The main aim of the Photo Injector Test Facility at DESY, Zeuthen (PITZ) site is to develop and test an FEL photo injector system capable of producing high charge short electron bunches of lowest possible transverse emittance to allow optimum FEL performance. The last major beamline upgrade realized in the second half of the year 2011 completed the evolution of the PITZ setup ongoing since 2005. The most recent upgrades include the installation of a new RF deflecting cavity - a prerequisite for longitudinal emittance and high resolution slice emittance measurements and installation of a new dispersive section for longitudinal phase space diagnostics of the high energy electron bunches. The paper will give an overview on electron beam diagnostics at PITZ, including the above mentioned upgrades.

CTA (Cherenkov Telescope Array) is one of the largest ground-based astronomy projects being pursued and will be the largest facility for ground-based γ-ray observations ever built. CTA will consist of two arrays (one in the Northern hemisphere and one in the Southern hemisphere) composed of telescopes of several sizes. A prototype for the Medium Size Telescope (MST) of a diameter of 12 m will be installed in Berlin by the end of 2012. This MST prototype will be composed of the mechanical structure, drive system and mirror facets mounted with powered actuators to enable active control. Five Charge-Coupled Device (CCD) cameras and a weather station will allow the measurement of the performance of the instrument. The Atacama Large Millimeter/submillimeter Array (ALMA) Common Software (ACS) distributed control framework is currently being considered by the CTA consortium to serve as the array control middleware. In order to evaluate the ACS software, it has been decided to implement an ACS-based readout and control system for the MST prototype. The design of the control software is following the concepts and tools under evaluation within the CTA consortium, like the use of a Unified Modeling Language (UML) based code generation framework for ACS component modeling, and the use of OPen Connectivity-Unified Architecture (OPC UA) for hardware access. In this contribution, the progress in the implementation of the control system for this CTA prototype telescope is described.

Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV to 10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.

a CTA Prototype Telescope I. Oya1, B. Behera2, D. Melkumyan2, T. Schmidt2, U. Schwanke1, ͏͏P. ͏Wegner2, S. Wiesand2, M. Winde2, for the CTA Consortium3 1Institut für Physik, Humboldt-Universität zu Berlin, Newtonstrasse 15, D-12489 Berlin, Germany, 2Deutsches Elektronen-Synchotron, DESY, Platanenallee 6, D-15738 Zeuthen, Germany, 3See http://www.cta-observatory.org for full author & affiliation list

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 Photo Injector Test facility at DESY, Zeuthen site (PITZ), is dedicated to develop and optimize high brightness electron sources for short wavelength FreeElectron 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.

Free electron LASer in Hamburg (FLASH) at DESY is a user facility with laser-like radiation source in the VUV and soft X-ray range. It is also a pilot facility for the future XFEL. A fast data acquisition system (DAQ) to support the accelerator operation and the user experiments was developed. The system collects data from hundreds of ADC channels in the range of 1 M up to 2 G samples per second. In addition it allows collecting images from digital video cameras. All the data is collected in a shared memory of a central multiprocessor computer. Several processes are used to calculate e.g., the orbit, energy or photon flux, or are used as feedback loops to improve the stability of the linac. A long time archiving of the collected data from the accelerator and from the FEL experiments on a 24 TB disk and finally on a tape is provided. The whole system is integrated in the DOOCS control system of FLASH. It is a novel approach to combine a fast DAQ system with a accelerator control system.

ISSN 0418-9833 Multiplicity Structure of the Hadronic Final State in Di ractive Deep-Inelastic Scattering at HERA H1 Collaboration Abstract The multiplicity structure of the hadronic system X produced in deep-inelastic processes at HERA of the type ep ! eXY , where Y is a hadronic system with mass MY < 1:6 GeV and where the squared momentum transfer at the pY vertex, t, is limited to jtj < 1 GeV2, is studied as a function of the invariant mass MX of the system X. Results are presented on multiplicity distributions and multiplicity moments, rapidity spectra and forward-backward correlations in the centre-ofmass system of X. The data are compared to results in e+e annihilation, xedtarget lepton-nucleon collisions, hadro-produced di ractive nal states and to nondi ractive hadron-hadron collisions. The comparison suggests a production mechanism of virtual photon dissociation which involves a mixture of partonic states and a signi cant gluon content. The data are well described by a model, based on a QCD-Regge analysis of the di ractive structure function, which assumes a large hard gluonic component of the colourless exchange at low Q2. A model with soft colour interactions is also successful.

For the VUV-FEL (Vacuum-Ultraviolet Free Electron Laser) at DESY a 1 GeV superconducting LINAC [1] is used and presently being commissioned. The control system of the LINAC consists of 900 fast and 500 slow data channels producing up to 100 MByte/s of data depending on the LINAC operation mode. To study, control and archive the machine status and performance, a data acquisition system (DAQ) has been developed which allows storing machine parameters together with user experiment data. The system will provide the ability to correlate easily the accelerator status with experimental data on a bunch-by-bunch basis. The paper gives an overview on the architecture of the DAQ system and describes its main components in more detail.

The VUV-FEL (Vacuum-Ultraviolet Free-Electron Laser) at DESY started recently its operation. As part of the Distributed Object-Oriented Control System (DOOCS) a novel Data AcQuisition (DAQ) System has been developed for this complex facility. To provide full diagnostics of all electron bunches, a fast ADC-based acquisition is used for collecting data from more than 800 channels at sampling rates of 1 to 9 MHz. The system allows data transfer rates of up to 100 MBytes per second to a central server. On this server data from all front end sources is synchronized and used by high level feedback and calculation programs. The data is stored for off-line analysis on a disk cache and eventually written to a tape server. A data volume of up to 70 TBytes per year is expected. The system implements technologies borrowed from High-Energy Physics experiments and integrate them fully into the existing DOOCS control system architecture.

The VUV-FEL (Vacuum-Ultraviolet Free-Electron Laser) at DESY started recently its operation. As part of the Distributed Object-Oriented Control System (DOOCS) a novel Data AcQuisition (DAQ) System has been developed for this complex facility. To provide full diagnostics of all electron bunches, a fast ADC-based acquisition is used for collecting data from more than 800 channels at sampling rates of 1 to 9 MHz. The system allows data transfer rates of up to 100 MBytes per second to a central server. On this server data from all front end sources is synchronized and used by high level feedback and calculation programs. The data is stored for off-line analysis on a disk cache and eventually written to a tape server. A data volume of up to 70 TBytes per year is expected. The system implements technologies borrowed from High-Energy Physics experiments and integrate them fully into the existing DOOCS control system architecture.

Cross sections for the production of two isolated muons up to high di-muon masses are measured in ep collisions at HERA with the H1 detector in a data sample corresponding to an integrated luminosity of 71 pb^-1 at a centre of mass energy of sqrts = 319 GeV. The results are in good agreement with Standard Model predictions, the dominant process being photon-photon interactions. Additional muons or electrons are searched for in events with two high transverse momentum muons using the full data sample corresponding to 114 pb^-1, where data at sqrts = 301 GeV and sqrts = 319 GeV are combined. Both the di-lepton sample and the tri-lepton sample agree well with the predictions.

Deep-inelastic e(+/-) p scattering at high squared momentum transfer Q(2) up to 30 000 GeV2 is used to search for eq contact interactions associated to scales far beyond the HERA centre of mass energy. The neutral current cross section measurements dsigma / dQ(2), corresponding to integrated luminosities of 16.4 pb(-1) of e(-) p data and 100.8 pb(-1) of e(+) p data, are well described by the Standard Model and are analysed to set constraints on new phenomena. For conventional contact interactions lower limits are set on compositeness scales A ranging between 1.6-5.5 TeV. Couplings and masses of leptoquarks and squarks in R-parity violating supersymmetry are constrained to M / lambda > 0.3-1.4 TeV. A search for low scale quantum gravity effects in models with large extra dimensions provides limits on the effective Planck scale of MS > 0.8 TeV. A form factor analysis yields a bound on the radius of light quarks of R-q < 1.0 10(-18) m. (C) 2003 Published by Elsevier B.V.

The photo injector test facility at DESY Zeuthen (PITZ) was built to develop, operate and optimize photo injectors for future free electron lasers and linear colliders. First photo electrons were produced in January 2002. An extensive conditioning work on the rf gun has been done in order to achieve high gradients for different pulse lengths and repetition rates. To increase the efficiency and safety aspects of the rf commissioning an Automatic Conditioning Program (ACP) was developed. In addition, a Data Aquisition system (DAQ) which enables a deeper analysis of the commissioning work was realized. The conditioning procedures, the specific diagnostic elements and the achieved results are described. Furthermore, dark current measurements under different conditions are presented.

A search for events with a high-energy isolated electron or muon and missing transverse momentum has been performed at the electron-proton collider HERA using an integrated luminosity of 13.6 pb(-1) in e(-) p scattering and 104.7 pb(-1) in e(+) p scattering. Within the Standard Model such events are expected to be mainly due to W boson production with subsequent leptonic decay. In e(-) p interactions one event is observed in the electron channel and none in the muon channel, consistent with the expectation of the Standard Model. In the e(+) p data a total of 18 events are seen in the electron and muon channels compared to an expectation of 12.4 +/- 1.7 dominated by W production (9.4 +/- 1.6). Whilst the overall observed number of events is broadly in agreement with the number predicted by the Standard Model, there is-an excess of events with transverse momentum of the hadronic system greater than 25 GeV with 10 events found compared to 2.9 +/- 0.5 expected. The results are used to determine the cross-section for events with an isolated electron or muon and missing transverse momentum. (C) 2003 Published by Elsevier Science B.V.

The cross section for the elastic photoproduction of pO mesons (yp ~ pop) has been measured with the H1 detector at HERA for two average photon-proton centre-of-mass energies of 55 and 187 GeV. The lower energy point was measured by observing directly the p0 decay giving a cross section of 9.1 + 0.9 (stat.) + 2.5 (syst.) /zb. The logarithmic slope parameter of the differential cross section, dtr /d t , is found to be 10.9 42.4 (stat.) + 1.1 (syst.) GeV -2. The pO decay polar angular distribution is found to be consistent with s-channel helicity conservation. The higher energy cross section was determined from analysis of the lower part of the hadronic invariant mass spectrum of diffractive photoproduction and found to be 13.6 -40.8 (star.) + 2.4 (syst.) ,ub.