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Full-Text Articles in Physics
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
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 …
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
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
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.
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
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 …
Modeling A Nb3Sn Cryounit In Gpt In Uitf, Sunil Pokharel, Geoffey A. Krafft, A. S. Hofler
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 …
Lower Temperature Annealing Of Vapor Diffused Nb3Sn For Accelerator Cavities, Jayendrika K. Tiskumara, Jean R. Delayen, G. V. Eremeev, U. Pudasaini
Lower Temperature Annealing Of Vapor Diffused Nb3Sn For Accelerator Cavities, Jayendrika K. Tiskumara, Jean R. Delayen, G. V. Eremeev, U. Pudasaini
Physics Faculty Publications
Nb3Sn is a next-generation superconducting material for the accelerator cavities with higher critical temperature and superheating field, both twice compared to Nb. It promises superior performance and higher operating temperature than Nb, resulting in significant cost reduction. So far, the Sn vapor diffusion method is the most preferred and successful technique to coat niobium cavities with Nb3Sn. Although several post-coating techniques (chemical, electrochemical, mechanical) have been explored to improve the surface quality of the coated surface, an effective process has yet to be found. Since there are only a few studies on the post-coating heat treatment …
Improved Electrostatic Design Of The Jefferson Lab 300 Kv Dc Photogun And The Minimization Of Beam Deflection, M. A. Mamun, D. B. Bullard, J. R. Delayen, J. M. Grames, C. Hernandez-Garcia, Geoffrey A. Krafft, M. Poelker, R. Suleiman, S.A.K. Wijethunga
Improved Electrostatic Design Of The Jefferson Lab 300 Kv Dc Photogun And The Minimization Of Beam Deflection, M. A. Mamun, D. B. Bullard, J. R. Delayen, J. M. Grames, C. Hernandez-Garcia, Geoffrey A. Krafft, M. Poelker, R. Suleiman, S.A.K. Wijethunga
Physics Faculty Publications
An electron beam with high bunch charge and high repetition rate is required for electron cooling of the ion beam to achieve the high luminosity required for the proposed electron-ion colliders. An improved design of the 300 kV DC high voltage photogun at Jefferson Lab was incorporated toward overcoming the beam loss and space charge current limitation experienced in the original design. To reach the bunch charge goal of ~ few nC within 75 ps bunches, the existing DC high voltage photogun electrodes and anode-cathode gap were modified to increase the longitudinal electric field (Ez) at the photocathode. The anode-cathode …
Few Body Effects In The Electron And Positron Impact Ionization Of Atoms, R. I. Campeanu, Colm T. Whelan
Few Body Effects In The Electron And Positron Impact Ionization Of Atoms, R. I. Campeanu, Colm T. Whelan
Physics Faculty Publications
Triple differential cross sections (TDCS) are presented for the electron and positron impact ionization of inert gas atoms in a range of energy sharing geometries where a number of significant few body effects compete to define the shape of the TDCS. Using both positrons and electrons as projectiles has opened up the possibility of performing complementary studies which could effectively isolate competing interactions that cannot be separately detected in an experiment with a single projectile. Results will be presented in kinematics where the electron impact ionization appears to be well understood and using the same kinematics positron cross sections will …
Design Of An Rf-Dipole Crabbing Cavity System For The Electron-Ion Collider, Subashini U. De Silva, Jean R. Delayen, H. Park, F. Marhauser, J. Henry, R. A. Rimmer
Design Of An Rf-Dipole Crabbing Cavity System For The Electron-Ion Collider, Subashini U. De Silva, Jean R. Delayen, H. Park, F. Marhauser, J. Henry, R. A. Rimmer
Physics Faculty Publications
The Electron-Ion Collider requires several crabbing systems to facilitate head-on collisions between electron and proton beams in increasing the luminosity at the interaction point. One of the critical rf systems is the 197 MHz crabbing system that will be used in crabbing the proton beam. Many factors such as the low operating frequency, large transverse voltage requirement, tight longitudinal and transverse impedance thresholds, and limited beam line space makes the crabbing cavity design challenging. The rf-dipole cavity design is considered as one of the crabbing cavity options for the 197 MHz crabbing system. The cavity is designed including the HOM …
Redesign Of The Jefferson Lab -300 Kv Dc Photo-Gun For High Bunch Charge Operations, S.A.K. Wijethunga, J. Benesch, Jean R. Delayen, C. Hernandez-Garcia, Geoffrey A. Krafft, Gabriel Palacios-Serrano, M.A. Mamun, M. Poelker, R. Suleiman
Redesign Of The Jefferson Lab -300 Kv Dc Photo-Gun For High Bunch Charge Operations, S.A.K. Wijethunga, J. Benesch, Jean R. Delayen, C. Hernandez-Garcia, Geoffrey A. Krafft, Gabriel Palacios-Serrano, M.A. Mamun, M. Poelker, R. Suleiman
Physics Faculty Publications
Production of high bunch charge beams for the ElectronIon Collider (EIC) is a challenging task. High bunch charge (a few nC) electron beam studies at Jefferson Lab using an inverted insulator DC high voltage photo-gun showed evidence of space charge limitations starting at 0.3 nC, limiting the maximum delivered bunch charge to 0.7 nC for beam at -225 kV, 75 ps (FWHM) pulse width, and 1.64 mm (rms) laser spot size. The low extracted charge is due to the modest longitudinal electric field (Ez) at the photocathode leading to beam loss at the anode and downstream beam pipe. To reach …
A Hard X-Ray Compton Source At Cbeta, K.E. Deitrick, J. Crone, C. Franck, G.H. Hoffstaetter, Geoffrey A. Krafft, B. D. Muratori, H. L. Owen, Balša Terzić, P. H. Williams
A Hard X-Ray Compton Source At Cbeta, K.E. Deitrick, J. Crone, C. Franck, G.H. Hoffstaetter, Geoffrey A. Krafft, B. D. Muratori, H. L. Owen, Balša Terzić, P. H. Williams
Physics Faculty Publications
Inverse Compton scattering (ICS) holds the potential for future high flux, narrow bandwidth x-ray sources driven by high quality, high repetition rate electron beams. CBETA, the Cornell-BNL Energy recovery linac (ERL) Test Accelerator, is the world’s first superconducting radiofrequency multi-turn ERL, with a maximum energy of 150 MeV, capable of ICS production of x-rays above 400 keV. We present an update on the bypass design and anticipated parameters of a compact ICS source at CBETA. X-ray parameters from the CBETA ICS are compared to those of leading synchrotron radiation facilities, demonstrating that, above a few hundred keV, photon beams produced …
Beam Dynamics Study In A Dual Energy Storage Ring For Ion Beam Cooling*, B. Dhital, Y. S. Derbenev, D. Douglas, A. Hutton, Geoffrey A. Krafft, F. Lin, V. S. Morozov, Y. Zhang
Beam Dynamics Study In A Dual Energy Storage Ring For Ion Beam Cooling*, B. Dhital, Y. S. Derbenev, D. Douglas, A. Hutton, Geoffrey A. Krafft, F. Lin, V. S. Morozov, Y. Zhang
Physics Faculty Publications
A dual energy storage ring designed for beam cooling consists of two closed rings with significantly different energies: the cooling and damping rings. These two rings are connected by an energy recovering superconducting RF structure that provides the necessary energy difference. In our design, the RF acceleration has a main linac and harmonic cavities both running at crest that at first accelerates the beam from low energy E_{L} to high energy E_{H} and then decelerates the beam from E_{H} to E_{L} in the next pass. The purpose of the harmonic cavities is to extend the bunch length in a dual …
Comparing Proton Momentum Distributions In A = 2 And 3 Nuclei Via 2H 3H And 3He (E,E′P) Measurements, R. Cruz-Torres, F. Hauenstein, A. Schmidt, D. Nguyen, D. Abrams, H. Albataineh, S. Alsalmi, D. Androic, K. Aniol, W. Armstrong, J. Arrington, H. Atac, D. Bulumulla, C. E. Hyde, V. Khachatryan, M. N.H. Rashad, L. B. Weinstein, Z. Y. Ye, J. Zhang, Jefferson Lab Hall A Tritium Collaboration
Comparing Proton Momentum Distributions In A = 2 And 3 Nuclei Via 2H 3H And 3He (E,E′P) Measurements, R. Cruz-Torres, F. Hauenstein, A. Schmidt, D. Nguyen, D. Abrams, H. Albataineh, S. Alsalmi, D. Androic, K. Aniol, W. Armstrong, J. Arrington, H. Atac, D. Bulumulla, C. E. Hyde, V. Khachatryan, M. N.H. Rashad, L. B. Weinstein, Z. Y. Ye, J. Zhang, Jefferson Lab Hall A Tritium Collaboration
Physics Faculty Publications
We report the first measurement of the (e, e' p) reaction cross-section ratios for Helium-3 (3He), Tritium (3H), and Deuterium (d). The measurement covered a missing momentum range of 40 ≤ pmiss ≤ 550 MeV/c, at large momentum transfer ({Q2} ≈ 1.9 (GeV/c)2) and xB > 1, which minimized contributions from non quasi-elastic (QE) reaction mechanisms. The data is compared with planewave impulse approximation (PWIA) calculations using realistic spectral functions and momentum distributions. The measured and PWIA-calculated cross-section ratios for 3He/d and 3H/d extend to just above the typical …
Compact Srf Linac For High Brilliance Inverse Compton Scattering Light Source, Kirsten E. Deitrick, Jean R. Delayen, Geoffrey A. Krafft, Balša Terzić
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.
The Us Electron Ion Collider Accelerator Designs, A. Seryi, S.V. Benson, S.A. Bogacz, P.D. Brindza, M.W. Brucker, A. Camsonne, E. Daly, P.V. Degtiarenko, Y.S. Derbenev, M. Diefenthaler, J. Dolbeck, R. Ent, R. Fair, D. Fazenbaker, Y. Furletova, B.R. Gamage, D. Gaskell, R.L. Geng, P. Ghoshal, R.C. York, Et Al.
The Us Electron Ion Collider Accelerator Designs, A. Seryi, S.V. Benson, S.A. Bogacz, P.D. Brindza, M.W. Brucker, A. Camsonne, E. Daly, P.V. Degtiarenko, Y.S. Derbenev, M. Diefenthaler, J. Dolbeck, R. Ent, R. Fair, D. Fazenbaker, Y. Furletova, B.R. Gamage, D. Gaskell, R.L. Geng, P. Ghoshal, R.C. York, Et Al.
Physics Faculty Publications
With the completion of the National Academies of Sciences Assessment of a US Electron-Ion Collider, the prospects for construction of such a facility have taken a step forward. This paper provides an overview of the two site-specific EIC designs: JLEIC (Jefferson Lab) and eRHIC (BNL) as well as brief overview of ongoing EIC R&D.
Analysis Of Higher Order Multipoles Of The 952.6 Mhz Rf-Dipole Crabbing Cavity For The Jefferson Lab Electron Ion Collider, Subashini U. De Silva, J. R. Delayen, V. S. Morozov, H. Park, S. Sosa
Analysis Of Higher Order Multipoles Of The 952.6 Mhz Rf-Dipole Crabbing Cavity For The Jefferson Lab Electron Ion Collider, Subashini U. De Silva, J. R. Delayen, V. S. Morozov, H. Park, S. Sosa
Physics Faculty Publications
The crabbing system is a key feature in the Jefferson Lab Electron-Ion Collider (JLEIC) required to increase the luminosity of the colliding bunches. A local crabbing system will be installed with superconducting rf-dipole crabbing cavities operating at 952.6 MHz. The field non-uniformity across the beam aperture in the crabbing cavities produces higher order multipole components, similar to that which are present in magnets. Knowledge of higher order mode multipole field effects is important for accurate beam dynamics study for the crabbing system. In this paper, we quantify the multipole components and analyse their effects on the beam dynamics.
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
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 …
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
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 …
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
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 …
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
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
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.
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
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 …
Design Of A Proof-Of-Principle Crabbing Cavity For The Jefferson Lab Electron-Ion Collider, Hyekyoung Park, Subashini U. De Silva, Salvador I. Sosa Guitron, Jean R. Delayen
Design Of A Proof-Of-Principle Crabbing Cavity For The Jefferson Lab Electron-Ion Collider, Hyekyoung Park, Subashini U. De Silva, Salvador I. Sosa Guitron, Jean R. Delayen
Physics Faculty Publications
The Jefferson Lab design for an electron-ion collider (JLEIC) requires crabbing of the electron and ion beams in order to achieve the design luminosity. A number of options for the crabbing cavities have been explored, and the one which has been selected for the proof-of-principle is a 952 MHz, 2-cell rf-dipole (RFD) cavity. This paper summarizes the electromagnetic design of the cavity and its HOM characteristics.
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
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 …
Electron-Ion Collider Performance Studies With Beam Synchronization Via Gear-Change, I. Neththikumara, Geoffrey A. Krafft, Y. Roblin, Balša Terzić
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 …
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
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.
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
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 …
Mobile Free-Electron Laser For Remote Atmospheric Survey, S. Johnson, Balša Terzić, Geoffrey A. Krafft
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 …
Harmonically Resonant Cavity As A Bunch Length Monitor, B. Roberts, M. Pablo, E. Forman, J. Grames, F. Hannon, R.Kazimi W. Moore, M. M. Ali
Harmonically Resonant Cavity As A Bunch Length Monitor, B. Roberts, M. Pablo, E. Forman, J. Grames, F. Hannon, R.Kazimi W. Moore, M. M. Ali
Physics Faculty Publications
A compact, harmonically-resonant cavity with a fundamental resonant frequency of 1497 MHz was used to evaluate the temporal characteristics of electron bunches produced by a 130 kV dc high voltage spin-polarized photoelectron source at the Continuous Beam Accelerator Facility (CEBAF) photoinjector, delivered at 249.5 and 499 MHz repetition rates and ranging in width from 45 to 150 picoseconds (FWHM). The cavity’s antenna was attached directly to a sampling oscilloscope that detected the electron bunches as they passed through the cavity bore with a sensitivity of ~ mV/ μA. The oscilloscope wave-forms are a superposition of the harmonic modes excited by …
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
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.