The main driving part of the X-ray free electron laser facility (SwissFEL) at Paul Scherrer Institute (PSI) is a compact electron linear accelerator (linac). The machine is highly optimized to generate a superior FEL radiation with the lowest suitable electron beam energy. In order to meet extremely stringent SwissFEL require-ments for electron beam quality and stability, a variety of advanced beam diagnostics tools were developed and implemented at PSI. All these tools are integrated into the SwissFEL control system. The paper describes basic control elements of advanced electron beam diagnostics tools and their operational performance.

Magnet measurements at the Paul Scherrer Institute (PSI) are performed with the use of a process control tool (PCT), which is fully integrated into the PSI control system. The tool is implemented as a set of user friendly graphical user interface applications dealing with particular magnet measurement techniques supported at PSI, which include advanced Hall probe, vibrating wire, and moving wire methods. The core of each application is the state machine software developed by magnet measurement and control system experts. Applications act as very efficient assistants to the magnet measurement personnel by monitoring the whole measurement process on-line and helping to react in a timely manner to any possible operational errors. The paper concentrates on the PCT structure and its performance.

An automated tool for converting MATLAB based controls algorithms into C codes executable directly on EPICS process control computers (IOCs), was developed at the Paul Scherrer Institute (PSI). Based on this tool, several high level control applications were embedded into the IOCs, which are directly connected to the control system sensors and actuators. Such embedded applications have significantly reduced the network traffic and, as a result, the controls data handling latency. The paper concentrates on the most important components of the automated tool and some performance results of MATLAB algorithms converted by this tool.

Based on a Mach-Zehnder intensity modulator, Bunch Arrival time Monitor (BAM) is a single-shot nondestructive multi-bunch diagnostic instrument, which measures the arrival time with <10 fs precision in the range of 10-200 pC at 100 Hz repetition rate. Being directly coupled to a length stabilized fiber optical link, it has intrinsically low drift (<10 fs/day) and is thus a useful instrument for the machine feedback. The overall monitor complexity demands the development of an extremely reliable control system that handles basic BAM operations. Two BAM prototypes were successfully used in the SwissFEL Injector Test Facility and further two are being presently commissioned at the SwissFEL. The system is very flexible. It provides a set of tools allowing one to implement a number of advanced control features such as tagging experimental data with a SwissFEL machine pulse number or embedding high level control applications into the process controllers (IOC). The paper presents the structure of the BAM control setup. The operational experience with this setup is also discussed.

3D Hall sensors generally suffer from cross-sensitivity among measurement axes, which limits their accuracy compared to 1D Hall sensors, and complicates their calibration. To overcome these issues, a time-effective and intuitive calibration and field reconstruction method is proposed which is well-suited, but not limited, to a new type of 3D Hall sensor ("Hallcube") consisting of six orthogonally arranged 1D Hall sensors that form a sub-millimeter active volume, and pairwise compensate for the planar Hall effect. Generally, the method is applicable to 3D Hall sensors that are composed of separate 1D Hall sensors, and show negligible planar Hall voltage (inherently or after compensation). The method is based on a twostep calibration scheme: (1) determination of the relative placement of the six constituent Hall sensors, and (2) calibration of each of the six sensors analogously to a standard 1D Hall sensor calibration. From the normal vectors and the voltage-to-magnetic-field characteristic of each sensor, the full magnetic field vector can be reconstructed. The proposed method was applied to the first prototype Hallcube sensor which achieved an accuracy of 800 ppm at the 1 T level for any direction of the field vector. The accuracy limiting factor was the underperformance of the 1D Hall sensors, whose Hall voltages display a long-term instability of >600 ppm. (C) 2017 Elsevier B.V. All rights reserved.

The paper provides mathematics and physics considerations concerning a special class of electron spin manipulating structures for future Electron-Ion Collider (EIC) projects. These structures, which we call Universal Synchronous Spin Rotators (USSR), consist of a sequence of standard basic spin manipulating elements or cells built with two solenoids and one bending magnet between them. When integrated into the ring arcs, USSR structures do not affect the central particle orbit, and their spin transformation functions can be described by a linear mathematical model. In spite of being relatively simple, the model allows one to design spin rotators, which are able to perform spin direction changes from vertical to longitudinal and vice versa in significant continuous intervals of the electron energy. This makes USSR especially valuable tools for EIC nuclear physics experiments.

The SwissFEL Injector Test Facility operated at the Paul Scherrer Institute between 2010 and 2014, serving as a pilot plant and testbed for the development and realization of SwissFEL, the X-ray Free-Electron Laser facility under construction at the same institute. The test facility consisted of a laser-driven rf electron gun followed by an S-band booster linac, a magnetic bunch compression chicane and a diagnostic section including a transverse deflecting rf cavity. It delivered electron bunches of up to 200 pC charge and up to 250 MeV beam energy at a repetition rate of 10 Hz. The measurements performed at the test facility not only demonstrated the beam parameters required to drive the first stage of an FEL facility, but also led to significant advances in instrumentation technologies, beam characterization methods and the generation, transport and compression of ultra-low-emittance beams. We give a comprehensive overview of the commissioning experience of the principal subsystems and the beam physics measurements performed during the operation of the test facility, including the results of the test of an in-vacuum undulator prototype generating radiation in the vacuum ultraviolet and optical range.

A medium energy electron-ion collider is envisioned as the primary future of the JLab nuclear science program beyond the 12 GeV upgraded CEBAF. The present conceptual design selects a ring-ring collider option, covers a CM energy range up to 65 GeV for collisions of polarized electrons with polarized light ions or unpolarized light to heavy ions, and reaches a luminosity at above 10 34 cm -2 s -1 per detector over multiple interaction points. This paper presents a brief description of the current conceptual design of the accelerator.

This document summarizes the design of Jefferson Lab's electron-ion collider, MEIC, as of January 20, 2015, and describes the facility whose cost was estimated for the United States Department of Energy Nuclear Sciences Advisory Committee EIC cost review of January 26-28, 2015. In particular, each of the main technical systems within the collider is presented to the level of the best current information.

For the quadrupole magnets of the future free electron laser facility (SwissFEL) at the Paul Scherrer Institute (PSI), the location of the magnetic axis has to be known to be better than 50 μm, to minimize the commissioning time, and facilitate the final positioning of magnets to an accuracy of 1 μm using beam alignment. For this purpose, the PSI Magnet Section has developed a vibrating wire measurement system with a new type of detector capable of measuring large numbers of magnets in a short period of time. The system has been upgraded and improved so that the total accuracy of finding the magnetic axis is better than 10 μm. A new measurement procedure is described and a method is detailed with which a submicrometer reproducibility of a magnetic axis location is achieved. In addition to the axis offset, the proposed method is applicable to the measurements of the magnet roll angle. With temperature sensors attached to magnets, the method allows for valuable studies of the effect of thermal dilation on the position of the magnetic axis which is of a particular interest for the SwissFEL air cooled quadrupole magnets. Results of measurements performed on SwissFEL prototype quadrupoles with 12 mm aperture are shown.

High brightness electron bunches will be guided in the future Free Electron Laser (SwissFEL) at the Paul Scherrer Institute (PSI) by several hundred magnets. The SwissFEL machine imposes very strict requirements not only at the field quality but also at the mechanical and magnetic alignments of these magnets. To ensure that the magnet specifications are met, and to develop reliable procedures for aligning magnets in the SwissFEL and correcting their field errors during machine operations, the PSI magnet test system was upgraded. The upgraded system is a high precision measurement setup based on Hall probe, rotating coil, vibrating wire and moving wire techniques. It is fully automated and integrated in the PSI controls. The paper describes the main controls components of the new magnet test setup and their performance.

The Free Electron Laser (SwissFEL) Injector Test Facility at the Paul Scherrer Institute has been in operation for more than three years. The Injector Test Facility machine is a valuable development and validation platform for all major SwissFEL subsystems including controls. Based on the experience gained from the Test Facility operations support, the paper presents current and some perspective controls solutions focusing on the future SwissFEL project.

Researchers have envisioned an electron-ion collider with ion species up to heavy ions, high polarization of electrons and light ions, and a well-matched center-of-mass energy range as an ideal gluon microscope to explore new frontiers of nuclear science. In its most recent Long Range Plan, the Nuclear Science Advisory Committee (NSAC) of the US Department of Energy and the National Science Foundation endorsed such a collider in the form of a 'half-recommendation.' As a response to this science need, Jefferson Lab and its user community have been engaged in feasibility studies of a medium energy polarized electron-ion collider (MEIC), cost-effectively utilizing Jefferson Lab's already existing Continuous Electron Beam Accelerator Facility (CEBAF). In close collaboration, this community of nuclear physicists and accelerator scientists has rigorously explored the science case and design concept for this envisioned grand instrument of science. An electron-ion collider embodies the vision of reaching the next frontier in Quantum Chromodynamics - understanding the behavior of hadrons as complex bound states of quarks and gluons. Whereas the 12 GeV Upgrade of CEBAF will map the valence-quark components of the nucleon and nuclear wave functions in detail, an electron-ion collider will determine the largely unknown role sea quarks play andmore » for the first time study the glue that binds all atomic nuclei. The MEIC will allow nuclear scientists to map the spin and spatial structure of quarks and gluons in nucleons, to discover the collective effects of gluons in nuclei, and to understand the emergence of hadrons from quarks and gluons. The proposed electron-ion collider at Jefferson Lab will collide a highly polarized electron beam originating from the CEBAF recirculating superconducting radiofrequency (SRF) linear accelerator (linac) with highly polarized light-ion beams or unpolarized light- to heavy-ion beams from a new ion accelerator and storage complex. Since the very beginning, the design studies at Jefferson Lab have focused on achieving high collider performance, particularly ultrahigh luminosities up to 10{sup 34} cm{sup -2}s{sup -1} per detector with large acceptance, while maintaining high polarization for both the electron and light-ion beams. These are the two key performance requirements of a future electron-ion collider facility as articulated by the NSAC Long Range Plan. In MEIC, a new ion complex is designed specifically to deliver ion beams that match the high bunch repetition and highly polarized electron beam from CEBAF. During the last two years, both development of the science case and optimization of the machine design point toward a medium-energy electron-ion collider as the topmost goal for Jefferson Lab. The MEIC, with relatively compact collider rings, can deliver a luminosity above 10{sup 34} cm{sup -2}s{sup -1} at a center-of-mass energy up to 65 GeV. It offers an electron energy up to 11 GeV, a proton energy up to 100 GeV, and corresponding energies per nucleon for heavy ions with the same magnetic rigidity. This design choice balances the scope of the science program, collider capabilities, accelerator technology innovation, and total project cost. An energy upgrade could be implemented in the future by adding two large collider rings housed in another large tunnel to push the center-of-mass energy up to or exceeding 140 GeV. After careful consideration of an alternative electron energy recovery linac on ion storage ring approach, a ring-ring collider scenario at high bunch repetition frequency was found to offer fully competitive performance while eliminating the uncertainties of challenging RD the third is for low energy ion beams stored in a dedicated low-energy compact storage ring, as a possible follow-on project.« less

This report presents a brief summary of the science opportunities and program of a polarized medium energy electron-ion collider at Jefferson Lab and a comprehensive description of the conceptual design of such a collider based on the CEBAF electron accelerator facility.

The nuclear physics program envisaged at the Medium-energy Electron-Ion Collider (MEIC) currently being developed at the Jefferson Lab calls for collisions of 3-11 GeV/c longitudinally polarized electrons and 20-100 GeV/c, in equivalent proton momentum, longitudinally/ transversely polarized protons/ deuterons/ light ions. We present a scheme that provides the required ion polarization arrangement in the MEIC's ion collider ring.