Electron beam trajectory reconstruction for transfer lines

The goal of the AWAKE Run 2a experiment is to study the electron-seeding of the self-modulation of a proton bunch propagating in plasma. To study the dependence of the electron-seeding on the relative alignment between the beams, a method to measure this alignment has been developed. The electron and proton beamlines are brought together into a common line before they are injected into the plasma. The BPMs within the common line cannot be used for electron measurements in the presence of a proton beam as the signal from the proton beam dominates. In this case, the electron beam trajectory through the common line needs reconstructing, event-by-event, using beam trajectory measurements from the first part of the electron line. Here we describe the use of Physics-Guided Neural Networks to propagate the trajectory of the electron beam through the common line to the entrance of the AWAKE plasma cell

TT20 unsplit beam optics for dedicated ECN3 operation

The Transfer Tunnel 20 (TT20) in the CERN North Area (NA) contains transfer lines TT21-25 to transport beam extracted from the Super Proton Synchrotron (SPS). The beam is shared between three primary production targets simultaneously using two sets of Lamberston septa magnets. Proposals for a future facility in the ECN3 underground cavern might require new optics in the TT20 transfer lines to provide high-intensity, `unsplit' beam directly to future NA experiment(s). Here, we present an optics to transmit an unsplit beam through the splitter magnets without collimation and through the transfer lines without losses. The T4 target is unsuitable for high beam intensity and a closed magnetic orbit bump is proposed to bypass the target

SPS MD5044: machine stability characterisation of Gamma Factory SPS Proof-of-Principle Experiment

The Gamma Factory (GF) initiative proposes an innovative method of producing high-energy, high-intensity photon beams via the laser-excitation and subsequent decay of relativistic partially stripped ions stored in the CERN LHC. An initial proof-of-principle experiment in the CERN SPS (GF-SPS-PoP) was proposed in 2019 [3] and would demonstrate the key concepts of this method. Such an experiment would require good control and stability of the SPS beam position and momentum, this was investigated during Machine Development (MD) study 5044. The SPS beam stability at the proposed GF interaction point (IP) location was measured over the millisecond-to-second time-scale. To demonstrate control over the position and angle of the beam at the IP, four-corrector orbit bumps were implemented. The use of radial steering for varying the revolution frequency and, thus, the orbit radius was tested. Here we present the results from these studies towards demonstrating that the stability and control achievable in the CERN SPS would be suitable for the GF Proof-of-Principle experiment

ATF report 2020

The KEK accelerator test faciliry (ATF) conducts R&D on a beam for the Linear Collider. The damping ring provides a low emittance electron beam and the final focus test beamline (ATF2) provides studies on small beam of nanometer level by utilizing a low emittance beam. These R&D are conducted under the ATF international collaboration with many contributions of graduate students around the world. A review meeting to discuss the further studies at ATF will be held on Septem- ber 29, 2020 as a short tele-conference. This report provides the information necessary for discussion. We summarize the remaining studies that will be done in the coming years and ILC preparatory period for further improvements of nanometer beam techno- logy, and the use of ATF facility as a test bench for ILC subsystem in the preparatory period and after. The possible utilizations of the ATF/ATF2 beams for R&D beyond Linear Colliders are also presented

Study of alternative locations for the SPS Beam Dump Facility

As part of the main focus of the BDF Working Group in 2021, this document reports on the study of alternative locations and possible optimisation that may accompany the reuse of existing facilities with the aim of significantly reducing the costs of the facility. Building on the BDF/SHiP Comprehensive Design Study (CDS), the assessment rests on the generic requirements and constraints that allow preserving the physics reach of the facility by making use of the 4 ⇥1019 protons per year at 400 GeV that are currently not exploited at the SPS and for which no existing facility is compatible. The options considered involve the underground areas TCC4, TNC, and ECN3. Recent improvements of the BDF design at the current location (referred to as ‘TT90-TCC9-ECN4’) are also mentioned together with ideas for yet further improvements. The assessments of the alternative locations compiled the large amount of information that is already available together with a set of conceptual studies that were performed during 2021. The document concludes with a qualitative comparison of the options, summarising the associated benefits and challenges of each option, such that a recommendation can be made about which location is to be pursued. The most critical location-specific studies required to specify the implementation and cost for each option are identified so that the detailed investigation of the retained option can be completed before the end of 2022

Findings of the Physics Beyond Colliders ECN3 Beam Delivery Task Force

The ECN3 Beam Delivery Task Force was mandated by the PBC Study Group to assess the technical feasibility of increasing the proton beam intensity to the ECN3 hall of the North Area to satisfy the demands of a compelling set of PBC experimental physics proposals. This report summarises the findings of the Task Force that converge on a technically feasible solution with an implementation timeline that could exploit and build upon the investment already foreseen as part of Phase 1 of the NA-CONS project, and take the SPS complex into a new intensity frontier for Fixed Target physics in Run4

Development of the self-modulation instability of a relativistic proton bunch in plasma

Self-modulation is a beam–plasma instability that is useful to drive large-amplitude wakefields with bunches much longer than the plasma skin depth. We present experimental results showing that, when increasing the ratio between the initial transverse size of the bunch and the plasma skin depth, the instability occurs later along the bunch, or not at all, over a fixed plasma length because the amplitude of the initial wakefields decreases. We show cases for which self-modulation does not develop, and we introduce a simple model discussing the conditions for which it would not occur after any plasma length. Changing bunch size and plasma electron density also changes the growth rate of the instability. We discuss the impact of these results on the design of a particle accelerator based on the self-modulation instability seeded by a relativistic ionization front, such as the future upgrade of the Advanced WAKefield Experiment

The AWAKE Run 2 Programme and Beyond

Plasma wakefield acceleration is a promising technology to reduce the size of particle accelerators. The use of high energy protons to drive wakefields in plasma has been demonstrated during Run 1 of the AWAKE programme at CERN. Protons of energy 400 GeV drove wakefields that accelerated electrons to 2 GeV in under 10 m of plasma. The AWAKE collaboration is now embarking on Run 2 with the main aims to demonstrate stable accelerating gradients of 0.5-1 GV/m, preserve emittance of the electron bunches during acceleration and develop plasma sources scalable to 100s of metres and beyond. By the end of Run 2, the AWAKE scheme should be able to provide electron beams for particle physics experiments and several possible experiments have already been evaluated. This article summarises the programme of AWAKE Run 2 and how it will be achieved as well as the possible application of the AWAKE scheme to novel particle physics experiments.LPA

The AWAKE Run 2 Programme and Beyond

Plasma wakefield acceleration is a promising technology to reduce the size of particle accelerators. The use of high energy protons to drive wakefields in plasma has been demonstrated during Run 1 of the AWAKE programme at CERN. Protons of energy 400 GeV drove wakefields that accelerated electrons to 2 GeV in under 10 m of plasma. The AWAKE collaboration is now embarking on Run 2 with the main aims to demonstrate stable accelerating gradients of 0.5-1 GV/m, preserve emittance of the electron bunches during acceleration and develop plasma sources scalable to 100s of metres and beyond. By the end of Run 2, the AWAKE scheme should be able to provide electron beams for particle physics experiments and several possible experiments have already been evaluated. This article summarises the programme of AWAKE Run 2 and how it will be achieved as well as the possible application of the AWAKE scheme to novel particle physics experiments.De fyra första författarna delar förstaförfattarskapet.</p