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.

Within the next two years the 2.3 km long storage ring PETRA will be rebuild into one of the most brilliant x-ray sources worldwide (PETRA III). The large bending radius and the use of damping wigglers allow to achieve small beam emittances and extremely brilliant x-ray beams. In this paper we describe the design and the expected performance of the vacuum system for the storage ring. It consists of standard arc sections, an experimental octant which is equipped with undulators and several straight sections that include the damping wigglers. Because of the long length of the storage ring a cost effective solution had to be found. Besides the requirement to quickly provide acceptable residual gas pressures the technical challenges of the system include the provision of high thermal stability with respect to magnets and BPM's, and the design of thin walled insertion device chambers as well as high power synchrotron radiation absorbers.

It is planned to rebuild the storage ringe PETRA II, presently used as pre-accelerator of HERA, into a high performance synchrotron light source. By making use of the large circumference and the installation of damping wigglers it will be possible to achieve exceptionally small emittances in the new storage ring. The requirements for the vacuum system are more advanced for the new storage ring as well. Besides the goal to achieve low pressures and fast conditioning times a major key for the new ring is a very high orbit stability which implies high thermal stability of BPM's and other vacuum components. We describe the basic concepts for chamber layout, pumping schemes, synchrotron radiation absorption and mechanical stability for the standard arcs and the experimental octant. Furthermore the expected performance will be discussed.

High order modes (HOM) are generated by the interaction of a bunched beam with an accelerator environment. They may act destructively on following particle bunches, lead- ing to an increase of the transverse oscillation amplitude and finally to the deterioration of the emittance. Dipole modes have been studied at the S-Band Test Facility at DESY. One accelerating structure, specially designed for this test linac, is equipped with waveguide pick-ups for measuring the HOMs. For one part of the experiments, a modulation of the transverse offset of the bunches at the structure entrance has been induced using a fast broadband kicker and the effect was measured with a precise stripline BPM. No high impedance modes were clearly found in the structure, which has been detuned and damped by both the tapered geometry of the structure and an absorbing stain- less steel coating applied on the iris tips.

High order modes (HOM) are generated by the interaction of a bunched beam with an accelerator environment. They may act destructively on following particle bunches, leading to an increase of the transverse oscillation amplitude and finally to the deterioration of the emittance. Dipole modes have been studied at the S-Band Test Facility at DESY. One accelerating structure, specially designed for this test linac, is equipped with waveguide pick-ups for measuring the HOMs. For one part of the experiments, a modulation of the transverse offset of the bunches at the structure entrance has been induced using a fast broadband kicker and the effect was measured with a precise stripline BPM. No high impedance modes were clearly found in the structure, which has been detuned and damped by both the tapered geometry of the structure and an absorbing stainless steel coating applied on the iris tips.

The 6.3 km long vacuum system for electrons of the new large storage ring HERA1 at Hamburg consists of about 1400 components having lengths between 0.14 and 12m. These components are mainly made by brazing variously shaped tubes of the copper alloy CuSn2 instead of using the common aluminium alloy extrusions. This copper alloy absorbs synchrotron light more efficiently than aluminium and therefore reduces radiation shielding problems. The system is mainly pumped by integrated sputter-ion pumps using the fields of the dipole and quadrupole magnets. The impedance of the beam environment is kept small by minimizing the dimensions of the pump slots and avoiding steps of greater than 1 mm inside the vacuum chamber. A vacuum pressure in the 10(-9) mbar range was achieved some days after assembly of the vacuum system and without bake-out in situ. A beam lifetime of more than one hour was observed during the first test runs of HERA.

Easy fabrication and production of S-band linear accelerator structures is one of the main requirements for a future linear collider based on 3 GHz technology. At DESY the series production of spare sections for the injector linac (LJNAC U) and the S-Band Test Facility has been started. Overall fourteen 5.2 meter long sections with a 20 em long integrated load have to be replaced and four 6 m long sections for the test facility are required. The status of the tests and the results achieved so far will be presented.