The CLEAR facility at CERN

CLEAR is a proposed new user facility at CERN dedicated to accelerator R&D.; By reconfiguring the existing CALIFES electron linac, presently used as the probe beam line of CTF3, the new stand-alone user facility - CLEAR - would be available for users from 2017 onwards. The primary focus for CLEAR is general accelerator R&D; and component studies for existing and possible future machines at CERN, based on a broad internal and external user community. The program covers two of the top priorities identified by the European Strategy for Particle Physics, namely the prototyping and validation of accelerator components for the upgrade of the Large Hadron Collider and its injector chain, and studies of high-gradient acceleration methods. The latter cover X-band studies for linear accelerators and also novel concepts as plasma and THz acceleration. The proposed facility would also provide unique training possibilities, as well as irradiation test capability, allowing for example, continuation of the collaboration with the European Space Agency (ESA). An initial five-year program is proposed including a mid-period evaluation. The main input to this program comes from a dedicated workshop held on 10-12 October 2016 at CERN [Workshop INDICO link]. This document presents a summary of the opportunities and ideas discussed during this workshop, emphasizing those where CLEAR offers unique possibilities in the timeframe considered, 2017-21. The R&D; program proposed for 2017 is presented in detail and requires only minor modifications of the existing CALIFES facility. The possibilities for expanding the testing capabilities and improving the beam quality at modest cost in 2018-2019 are discussed, highlighting the performance potential of the facility. Additionally, an outline of the possible R&D; topics for 2018 and beyond is presented, though necessarily in less detail at this stage. The overall resources needed at CERN amount to ~1.7 MCHF/year (material and personnel) from 2017 onwards. This would cover the operation, maintenance and adaptations of the facility. The facility will use one third of the existing CTF3 area and all essential equipment is available. The personnel estimate for operation and maintenance is about 8 FTE out of which four are expected to come from the CLEAR user community. Local support of personnel from external collaborators and fellows is included in the estimate above. The current LC budget at CERN can be re-prioritized to cover these costs without significantly affecting high-priority CLIC deliverables.