Search

The European physical journal / H 47(1), 16 (2022). doi:10.1140/epjh/s13129-022-00047-8, The JADE experiment was one of five large detector systems taking data at the electron-positron collider PETRA, from 1979 to 1986, at $e^+e^-$ annihilation centre-of-mass energies from 12 to 46.7 GeV. The forming of the JADE collaboration, the construction of the apparatus, the most prominent physics highlights, and the post-mortem resurrection and preservation of JADE's data and software are reviewed., Published by Springer, Heidelberg

The JADE experiment was one of five large detector systems taking data at the electron-positron collider PETRA, from 1979 to 1986, at $e^+e^-$ annihilation centre-of-mass energies from 12 to 46.7 GeV. The forming of the JADE collaboration, the construction of the apparatus, the most prominent physics highlights, and the post-mortem resurrection and preservation of JADE's data and software are reviewed.

24th International Conference on Computing in High Energy and Nuclear Physics (CHEP 2019), CHEP 2019, Adelaide, Australia, 4 Nov 2019 - 8 Nov 2019; The European physical journal / Web of Conferences 245, 07036 (2020). doi:10.1051/epjconf/202024507036, DESY is one of the largest accelerator laboratories in Europe. It develops and operates state of the art accelerators for fundamental science in the areas of high energy physics, photon science and accelerator development. While for decades high energy physics (HEP) has been the most prominent user of the DESY compute, storage and network infrastructure, various scientific areas as science with photons and accelerator development have caught up and are now dominating the demands on the DESY infrastructure resources, with significant consequences for the IT resource provisioning. In this contribution, we will present an overview of the computational, storage and network resources covering the various physics communities on site.Ranging from high-throughput computing (HTC) batch-like offline processing in the Grid and the interactive user analyses resources in the National Analysis Factory (NAF) for the HEP community, to the computing needs of accelerator development or of photon sciences such as PETRA III or the European XFEL. Since DESY is involved in these experiments and their data taking, their requirements include fast low-latency online processing for data taking and calibration as well as offline processing, thus high-performance computing (HPC) workloads, that are run on the dedicated Maxwell HPC cluster.As all communities face significant challenges due to changing environments and increasing data rates in the following years, we will discuss how this will reflect in necessary changes to the computing and storage infrastructures.We will present DESY compute cloud and container orchestration plans as a basis for infrastructure and platform services. We will show examples of Jupyter notebooks for small scale interactive analysis, as well as its integration into large scale resources such as batch systems or Spark clusters.To overcome the fragmentation of the various resources for all scientific communities at DESY, we explore how to integrate them into a seamless user experience in an Interdisciplinary Data Analysis Facility., Published by EDP Sciences, Les Ulis

Quantum or torsion gravity models predict unusual properties of space-time at very short distances. In particular, near the Planck length, around $10^{-35}m$, empty space may behave as a crystal, singly or doubly refractive. This hypothesis, however, remains uncheckable for any direct measurement since the smallest distance accessible in experiment is about $10^{-19}m$ at the LHC. Here we propose a laboratory test to measure space birefringence or refractivity induced by gravity. A sensitivity $10^{-31}m$ for doubly and $10^{-28}m$ for singly refractive vacuum could be reached with PETRA 6 GeV beam exploring UV laser Compton scattering., 11 figures, 8 tables; method is proposed by arXiv:1207.7297

This archive summarizes a working paper and conference proceedings related to laser wire scanner development for the Future Linear Collider (FLC) in the years 2001 to 2006. In particular the design, setup and data taking for the laser wire experiments at PETRA II and CT2 are described. The material is focused on the activities undertaken by Royal Holloway University of London (RHUL)., Comment: 61 pages

The 8th European Particle Accelerator Conference, EPAC2002, Paris, France, 3 Jun 2002 - 7 Jun 2002; 1912-1914 (2002)., Laser wires will play an important role as the standard monitor for beam size measurements with micrometre resolution for the beam delivery system at any future linear collider. Some R&D work is still necessary to elevate preliminary laser wire designs to a compact, non-invasive and fast-scanning device. In this paper the latest R&D together with recent measurements and simulations are presented. Schemes to measure the beam size in a bunch train and from train-to-train are presented together with an evaluation of scanning techniques meeting these requirements. Results from simulations and measurements with a laser focus system and of a proposed Compton calorimeter are reported. Furthermore plans are outlined for the installation of a fast laser wire experiment at the PETRA accelerator at DESY.

The 7th European Particle Accelerator Conference EPAC 2000, EPAC 2000, Vienna, Austria, 26 Jun 2000 - 30 Jun 2000; Hamburg : DESY 1277-1279 (2000)., An increase in the luminosity of the circular hadron - lepton collider HERA may be achieved via electron cooling of hadrons in the PETRA-preaccelerator. The cooling of high energy ($\simeq$ 15-20 GeV ) protons requires a high electron beam current ($\simeq$ few amperes ) with low emittances ( < 4 $\pi$ mm mrad normalized ) to reach reasonable cooling times of < 10 min. For this purpose a linac-based scheme including recirculator and magnetized cooling section has been considered. In this scheme short electron bunches are accelerated in rf-fields. After longitudinal extension to match the bunch length in PETRA their correlated energy spread is removed. Matching is provided for the technically unavoidable gaps in the solenoidal field. This paper presents the status of the development of the proposed scheme for electron cooling., Published by DESY, Hamburg

The 7th European Particle Accelerator Conference EPAC 2000, EPAC 2000, Vienna, Austria, 26 Jun 2000 - 30 Jun 2000; Hamburg : DESY 1256-1258 (2000)., Electron cooling is being discussed as a method to reduce the emittance of hadron beams in the PETRA preaccelerator ring for HERA. In connection with a linac based cooler scheme,it is desirable to use a re-circulator for the electron bunches in order to reduce the average beamcurrent,which must be delivered by the linac. A possible design for such a re-circulator ring with 50m long solenoid in the cooling section is presented in this paper., Published by DESY, Hamburg

17th IEEE Particle Accelerator Conference, PAC 97, Vancouver, USA, 12 May 1997 - 16 May 1997; 65 pp. (1997)., The upgrade of the Petra bunch rotation scheme for protons will be described. Bunch compression in Petra is necessary for stable longitudinal transfer matching with Hera. The influence of beam loading in Petra has to be taken into account for currents above 50 mA even though a strong fast rf feedback system is installed. Amplitude modulation in a short push-pull cycle is chosen for bunch rotation and a bunch length compression factor of 0.7 is established with tolerable distortion.

Many accelerators of electron beams are susceptible to persistent beam lifetime disruptions, with correspondingly reduced performance. One distinguishes between three prevailing explanations of these disruptions: (1) trapping of positive atomic ions in the negatively charged beam; (2) trapping of small highly positively ionised micro-objects (“dust”) in the negatively charged beam; (3) disruptions due to stray magnetic objects trapped in the magnetic field of undulators. The lifetime disruption of certain electron storage rings that employ ion-getter pump systems are attributed by most researchers to explanation (2), the trapped dust hypothesis. Systematic experimental studies of HERA, PETRA and DORIS reinforce the suspicion that specifically this type of pump system is the culprit. Examples of beam lifetime disruptions are presented, together with a summary of observations and experiments performed at various afflicted storage rings to investigate dust trapping and the connection between ion getter pumps and dust particle release. Observations of the disrupted beam are found to agree with the dust trapping hypothesis.

Universität Hamburg, Diss., 1993; 161 pp. (1993). = Universität Hamburg, Diss., 1993

Universität Hamburg, Diplomarbeit, 1992; 96 pp. (1992). = Universität Hamburg, Diplomarbeit, 1992

Universität Hamburg, Diss., 1992; 167 pp. (1992). = Universität Hamburg, Diss., 1992

Universität Hamburg, Diss., 1992; 157 pp. (1992). = Universität Hamburg, Diss., 1992

22 pp. (1991)., The reactionγγ→3π+3π- has been studied usig the JADE detector at PETRA. The topological cross sectionσ(γγ→3π+3π-) was measured in the CM energy range 1.5–5.5 GeV. The production ofρ0,s was observed and the average number ofρ0,s per event measured. The contributions of the subprocessesγγ→ρ02π+2π-,γγ→ρ0ρ0π+2π- andγγ→ 3π+3π- (phase space) were studied and 95% C.L. upper limits for the cross sectionσ(γγ→ρ0ρ0π+π- determined. Finally the Bose-Einstein correlation for pairs of like signed pions was observed. A fit to a standard parametrization gave results consistent with other studies of this effect in pion systems.

24 pp. (1991)., We have measured the cross section and $Q^2$-dependence of the reaction γγ→ multihadrons, using the CELLO detector at DESY, for visible final-state masses between 4 and 9 GeV. The data are well fitted by an incoherent sum of Generalised Vector Meson Dominance and Quark Parton Model terms, but at lowQ2 require the addition of a third component which resembles the QPM but is less two-jet-like. With and without this term, the GVDM cross section atQ2=0 is found to be 200±20 and 250±25 nb, respectively.

188 pp. (1991).

40 pp. (1990).

42 pp. (1990).

The limitation of beam currents in PETRA by the beam-beam effect is investigated. The horizontal and vertical betatron frequency shifts ?Q are measured as a function of bunch currents for different operating conditions. The direct measurement of ?Q by coherent excitation of the eigenmodes of the coupled betatron oscillations of the bunches is described. This method allows to determine independently the horizontal and vertical beam dimensions at the interaction point.

This paper reports the results of a study of hadron production in e/sup +/e/sup -/ collisions at c.m. energies of 33, 35, and 35.8 GeV. Production of a new quark flavor has been sought. The measured values of the total cross section, the thrust distributions, and the study of inclusive muon production show no evidence for the production of a new charge-2/3e quark near threshold. In addition, during an energy scan in the region 29.9< or =..sqrt..s< or =31.6 GeV, no hadron resonance indicating the existence of a bound state composed of charge-2/3e quarks has been found.

The shift in frequency of the fundamental m = 0 head tail mode in a storage ring can be calculated from the optics and the wake potentials. Such calculations have been performed for various beam pipe components in PETRA and are summarized here. Comparison with measurements shows good agreement for long bunches and that the theoretical description of the impedance is incomplete for short bunches (high frequencies).

Six e+ e- accelerators are working at DESY. All of them are operated from one central control room via the new common control system. The report describes some design aspects, system structure, first experience, and the control room.

Recent measurements of beam polarization in the electron-positron storage ring PETRA are presented. A method is described for compensating the depolarizing effects caused by vertical closed orbit distortions. This technique has been successfully applied, and reproducible polarization up to 80 % has been obtained both in single beam and colliding beam operation with luminosities of about 3 · 1030 cm-2S-1· Polarization measurements as a diagnostic tool for studying other beam parameters such as absolute energy and momentum compaction factor are also briefly described. These latter measurements have been performed with the help of a fast depolarizing device.

This paper describes the overall setup and struture of the PETRA Control System. Experience with the system during construction and first running periods are reported. Typical applications in the fields of vacuum, magnets, monitors, and RF illustrate the operational possibilities which the control system provides for `normal' users, who are not computer professionals. Possibilities for future developments are mentioned.

27 pp. (1983).

6 pp. (1985).

28 pp. (1979).

31 pp. (1982).

The cross section for the processe+e−→π0+ anything has been measured at an average center of mass energy of 34.6 GeV for π0 energies between 0.7 and 17 GeV. The angular distribution for π0 energies larger than 2 GeV is of the formdσ/dΩ∼1+Acos2θ, withA=1.2±0.5. The ratio of π0 to π± production in the measured energy range is 2σ(π0)/(σ(π+)+σ(π−))=1.13±0.18

107 pp. (1981).

19 pp. (1983).

(1983). doi:10.1103/PhysRevLett.51.443, The results of a high-statistics study of inclusive muon spectra at PETRA are reported. Improved mass limits have been obtained for heavy quarks, heavy leptons, and charged Higgs particles. It is shown that the fragmentation properties of b quarks and c quarks are different, with the mean fragmentation variables 〈zb〉=0.75±0.03±0.06, 〈zc〉=0.46±0.02±0.05 and the average semileptonic branching ratio for the B and C hadrons R(B)=(10.5±1.5±1.3)%, R(C)=(11.5±1.0±1.7)%.

77 pp. (1983).

61 pp. (1988)., The measurements on properties of jets produced in $e^+e^−$ collisions are reviewed. Special emphasis is given to the experimental information obtained on the space time development of jets and the evidence on coherent gluon emission. The recently published data on jets originating from a special kind of parton are summarized. The extraction of the properties of the original parton from jets is discussed.

At the natural bunchlength the single bunch currents in PETRA are limited by satellite resonances and a new vertical instability, which causes a vertical blow-up of a oarticle bunch if the single bunch current reaches the threshold value of that instability. The "PETRA instability" was explained in terms of head-tail mode coupling and according to this model the vertical blow-up was cured by bunchlengthening changing the longitudinal damping partition. The disadvantage of this kind of bunchlengthening is the increase of energy spread leading to a reduction of quantum life time during energy ramminq. The satellite resonances are avoided by a careful steering of the longitudinal and transverse tunes. A more effective method of bunch lengthening is the use of a higher harmonic rf system. Such a system was installed in PETRA. Wiith the higher harmonic rf system the threshold current of the vertical "PETRA instability" could be increased from 3 mA (natural bunchlength) to 15 mA (with higher harmonic rf system). Besides bunchlengthening the higher harmonic system leads to a considerable reduiction of satellite effects in the range of normal PETRA tunes.

13 pp. (1981).

Physical review letters 43(12), 830 - 833 (1979). doi:10.1103/PhysRevLett.43.830, We report the analysis of the spatial energy distribution of data for e+e−→hadrons obtained with the MARK-J detector at PETRA. We define the quantity 'oblateness' to describe the flat shape of the energy configuration and the three-jet structure which is unambiguously observed for the first time. Our data can be explained by quantum chromodynamic predictions for the production of quark-antiquark pairs accompanied by hard noncollinear gluons., Published by APS, College Park, Md.

31 pp. (1985).

Results onK0 and Λ production ine+e− annihilation at c.m. energies of 14, 22 and 34 GeV are presented. The shape of theK0 and Λ differential cross sections are very similar to each other and to those of π±,K± and\(p(\bar p)\). Scaling violations are observed forK0 production. We obtain a value for the probability to produce strange quark-antiquark pairs relative to that to produce up or down quark-antiquark pairs of 0.35±0.02±0.05. The value ofRh=σ(e+e-→hX)/σµµ is shown to rise steadily with c.m. energy for all particle species. At 34 GeV we find 1.48±0.05K0 and 0.31±0.03 Λ per event. We have searched for possible Λ polarization. The production ofK0's and Λ's in jets is examined as a function ofpT2 and rapidity and compared to that of all charged particles; the yields in two and three jets are also investigated. Results are presented from events with two baryons\((\Lambda ,\bar \Lambda ,por\bar p)\) observed.