Author: Apsimon, O.    [Apsimon, Ö.]
Paper Title Page
MOPOPT054 A Modified Nomarski Interferometer to Study Supersonic Gas Jet Density Profiles 385
 
  • C. Swain, Ö. Apsimon, A. Salehilashkajani, C.P. Welsch, J. Wolfenden, H.D. Zhang
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • Ö. Apsimon, A. Salehilashkajani, C. Swain, C.P. Welsch, J. Wolfenden, H.D. Zhang
    The University of Liverpool, Liverpool, United Kingdom
 
  Funding: This work is supported by the AWAKE-UK phase II project grant No. ST/T001941/1, the STFC Cockcroft core grant No. ST/G008248/1 and the HL-LHC-UK phase II project funded by STFC under Grant Ref: ST/T001925/1.
Gas jet-based non-invasive beam profile monitors, such as those developed for the high luminosity Large Hadron Collider (HL-LHC) upgrade, require accurate, high resolution methods to characterise the supersonic gas jet density profile. This paper proposes a modified Nomarski interferometer to non-invasively study the behaviour of these jets, with nozzle diameters of 1 mm or less in diameter. It discusses the initial design and results, alongside plans for future improvements. Developing systems such as this which can image on such a small scale allows for improved monitoring of supersonic gas jets used in several areas of accelerator science, thus allowing for improvements in the accuracy of experiments they are utilised in.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT054  
About • Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 03 July 2022
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WEPOPT007 First Interaction Region Local Coupling Corrections in the LHC Run 3 1838
 
  • F. Soubelet, T.H.B. Persson, R. Tomás García
    CERN, Meyrin, Switzerland
  • Ö. Apsimon, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: This research is supported by the LIV. DAT Center for Doctoral Training, STFC and the European Organization for Nuclear Research
The successful operation of large scale particle accelerators depends on the precise correction of unavoidable magnetic field or magnet alignment errors present in the machine. During the LHC Run 2, local linear coupling in the interaction regions (IR) was shown to have a significant impact on the beam size, making its proper handling a necessity for Run 3 and the High Luminosity LHC (HL-LHC). A new approach to accurately minimise the local IR linear coupling based on correlated external variables such as the |C-| had been proposed, which relies on the application of a rigid waist shift in order to create an asymmetry in the IR optics. In this contribution, preliminary corrections from the 2021 beam test and the early 2022 commissioning are presented, as well as first results of the new method’s experimental configuration tests in the LHC Run 3 commissioning.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT007  
About • Received ※ 03 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 19 June 2022
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WEPOPT008 Supervised Machine Learning for Local Coupling Sources Detection in the LHC 1842
SUSPMF001   use link to see paper's listing under its alternate paper code  
 
  • F. Soubelet, T.H.B. Persson, R. Tomás García
    CERN, Meyrin, Switzerland
  • Ö. Apsimon, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: This research is supported by the LIV. DAT Center for Doctoral Training, STFC and the European Organization for Nuclear Research
Local interaction region (IR) linear coupling in the LHC has been shown to have a negative impact on beam size and luminosity, making its accurate correction for Run 3 and beyond a necessity. In view of determining corrections, supervised machine learning has been applied to the detection of linear coupling sources, showing promising results in simulations. An evaluation of different applied models is given, followed by the presentation of further possible application concepts for linear coupling corrections using machine learning.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT008  
About • Received ※ 03 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 29 June 2022
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WEPOTK030 Modelling Growth and Asymmetry in Seeded Self-Modulation of Elliptical Beams in Plasma 2122
 
  • A. Perera, Ö. Apsimon, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • Ö. Apsimon, A. Perera, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: This work was supported by STFC UK grant ST/P006752/1. The Authors are grateful for computing time provided by the STFC Scientific Computing Department’s SCARF cluster.
The seeded self-modulation (SSM) of long particle bunches for the generation of gigavolts-per-meter wakefields that can accelerate witness electron beams was first shown using the Super Proton Synchrotron beam as a driver by the AWAKE experiment. The stability of the produced microbunch trains over tens or hundreds of meters is crucial for extrapolating this scheme as proposed for use in several high energy plasma-based linear colliders. However, aside from the competing hosing instability, which has been shown to be suppressible by SSM when that process saturates, few works have examined other effects of transverse asymmetry in this process. Here, we use analytical modelling and 3D particle-in-cell simulations with QuickPIC to characterise the impact on the SSM growth process due to transverse asymmetry in the beam. A metric is constructed for asymmetry in simulation results, showing that the initial azimuthal complexity changes only slightly during SSM growth. Further, we show quantitative agreement between simulations and analytical predictions for the scaling of the reduction SSM growth rate with unequal aspect ratio of the initial beam profile. These results serve to inform planning and tolerances for both AWAKE and other SSM-based novel acceleration methods in the future.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK030  
About • Received ※ 09 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 23 June 2022
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MOPOPT063 Reconstruction of Beam Parameters from Betatron Radiation Using Maximum Likelihood Estimation and Machine Learning 407
 
  • S. Zhang, G. Andonian, C.E. Hansel, P. Manwani, B. Naranjo, M.H. Oruganti, J.B. Rosenzweig, M. Yadav
    UCLA, Los Angeles, California, USA
  • Ö. Apsimon, C.P. Welsch, M. Yadav
    The University of Liverpool, Liverpool, United Kingdom
 
  Funding: US Department of Energy, Division of High Energy Physics, Contract No. DE-SC0009914 STFC Liver-pool Centre for Doctoral Training on Data Intensive Science, grant agreement ST/P006752/1
Betatron radiation that arises during plasma wakefield acceleration can be measured by a UCLA-built Compton spectrometer, which records the energy and angular position of incoming photons. Because information about the properties of the beam is encoded in the betatron radiation, measurements of the radiation can be used to reconstruct beam parameters. One method of extracting information about beam parameters from measurements of radiation is maximum likelihood estimation (MLE), a statistical technique which is used to determine unknown parameters from a distribution of observed data. In addition, machine learning methods, which are increasingly being implemented for different fields of beam diagnostics, can also be applied. We assess the ability of both MLE and other machine learning methods to accurately extract beam parameters from measurements.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT063  
About • Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 24 June 2022 — Issue date ※ 26 June 2022
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MOPOPT066 Gas Sheet Diagnostics Using Particle in Cell Code 410
 
  • M. Yadav, P. Manwani, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • G. Andonian
    RadiaBeam, Santa Monica, California, USA
  • Ö. Apsimon, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • N.M. Cook, A. Diaw, C.C. Hall
    RadiaSoft LLC, Boulder, Colorado, USA
  • N.P. Norvell
    UCSC, Santa Cruz, California, USA
 
  Funding: This work was supported by the STFC Liverpool Centre for Doctoral Training on Data Intensive Science (LIV. DAT) under grant agreement ST/P006752/1 and DE-SC0019717.
When intense particle beam propagates in dense plasma or gas, ionization can yield valuable information on the drive beam properties. Impact ionization and tunnel ionization are the two ionization regimes that must be accounted for varying beam properties. Due to these ionization mechanisms, new plasma electrons are generated causing different instabilities, dependent on the dominant ionization process considered. In order to accomplish the ambitious experimental goals of sophisticated beam diagnostics using ionization imaging, careful studies on the different ionization regimes, and the cross-over periods, required. Here we will discuss the impact ionization using fully parallel PIC code OSIRIS. We focus on understanding the gas sheet ionization diagnostics for characterizing high intensity charged particle beams. We study the interaction of neutral gas with an electron beam and varying density. We will also investigate the principle of detecting photon emission, rather than direct primary ion imaging, from the ionization induced in the interaction between the gas jet and charged particle beams.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT066  
About • Received ※ 07 June 2022 — Revised ※ 19 June 2022 — Accepted ※ 21 June 2022 — Issue date ※ 26 June 2022
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MOPOMS016 Application of Nanostructures and Metamaterials in Accelerator Physics 659
 
  • J. Resta-López
    ICMUV, Paterna, Spain
  • Ö. Apsimon, C. Bonțoiu, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • A. Bonatto
    Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil
  • B. Galante
    CERN, Meyrin, Switzerland
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • G.X. Xia
    UMAN, Manchester, United Kingdom
 
  Funding: This work is supported by the Generalitat Valenciana under Grant agreement No. CIDEGENT/2019/058.
Carbon-based nanostructures and metamaterials offer extraordinary mechanical and opto-electrical properties, which make them suitable for applications in diverse fields, including, for example, bioscience, energy technology and quantum computing. In the latest years, important R&D efforts have been made to investigate the potential use of graphene and carbon-nanotube (CNT) based structures to manipulate and accelerate particle beams. In the same way, the special interaction of graphene and CNTs with charged particles and electromagnetic radiation might open interesting possibilities for the design of compact coherent radiation sources, and novel beam diagnostics techniques as well. This paper gives an overview of novel concepts based on nanostructures and metamaterials with potential application in the field of accelerator physics. Several examples are shown and future prospects discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOMS016  
About • Received ※ 08 June 2022 — Accepted ※ 12 June 2022 — Issue date ※ 13 June 2022  
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WEPOST041 Physical Aspects of Collinear Laser Injection at SLAC FACET-II E-310: Trojan Horse Experiment 1787
 
  • M. Yadav, Ö. Apsimon, E. Kukstas, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • C.E. Hansel, P. Manwani, B. Naranjo, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • B. Hidding
    USTRAT/SUPA, Glasgow, United Kingdom
 
  Funding: This work was performed with support of the US Department of Energy, Division of High Energy Physics, un-der Contract No. DE-SC0009914, and the STFC grant ST/P006752/1.
The Facility for Advanced Accelerator Experimental Tests (FACET-II) is a test accelerator infrastructure at SLAC dedicated to the research and development of advanced accelerator technologies. We performed simulations of electron beam driven wakefields, with collinear lasers used for ionization injection of electrons. We numerically generated a witness beam using the OSIRIS code in an up ramp plasma as well as uniform plasma regimes. We report on challenges and details of the E-310 experiment which aims to demonstrate this plasma photocathode injection at FACET-II. We examine the phenomena beam hosing and drive beam depletion. Details of the witness beam generated are discussed. Computation of betatron-radiation X-ray spatial distribution and critical energy are done for FACET-II low emittance beams.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST041  
About • Received ※ 07 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 21 June 2022 — Issue date ※ 23 June 2022
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WEPOST042 Radiation Diagnostics for AWA and FACET-II Flat Beams in Plasma 1791
 
  • M. Yadav, Ö. Apsimon, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • H.S. Ancelin, G. Andonian, P. Manwani, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
 
  Funding: This work was performed with support of the US Department of Energy, Division of High Energy Physics, under Contract No. DE-SC0009914, DE-SC0017648 - AWA and STFC grant ST/P006752/1 ,
In energy beam facilities like FACET and AWA, beams with highly asymmetric emittance are of interest because they are the preferred type of beam for linear colliders. That is ultimately the motivation: building a plasma based LC. In this case, the blowout region is no longer symmetric around an axis is not equal in the two transverse planes. Focusing is required to keep the particles within the tight apertures and characterizing these accelerators shows the benefits of employing ultra low beam emittances. Beams with high charge and high emittance ratios in excess of 100:1 are available at AWA. If the focusing will not be equal, then we will have different radiation signatures for the flat and symmetric beams in plasma. We use OSIRIS particle-in-cell codes to compare various scenarios including a weak blowout and a strong blowout. Further, we determine the radiation generated in the system by importing particle trajectories into a Liénard Weichert code. We discuss future steps towards full diagnostics of flat beams using radiation.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST042  
About • Received ※ 07 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 20 June 2022 — Issue date ※ 05 July 2022
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WEPOST043 An Effective-Density Model for Accelerating Fields in Laser-Graphene Interactions 1795
 
  • C. Bonțoiu, Ö. Apsimon, E. Kukstas, C.P. Welsch, M. Yadav
    The University of Liverpool, Liverpool, United Kingdom
  • A. Bonatto
    Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil
  • J. Resta-López
    ICMUV, Paterna, Spain
  • G.X. Xia
    UMAN, Manchester, United Kingdom
 
  Funding: This work was supported by STFC Liverpool Centre for Doctoral Training on Data Intensive Science (LIV. DAT)
With the advancement of high-power UV laser technology, the use of nanostructures for particle acceleration attracts renewed interest due to its possibility of achieving TV/m accelerating gradients in solid state plasmas. Electron acceleration in ionized materials such as carbon nanotubes and graphene is currently considered as a potential alternative to the usual laser wakefield acceleration (LWFA) schemes. An evaluation of the suitability of a graphene target for LWFA can be carried out using an effective density model, thus replacing the need to model each layer. We present a 2D evaluation of the longitudinal electric field driven by a short UV laser pulse in a multi-layer graphene structure, showing that longitudinal fields of ~5 TV/m are achievable.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST043  
About • Received ※ 20 May 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 20 June 2022
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WEPOST045 Simulating Enhanced Focusing Effects of Ion Motion in Adiabatic Plasmas 1798
 
  • D.R. Chow, C.E. Hansel, P. Manwani, J.B. Rosenzweig, M. Yadav
    UCLA, Los Angeles, California, USA
  • Ö. Apsimon, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
 
  Funding: This work was performed with support of the US Department of Energy, Division of High Energy Physics, under Contract No. DE-SC0009914, and the STFC Liverpool Centre for Doctoral Training on Data Intensive Science (LIV. DAT) under grant agreement ST/P006752/1.
The FACET-II facility offers the unique opportunity to study low emittance, GeV beams and their interactions with high density plasmas in plasma wakefield acceleration (PWFA) scenarios. One of the experiments relevant to PWFA research at FACET-II is the ion collapse experiment E-314, which aims to study how ion motion in a PWFA can produce dual-focused equilibrium. As nonlinear focusing effects due to nonuniform ion distributions have not been extensively studied; we explore the difficulties of inducing ion motion in an adiabatic plasma and examines the effect an ion column has on beam focusing. A case study is performed on a system containing a plasma lens and adiabatic PWFA. Ions in the lens section are assumed to be static, while simulations of an adiabatic matching section are modified to include the effects of ion column collapse and their nonlinear focusing fields. Using the parameters of the FACET-II beam, we find that a collapsed ion column amplifies the focusing power of a plasma without compromising emittance preservation. This led to a spot size orders of magnitude less than that of a simply matched beam.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST045  
About • Received ※ 07 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 25 June 2022
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