In order to allow THz pump–X-ray probe experiments at full bunch repetition rate for users at the European XFEL, the Photo Injector Test Facility at DESY in Zeuthen (PITZ) is building a prototype of an accelerator-based THz source. The goal is to generate THz SASE FEL radiation with a mJ energy level per pulse using an LCLS-I undulator driven by the electron beam from the PITZ linac. Therefore, the existing PITZ beam line is upgraded and extended into a tunnel annex downstream of the existing accelerator tunnel. The beam line upgrade in the PITZ tunnel consists of three quadrupole magnets, a bunch compressor, a collimation system and a beam dump followed by the connection to the second tunnel. In the second tunnel a dipole magnet allows to serve two beam lines, one of them is the THz@PITZ beam line. It consists of one LCLS-I undulator for the production of the THz radiation, a quadrupole triplet in front of it for matching the beam parameters for the FEL process, and a quadrupole doublet for the electron beam transport to the beam dump behind it. For the electron beam diagnostic six new screen stations are built, three of them also allow for the observation of the THz radiation for measurements like bunch compression, pulse energy or spatial and transverse distribution. Additionally, five BPMs and a new BLM system for machine protection and FEL gain curve measurement will be installed. The progress of the beam line installation and the instrumentation will be presented.

At the Free Electron Laser Hamburg the laser beam is diverted towards 5 different test sites by massive silicon mirrors, which are mounted into vacuum vessels. One of these vessels is operated in permanent switching mode. The pursued switching frequency is 5 Hz. The initial motion concept is characterized by the motion of the entire vessel perpendicular to the laser beam by a linear drive. The initial vessel with a steel body allowed a switching at 2.5 Hz at the demanded precision. By substituting the steel body with one made of titanium, the frequency could be increased to 3.125 Hz. Further increase should be possible with a new motion concept, leaving the vessel stationary, which is not yet implemented. Another concept which is currently examined is the exclusive motion of the mirror inside the vacuum with piezo motors. Although the motors meet the requirements concerning the accuracy and driving speed, a steady motion under ultra-high vacuum conditions is not yet possible since the cooling of the motors is still insufficient.

The Free Electron Laser at Hamburg (FLASH) facility at the Deutsches Elektronen-Synchrotron (DESY) is a linear accelerator that is operated in superconducting technology and produces soft X-ray laser light from 4.5 to 47 nm.Several switching mirrors, located in the experimental hall, provide different beam lines with laser light, where the switching procedure lasts up to 1 h and is performed at intervals of days or sometimes weeks. Since the experiments would be sufficient even with a lower repetition rate of the beam, a new kind of switching mirror has been invented.In this paper, the design and implementation of a fast switching mirror at FLASH are presented where focussed and unfocussed beam trains can be distributed between two beam lines with a frequency of up to 2.5 Hz. The challenge lies in the precise repetition accuracy of position (few mu m) and angle (about 1 arcsec) of the mirror. In addition, first measurements taken at FLASH are analyzed and they show only little influence of the developed switching mirror on the beam position. (C) 2010 Elsevier B.V. All rights reserved.

The photoinjector test facility at DESY, Zeuthen site (PITZ), was built to develop and optimize photoelectron sources for superconducting linacs for high-brilliance, short-wavelength free-electron laser (FEL) applications like the free-electron laser in Hamburg (FLASH) and the European x-ray free-electron laser (XFEL). In this paper, the detailed characterization of two laser-driven rf guns with different operating conditions is described. One experimental optimization of the beam parameters was performed at an accelerating gradient of about 43 MV=m at the photocathode and the other at about 60 MV=m. In both cases, electron beams with very high phase-space density have been demonstrated at a bunch charge of 1 nC and are compared with corresponding simulations. The rf gun optimized for the lower gradient has surpassed all the FLASH requirements on beam quality and rf parameters (gradient, rf pulse length, repetition rate) and serves as a spare gun for this facility. The rf gun studied with increased accelerating gradient at the cathode produced beams with even higher brightness, yielding the first demonstration of the beam quality required for driving the European XFEL: The geometric mean of the normalized projected rms emittance in the two transverse directions was measured to be 1:26 ` 0:13 mm mrad for a 1-nC electron bunch. When a 10% charge cut is applied excluding electrons from those phase-space regions where the measured phase-space density is below a certain level and which are not expected to contribute to the lasing process, the normalized projected rms emittance is about 0.9 mm mrad.

The nanocomposite magnet Pr4Fe76C10B6Nb3Cu1 has been obtained by nanocrystallization of a rapidly-quenched amorphous flake. The influence of the annealing process on the structural and the magnetic properties are investigated. High magnetic hardness was reached with of large coercivity of H-c = 3.65 kOe, a remanent induction of M-r = 12.0 kG, M-r/M-s = 0.79 and maximum energy product (BH)(max) = 17.6 MGOe at optimal annealing conditions. The multiphase structures of Fe3B as soft phases and of Pr2Fe14B as hard phase were confirmed by X-ray diffraction data. The magnetic viscosity as a function of the reverse field was evaluated for all specimen. The results show that the magnetic viscosity coefficient peaks at a critical nucleation field, at which the magnetization reversal of the specimens becomes irreversible.

Nanocomposite hard magnetic materials (Nd,Dy) 4.5Fe77.5B18 ( No. 1) and (Nd,Dy) 4.5Fe76B18Nb1.2Cu0.3 (No. 2) have been prepared by crystallizing amorphous ribbons, fabricated by single roll melt-spinning. The evolution of a multiphase structure was monitored by an x-ray diffractometer and by thermomagnetic measurement. We observed that, at annealing temperatures below 670 degrees C, there is crystallization of soft phase Fe3B and a small amount of hard phase Nd2Fe14B. At annealing temperatures above 670 degrees C, crystallization of alpha-Fe and probably Dy2Fe14B phases with large magnetocrystalline anisotropy led to a drastic enhancement in the hard magnetic properties of the materials. The maximum value of H-C is found to be 4.2 kOe for sample No. 1. For sample No. 2, with co-doping of Nb and Cu, nanostructure refinement yields a strong enhancement in exchange coupling between the component phases. Thereby, we obtained high reduced-remanence of 0.78, high remanence of 1.15 and a high (BH)(max) value up to 16.2 MGOe.

Soft magnetic ribbons of Finemet compound with Zn, Ag and Au substituted for Cu: Fe73.5Si13.5B9Nb3Cu1−xMx (M=Zn, Ag, Au; x=0.5, 1.0) have been fabricated by rapid quenching technique with wheel speeds of 10, 25 and 30m/s, respectively. The crystallization evolution of samples examined by DSC measurements showed that the high cooling rates make the ribbons in amorphous state whereas the samples with M=Zn; x=0.5, 1.0 showed to be partly crystallized when they fabricated by the wheel speed of 10m/s. In the case of Zn (x=0.5, 1.0) and Ag (x=1.0) substitution there is a sharp peak in the DSC curve corresponding to crystallization of α-Fe(Si) phase. However, the role of Au is similar to that of Cu. Hysteresis loops of as-cast samples exhibited square form which relates to the pinning centers in domain wall displacement. After appropriate annealing, the ultrasoft magnetic properties of studied ribbons are obtained.

The Photo Injector Test facility at DESY, Zeuthen site (PITZ), is dedicated to develop and optimize high brightness electron sources for short wavelength Free- Electron Lasers (FELs) like FLASH and the European XFEL, both in Hamburg (Germany). Since October 2009 a major upgrade is ongoing with the goal to improve the accelerating components, the photocathode drive laser system and the beam diagnostics as well. The essential new feature in the running will be an in-vacuum 10 MW RF directional coupler to be used for the RF monitoring and control. In this context a significant improvement of the RF stability is expected. RF pulses of 800 microseconds with 10 Hz repetition rate will be used. The most important upgrade of the diagnostics system will be the implementation of a phase space tomography module (PST) consisting of three FODO cells each surrounded by two screen stations. The goal is an improved measurement of the transverse phase space at different charge levels. The upgraded facility will be described.