Measurements of high-order magnetic field components of permanent quadrupole magnets for a laser-plasma-driven undulator x-ray source

Laser wake-field accelerators as a novel sources of high-energy electron beam are prominent candidates to drive a next generation of compact light sources. Howev-er, to preserve the unique properties of laser-plasma driv-en electron beams, it is crucial to capture the beam direct-ly after the target using quadrupole magnets with ex-tremely high field gradient. We designed and manufac-tured compact permanent quadrupole magnets based on a Halbach design using 12 NdFeB wedges with 1.02 T remanent field which provide field gradients up to ~500 T/m at an aperture radius of only of a few mm. We meas-ured the magnetic field of the permanent magnet quadru-poles using both the pulsed-wire and rotating-coil tech-nique. Here, we present a first analysis of the magnetic field quality, the integrated field gradient and high-order field components. We briefly discuss the influence of field imperfections on the electron beam quality and its consequences for application in the transport line of a laser-plasma-driven undulator X-ray source

Measurements of high-order magnetic field components of permanent quadrupole magnets for a laser-plasma-driven undulator x-ray source

Laser wakefield accelerators as a novel source of high-energy electron beam [1] are prominent candidates to drive a next generation of compact light sources [2,3]. To preserve the unique properties of laser-plasma driven electron beams, it is crucial to capture the beam directly after the target using high field gradient quadrupole magnets [5]. We designed and manufactured compact permanent quadrupole magnets which provide field gradients up to ~500 T/m at an aperture radius of only of a few mm. We measured the magnetic field of the PQM using a pulsed-wire and a rotating-coil technique. Here, we present a first analysis of the field quality and the integrated field gradient. We briefly discuss the influence of field imperfections on the electron beam quality and its consequences for application in the transport line of a laser-plasma-driven undulator X-ray source

Layout considerations for a future electron plasma research accelerator facility EuPRAXIA

International audienceThe Horizon 2020 Project EuPRAXIA (“European Plasma Research Accelerator with eXcellence In Applications”) is preparing a conceptual design for a highly compact and cost-effective European facility with multi-GeV electron beams using plasma as the acceleration medium. The design includes two user areas: one for FEL science and one for High Energy Physics (HEP) detector development and other pilot applications. The accelerator facility will be based on a laser and/or a beam driven plasma acceleration approach. This contribution introduces layout considerations of the future plasma accelerator facilities in the context of EuPRAXIA. It compares conventional and novel plasma accelerator facility requirements and presents potential layouts for the future site. Together with performance analysis, cost effectiveness, and targeted user cases of the individual configurations, such layout studies will later enable a ranking of potential configurations. Based on this information the optimal combination of technologies will be defined for the 2019 conceptual design report of the EuPRAXIA facility

InAs-Al Hybrid Devices Passing the Topological Gap Protocol

We present measurements and simulations of semiconductor-superconductor heterostructure devices that are consistent with the observation of topological superconductivity and Majorana zero modes. The devices are fabricated from high-mobility two-dimensional electron gases in which quasi-one-dimensional wires are defined by electrostatic gates. These devices enable measurements of local and non-local transport properties and have been optimized via extensive simulations for robustness against non-uniformity and disorder. Our main result is that several devices, fabricated according to the design's engineering specifications, have passed the topological gap protocol defined in Pikulin {\it et al.}\ [arXiv:2103.12217]. This protocol is a stringent test composed of a sequence of three-terminal local and non-local transport measurements performed while varying the magnetic field, semiconductor electron density, and junction transparencies. Passing the protocol indicates a high probability of detection of a topological phase hosting Majorana zero modes. Our experimental results are consistent with a quantum phase transition into a topological superconducting phase that extends over several hundred millitesla in magnetic field and several millivolts in gate voltage, corresponding to approximately one hundred micro-electron-volts in Zeeman energy and chemical potential in the semiconducting wire. These regions feature a closing and re-opening of the bulk gap, with simultaneous zero-bias conductance peaks at {\it both} ends of the devices that withstand changes in the junction transparencies. The measured maximum topological gaps in our devices are 20-$30\,\mu$eV. This demonstration is a prerequisite for experiments involving fusion and braiding of Majorana zero modes.Comment: Fixed typos. Fig. 3 is now readable by Adobe Reade

HORIZON 2020 EuPRAXIA Design Study

The Horizon 2020 Project EuPRAXIA (European Plasma Research Accelerator with eXcellence In Applications) aims at producing a design report of a highly compact and cost-effective European facility with multi-GeV electron beams using plasma as the acceleration medium. The accelerator facility will be based on a laser and/or a beam driven plasma acceleration approach and will be used for photon science, high-energy physics (HEP) detector tests, and other applications such as compact X-ray sources for medical imaging or material processing. EuPRAXIA started in November 2015 and will deliver the design report in October 2019. EuPRAXIA aims to be included on the ESFRI roadmap in 2020

Status of the Horizon 2020 EuPRAXIA Conceptual Design Study

The Horizon 2020 Project EuPRAXIA (European Plasma Research Accelerator with eXcellence In Applications) is producing a conceptual design report for a highly compact and cost-effective European facility with multi-GeV electron beams accelerated using plasmas. EuPRAXIA will be set up as a distributed Open Innovation platform with two construction sites, one with a focus on beam-driven plasma acceleration (PWFA) and another site with a focus on laser-driven plasma acceleration (LWFA). User areas at both sites will provide access to FEL pilot experiments, positron generation and acceleration, compact radiation sources, and test beams for HEP detector development. Support centres in four different countries will complement the pan-European implementation of this infrastructure