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J. Frisch

Publications and source records attributed to J. Frisch.

8 recordsLinked to original sources
arXiv2019

SLAC UED LLRF System Upgrade

The SLAC mega-electron-volt (MeV) ultrafast electron diffraction (UED) instrument is a powerful "electron camera" for the study of time-resolved, ultrafast atomic & molecular dynamics in chemical and solid-state systems. The UED laser timing synchronization is upgraded to SLAC (Advanced Telecommunications Computing Architecture) ATCA based femtosecond laser timing synchronization system. UED radio frequency (RF) gun cavity low level RF (LLRF) control is also being upgraded to SLAC ATCA based LLRF system to provide improved performance and maintainability. The new laser timing synchronization and LLRF control are implemented in one ATCA crate located in the laser room. A 2nd ATCA crate is set up to monitor the Klystron and sub-booster performance. With the ATCA based RF control system, the laser timing jitter has achieved 10 fs. The UED operation beam rate is being upgraded from 180 Hz to 360 Hz, which paves the way for a further upgrade of operation beam rate to 1 kHz in the future. In this paper, we present design details and characterization results of the implementation.

physics.acc-ph↗
arXiv2019

ATCA LLRF System for ASU Compact FEL

SLAC National Accelerator Laboratory is collaborating with Arizona State University to design a LLRF system towards the advancement of the ASU Compact X-ray Light Source (CXLS). The CXLS is a phased project to develop small brilliant x-ray sources that may produce coherent x-rays appropriate as a seed source for LCLS and LCLS II. The CXLS electron beam is produced by an x-band photoinjector and linac operating at 9.3 GHz RF frequency and 1 kHz repetition rate with up to 300 pC per bunch. The linac consists of 3 short 20-cell sections of standing wave linac. The RF gun and linac sections are powered by two 6 MW transmitters using L3 klystrons and Scandi-nova K1 modulators. The accelerator will initially operate in single-bunch mode and may be upgraded to multi-bunch operation at a later date. SLAC National Laboratory has developed a LLRF system in Advanced Telecommunication Computing Architecture (ATCA) for the ASU project. This talk will discuss the design of the LLRF for this project and discuss the ATCA implementation.

physics.acc-ph↗
arXiv2015

Direct observation and imaging of a spin-wave soliton with $p-$like symmetry

The prediction and realization of magnetic excitations driven by electrical currents via the spin transfer torque effect, enables novel magnetic nano-devices where spin-waves can be used to process and store information. The functional control of such devices relies on understanding the properties of non-linear spin-wave excitations. It has been demonstrated that spin waves can show both an itinerant character, but also appear as localized solitons. So far, it was assumed that localized solitons have essentially cylindrical, $s-$like symmetry. Using a newly developed high-sensitivity time-resolved magnetic x-ray microscopy, we instead observe the emergence of a novel localized soliton excitation with a nodal line, i.e. with $p-$like symmetry. Micromagnetic simulations identify the physical mechanism that controls the transition from $s-$ to $p-$like solitons. Our results suggest a potential new pathway to design artificial atoms with tunable dynamical states using nanoscale magnetic devices.

cond-mat.mes-hall↗
arXiv2014

Laser Wire Scanner Compton Scattering Techniques for the Measurement of the Transverse Beam Size of Particle Beams at Future Linear Colliders

This archive summarizes a working paper and conference proceedings related to laser wire scanner development for the Future Linear Collider (FLC) in the years 2001 to 2006. In particular the design, setup and data taking for the laser wire experiments at PETRA II and CT2 are described. The material is focused on the activities undertaken by Royal Holloway University of London (RHUL).

physics.acc-ph↗
arXiv2013

Cavity beam position monitor system for the Accelerator Test Facility 2

The Accelerator Test Facility 2 (ATF2) is a scaled demonstrator system for final focus beam lines of linear high energy colliders. This paper describes the high resolution cavity beam position monitor (BPM) system, which is a part of the ATF2 diagnostics. Two types of cavity BPMs are used, C-band operating at 6.423 GHz, and S-band at 2.888 GHz with an increased beam aperture. The cavities, electronics, and digital processing are described. The resolution of the C-band system with attenuators was determined to be approximately 250 nm and 1 m for the S-band system. Without attenuation the best recorded C-band cavity resolution was 27 nm.

physics.acc-ph↗
arXiv2005

A Test Facility for the International Linear Collider at SLAC End Station A, for Prototypes of Beam Delivery and IR Components

The SLAC Linac can deliver damped bunches with ILC parameters for bunch charge and bunch length to End Station A. A 10Hz beam at 28.5 GeV energy can be delivered there, parasitic with PEP-II operation. We plan to use this facility to test prototype components of the Beam Delivery System and Interaction Region. We discuss our plans for this ILC Test Facility and preparations for carrying out experiments related to collimator wakefields and energy spectrometers. We also plan an interaction region mockup to investigate effects from backgrounds and beam-induced electromagnetic interference.

physics.ins-det↗
arXiv2002

SLAC's Polarized Electron Source Laser System and Minimization of Electron Beam Helicity Correlations for the E-158 Parity Violation Experiment

SLAC E-158 is an experiment designed to make the first measurement of parity violation in Moller scattering. E-158 will measure the right-left cross-section asymmetry, A_LR^Moller, in the elastic scattering of a 45-GeV polarized electron beam off unpolarized electrons in a liquid hydrogen target. E-158 plans to measure the expected Standard Model asymmetry of ~10^-7 to an accuracy of better than 10^-8. To make this measurement, the polarized electron source requires for operation an intense circularly polarized laser beam and the ability to quickly switch between right- and left-helicity polarization states with minimal right-left helicity-correlated asymmetries in the resulting beam parameters (intensity, position, angle, spot size, and energy), ^beam A_LR's. This laser beam is produced by a unique SLAC-designed flashlamp-pumped Ti:Sapphire laser and is propagated through a carefully designed set of polarization optics. We analyze the transport of nearly circularly polarized light through the optical system and identify several mechanisms that generate ^beam A_LR's. We show that the dominant effects depend linearly on particular polarization phase shifts in the optical system. We present the laser system design and a discussion of the suppression and control of ^beam A_LR's. We also present results on beam performance from engineering and physics runs for E-158.

physics.acc-ph↗