Operation of the APS photoinjector drive laser system.

The APS photoinjector drive laser system has been in operation since 1999 and is achieving a performance level exceeding the requirement of stable operation of the LEUTL FEL system. One remarkable number is the UV energy stability of better than 2% rms, sometimes less than 1% rms. This report summarizes the operation experience of the laser system and the improvements made along the way. We also outline the route of upgrade of the system and some frontier laser research and development opportunities in ultrabright electron beam generation

Achievable magnetic fields of super-ferric helical undulators for the ILC.

The magnetic fields on the beam axis of helical undulators for the proposed International Linear Collider (ILC) gamma-ray production were calculated for undulator periods of 10 mm and 12 mm. The calculation assumed the use of low-carbon steel for the magnetic poles and a beam chamber outer diameter of 6.3 mm. Using NbTi superconducting coils at 4.2 K, the on-axis field for a 10-mm-period undulator was 0.62 T at the critical current density. The field for a 12-mm undulator period was 0.95 T, which gives a K value of 1.06. The K value for an 11-mm undulator with Nb{sub 3}Sn superconducting coils was estimated to about 1.1

On-Axis Brilliance and Power of In-Vacuum Undulators for the Advanced Photon Source.

A request for studying the spectral performance of in-vacuum undulators (IVUs) for the APS storage ring was recently put forward. In-vacuum undulators are prevalent at other synchrotron radiation facilities such as the ESRF and the Spring-8. However, they never made it into the arsenal of undulators at the APS because the brilliance tuning curves were sufficiently wide due to the fact that the undulator minimum gap could be set as low as 10.5 mm. For sector 3, which in the past used a narrow-gap vacuum chamber, the minimum undulator pole gap was allowed to be set as low as 8.5 mm, providing contiguous tuning curves between the first and third harmonic radiation for a 2.7-cm-period device. (Subsequently, the narrow-gap vacuum chamber was removed and replaced with a standard vacuum chamber, which allows a minimum gap of 10.5 mm.) For sector 4, which currently holds the only narrow-gap vacuum chamber at the APS, the minimum gap is 9.5 mm. In this sector, a permanent magnet hybrid undulator with SmCo magnets is used instead of NdFeB magnets because of their higher radiation resistance and their better protection against radiation-induced demagnetization of the magnets. In the realm of looking to the future, new concepts and technologies are being revisited. Most notable is the superconducting undulator (SCU) technology, which provides the ultimate highest magnetic field of any technology and design. The SCU program has been ongoing at the APS for several years and substantial progress has been made.3,4 However, the in-vacuum undulators may bridge some of the user demands, and it is therefore worthwhile revisiting their potential at the APS. In this work, the following were assumed or required: (1) the smallest in-vacuum beam-stay-clear gap is 5.0 mm, (2) a beam-liner of 2 x 0.060 mm, which increases the pole gap by the same amount, (3) both NdFeB and SmCo magnets shall be studied, even though SmCo magnets are the preferred choice for very small gaps, (4) compare the in-vacuum undulators with superconducting NbTi undulators with a wall thickness/space of 2 x 1.0 mm, and (5) all undulators will have an effective magnetic length of 2.4 m. Three short undulator period lengths were chosen somewhat arbitrary and studied. We will compare the performance of undulators with period lengths of 2.5 cm and 2.0 cm to one with a 1.6-cm period, which is the chosen period length of the first designed and tested short-length SCU for the APS. Additionally, we will make comparisons with the undulator A, which has a period length of 3.3 cm

The new Magnetic Measurement System at the Advanced Photon Source

A new system for precise measurements of the field integrals and multipole components of the APS magnetic insertion devices is described. A stretched coil is used to measure magnetic field characteristics. The hardware includes a number of servomotors to move (translate or rotate) the coil and a fast data acquisition board to measure the coil signal. A PC under Linux is used as a control workstation. The user interface is written as a Tcl/tk script. The hardware is accessed from the script through a shared C-library. A description of the hardware system and the control program is given.Comment: 3 pages, 5 figures, paper 3271 submitted to ICALEPCS 2001 Conferenc

Terahertz Diagnostic for the Advanced Photon Source Particle Accumulator Ring

Terahertz Diagnostic for the Advanced Photon Source Particle Accumulator Rin

Chamber Surface Roughness and Electron Cloud for the Advanced Photon Source Superconducting Undulator

The electron cloud is a possible heat source in the superconducting undulator (SCU) designed for the Advanced Photon Source (APS), a 7-GeV electron synchrotron radiation source at Argonne National Laboratory. In electron cloud generation extensive research has been done, and is continuing, to understand the secondary electron component. However, little work has been done to understand the parameters of photoemission in the accelerator environment. To better understand the primary electron generation in the APS; a beamline at the Australian Light Source synchrotron was used to characterize two samples of the Al APS vacuum chamber. The total photoelectron yield and the photoemission spectra were measured. Four parameters were varied: surface roughness, sample temperature, incident photon energy, and incident photon angle, with their results presented here.Comment: presented at ECLOUD'12: Joint INFN-CERN-EuCARD-AccNet Workshop on Electron-Cloud Effects, La Biodola, Isola d'Elba, Italy, 5-9 June 201

The Advanced Photon Source Injector Test Stand Control System

The Advanced Photon Source (APS) primary and backup injectors consist of two thermionic-cathode rf guns. These guns are being upgraded to provide improved performance, to improve ease of maintenance, and to reduce downtime required for repair or replacement of a failed injector. As part of the process, an injector test stand is being prepared. This stand is effectively independent of the APS linac and will allow for complete characterization and validation of an injector prior to its installation into the APS linac. A modular control system for the test stand has been developed using standard APS control solutions with EPICS to deliver a flexible and comprehensive control system. The modularity of the system will allow both future expansion of test stand functionality and evaluation of new control techniques and solutions.Comment: Poster paper (TUAP015) at ICALEPCS 2001, 3 pages, 2 figures, pd

RF System Upgrades to the Advanced Photon Source Linear Accelerator in Support of the Fel Operation

The S-band linear accelerator, which was built to be the source of particles and the front end of the Advanced Photon Source injector, is now also being used to support a low-energy undulator test line (LEUTL) and to drive a free-electron laser (FEL). The more severe rf stability requirements of the FEL have resulted in an effort to identify sources of phase and amplitude instability and implement corresponding upgrades to the rf generation chain and the measurement system. Test data and improvements implemented and planned are describedComment: LC 2000 (3 pages, 6 figures

Optimizing floating guard ring designs for FASPAX N-in-P silicon sensors

FASPAX (Fermi-Argonne Semiconducting Pixel Array X-ray detector) is being developed as a fast integrating area detector with wide dynamic range for time resolved applications at the upgraded Advanced Photon Source (APS.) A burst mode detector with intended \mbox{13 MHz} image rate, FASPAX will also incorporate a novel integration circuit to achieve wide dynamic range, from single photon sensitivity to $10^{\text{5}}$ x-rays/pixel/pulse. To achieve these ambitious goals, a novel silicon sensor design is required. This paper will detail early design of the FASPAX sensor. Results from TCAD optimization studies, and characterization of prototype sensors will be presented.Comment: IEEE NSS-MIC 2015 Conference recor