SplitLab: A shear-wave splitting environment in Matlab

International audienceWe present a graphical user interface to facilitate the processing of teleseismic shear-wave splitting observations. In contrast to a fully automated technique, we present a manual, per-event approach that maintains user control during the sequence of processing. The SplitLab environment is intended to undertake the repetitive processing steps while enabling the user to focus on quality control and eventually the interpretation of the results. Pre-processing modules of SplitLab create a database of events and link the corresponding seismogram files. The seismogram viewer tool uses this database to perform the measurement interactively. Post-processing of the combined results of such a project includes a viewer and export option. Our emphasis lies in the application to teleseismic shear-wave splitting analysis, but our code can be extended easily for other purposes. SplitLab can be downloaded at http://www.gm.univ-montp2.fr/splitting/

THz Bursting Thresholds Measured at the Metrology Light Source

At the Metrology Light Source MLS [1] owned by the Physikalisch Technische Bundesanstalt PTB the bunch length can be varied by more than two orders of magnitude [2]. The bunch length manipulation is achieved by varying different machine parameters, such as RF voltage amplitude up to 500 kV and the momentum compaction factor amp; 945; over three orders of magnitude. The subject of this article is the measurement of THz bursting thresholds at the MLS for different bunch length

Single Particle Tracking for Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring

A scheme where 1.5 ps and 15 ps long bunches rms can be stored simultaneously in the BESSY II storage ring has recently been proposed BESSYVSR . This paper presents simulations of single particle beam dynamics influenced by superconducting cavities used for the strong longitudinal beam focusing. The effect of RF jitter on very short bunches is investigated and results are discussed. Furthermore, possible effects on beam dynamics during ramp up and ramp down of the high gradient fields in the cavities are studied. The primary goal is to reveal preliminary design specifications for RF jitter on the basis of single particle dynamic

Lifetime Studies at Metrology Light Source and ANKA

The Metrology Light Source MLS , situated in Berlin Germany is an electron storage ring operating from 105 MeV to 630 MeV and is serving as the national primary radiation source standard from the near infrared to the extrem ultraviolet spectral region [1]. In its standard user mode, the lifetime is dominated by the Touschek effect. Measurements and analysis of the Touschek lifetime as a function of beam current and RF Voltage will be presented and compared to measurements done at the A amp; 730; ngstro mquelle Karlsruhe ANKA electron storage ring Karlsruhe, Germany which operates at 0.5 to 2.5 GeV [2

Influence of Transient Beam Loading on the Longitudinal Beam Dynamics at BESSY VSR

BESSY VSR, a scheme where 1.7 ps and 15 ps long bunches rms can be stored simultaneously in the BESSY II storage ring has recently been proposed [1]. The strong longitudinal bunch focusing is achieved by superconducting high gradient RF cavities. If the bunch fill pattern exhibits a significant inhomogeneity, e.g. due to gaps, transient beam loading causes a distortion of the longitudinal phase space which is different for each bunch. The result are variations along the fill pattern in synchronous phase, synchrotron fre quency and bunch shape. This paper presents investigations of transient beam loading and depicts the consequences on bunch length, phase stability and longitudinal multi bunch oscillations for the projected setup of BESSY VS

RF Feedback and Detuning Studies for the BESSY Variable Pulse Length Storage Ring Higher Harmonic SC Cavities

For the feasibility of the BESSY VSR upgrade project of BESSY II two higher harmonic systems at a factor of 3 and 3.5 of the ring s RF fundamental of 500 MHz will be installed in the ring. Operating in continuous wave at high average accelerating field of 20 MV m and phased at zerocrossing, the superconducting cavities have to be detuned within tight margins to ensure stable operation and lowpower consumption at a loaded Q of 5 107. The field variation of the cavities is mainly driven by the repetitive transient beam loading of the envisaged complex bunch fill pattern in the ring. Within this work combined LLRF cavity and longitudinal beam dynamics simulation will demonstrate the limits for stable operation, especially the coupling between synchrotron oscillation and RF feedback settings. Further impact by beam current decay and top up injection shots are being simulate

Coherent THz Measurements at the Metrology Light Source

The Metrology Light Source MLS [1] is the first storage ring optimized for THz generation [2]. It applies a bunch shortening mode, based on a flexible momentum compaction factor optics. The short bunches emit coherent THz radiation. We report on measured THz signals as a function of different machine parameters. Two type of measurements are presented in this paper. The first part presents THz bursting thresholds for a variety of ring parameters compared with theoretical predictions and similar results achieved at BESSY II. The second part discusses an example of a special machine tuning, where the coherent THz signal suddenly and unexpectedly vanishes. Some measurements are shown to demonstrate this effect, a physical explanation is missing

Non-thermal response of YBCO thin films to picosecond THz pulses

The photoresponse of YBa2Cu3O7-d thin film microbridges with thicknesses between 15 and 50 nm was studied in the optical and terahertz frequency range. The voltage transients in response to short radiation pulses were recorded in real time with a resolution of a few tens of picoseconds. The bridges were excited by either femtosecond pulses at a wavelength of 0.8 \mu m or broadband (0.1 - 1.5 THz) picosecond pulses of coherent synchrotron radiation. The transients in response to optical radiation are qualitatively well explained in the framework of the two-temperature model with a fast component in the picosecond range and a bolometric nanosecond component whose decay time depends on the film thickness. The transients in the THz regime showed no bolometric component and had amplitudes up to three orders of magnitude larger than the two-temperature model predicts. Additionally THz-field dependent transients in the absence of DC bias were observed. We attribute the response in the THz regime to a rearrangement of vortices caused by high-frequency currents