Continuous wave superconducting radio frequency electron linac for nuclear physics research

Reece, Charles

doi:10.1103/physrevaccelbeams.19.124801

Cited by 31 publications

(26 citation statements)

References 16 publications

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“…The three experimental halls were operated simultaneously with different beam settings, and therefore it was three independent laser beams (operating out of phase with one another) that induced electron beams which then advanced through the injector system [39] [40]. Circularly polarised laser light generated longitudinally polarised electrons (with energy of ∼ 100 keV) via photo-emission from a Gallium Arsenide photoconductor cathode.…”

Section: Injector Systemmentioning

confidence: 99%

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Beam-, Target- and Double- Spin Asymmetry Measurements in Deeply Virtual π0, π+ and π- Meson Production

Murdoch

2019

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This thesis presents measurements of spin asymmetries in single pion electroproduction from the EG1-DVCS experiment carried out at the Thomas Jefferson National Accelerator Facility in 2009 with use of the CEBAF Large Acceptance Spectrometer. The experiment made use of a 6 GeV longitudinally polarised electron beam and (dynamically) longitudinally polarised targets of 14 NH 3 and 14 ND 3 (giving access to protons and deuterons), providing the means to measure three spin asymmetries: beam-, target-, and double-spin. Deeply Virtual Meson Production for the π 0 , π + and π − channels were studied for the kinematic range of Q 2 > 1 GeV 2 and W > 2 GeV. The collection of measurements includes the analysis of numerous reconstruction topologies, as well as making use of different target materials. These are the world's first charged pion spin asymmetry measurements in this kinematic regime. The sPlot maximum likelihood fitbased background subtraction technique was implemented in the data analysis, showing strong agreement with a traditional and commonly used cuts-based approach. This novel technique was thoroughly tested to develop implementation and execution. The results obtained will provide a reference point for future analyses at the upgraded experimental facility and motivate the use of the sPlot technique. These measurements will provide insight into the structure of nucleons through their interpretation in relation to Generalised Parton Distributions which describe substructure correlations between longitudinal momentum and transverse position of partons. In particular, here the spin asymmetries dependence on t, the squared four-momentum transfer to the target nucleon, carries information on the spatial parton distributions in the transverse plane.

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Section: Injector Systemmentioning

confidence: 99%

“…The cavities accelerated the beam of electrons according to well defined resonant electromagnetic fields within the geometry of the chambers. It was the "C50" cryomodule refurbishment project that recovered the accelerator's full 6 GeV beam energy reach in 2009, having been damaged during Hurricane Isabel in 2003 [40].…”

Section: Racetrack and Deliverymentioning

confidence: 99%

Beam-, Target- and Double- Spin Asymmetry Measurements in Deeply Virtual π0, π+ and π- Meson Production

Murdoch

2019

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“…For the sake of completeness, it has to be noted that a two-pass acceleration in a linac can be implemented also with race-track scheme, e.g., the CEBAF one [5] where it has been proven that a beam can be accelerated several times in the same linac, without a two-way region. The drawback is a considerably larger footprint, and radio protected area, that in densely populated areas (e.g., Milano's suburbs) can be a severe issue concerning the costs of real estate necessary for the machine.…”

Section: Introductionmentioning

confidence: 99%

Two-pass two-way acceleration in a superconducting continuous wave linac to drive low jitter x-ray free electron lasers

Bacci

Conti

Bosotti

et al. 2019

Phys. Rev. Accel. Beams

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We present a design study of an innovative scheme to generate high rep rate (MHz-class) GeV electron beams by adopting a two-pass two-way acceleration in a superconducting (SC) linac operated in continuous wave (CW) mode. The electron beam is accelerated twice by being reinjected in opposite direction of propagation into the linac after the first passage. Acceleration in opposite directions is accomplished thanks to standing waves supported in rf cavities. The task of recirculating the electron beam when it leaves the linac after first pass is performed by a bubble-shaped arc compressor composed by a sequence of double bend achromat. In this paper we address the main issues inherent to the two-pass acceleration process and the preservation of the electron beam quality parameters (emittance, energy spread, peak current) required to operate x-ray free electron lasers (FEL) with low jitters in the amplitude, spectral and temporal domain, as achieved by operating in seeding and/or oscillator mode a CW FEL up to 1 MHz rep rate. Detailed start-toend simulations are shown to assess the capability of this new scheme to double the electron beam energy as well as to compress the electron bunch length from picoseconds down to tens of femtoseconds. The advantage of such a scheme is to halve the requested linac length for the same final electron beam energy, which is typically in the few GeV range, as needed to drive an x-ray FEL. The AC power to supply the cryogenic plant is also significantly reduced with respect to a conventional single-pass SC linac for the same final energy. We are reporting also x-ray FEL simulations for typical values of wavelengths of interest (in the 200 eV-8 keV photon energy range) to better illustrate the potentiality of this new scheme.

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“…However, the huge construction and operation costs of the SC linac are critical issues. To reduce these costs, several projects accelerate the electron beam multiple times through the SC linac [19][20][21][22]. In this article, we propose another approach: effective use of an SC linac by sharing of multipurpose tasks.…”

Section: Introductionmentioning

confidence: 99%

Lattice layout and linear optics for sharing superconducting linac

Shimada

2019

Phys. Rev. Accel. Beams

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A superconducting (SC) linac allows a few orders of magnitude larger average beam current than a normal conducting linac, therefore the powerful beam is expected to lead to outstanding discoveries in various scientific fields, such as high luminosity accelerators and high brilliance light source. However, the high construction and operation costs of the SC linac is a critical issue for realizing large scale facilities. To resolve this problem, we propose a continuous wave (cw) operation of an SC linac shared by electron/ positron beams for effective multipurpose utilization. A high current positron source is required for high-energy physics projects: a linear electron-positron collider and a muon collider, while high-current and high-quality electron beams are expected to realize the high brilliant x-ray light sources. As an example, we discuss the injector of the International Linear Collider, an x-ray free-electron laser, and an energy-recovery linac light source. We found a feasible solution of a basic design for the proposed multibeam operation despite the high-quality beam requirements and complicated operation: control of mixed beams without pulsed magnets, and heat load in the cavity, high stability of beam energy, and operation at high average current.

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Continuous wave superconducting radio frequency electron linac for nuclear physics research

Cited by 31 publications

References 16 publications

Beam-, Target- and Double- Spin Asymmetry Measurements in Deeply Virtual π<sup>0</sup>, π<sup>+</sup> and π<sup>-</sup> Meson Production

Beam-, Target- and Double- Spin Asymmetry Measurements in Deeply Virtual π<sup>0</sup>, π<sup>+</sup> and π<sup>-</sup> Meson Production

Two-pass two-way acceleration in a superconducting continuous wave linac to drive low jitter x-ray free electron lasers

Lattice layout and linear optics for sharing superconducting linac

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