IPAC2021 - List of Authors (Snively, E.J.C.)

Paper	Title	Page
MOPAB141	Terahertz Driven Compression and Time-Stamping Technique for Single-Shot Ultrafast Electron Diffraction	492
	M.A.K. Othman, A.E. Gabriel, M.C. Hoffmann, F. Ji, E.A. Nanni, X. Shen, E.J.C. Snively, X.J. Wang SLAC, Menlo Park, California, USA
	Funding: This research has been supported by the U.S. Department of Energy (DOE) under Contract No. DE-AC02-76SF00515 and DE-AC02-05-CH11231. Ultrafast structural dynamics are well understood through pump-probe characterization using ultrafast electron diffraction (UED). Advancements in electron diffraction and spectroscopy techniques open new frontiers for scientific discovery through interrogation of ultrafast phenomena, such as quantum phase transitions. Previously, we have demonstrated that strong-field THz radiation can be utilized to efficiently manipulate and compress ultrafast electron probes , and also offer temporal diagnostics with sub-femtosecond resolution * enabled by the inherent phase locking of THz radiation to the photoemission optical drive. In this work, we demonstrate a novel THz compression and time-stamping technique to probe solid-state materials at time scales previously inaccessible with standard UED. A high-frequency THz generation method using the organic OH-1 crystals is employed to enable a threefold reduction in the electron probes length and overall timing jitter. These time-stamped probes are used to demonstrate a substantial enhancement in the UED temporal resolution using pump-probe measurement in both photoexcited single crystal and polycrystalline samples. * E. C. Snively et al., Phys. Rev. Lett, vol. 124, no. 6, p. 054801, 2020. ** R. K. Li et al., Phys. Rev. Accel. Beams, vol. 22, no. 1, p. 012803, Jan. 2019.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB141
About •	paper received ※ 20 May 2021 paper accepted ※ 21 June 2021 issue date ※ 19 August 2021
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THPAB170	RF Deflector Design for Rapid Proton Therapy	4086
	E.J.C. Snively, G.B. Bowden, V.A. Dolgashev, Z. Li, E.A. Nanni, D.T. Palmer, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: This work is supported by US Department of Energy Contract No. DE-AC02-76SF00515. Pencil beam scanning of charged particle beams is a key technology enabling high dose rate cancer therapy. The potential benefits of high-speed dose delivery include not only a reduction in total treatment time and improvements to motion management during treatment but also the possibility of enhanced healthy tissue sparing through the FLASH effect, a promising new treatment modality. We present here the design of an RF deflector operating at 2.856 GHz for the rapid steering of 150 MeV proton beams. The design utilizes a TE11-like mode supported by two posts protruding into a pillbox geometry to form an RF dipole. This configuration provides a significant enhancement to the efficiency of the structure, characterized by a transverse shunt impedance of 68 MOhm/m, as compared to a conventional TM11 deflector. We discuss simulations of the structure performance for several operating configurations including the addition of a permanent magnet quadrupole to amplify the RF-driven deflection. In addition to simulation studies, we will present preliminary results from a 3-cell prototype fabricated using four copper slabs to accommodate the non-axially symmetric cell geometry.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB170
About •	paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 27 August 2021
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THPAB171	mm-Wave Linac Design for Next Generation VHEE Cancer Therapy Systems	4090
	E.J.C. Snively, K.C. Deering, E.A. Nanni SLAC, Menlo Park, California, USA
	Direct electron therapy offers an attractive method for providing the high dose rates necessary for FLASH radiation therapy, a new treatment modality with the potential for enhanced healthy tissue sparing. Direct electron therapy has been limited by the low beam energies, up to 20 MeV, provided by today’s medical linacs, restricting the achievable dose depth to superficial tumors. Very High Energy Electron (VHEE) therapy could reach deep-seated tumors throughout the body. A clinically viable VHEE system must provide electron energies of around 100 MeV in a compact footprint, roughly 1 to 2 meters, with modest power requirements. We investigate the development of mm-wave linacs to provide the necessary beam energies on the sub-meter scale, taking advantage of the favorable scaling of high-frequency operation to support gradients well above 100 MeV/m. We discuss the design parameters necessary for high-efficiency structures, with shunt impedance on the order of 1 GOhm/m, producing high gradients with only a few megawatts of power. We present simulations of cavity performance in the mm-wave operating regime, with an emphasis on compatibility with the requirements of VHEE therapy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB171
About •	paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 15 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Terahertz Driven Compression and Time-Stamping Technique for Single-Shot Ultrafast Electron Diffraction

492

M.A.K. Othman, A.E. Gabriel, M.C. Hoffmann, F. Ji, E.A. Nanni, X. Shen, E.J.C. Snively, X.J. Wang
SLAC, Menlo Park, California, USA

Funding: This research has been supported by the U.S. Department of Energy (DOE) under Contract No. DE-AC02-76SF00515 and DE-AC02-05-CH11231.
Ultrafast structural dynamics are well understood through pump-probe characterization using ultrafast electron diffraction (UED). Advancements in electron diffraction and spectroscopy techniques open new frontiers for scientific discovery through interrogation of ultrafast phenomena, such as quantum phase transitions. Previously, we have demonstrated that strong-field THz radiation can be utilized to efficiently manipulate and compress ultrafast electron probes *, and also offer temporal diagnostics with sub-femtosecond resolution ** enabled by the inherent phase locking of THz radiation to the photoemission optical drive. In this work, we demonstrate a novel THz compression and time-stamping technique to probe solid-state materials at time scales previously inaccessible with standard UED. A high-frequency THz generation method using the organic OH-1 crystals is employed to enable a threefold reduction in the electron probes length and overall timing jitter. These time-stamped probes are used to demonstrate a substantial enhancement in the UED temporal resolution using pump-probe measurement in both photoexcited single crystal and polycrystalline samples.
* E. C. Snively et al., Phys. Rev. Lett, vol. 124, no. 6, p. 054801, 2020.
** R. K. Li et al., Phys. Rev. Accel. Beams, vol. 22, no. 1, p. 012803, Jan. 2019.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB141

About •

paper received ※ 20 May 2021 paper accepted ※ 21 June 2021 issue date ※ 19 August 2021

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB170

RF Deflector Design for Rapid Proton Therapy

4086

E.J.C. Snively, G.B. Bowden, V.A. Dolgashev, Z. Li, E.A. Nanni, D.T. Palmer, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This work is supported by US Department of Energy Contract No. DE-AC02-76SF00515.
Pencil beam scanning of charged particle beams is a key technology enabling high dose rate cancer therapy. The potential benefits of high-speed dose delivery include not only a reduction in total treatment time and improvements to motion management during treatment but also the possibility of enhanced healthy tissue sparing through the FLASH effect, a promising new treatment modality. We present here the design of an RF deflector operating at 2.856 GHz for the rapid steering of 150 MeV proton beams. The design utilizes a TE11-like mode supported by two posts protruding into a pillbox geometry to form an RF dipole. This configuration provides a significant enhancement to the efficiency of the structure, characterized by a transverse shunt impedance of 68 MOhm/m, as compared to a conventional TM11 deflector. We discuss simulations of the structure performance for several operating configurations including the addition of a permanent magnet quadrupole to amplify the RF-driven deflection. In addition to simulation studies, we will present preliminary results from a 3-cell prototype fabricated using four copper slabs to accommodate the non-axially symmetric cell geometry.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB170

About •

paper received ※ 19 May 2021 paper accepted ※ 14 July 2021 issue date ※ 27 August 2021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB171

mm-Wave Linac Design for Next Generation VHEE Cancer Therapy Systems

4090

E.J.C. Snively, K.C. Deering, E.A. Nanni
SLAC, Menlo Park, California, USA

Direct electron therapy offers an attractive method for providing the high dose rates necessary for FLASH radiation therapy, a new treatment modality with the potential for enhanced healthy tissue sparing. Direct electron therapy has been limited by the low beam energies, up to 20 MeV, provided by today’s medical linacs, restricting the achievable dose depth to superficial tumors. Very High Energy Electron (VHEE) therapy could reach deep-seated tumors throughout the body. A clinically viable VHEE system must provide electron energies of around 100 MeV in a compact footprint, roughly 1 to 2 meters, with modest power requirements. We investigate the development of mm-wave linacs to provide the necessary beam energies on the sub-meter scale, taking advantage of the favorable scaling of high-frequency operation to support gradients well above 100 MeV/m. We discuss the design parameters necessary for high-efficiency structures, with shunt impedance on the order of 1 GOhm/m, producing high gradients with only a few megawatts of power. We present simulations of cavity performance in the mm-wave operating regime, with an emphasis on compatibility with the requirements of VHEE therapy.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB171

About •

paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 15 August 2021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)