20th Advanced Accelerator Concepts Workshop

6 Nov 2022, 15:00 → 11 Nov 2022, 17:10 America/New_York

Hyatt Regency Long Island

Mark Palmer (Brookhaven National Laboratory) , Navid Vafaei-Najafabadi (Stony Brook University)

The AAC’22 workshop is the 20th in a series of by-invitation biennial fora for intensive discussions on long-term research in advanced accelerator physics and technology. This research supports the development of capabilities for the basic sciences, from photon science to high energy physics, as well as the development of compact accelerators for industrial, medical and security applications.

AAC'22 will be organized into eight working groups covering the following topical areas:

1. Laser-Plasma Wakefield Acceleration 
2. Computation for Accelerator Physics
3. Laser and High-Gradient Structure-Based Acceleration
4. Beam-Driven Acceleration
5. Beam Sources, Monitoring, and Control
6. Laser-Plasma Acceleration of Ions
7. Radiation Generation and Advanced Concepts
8. Advanced Laser and Beam Technology and Facilities

Conference Home:  https://www.aac2022.org/

 

Sunday, 6 November

18:00 → 19:30 Welcome Reception

Monday, 7 November

10:20 → 10:40 Coffee Break

12:10 → 13:30 Lunch

15:00 → 15:30 Coffee Break

Tuesday, 8 November

10:00 → 10:30 Coffee Break

12:00 → 13:20 Lunch

15:00 → 15:30 Coffee Break/Exhibits

Wednesday, 9 November

10:00 → 10:30 Coffee Break/Exhibits

12:00 → 13:20 Lunch

13:30 → 15:00 WGs 4+7 Joint Session: Session 1 of 1

Joint session of working groups 4 & 7:
WG4 - Beam-Driven Acceleration
WG7 - Radiation Generation and Advanced Concepts

Conveners: Jens Osterhoff (DESY) , John Palastro (University of Rochester, Laboratory for Laser Energetics) , Julia Mikhailova, Spencer Gessner (SLAC)

13:30 FACET-II E-305: Beam filamentation and bright gamma-ray bursts

Relativistic streaming plasma instabilities and their growth rates are subject of research for the description of jet-like astrophysical plasmas due to their strong influence on energy transfer between plasma-constituent, electromagnetic fields and photons. Therefore, these instabilities are of relevance in the description of highly energetic astrophysical phenomena such as e.g. the formation of gamma-ray bursts.
Moreover, recent studies indicate that the magnetic fields arising from the transverse filamentation instability in relativistic electron beams can be harnessed to generate intense gamma-ray flashes from synchrotron-like radiation.
The E-305 collaboration aims to study relativistic beam-plasma instabilities with the 10 GeV electron beam of unprecedented intensity provided by FACET-II at SLAC National Accelerator Laboratory. By propagating the beam through solid-density targets and high-density gas jets the dynamic of instabilities will be probed and the efficacy of gamma-ray generation will be evaluated.
We report on the status of commissioning efforts and first experimental results attained in recent beamtime. Next steps, goals and prospects will be discussed.

Speaker: Alexander Knetsch

AAC2022_E305.pdf

13:50 First X-ray and Gamma-ray measurements at FACET-II

The upgraded Facility for Advanced Accelerator Experimental Tests (FACET-II) at SLAC has started delivering the first electron beams for the initial phase of several experimental campaigns hosted at the facility. During these first runs, the users have been able to test and commission different elements of their set-up, but also to obtain preliminary data to characterise the experimental conditions. For most of these experiments, the X-ray and gamma radiation detectors installed at the end of the FACET-II beam line have provided a very useful insight of the different beam-plasma and beam-laser interactions. In this talk we will present the initial design, commissioning phase, and first preliminary data of the X-ray and gamma radiation diagnostics taken during these initial runs.

This presentation will cover the use of these detectors in the context of three different experiments. First, the E300 (PWFA) experiment~[C. Joshi \emph{et al.}, Plasma Phys. Control. Fusion 60, 034001 (2018)] will rely on these detectors to measure the matching dynamics of the accelerated trailing beam in the plasma~[P. San Miguel Claveria \emph{et al.}, Phil. Trans. R. Soc. A 377, 20180173 (2019)]. During the initial runs, a beam-ionised $\rm H_2$ plasma of several meters of length was used to produce betatron radiation and measure it with the detectors, enabling the characterisation of the spatial and spectral distribution of the radiation at different plasma densities. This, together with the comparison of the data taken at FACET-I, confirms the physical basis of the working principle of the detectors. Similarly, in the context of the E305 experiment (Beam filamentation and bright gamma-ray bursts) the radiation produced in the beam-plasma interaction using a laser-ionised high density plasma has been measured at different gas-jet backing pressures. Finally, preliminary measurements of the bremsstrahlung radiation emitted in the interaction of the electron beam with solid foils and inverse-Compton radiation emitted in the beam-laser collision (E320, Strong-Field QED experiment) will be presented.

Speaker: Pablo San Miguel (Laboratoire d'Optique Appliquée / Instituto Superior Técnico)

AAC_2022_E300_GAMMAS_PSanMiguel.pdf

14:10 Positron Driven High-Field Terahertz Waves via Dielectric Wakefield Interaction

Advanced acceleration methods based on wakefields generated by high energy electron bunches passing through dielectric-based structures have demonstrated >GV/m fields, paving the first steps on a path to applications such as future compact linear colliders. For a collider scenario, it is desirable that, in contrast to plasmas, wakefields in dielectrics do not behave differently for positron and electron bunches. In this article, we present measurements of large amplitude fields excited by positron bunches with collider-relevant parameters (energy 20 GeV, and 0.7x10^10 particles per bunch) in a 0.4 THz, cylindrically symmetric dielectric structure. Interferometric measurements of emitted coherent Cerenkov radiation permit spectral characterization of the positron-generated wakefields, which are compared to those excited by electron bunches. Statistical equivalence tests are incorporated to show the charge-sign invariance of the induced wakefield spectra. Transverse effects on positron beams resulting from off-axis excitation are examined and found to be consistent with the known linear response of the DWA system. The results are supported by numerical simulations and demonstrate high-gradient wakefield excitation in dielectrics for positron beams.

Speaker: Nathan Majernik

Majernik - Positron DWA.pdf

14:30 First results from the E332 Experiment Studying the Near-Field-CTR-based Self-Focusing Effect with High Intensity Electron Beams at FACET-II

The Near-Field Coherent Transition Radiation (NF-CTR) generated in the passage of an intense, highly compressed electron beam through a foil produces surface fields that can provide a strong self-focusing force back on the beam itself, and the intense emission of gamma-rays by the beam. This self-focusing effect can be enhanced by passing the beam through multiple foils of order micrometer thickness. The E332 experiment taking place at FACET-II at the SLAC National Accelerator Laboratory will investigate this interaction using the unprecedented beam intensities that will be provided by the facility. In the initial experimental run of FACET-II, the experiment used single foils of varying thickness to develop beam delivery and diagnostic tools, to understand the damage mechanism to the foils by the high intensity beams, and to search for evidence of the NF-CTR focusing effect. The status, first results, and future plans of the E332 experiment will be discussed. The mechanism and observations of beam heating damage to the foils will also be presented.

Speaker: Doug Storey (SLAC National Accelerator Laboratory)

dstorey_AAC2022_E332_NFCTR.pdf

Thursday, 10 November

10:00 → 10:30 Coffee Break/Exhibits

12:00 → 13:20 Lunch

15:00 → 18:00 Afternoon at Leisure

Friday, 11 November

10:00 → 10:30 Coffee Break

12:00 → 13:00 Lunch

14:40 → 15:00 Coffee Break