity performance beyond the bulk niobium (Nb) intrinsic limits, a promising concept uses superconductor-insulator-superconductor (SIS) thin film structures that allows magnetic flux shielding in accelerator cavities to higher fields [1]. Candidate materials for such structures are NbTiN as the superconductor and AlN as the insulator. We have demonstrated high quality NbTiN and AlN deposited by reactive DC magnetron sputtering (DCMS), both for individual layers and multilayers. Interface quality has been assessed for bilayer stacks with 250 nm NbTiN layers and AlN thicknesses from 30 nm down to1 nm. These SIS …


High Resolution Diagnostic Tools For Superconducting Radio Frequency Cavities, I. Parajuli, G. Ciovati, J. R. Delayen 2022 Old Dominion University

High Resolution Diagnostic Tools For Superconducting Radio Frequency Cavities, I. Parajuli, G. Ciovati, J. R. Delayen

Physics Faculty Publications

Superconducting radio-frequency (SRF) cavities are one of the fundamental building blocks of modern particle accelerators. To achieve the highest quality factors (1010–1011), SRF cavities are operated at liquid helium temperatures. Magnetic flux trapped on the surface of SRF cavities during cool-down below the critical temperature is one of the leading sources of residual RF losses. Instruments capable of detecting the distribution of trapped flux on the cavity surface are in high demand in order to better understand its relation to the cavity material, surface treatments and environmental conditions. We have designed, developed, and commissioned two high-resolution …


Bunch Length Measurements At The Cebaf Injector At 130 Kv, Sunil Pokharel, M. W. Bruker, J. M. Grames, A. S. Hofler, R. Kazimi, Geoffrey A. Krafft, S. Zhang 2022 Old Dominion University

Bunch Length Measurements At The Cebaf Injector At 130 Kv, Sunil Pokharel, M. W. Bruker, J. M. Grames, A. S. Hofler, R. Kazimi, Geoffrey A. Krafft, S. Zhang

Physics Faculty Publications

In this work, we investigated the evolution in bunch length of beams through the CEBAF injector for low to high charge per bunch. Using the General Particle Tracer (GPT), we have simulated the beams through the beamline of the CEBAF injector and analyzed the beam to get the bunch lengths at the location of chopper. We performed these simulations with the existing injector using a 130 kV gun voltage. Finally, we describe measurements to validate these simulations. The measurements have been done using chopper scanning technique for two injector laser drive frequency modes: one with 500 MHz, and another with …


Deep Learning Based Superconducting Radio-Frequency Cavity Fault Classification At Jefferson Laboratory, Lasitha Vidyaratne, Adam Carpenter, Tom Powers, Chris Tennant, Khan M. Iftekharuddin, Md. Monibor Rahman, Anna S. Shabalina 2022 Old Dominion University

Deep Learning Based Superconducting Radio-Frequency Cavity Fault Classification At Jefferson Laboratory, Lasitha Vidyaratne, Adam Carpenter, Tom Powers, Chris Tennant, Khan M. Iftekharuddin, Md. Monibor Rahman, Anna S. Shabalina

Electrical & Computer Engineering Faculty Publications

This work investigates the efficacy of deep learning (DL) for classifying C100 superconducting radio-frequency (SRF) cavity faults in the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. CEBAF is a large, high-power continuous wave recirculating linac that utilizes 418 SRF cavities to accelerate electrons up to 12 GeV. Recent upgrades to CEBAF include installation of 11 new cryomodules (88 cavities) equipped with a low-level RF system that records RF time-series data from each cavity at the onset of an RF failure. Typically, subject matter experts (SME) analyze this data to determine the fault type and identify the cavity of …


Beamline For E-Beam Processing At Uitf, G. Ciovati, C. Bott, S. Gregory, F. Hannon, Xi Li, M. McCaughan, R. Pearce, M. Poelker, H. Vennekate 2022 Old Dominion University

Beamline For E-Beam Processing At Uitf, G. Ciovati, C. Bott, S. Gregory, F. Hannon, Xi Li, M. Mccaughan, R. Pearce, M. Poelker, H. Vennekate

Electrical & Computer Engineering Faculty Publications

No abstract provided.


Theoretical Investigation On Optical Properties Of 2d Materials And Mechanical Properties Of Polymer Composites At Molecular Level, Geeta Sachdeva 2022 Michigan Technological University

Theoretical Investigation On Optical Properties Of 2d Materials And Mechanical Properties Of Polymer Composites At Molecular Level, Geeta Sachdeva

Dissertations, Master's Theses and Master's Reports

The field of two-dimensional (2D) layered materials provides a new platform for studying diverse physical phenomena that are scientifically interesting and relevant for technological applications. Theoretical predictions from atomically resolved computational simulations of 2D materials play a pivotal role in designing and advancing these developments. The focus of this thesis is 2D materials especially graphene and BN studied using density functional theory (DFT) and molecular dynamics (MD) simulations. In the first half of the thesis, the electronic structure and optical properties are discussed for graphene, antimonene, and borophene. It is found that the absorbance in (atomically flat) multilayer antimonene (group …


Athena Detector Proposal — A Totally Hermetic Electron Nucleus Apparatus Proposed For Ip6 At The Electron-Ion Collider, J. Adam, L. Adamczyk, N. Agrawal, C. Aidala, W. Akers, M. Alekseev, M.M. Allen, F. Ameli, A. Angerami, P. Antonioli, N. J. Apadula, A. Aprahamian, W. Armstrong, M. Arratia, J. R. Arrington, A. Asaturyan, E. C. Aschenauer, K. Augsten, S. Aune, M. Żurek, Et al. 2022 Old Dominion University

Athena Detector Proposal — A Totally Hermetic Electron Nucleus Apparatus Proposed For Ip6 At The Electron-Ion Collider, J. Adam, L. Adamczyk, N. Agrawal, C. Aidala, W. Akers, M. Alekseev, M.M. Allen, F. Ameli, A. Angerami, P. Antonioli, N. J. Apadula, A. Aprahamian, W. Armstrong, M. Arratia, J. R. Arrington, A. Asaturyan, E. C. Aschenauer, K. Augsten, S. Aune, M. Żurek, Et Al.

Physics Faculty Publications

ATHENA has been designed as a general purpose detector capable of delivering the full scientific scope of the Electron-Ion Collider. Careful technology choices provide fine tracking and momentum resolution, high performance electromagnetic and hadronic calorimetry, hadron identification over a wide kinematic range, and near-complete hermeticity. This article describes the detector design and its expected performance in the most relevant physics channels. It includes an evaluation of detector technology choices, the technical challenges to realizing the detector and the R&D required to meet those challenges.


Improving The Electrostatic Design Of The Jefferson Lab 300 Kv Dc Photogun, S.A.K. Wijethunga, M. A. Mamun, R. Suleiman, C. Hernandez-Garcia, B. Bullard, J. R. Delayen, J. Grames, G. A. Krafft, G. Palacios-Serrano, M. Poelker 2022 Old Dominion University

Improving The Electrostatic Design Of The Jefferson Lab 300 Kv Dc Photogun, S.A.K. Wijethunga, M. A. Mamun, R. Suleiman, C. Hernandez-Garcia, B. Bullard, J. R. Delayen, J. Grames, G. A. Krafft, G. Palacios-Serrano, M. Poelker

Physics Faculty Publications

The 300 kV DC high voltage photogun at Jefferson Lab was redesigned to deliver electron beams with a much higher bunch charge and improved beam properties. The original design provided only a modest longitudinal electric field (Ez) at the photocathode, which limited the achievable extracted bunch charge. To reach the bunch charge goal of approximately few nC with 75 ps full-width at half-maximum Gaussian laser pulse width, the existing DC high voltage photogun electrodes and anode–cathode gap were modified to increase Ez at the photocathode. In addition, the anode aperture was spatially shifted with respect to the beamline longitudinal axis …


Magnetic Field Penetration Technique To Study Field Shielding Of Multilayered Superconductors, Iresha Harshani Senevirathne, Alex Gurevich, Jean R. Delayen, A-M Valente-Feliciano 2022 Old Dominion University

Magnetic Field Penetration Technique To Study Field Shielding Of Multilayered Superconductors, Iresha Harshani Senevirathne, Alex Gurevich, Jean R. Delayen, A-M Valente-Feliciano

Physics Faculty Publications

The SIS structure which consists of alternative thin layers of superconductors and insulators on a bulk niobium has been proposed to shield niobium cavity surface from high magnetic field and hence increase the accelerating gradient. The study of the behavior of multilayer superconductors in an external magnetic field is essential to optimize their SRF performance. In this work we report the development of a simple and efficient technique to measure penetration of magnetic field into bulk, thin film and multilayer superconductors. Experimental setup contains a small superconducting solenoid which can produce a parallel surface magnetic field up to 0.5 T …


Magnetic Field Mapping Of 1.3 Ghz Superconducting Radio Frequency Niobium Cavities, Ishwari P. Parajuli, Gianluigi Ciovati, Jean R. Delayen, Alex V. Gurevich 2022 Old Dominion University

Magnetic Field Mapping Of 1.3 Ghz Superconducting Radio Frequency Niobium Cavities, Ishwari P. Parajuli, Gianluigi Ciovati, Jean R. Delayen, Alex V. Gurevich

Physics Faculty Publications

Niobium is the material of choice to build superconducting radio frequency (SRF) cavities, which are fundamental building blocks of modern particle accelerators. These cavities require a cryogenic cool-down to ~2 - 4 K for optimum performance minimizing RF losses on the inner cavity surface. However, temperature-independent residual losses in SRF cavities cannot be prevented entirely. One of the significant contributor to residual losses is trapped magnetic flux. The flux trapping mechanism depends on different factors, such as surface preparations and cool-down conditions. We have developed a diagnostic magnetic field scanning system (MFSS) using Hall probes and anisotropic magneto-resistance sensors to …


Preliminary Results Of Magnetic And Temperature Map System For 3 Ghz Superconducting Radio Frequency Cavities, Ishwari Parajuli, Bashu Khanal, Gianluigi Ciovati, Jean Delayen, Alex Gurevich 2022 Old Dominion University

Preliminary Results Of Magnetic And Temperature Map System For 3 Ghz Superconducting Radio Frequency Cavities, Ishwari Parajuli, Bashu Khanal, Gianluigi Ciovati, Jean Delayen, Alex Gurevich

Physics Faculty Publications

Superconducting radio frequency (SRF) cavities are fundamental building blocks of modern particle accelerators. When we cool these cavities at cryogenic temperature ~2 – 4 K, we can get optimum performance by minimizing RF losses on the inner cavity surface. However, temperature-independent residual losses in SRF cavities cannot be prevented entirely. One of the leading sources of residual losses in SRF cavities is trapped magnetic flux. The flux trapping mechanism depends on different surface preparations and cool-down conditions. We have designed, developed, and commissioned a combined magnetic (B) and temperature (T) mapping system using anisotropic magneto-resistance (AMR) sensors and carbon resistors …


New Results At Jlab Describing Operating Lifetime Of Gaas Photo-Guns, M. Bruker, J. Grames, C. Hernández-García, M. Poelker, S. Zhang, V. Lizárraga-Rubio, C. Valerio-Lizárraga, Joshua T. Yoskowitz 2022 Old Dominion University

New Results At Jlab Describing Operating Lifetime Of Gaas Photo-Guns, M. Bruker, J. Grames, C. Hernández-García, M. Poelker, S. Zhang, V. Lizárraga-Rubio, C. Valerio-Lizárraga, Joshua T. Yoskowitz

Physics Faculty Publications

Polarized electrons from GaAs photocathodes have been key to some of the highest-impact results of the Jefferson Lab science program over the past 30 years. During this time, various studies have given insight into improving the operational lifetime of these photocathodes in DC high-voltage photo-guns while using lasers with spatial Gaussian profiles of typically 0.5 mm to 1 mm FWHM, cathode voltages of 100 kV to 130 kV, and a wide range of beam currents up to multiple mA. In this contribution, we show recent experimental data from a 100 kV to 180 kV setup and describe our progress at …


197 Mhz Waveguide Loaded Crabbing Cavity Design For The Electron-Ion Collider, Subashini De Silva, Jean Delayen, J. Guo, R. A. Rimmer, Z. Li, B. P. Xiao 2022 Old Dominion University

197 Mhz Waveguide Loaded Crabbing Cavity Design For The Electron-Ion Collider, Subashini De Silva, Jean Delayen, J. Guo, R. A. Rimmer, Z. Li, B. P. Xiao

Physics Faculty Publications

The Elec­tron-Ion Col­lider will re­quire crab­bing sys­tems at both hadron and elec­tron stor­age rings in order to reach the de­sired lu­mi­nos­ity goal. The 197 MHz crab cav­ity sys­tem is one of the crit­i­cal rf sys­tems of the collider. The crab cav­ity, based on the rf-di­pole de­sign, explores the op­tion of wave­guide load damp­ing to sup­press the higher order modes and meet the tight im­ped­ance spec­i­fi­ca­tions. The cav­ity is de­signed with com­pact dog-bone wave­guides with tran­si­tions to rec­tan­gu­lar wave-guides and wave­guide loads. This paper pre­sents the com­pact 197 MHz crab cav­ity de­sign with wave­guide damp­ing and other an­cil­lar­ies.


Preliminary Results From Magnetic Field Scanning System For A Single-Cell Niobium Cavity, Ishwari Prasad Parajuli, Gianluigi Ciovati, Jean R. Delayen, Alex V. Gurevich 2022 Old Dominion University

Preliminary Results From Magnetic Field Scanning System For A Single-Cell Niobium Cavity, Ishwari Prasad Parajuli, Gianluigi Ciovati, Jean R. Delayen, Alex V. Gurevich

Physics Faculty Publications

One of the building blocks of modern particle accelerators is superconducting radiofrequency (SRF) cavities. Niobium is the material of choice to build such cavities, which operate at liquid helium temperature (2 - 4 K) and have some of the highest quality factors found in Nature. There are several sources of residual losses, one of them is trapped magnetic flux, which limits the quality factor in SRF cavities. The flux trapping mechanism depends on different niobium surface preparations and cool-down conditions. Suitable diagnostic tools are not yet available to study the effects of such conditions on magnetic flux trapping. A magnetic …


Structural, Electrical And Optical Properties Of Copper Oxide Phase Mixture: An Active Layer Of Solar Cell, Rifat Ara Shams 2022 Missouri State University

Structural, Electrical And Optical Properties Of Copper Oxide Phase Mixture: An Active Layer Of Solar Cell, Rifat Ara Shams

MSU Graduate Theses

Both CuO and Cu2O have been well studied and implemented individually as an active layer of a solar cell from early age of manufacturing. A mixture of these two-phase contents at different ratios can bring variance in absorbance which can present new and diverse aspect in solar cell fabrication with added efficiency. Previous works were successful to vary the phase mixture, and the nanostructures provided very high absorption co-efficient but poor optical response on electrical conductivity. The goal of this research is to find out the optimum parameter for the phase mixture of copper oxide with high absorption coefficient as …


Field Shielding Of NBT��N Based Multilayer Structure For Accelerating Cavities, Iresha Harshani Senevirathne, Jean R. Delayen, Alex Gurevich, D. R. Beverstock, A.-M. Valente-Feliciano 2022 Old Dominion University

Field Shielding Of NBT��N Based Multilayer Structure For Accelerating Cavities, Iresha Harshani Senevirathne, Jean R. Delayen, Alex Gurevich, D. R. Beverstock, A.-M. Valente-Feliciano

Physics Faculty Publications

Over the past few decades, bulk niobium (Nb) has been the material of choice for superconducting radio frequency (SRF) cavities used in particle accelerators to achieve higher accelerating gradients and lower RF losses. Multi-layer (SIS) structures consisting of alternating thin layers of superconductor(S) and insulator(I) deposited on a bulk Nb have been proposed to enhance the peak surface magnetic field and sustain a higher accelerating gradient. In this study, multilayers based NbTiN and AlN deposited on bulk Nb are used to test the proposed enhancement using the DC magnetic Hall probe technique. The technique detects a penetrating magnetic field through …


Cooling Performance In A Dual Energy Storage Ring Cooler, B. Dhital, Y. S. Derbenev, D. Douglas, G. A. Krafft, H. Zhang, F. Lin, V. S. Morozov, Y. Zhang 2022 Old Dominion University

Cooling Performance In A Dual Energy Storage Ring Cooler, B. Dhital, Y. S. Derbenev, D. Douglas, G. A. Krafft, H. Zhang, F. Lin, V. S. Morozov, Y. Zhang

Physics Faculty Publications

The longitudinal and transverse emittance growth in hadron beams due to intra-beam scattering (IBS) and other heating sources deteriorate the luminosity in a collider. Hence, a strong hadron beam cooling is required to reduce and preserve the emittance. The cooling of high energy hadron beam is challenging. We propose a dual energy storage ring-based electron cooler that uses an electron beam to extract heat away from hadron beam in the cooler ring while the electron beam is cooled by synchrotron radiation damping in the high energy damping ring. In this paper, we present a design of a dual energy storage …


Cebaf Injector Model For KL Beam Conditions, Sunil Pokharel, Geoffrey A. Krafft, A. S. Hofler, R. Kazimi, M. Bruker, J. Grames, S. Zhang 2022 Old Dominion University

Cebaf Injector Model For KL Beam Conditions, Sunil Pokharel, Geoffrey A. Krafft, A. S. Hofler, R. Kazimi, M. Bruker, J. Grames, S. Zhang

Physics Faculty Publications

The Jefferson Lab KL experiment will run at the Continuous Electron Beam Accelerator Facility with a much lower bunch repetition rate (7.80 or 15.59 MHz) than nominally used (249.5 or 499 MHz). While the proposed average current of 2.5 - 5.0 µA is relatively low compared to the maximum CEBAF current of approximately 180 µA, the corresponding bunch charge is atypically high for CEBAF injector operation. In this work, we investigated the evolution and transmission of low-rep-rate, high-bunch-charge (0.32 to 0.64 pC) beams through the CEBAF injector. Using the commercial software General Particle Tracer, we have simulated and analyzed the …


Modeling A Nb3Sn Cryounit In Gpt In Uitf, Sunil Pokharel, Geoffey A. Krafft, A. S. Hofler 2022 Old Dominion University

Modeling A Nb3Sn Cryounit In Gpt In Uitf, Sunil Pokharel, Geoffey A. Krafft, A. S. Hofler

Physics Faculty Publications

Nb₃Sn is a prospective material for future superconducting RF (SRF) accelerator cavities. The material can achieve higher quality factors, higher temperature operation and potentially higher accelerating gradients (E_{acc} 96 MV/m) compared to conventional niobium. In this work, we performed modeling of the Upgraded Injector Test Facility (UITF) at Jefferson Lab utilizing newly constructed Nb₃Sn cavities. We studied the effects of the buncher cavity and varied the gun voltages from 200-500 keV. We have calibrated and optimized the SRF cavity gradients and phases for the Nb₃Sn five-cell cavities energy gains with the framework of General Particle Tracer (GPT). Our calculations show …


Direct Current Magnetic Hall Probe Technique For Measurement Of Field Penetration In Thin Film Superconductors For Superconducting Radio Frequency Resonators, Iresha Harshani Senevirathne, Alex Gurevich, Jean Delayen 2022 Old Dominion University

Direct Current Magnetic Hall Probe Technique For Measurement Of Field Penetration In Thin Film Superconductors For Superconducting Radio Frequency Resonators, Iresha Harshani Senevirathne, Alex Gurevich, Jean Delayen

Physics Faculty Publications

Superconducting Radio Frequency (SRF) cavities used in particle accelerators are typically formed from or coated with superconducting materials. Currently, high purity niobium is the material of choice for SRF cavities that have been optimized to operate near their theoretical field limits. This brings about the need for significant R & D efforts to develop next generation superconducting materials that could outperform Nb and keep up with the demands of new accelerator facilities. To achieve high quality factors and accelerating gradients, the cavity material should be able to remain in the superconducting Meissner state under a high RF magnetic field without …


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