Extreme-ultraviolet to x-ray free-electron lasers (FELs) in operation for scientific applications are up to now single-user facilities. While most FELs generate around 100 photon pulses per second, FLASH at DESY can deliver almost two orders of magnitude more pulses in this time span due to its superconducting accelerator technology. This makes the facility a prime candidate to realize the next step in FELs-dividing the electron pulse trains into several FEL lines and delivering photon pulses to several users at the same time. Hence, FLASH has been extended with a second undulator line and self-amplified spontaneous emission (SASE) is demonstrated in both FELs simultaneously. FLASH can now deliver MHz pulse trains to two user experiments in parallel with individually selected photon beam characteristics. First results of the capabilities of this extension are shown with emphasis on independent variation of wavelength, repetition rate, and photon pulse length.

The 3rd generation low-emittance 6 GeV PETRA III facility has been substantially modified to add new beamlines. This extension project involved the complete removal and reconstruction of part of the storage ring with a double-bend achromat lattice as well as the construction of two new experimental halls. Making use of two long straight sections and a canted undulator scheme in the rebuilt arcs, up to ten new insertion device beamlines can be accommodated. In the current phase of the project, seven insertion device and one bending magnet beamline are being implemented.

The extension of the FLASH facility at DESY (Hamburg, Germany) – FLASH II Project – is under way. The extension includes a second undulator line with variable gap undulators to allow a more flexible operation, and a new experimental hall for photon experiments. The present FLASH linac will drive the both undulator beamlines. Civil construction of the new buildings has been started in autumn 2011 continuing in several steps until spring 2013. The design of the new electron beamline including the extraction from the FLASH linac and the undulator section is mostly finished, and the manufacturing of the components is under way. Design of the photon beamline and layout of the experimental hall is in an advanced stage. The beamline mounting starts end of 2012, and the commissioning with beam is scheduled for the second half of 2013.

FLASH has been a user facility since 2005, delivering radiation in the wavelength range between 4.1 and 45 nm using the SASE principle. So far the user requests for beam time by far exceeds the time available. In order to increase user beam time and improve the radiation properties delivered to users, a mayor extension of the user facility called FLASH II has been proposed by DESY in collaboration with the HZB, which is a seeded FEL over the parameter range of FLASH. After several years of design, the project now enters its construction phase, which will last approximately 2 years. In the mean time, tests are performed in order to prepare for a multi-undulator operation of the facility. In addition, complete start-to-end simulations will complete the simulations which have been performed so far.

FLASH has been a user facility since 2005, delivering radiation in the wavelength range between 7 and 47 nm using the SASE principle. After the present upgrade, the wavelength range is extended to 4.45 nm. With the third harmonic accelerating module in place to linearize the longitudinal phase space, the stability and reproducibility of the machine is substantially improved. The user requests for beam time by far exceeds the time available. In order to increase user beam time and to improve the radiation properties delivered to users, a major extension of the user facility called FLASH II has been proposed by DESY in collaboration with the HZB. FLASH II is a seeded FEL in the parameter range of FLASH. As logical continuation, the seeding with HHG which started with sFLASH will result in direct seeding. Because in the foreseeable future there will probably not be HHG seed lasers available at high repetition rates down to wavelengths of 4 nm, a cascaded HGHG scheme is proposed to produce short wavelengths.After a first design report, the project now enters its technical design phase. During this time, the FLASH beam parameters after the present upgrade 2009/2010 will be characterized and the present design will be re-evaluated and adjusted. In addition, start-to-end simulations will complete the simulations which have been performed so far, including a design of the extraction area. (C) 2010 Elsevier B.V. All rights reserved.

Inclusive doubly differential cross sections d(2)sigma(pA)/dx(F)d(p2T) as a function of Feynman-x (x(F)) and transverse momentum (p(T)) for the production of K-S(0), Lambda and (Lambda) over bar in proton-nucleus interactions at 920 GeV are presented. The measurements were performed by HERA-B in the negative xF range (-0.12 < x(F) < 0.0) and for transverse momenta up to p(T) = 1.6 GeV/c. Results for three target materials: carbon, titanium and tungsten are given. The ratios of production cross sections are presented and discussed. The Cronin effect is clearly observed for all three V 0 species. The atomic number dependence is parameterized as sigma(pA) = sigma(pN) . A(alpha) where sigma(pN) is the proton-nucleon cross section. The measured values of a are all near one. The results are compared with EPOS 1.67 and PYTHIA 6.3. EPOS reproduces the data to within approximate to 20% except at very low transverse momentum.

Inclusive doubly differential cross sections d 2 σ pA / dx F dp T 2 as a function of Feynman-x ( x F ) and transverse momentum ( p T ) for the production of K S 0 , Λ and in proton-nucleus interactions at 920 GeV are presented. The measurements were performed by HERA-B in the negative x F range (−0.12< x F <0.0) and for transverse momenta up to p T =1.6 GeV/ c . Results for three target materials: carbon, titanium and tungsten are given. The ratios of production cross sections are presented and discussed. The Cronin effect is clearly observed for all three V 0 species. The atomic number dependence is parameterized as σ pA = σ pN ⋅ A α where σ pN is the proton-nucleon cross section. The measured values of α are all near one. The results are compared with EPOS 1.67 and PYTHIA 6.3. EPOS reproduces the data to within ≈20

I. Abt, M. Adams, M. Agari, H. Albrecht, A. Aleksandrov, V. Amaral, A. Amorim, S. J. Aplin, V. Aushev, Y. Bagaturia, V. Balagura, M. Bargiotti, O. Barsukova, J. Bastos, J. Batista, C. Bauer, Th. S. Bauer, A. Belkov,* Ar. Belkov, I. Belotelov, A. Bertin, B. Bobchenko, M. Böcker, A. Bogatyrev, G. Bohm, M. Bräuer, M. Bruinsma, M. Bruschi, P. Buchholz, T. Buran, J. Carvalho, P. Conde, C. Cruse, M. Dam, K.M. Danielsen, M. Danilov, S. De Castro, H. Deppe, X. Dong, H. B. Dreis, V. Egorytchev, K. Ehret, F. Eisele, D. Emeliyanov, S. Essenov, L. Fabbri, P. Faccioli, M. Feuerstack-Raible, J. Flammer, B. Fominykh,* M. Funcke, Ll. Garrido, A. Gellrich, B. Giacobbe, J. Gläß, D. Goloubkov, Y. Golubkov, A. Golutvin, I. Golutvin, I. Gorbounov, A. Gorišek, O. Gouchtchine, D. C. Goulart, S. Gradl, W. Gradl, F. Grimaldi, J. Groth-Jensen, Yu. Guilitsky, J. D. Hansen, J.M. Hernández, W. Hofmann, M. Hohlmann, T. Hott, W. Hulsbergen, U. Husemann, O. Igonkina, M. Ispiryan, T. Jagla, C. Jiang, H. Kapitza, S. Karabekyan, N. Karpenko, S. Keller, J. Kessler, F. Khasanov, Yu. Kiryushin, I. Kisel, E. Klinkby, K. T. Knöpfle, H. Kolanoski, S. Korpar, C. Krauss, P. Kreuzer, P. Križan, D. Krücker, S. Kupper, T. Kvaratskheliia, A. Lanyov, K. Lau, B. Lewendel, T. Lohse, B. Lomonosov, R. Männer, R. Mankel, S. Masciocchi, I. Massa, I. Matchikhilian, G. Medin, M. Medinnis, M. Mevius, A. Michetti, Yu. Mikhailov, R. Mizuk, R. Muresan, M. zur Nedden, M. Negodaev, M. Nörenberg, S. Nowak, M. T. Núñez Pardo de Vera, M. Ouchrif, F. Ould-Saada, C. Padilla, D. Peralta, R. Pernack, R. Pestotnik, B. AA. Petersen, M. Piccinini, M.A. Pleier, M. Poli, V. Popov, D. Pose, S. Prystupa, V. Pugatch, Y. Pylypchenko, J. Pyrlik, K. Reeves, D. Reßing, H. Rick, I. Riu, P. Robmann, I. Rostovtseva, V. Rybnikov, F. Sánchez, A. Sbrizzi, M. Schmelling, B. Schmidt, A. Schreiner, H. Schröder, U. Schwanke, A. J. Schwartz, A. S. Schwarz, B. Schwenninger, B. Schwingenheuer, F. Sciacca, N. Semprini-Cesari, S. Shuvalov, L. Silva, L. Sözüer, S. Solunin, A. Somov, S. Somov, J. Spengler, R. Spighi, A. Spiridonov, A. Stanovnik, M. Starič, C. Stegmann, H. S. Subramania, M. Symalla, I. Tikhomirov, M. Titov, I. Tsakov, U. Uwer, C. van Eldik, Yu. Vassiliev, M. Villa, A. Vitale,* I. Vukotic, H. Wahlberg, A. H. Walenta, M. Walter, J. J. Wang, D. Wegener, U. Werthenbach, H. Wolters, R. Wurth, A. Wurz, S. Xella-Hansen, Yu. Zaitsev, M. Zavertyaev, T. Zeuner, A. Zhelezov, Z. Zheng, R. Zimmermann, T. Živko, and A. Zoccoli

A study of the angular distributions of leptons from decays of J/psi's produced in p-C and p-W collisions at sqrt{s}=41.6 GeV has been performed in the Feynman-x region -0.34 < x_F < 0.14 and for transverse momentum up to 5.4 GeV/c. The data were collected by the HERA-B experiment at the HERA proton ring of the DESY laboratory. The results, based on a clean selection of 2.3 x 10^5 J/psi's reconstructed in both the e^+ e^- and mu^+ mu^- decay channels, indicate that J/psi's are produced with longitudinal polarization. The magnitude of the effect is maximal at low p_T. For p_T >1 GeV/c a significant dependence on the reference frame is found: the polar anisotropy is more pronounced in the Collins-Soper frame and almost vanishes in the helicity frame, where, instead, a significant azimuthal anisotropy arises.

Inclusive doubly differential cross sections d2σpA/dxF dp 2 T as a function of Feynman-x (xF ) and transverse momentum (pT ) for the production of K 0 S, Λ and Λ̄ in proton-nucleus interactions at 920 GeV are presented. The measurements were performed by HERA-B in the negative xF range (−0.12 < xF < 0.0) and for transverse momenta up to pT = 1.6 GeV/c. Results for three target materials: carbon, titanium and tungsten are given. The ratios of production cross sections are presented and discussed. The Cronin effect is clearly observed for all three V 0 species. The atomic number dependence is parameterized as σpA = σpN · A α where σpN is the proton-nucleon cross section. The measured values of α are all near one. The results are compared with EPOS1.67 and PYTHIA6.3. EPOS reproduces the data to within ≈ 20% except at very low transverse momentum. PACS 13.85.Hd, 14.20.Jn, 14.40.Aq

Inclusive doubly differential cross sections d^2σ_pA/dx_Fdp_T^2 as a function of Feynman-x (x_F) and transverse momentum (p_T) for the production of K^0_s, Lambda^0 and anti-Lambda^0 in proton-nucleus interactions at 920 GeV are presented. The measurements were performed by HERA-B in the negative x_F range (-0.12<x_F<0.0) and for transverse momenta up to p_T= 1.6 GeV/c. Results for three target materials: carbon, titanium and tungsten are given. The ratios of production cross sections are presented and discussed. The Cronin effect is clearly observed for all three V^0 species. The atomic number dependence is parameterized as σ_pA = σ_pN ·A^αwhere σ_pN is the proton-nucleon cross section. The measured values of αare all near one. The results are compared with EPOS 1.67 and PYTHIA 6.3. EPOS reproduces the data to within ≈20

A measurement of the ratio R-chi c = (chi(c) --> J/psi + gamma)/J/psi in pC, pTi, and pW interactions at 920 GeV/c (root s = 41.6 GeV) in the Feynman-x range -0.35 < x(F)(J/psi) < 0.15 is presented. Both mu(+)mu(-) and e(+)e(-) J/psi decay channels are observed with an overall statistics of about 15 000 chi(c) events, which is by far the largest available sample in pA collisions. The result is R chi(c) = 0.188 +/- 0.013(st-0.022sys)(+0.024) averaged ratio R-12 = R-chi c1/R-chi c2 is measured to be 1.02 +/- 0.40, leading to a cross section ratio sigma(chi(c1))/sigma(chi(c2)) = 0.57 +/- 0.23. The dependence of R-chi c on the Feynman-x of the J/psi, x(F)(J/psi), and its transverse momentum, p(T)(J/psi), is studied, as well as its dependence on the atomic number, A, of the target. For the first time, an extensive study of possible biases on R-chi c and R-12 due to the dependence of acceptance on the polarization states of J/psi and chi(c) is performed. By varying the polarization parameter, lambda(obs), of all produced J/psi's by two sigma around the value measured by HERA-B, and considering the maximum variation due to the possible chi(c1) and chi(c2) polarizations, it is shown that R-chi c could change by a factor between 1.02 and 1.21 and R-12 by a factor between 0.89 and 1.16.

Measurements of the kinematic distributions of J/ψ mesons produced in p–C, p–Ti and p–W collisions at \(\sqrt{s}=41.6~\mathrm{GeV}\) in the Feynman-x region −0.34<x F <0.14 and for transverse momentum up to p T =5.4 GeV/c are presented. The x F and p T dependencies of the nuclear suppression parameter, α, are also given. The results are based on 2.4×105 J/ψ mesons reconstructed in both the e + e − and μ + μ − decay channels. The data have been collected by the HERA-B experiment at the HERA proton ring of the DESY laboratory. The measurement explores the negative region of x F for the first time. The average value of α in the measured x F region is 0.981±0.015. The data suggest that the strong nuclear suppression of J/ψ production previously observed at high x F turns into an enhancement at negative x F .

Inclusive doubly differential cross sections d 2 σ pA /dx F   dp T 2 as a function of Feynman-x (x F ) and transverse momentum (p T ) for the production of K S 0 , Λ and \(\bar{\varLambda}\) in proton-nucleus interactions at 920 GeV are presented. The measurements were performed by HERA-B in the negative x F range (−0.12<x F <0.0) and for transverse momenta up to p T =1.6 GeV/c. Results for three target materials: carbon, titanium and tungsten are given. The ratios of production cross sections are presented and discussed. The Cronin effect is clearly observed for all three V 0 species. The atomic number dependence is parameterized as σ pA =σ pN ⋅A α where σ pN is the proton-nucleon cross section. The measured values of α are all near one. The results are compared with EPOS 1.67 and PYTHIA 6.3. EPOS reproduces the data to within ≈20% except at very low transverse momentum.

Ratios of the ψ′ over the J/ψ production cross sections in the dilepton channel for C, Ti and W targets have been measured in 920 GeV proton-nucleus interactions with the HERA-B detector at the HERA storage ring. The ψ′ and J/ψ states were reconstructed in both the μ+μ- and the e+e- decay modes. The measurements covered the kinematic range -0.35≤xF≤0.1 with transverse momentum pT≤4.5 GeV/c. The angular dependence of the ratio has been used to measure the difference of the ψ′ and J/ψ polarization. All results for the muon and electron decay channels are in good agreement: their ratio, averaged over all events, is Rψ′(μ)/Rψ′(e)=1.00±0.08±0.04. This result constitutes a new, direct experimental constraint on the double ratio of branching fractions, (B′(μ)B(e))/(B(μ)B′(e)), of ψ′ and J/ψ in the two channels. The ψ′ to J/ψ production ratio is almost constant in the covered xF range and shows a slow increase with pT.

The inclusive production cross sections of the charmed mesons D-0,D+,D-s(+) and D*(+) have been measured in interactions of 920 GeV protons on C, Ti, and W targets with the HERA-B detector at the HERA storage ring. Differential cross sections as a function of transverse momentum and Feynman's x variable are given for the central rapidity region and for transverse momenta up to p(T)=3.5 GeV/c. The atomic mass number dependence and the leading to non-leading particle production asymmetries are presented as well.

At present, the storage ring DORIS III (4.5 GeV, 150 mA) serves as the main source for synchrotron radiation experiments at DESY. DORIS III is a second generation storage ring with a rather large emittance of 404 nmrad, thus producing high flux X-ray beams of comparatively low brilliance. In order to follow the increasing user request for high brilliance beams, DESY will rebuild the storage ring PETRA into a very low emittance synchrotron radiation source called PETRA III. PETRA (positron electron tandem ring accelerator) is a storage ring with 2.304 km circumference, which was built in 1976 as an e+ - e− collider. Currently PETRA is used as a pre-accelerator for the proton-lepton collider HERA. In parallel it also serves one undulator beamline in parasitic mode.

The b (b) over bar production cross section in 920 GeV proton-nucleus fixed target collisions is measured by observing double muonic decays of b-flavoured hadrons in the kinematic region -0.3 < X-F(mu) < 0.15. A total number of 83 +/- 12b (b) over bar events is obtained with a likelihood fit of the signal and background simulated events to the data. The resulting cross section is sigma(b (b) over bar) = 17.5 +/- 2.6(stat) +/- 3.3(sys) nb/nucleon, or, when combined with a previous HERA-B measurement of similar precision, sigma(b (b) over bar) = 15.8 +/- 1.7(stat) +/- 1.3(sys)(uncorr) +/- 2.0(sys)(corr) nb/nucleon, which is consistent with recent NLO calculations. (C) 2007 Published by Elsevier B.V.