The compact linear accelerator for research and applications (CLARA) is an ultrabright electron beam test facility being developed at STFC Daresbury Laboratory. The ultimate aim of CLARA is to test advanced free electron laser (FEL) schemes that can later be implemented on existing and future short-wavelength FELs. In addition, CLARA is a unique facility to provide a high-quality electron beam to test novel concepts and ideas in a wide range of disciplines and to function as a technology demonstrator for a future United Kingdom x-ray FEL facility. CLARA is being built in three phases; the first phase, or front end (FE), comprises an S-band rf photoinjector, a linac, and an S-bend merging with the existing versatile electron linear accelerator beam line; the second phase will complete the acceleration to full beam energy of 250 MeV and also incorporate a separate beam line for use of electrons at 250 MeV; and the third phase will include the FEL section. The CLARA FE was commissioned during 2018, and the facility was later made available for user experiments. Significant advancements have been made in developing high-level software and a simulation framework for start-to-end simulations. The high-level software has been successfully used for unmanned rf conditioning and for characterization of the electron beam. This paper describes the design of the CLARA FE, performance of technical systems, high-level software developments, preliminary results of measured beam parameters, and plans for improvements and upgrades.

Electric dipole moments (EDM) of fundamental particles inherently violate time-reversal (T) and the combined charge-conjugation and parity symmetry (CP). We aim to measure the EDM of the muon using the frozen-spin technique within a compact storage trap. This method exploits the high effective electric field, $$E\approx {165\,\mathrm{MV/m}}$$ E ≈ 165 MV / m , experienced in the rest frame of the muon with a momentum of about $${23\,\mathrm{MeV/}}c$$ 23 MeV / c when it passes through a solenoidal magnetic field of $$|\vec {B}|={2.5\,\textrm{T}}$$ | B → | = 2.5 T . In this paper, we outline the fundamental considerations for a muon EDM search and present a conceptual design for a demonstration experiment to be conducted at secondary muon beamlines of the Paul Scherrer Institute in Switzerland. In Phase I, with an anticipated data acquisition period of 200 days, the expected sensitivity to a muon EDM is $$\sigma (d)\le {4E-21\,\mathrm{{\text {e}}\!\cdot \!\text {cm}}}$$ σ ( d ) ≤ 4 E - 21 e · cm . In a subsequent phase, Phase II, we propose to improve the sensitivity to $$\sigma (d)\le {6E-23\,\mathrm{{\text {e}}\!\cdot \!\text {cm}}}$$ σ ( d ) ≤ 6 E - 23 e · cm using a dedicated instrument installed on a different beamline that produces muons of momentum 125 $$\textrm{MeV}\!/\!{ c}$$ MeV / c .

The compact linear accelerator for research and applications (CLARA) is a 250 MeV ultrabright electron beam test facility at STFC Daresbury Laboratory. A user beamline has been designed to maximize the exploitation of CLARA in a variety of fields, including novel acceleration and new modalities of radiotherapy. In this paper, we present the specification and design of this beamline for full energy beam exploitation. We outline the key elements that will provide users access to ultrashort, low emittance electron bunches in two large experiment chambers. The results of start-to-end simulations are reported that verify the expected beam parameters delivered to these chambers. Key technical systems are detailed, including those which facilitate a combination of electron bunches with high-power laser pulses. Published by the American Physical Society 2024

We present the design, construction, measurement, and troubleshooting of a prototype hybrid Halbach quadrupole magnet. This magnet was significantly under-strength due to local demagnetization in the permanent magnet material. We discuss how this effect was uncovered, how it was verified by performing Hall probe measurements of the individual magnet blocks, and how the effect was reconstructed in simulations.

The UK Extreme Photonics Applications Centre (EPAC) intends to flexibly provide laser-accelerated GeV-scale electrons to a wide array of experiments and like other such facilities must efficiently capture them from a laser-wakefield acceleration (LWFA) source. Here we describe a unique, modular beam capture optics system based on a FODO array of Halbach permanent-magnet quadrupoles and show how that modular arrangement can be used in different configurations to provide energy-selected and focused bunches for different purposes. We present an engineering concept for the beamline that incorporates diagnostics and drive laser extraction and describe the effect of field errors and misalignments and their mitigation.

Boundary Element Methods (BEMs) can be applied to determine the value of the magnetic field at any point within a domain if the magnetic field components are measured on the surface of the domain. For large magnetic volumes, BEMs provide an attractive alternative to fine three-dimensional Hall probe scans for determining the local shape of the field as the fields can be evaluated inside the volume with an arbitrary position and with a reduced measurement time. BEMs have been applied to the field data measured on the boundary of three-dimensional Hall probe scans for two example magnets, which have been measured at STFC Daresbury Laboratory, UK. The fields reconstructed using BEMs are compared to the fields directly measured during the Hall probe scans. The reconstructed fields can be calculated to within 1 mT rms of the directly measured fields. For the transverse field components greater than 1 mT, the fields can be reconstructed to within 5% rms of the directly measured fields.