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The EDDA-Detector at the Cooler-Synchrotron COSY/J\"ulich has been operated with an internal CH$_2$ fiber target to measure proton-proton elastic scattering differential cross sections. For the data analysis knowledge of beam parameters, like position, width and angle, are indispensable. We have developed a method to obtain these values with high precision from the azimuthal and polar angles of the ejectiles only, by exploiting the coplanarity of the two final state protons with the beam and the kinematic correlation. The formalism is described and results for beam parameters obtained during beam acceleration are given., Comment: 20 pages 10 figures

We present the results obtained from beam position measurements using the wirescanners in the undulator section of VUV FEL [1]. The measurements have been carriedout on 19th and 20th of January. The purpose of this paper is to document these mea- surements which correlate the position reference system of the wirescanners with respectto the position reference system of the quadrupoles using the beam position as reference.

11 pp. (2005)., We have applied beam-based alignment techniques to correlate the position reference systems of quadrupoles and wirecanners in the undulator section of VUV FEL [1]. Procedure, error analysis and results obtained between October 8 and 11 are presented.

TESLA Reports 2004 9 pp. (2004)., Operational principles of stripline and pill-box cavity beam position monitors (BPMs) are discussed. Their theoretically best achievable position and time resolutions are computed. Numbers are estimated using design values of the proposed e$^{+}$ e$^{−}$ linear collider TESLA.

22 pp. (2004)., The operation of a Free Electron Laser at the TESLA Test Facility requires the electron trajectory to be aligned with precision of few micrometer in overlap with the photon beam. To achieve this goal precise position monitoring of the electron beam in the narrow undulator gap is mandatory. A beam position monitor based on a new microwave concept was designed, built and tested. It consists of four ridged waveguides which couple by small slots to the magnetic field of the electron beam. The paper reports the concept, the design and tests of prototypes in a test bench in the laboratory and with beam. TTF FEL measurement results are also presented and possible improvements are discussed.

TESLA Reports 2004 14 pp. (2004)., A new type of a cavity BPM proposed for beam position determination along the TESLA linac was tested at the accelerator ELBE in Rossendorf/ Dresden. Measurements using animproved BPM (large and stable cross-talk isolation, significantly less energy dissipation, a novel LO signal generation) were performed in single- and multi-bunch regimes. Agreement with expectations was found. The low bunch charge available allowed for preliminary measurements on sensitivity and position resolution, which extrapolated to TESLAwould fulfil the demands for precise bunch-to-bunch position determination. Possible improvements, in particular on the signal processing scheme, are also discussed.

We discuss the polarisation of dipole modes, excited when a bunch of particles passes a cylindrical cavity beam position monitor. In dependence on the polarisation axis, cross-talk between antennas in x and y directions can be unacceptably strong, in an uncontrolled manner. We propose and apply a solution to get minimal cross-talk between coupling antennas in perpendicular axes.

16 pp. (2003)., Cavity-type beam position monitors were developed to measure the beam alignment at the undulator section of DESY’s TESLA Test Facility (TTF). This paper describes some theoretical aspects and the experimental setup. The results of some in-beam measurements at the TTF are presented and pros and cons of the monitor concept are discussed.

The 2001 Particle Accelerator Conference, PAC2001, Chicago, USA, 18 Jun 2001 - 22 Jun 2001; 3771-3773 (2001)., This paper reports on recent beam measurements of higher order modes in the TESLA Test Facility (TTF) accelerating modules. Using bunch trains of about 0.5 ms with 54MHz bunch repetition and up to 90% modulated intensity, transverse higher order modes are resonantly excited when the beam is offset and their frequency on resonance with the modulation frequency. With this method, the trapped modes can be excited and their counteraction on the beam observed on a wide-band BPM downstream of the module. Scanning the modulation frequency from 0 to 27MHz allows a systematic investigation of all possible dangerous modes in the modules.

The 8th European Particle Accelerator Conference, EPAC2002, Paris, France, 3 Jun 2002 - 7 Jun 2002; 20-24 (2002)., HERA, the only lepton-hadron-collider is entering a 2${nd}$ phase of operation. The commissioning of the accelerator with new interaction regions built for increasing the luminosity by a factor of 3.5 to 7x10${-31}$cm${-2}$sec${-1}$ is in progress while new ideas are being discussed for the next generation of Lepton-Hadron colliders, which go beyond the kinematics and luminosity limitations of HERA. These are presented and discussed briefly.

Development and test of wire scanners for the Free Electron Laser (FEL) at the Tesla Test Facility phase II are described. The design fulfills the requirements of high precision measurements, of compact and easily exchangeable and referable structures as well as user friendly implementation into the accelerator environment. The basic principle of the measurements consist in detecting the secondary particles created when the wire transverses the electron beam with a constant velocity of up to 1 m/sec. A high resolution measurement system connected with the wire determines the profile and position of the beam with high precision. A reference system connected with the wire scanner components enables the in situ determination of the absolute position of the beam within 20 - 30 $μ$m.

The 8th European Particle Accelerator Conference, EPAC2002, Paris, France, 3 Jun 2002 - 7 Jun 2002; 407-409 (2002)., The orbit-response matrix (ORM) of an accelerator is obtained by measuring the closed orbit deviation produced by an individual excitation of each correction coil. In theory, this matrix only depends on the beta functions and betatron phases at the beam position monitors (BPMs) andat the correction coils. By solving this nonlinear dependence by an iterative method, we have measured the Twiss functions of the HERA rings. Furthermore one can fit optical errors like quadrupole strength or roll angles to obtain the field deviations that produce a discrepancy between themeasured and the theoretical ORM. Both methods are useful tools for finding errors of BPMs and of correction coils. While both methods, especially the second one, have been used at several circular accelerators, they have been found to become less useful and less accurate with an increasing size of the accelerator. Therefore they have never been intensively applied to an accelerator as large as HERA. Here we will report that the ORM analysis has nevertheless been found to be very useful for checking HERA’s BPM system, for finding erroneous correction coils and for finding erroneous quadrupole settings.

Model independent analysis (MIA) can be used in linear accelerators to analyse large statistical samples of orbit data in order to address questions like number of jittering variables that affect the beam, residual dispersion, and resolution of beam position monitors. We describe the application of MIA to TTF and try to answer some questions of practical interest.

The 8th European Particle Accelerator Conference, EPAC2002, Paris, France, 3 Jun 2002 - 7 Jun 2002; 242-244 (2002)., The TESLA Test Facility (TTF) phase II will be the second LINAC at the DESY, based on TESLA accelerator technology[1]. The goal of this machine is twofold: Test and demonstrate the performance of the technology developed for the TESLA linear collider. Furthermore, the excellent beam quality allows to drive a SASE FEL to produce soft X-rays for a 4th Generation Light Source. This paper presents the design of the diagnostic systemfor TTF II, and will give a brief overview over their variety and status.

4 pp. (2002)., This paper presents an overview of the electron beam diagnostics for the upgrade of the TELSA Test Facility (TTF II). Beside of a program for testing components, especially superconducting accelerating structures, for the linear collider project TESLA, TTF II will serve as SASE FEL 4th generation synchrotron radiation user facility.

In this report the conceptual design for the TESLA X-ray free-electron laser photoinjector is presented. Beam dynamics, design and operational issues are addressed.

2 pp. (2001).

The 2001 Particle Accelerator Conference, PAC2001, Chicago, USA, 18 Jun 2001 - 22 Jun 2001; 3099-3101 (2001)., The beam dynamics simulation code V [1,2], based on the Ensemble Model [3], is being developed for on-line simulations. One practical application of the V-Code is the beam-based alignment (BBA) of accelerator (TESLA Test Facility) elements. Before we started with BBA thefirst beam position monitor (BPM1), located after the RFgun cavity, showed non-zero readings. Moreover the readings depended on RF-power, RF-phase and primary and secondary solenoid currents. This effect could be explained by misalignments of the gun and the solenoids. Such beam offsets must be compensated by means of steering coils but such a procedure can be one of the sources of increased emittances. Based on the V-Code solver a dedicated utility was developed for alignment studies. The laser beam mismatch at the cathode, as well as the primary and secondary solenoid displacements were considered as probable reasons for the misalignment of the beam. A new method for the correction of these misalignments combines a sequence of measurements, simulations and the elimination of the largest imperfections. This semi-automatic method applied to the TTF RF-gun yields a centering of the beam within the accuracy of the BPM1.

16 pp. (2001).

The 18th International Conference on High Energy Accelerators, HEACC2001, Tsukuba, Japan, 26 Mar 2001 - 30 Mar 2001; 16-18 (2001)., To achieve high luminosity in the TESLA Linear Collider feedback systems will be needed to provide orbit corrections within the bunch train. A prototype of the complete vertical feedback system has been installed in the TESLA Test Facility at DESY. The use of digital signal processing techniques led to a fast and highly flexible solution for the controller function. Additional features such as data logging and analysis allow easyadjustment of the feedback parameters to achieve the optimum performance of the system. An overview of the system will be presented as well as the results of first measurements.

20 pp. (2001).

3 pp. (2000)., To ensure overlap between the photon beam and electron beam at the SASE-FEL at the TESLA Test Facility [1], several position-sensitive diagnostics components are installed along the beamline of the FEL. For the undulator part, a new type of waveguide beam position monitors (BPMs) is designed, tested, and installed inside the beam pipe of one undulator module. This paper proposes a method to calibrate these monitors with beam-based measurements

TESLA Reports 2000 15 pp. (2000).

6 pp. (2000)., Three vacuum chambers for the VUV SASE FEL undulator sections at the TESLA Test Facility (TTF) were designed, built, tested and installed. Each chamber is 4.5 m long and of 11.5 mm thick. The inner diameter of the beam pipe is 9.5 mm. The rectangular chamber profile with a width of 128 mm is used to integrate beam position monitors and steerers. This is needed to provide a good overlap between the electron and the photon beam over the entire undulator length. The chambers are built in an aluminum extrusion technology developed for the insertion device vacuum chambers of the Advanced Photon Source. After manufacturing, special processing was performed to reach low outgassing rates (

TESLA Reports 78 pp. (1999).

5 pp. (1999)., The electron beam trajectory inside an undulator with integrated strong focusing quadrupoles is disturbed by any kind of magnetic or alignment errors of the guiding field. The electron and photon beam must overlap over the entire undulator length to achieve an optimum output of the TTF FEL (A VUV Free Electron Laser at the TESLA Test Facility: Conceptual Design Rep., DESY Print TESLA-FEL 95-03, Hamburg, 1995). Therefore, it is necessary to measure and correct the electron beam trajectory. The orbit correction in the undulator is based on two principles of orbit measurement. The absolute position of the electron beam inside the undulator can be measured at 4 points of support with calibrated monitors. The second method of measuring the beam trajectory is a beam based alignment algorithm which uses relative orbit changes at 30 distributed beam position monitors along the undulator. A mismatching of the optic at the entrance of the undulator can be seen by measuring the beam size at different locations along the undulator.

199 pp. (1998).

TESLA-FEL Reports 20 pp. (1997).

The 7th European Particle Accelerator Conference EPAC 2000, EPAC 2000, Vienna, Austria, 26 Jun 2000 - 30 Jun 2000; Hamburg : DESY 1803-1805 (2000)., The design, construction and first tests of a prototype of the beam trajectory monitor at the TTF-FEL are presented. With this monitor the off-axis spontaneous undulator radiation is imaged through a set of pinholes onto silicon pixel detectors. This allows to measure simultaneously 12 points of the transverse beam position with an accuracy of better than 10 $\mu$m over a length of 5 m. The prototype consists of a pinhole mask and the pixel detectors accurately placed to each other inside a vacuum chamber which is held under beam vacuum. We first present the design and the production technology of the silicon pixel detector. Then the optimization of the pinhole mask and its realization using lithographic methods are discussed. To determine its spatial accuracy the detector is scanned using a laser test stand and a low-intensity electron beam of an electron microscope. The symmetry axis of the detector defines a straight line within 0.4 $\mu$m. Additionally, the electron microscope is used to study the radiation hardness of the detector. The sensitivity of the detector to low energy X-rays is measured using a vacuum ultraviolet beam at the synchrotron light source HASYLAB. Finally first calibration measurementsof the BTM prototype detectors are shown., Published by DESY, Hamburg