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Multiple Aperture-Based Antihydrogen Parallel Plate Gravity Experiment

Description: This paper from the 23rd Conference on Application of Accelerators in Research and Industry conference proceedings describes an experiment that could be carried out at the CERN Antiproton Decelerator facility to determine the direction of acceleration of antihydrogen in the earth's gravitational field.
Date: June 8, 2015
Creator: Treacher, A. H.; Hedlof, R. M. & Ordonez, Carlos A.
Partner: UNT College of Arts and Sciences

Report of the Event Tag Review and Recommendation Group

Description: In order to facilitate access to the large volumes of data (multiple petabytes per year) which will be produced during data taking and Monte Carlo production at ATLAS, work has proceeded on building a system of event-level metadata to allow selections of a subset of events to use as input to an analysis. This was included in the ATLAS Computing Model and was first studied and implemented by the Physics Analysis Tools group based on the decisions of the ESD/AOD Task Force. They used tools developed and supported by the CERN IT group and the ATLAS Database group. During 2005 this structure was put through various tests and evaluations. Also, work by physicists on reconstruction and analysis led to an improved understanding of the requirements on the TAG. This report addresses the effect of these new inputs on the previous work with regard to content and the infrastructure needed to support it.
Date: April 12, 2006
Creator: Group, ATLAS; Assamagan, K.A.; Barberis, D.; Bentvelsen, S.; Brooijmans, G.; Cranmer, K. et al.
Partner: UNT Libraries Government Documents Department

Update on Electron-Cloud Simulations Using the Package WARP-POSINST

Description: At PAC05[1] and PAC07[2], we presented the package WARP-POSINST for the modeling of the effect of electron clouds on high-energy beams. We present here the latest developments in the package. Three new modes of operations were implemented: (1) a build-up mode where, similarly to POSINST (LBNL) or ECLOUD (CERN), the build-up of electron clouds driven by a legislated bunch train is modeled in one region of an accelerator; (2) a quasistatic mode where, similarly to HEADTAIL (CERN) or QuickPIC (USC/UCLA), the frozen beam approximation is used to split the modeling of the beam and the electrons into two components evolving on their respective time scales; and (3) a Lorentz boosted mode where the simulation is performed in a moving frame where the space and time scales related to the beam and electron dynamics fall in the same range. The implementation of modes (1) and (2) was primary motivated by the need for benchmarking with other codes, while the implementation of mode (3) fulfills the drive toward fully self-consistent simulations of e-cloud effects on the beam including the build-up phase.
Date: April 1, 2009
Creator: Vay, J.-L.; Celata, Christine M.; Furman, Miguel; Venturini, Marco; Sonnad, Kiran G.; Penn, G. et al.
Partner: UNT Libraries Government Documents Department

ATLAS Metadata Task Force

Description: This document provides an overview of the metadata, which are needed to characterizeATLAS event data at different levels (a complete run, data streams within a run, luminosity blocks within a run, individual events).
Date: April 4, 2007
Creator: Collaboration, ATLAS; Costanzo, D.; Cranshaw, J.; Gadomski, S.; Jezequel, S.; Klimentov, A. et al.
Partner: UNT Libraries Government Documents Department

Root status and future developments

Description: In this talk the authors review the major additions and improvements made to the ROOT system in the last 18 months and present their plans for future developments. The additions and improvements range from modifications to the I/O sub-system to allow users to save and restore objects of classes that have not been instrumented by special ROOT macros, to the addition of a geometry package designed for building, browsing, tracking and visualizing detector geometries. Other improvements include enhancements to the quick analysis sub-system (TTree::Draw()), the addition of classes that allow inter-file object references (TRef, TRefArray), better support for templates and STL classes, amelioration of the Automatic Script Compiler and the incorporation of new fitting and mathematical tools. Efforts have also been made to increase the modularity of the ROOT system with the introduction of more abstract interfaces and the development of a plug-in manager. In the near future, they intend to continue the development of PROOF and its interfacing with GRID environments. They plan on providing an interface between Geant3, Geant4 and Fluka and the new geometry package. The ROOT-GUI classes will finally be available on Windows and they plan to release a GUI inspector and builder. In the last year, ROOT has drawn the endorsement of additional experiments and institutions. It is now officially supported by CERN and used as key I/O component by the LCG project.
Date: October 1, 2003
Creator: al., Rene Brun et
Partner: UNT Libraries Government Documents Department

Strangelet Search at the BNL Relativistic Heavy Ion Collider

Description: We have searched for strangelets in a triggered sample of 61 million central (top 4percent) Au+Au collisions at sqrt sNN = 200 GeV near beam rapidities at the STAR solenoidal tracker detector at the BNL Relativistic Heavy Ion Collider. We have sensitivity to metastable strangelets with lifetimes of order>_0.1 ns, in contrast to limits over ten times longer in BNL Alternating Gradient Synchrotron (AGS) studies and longer still at the CERN Super Proton Synchrotron (SPS). Upper limits of a few 10-6 to 10-7 per central Au+Au collision are set for strangelets with mass>~;;30 GeV/c2.
Date: November 27, 2005
Creator: Ritter, Ha
Partner: UNT Libraries Government Documents Department

Characterizations of a CERN NbTi Reference Wire at LBNL

Description: We report on the measurement of two NbTi reference samples,obtained from CERN through BNL, wire number02R00056A01UX.265. The purposeof these characterizations is two-fold: 1) To establish aninter-laboratory comparisonof short sample tests and analysis betweenLBNL, BNL and Fermilab within the LARP collaboration. Due to differencesin reaction and mounting procedures and their resulting straindifferences, Nb3Sn is not suited for this purpose. 2) To determine theaccuracy of LBNL's system with regard to magnetic field, temperature andcurrent after a major system overhaul. The results show that at mu0H = 8T, the critical current result falls within the standard deviation of theCERN database, whereas at mu0H = 5 T, it falls outside the CERN standarddeviation, but within the range of critical current values that arereported by CERN for this wire. It is concluded that the LBNL resultsfall within the characterization variance as reported in the CERNdatabase.
Date: February 1, 2007
Creator: Godeke, A.; Dietderich, D.R.; Higley, H.C. & Liggins, N.L.
Partner: UNT Libraries Government Documents Department

LHC crab-cavity aspects and strategy

Description: The 3rd LHC Crab Cavity workshop (LHC-CC09) took place at CERN in October 2009. It reviewed the current status and identified a clear strategy towards a future crab-cavity implementation. Following the success of crab cavities in KEK-B and the strong potential for luminosity gain and leveling, CERN will pursue crab crossing for the LHC upgrade. We present a summary and outcome of the variousworkshop sessions which have led to the LHC crab-cavity strategy, covering topics like layout, cavity design, integration, machine protection, and a potential validation test in the SPS.
Date: May 23, 2010
Creator: Calaga, R.; Tomas, R. & Zimmermann, F.
Partner: UNT Libraries Government Documents Department

Long-range and head-on beam-beam compensation studies in RHIC with lessons for the LHC

Description: Long-range as well as head-on beam-beam effects are expected to limit the LHC performance with design parameters. They are also important consideration for the LHC upgrades. To mitigate long-range effects, current carrying wires parallel to the beam were proposed. Two such wires are installed in RHIC where they allow studying the effect of strong long-range beam-beam effects, as well as the compensation of a single long-range interaction. The tests provide benchmark data for simulations and analytical treatments. Electron lenses were proposed for both RHIC and the LHC to reduce the head-on beam-beam effect. We present the experimental long-range beam-beam program at RHIC and report on head-on compensations studies based on simulations.
Date: January 12, 2009
Creator: Fischer, W.; Luo, Y.; Abreu, N.; Calaga, R.; Montag, C.; Robert-Demolaize, G. et al.
Partner: UNT Libraries Government Documents Department

Analysis of barrel support saddles and forces between modules during assembly.

Description: As the Barrel Tile Calorimeter is constructed, the support saddles and the modules will be subjected to different forces, stresses, and deflections than when completely assembled. The purpose of this analysis is to examine the forces, stresses, and deflections acting on the support saddles and modules at various stages of assembly. The nominal weight of a barrel module is 20 tons. CERN Document number ATL-LB-EA-0001 'Summary of the Structural Analysis of the Barrel Support Saddles' describes in detail the structural analysis of the saddles and the completed barrel assembly. These calculations followed Eurocode 3. This paper examined several load cases which occur during the assembly of the Barrel. The following are the main conclusions: (1) The assembly is not stable until 18 modules are in place, and only then can the support cradle be removed; (2) The forces between modules are nominal and are far less that the forces in the completed cylinder with 64 modules in place and the cryostat load applied; (3) All of the stresses in the connections between modules are within acceptable limits; and (4) The interface between the cryostat supports and the cryostat move approximately 1.0 mm in the X and Y directions when the load of the cryostat is transferred to the Barrel.
Date: April 23, 2003
Creator: Guarino, V. J. & Physics, High Energy
Partner: UNT Libraries Government Documents Department

Heavy Quarks

Description: No abstract prepared.
Date: March 27, 2006
Creator: Baines, J.; Baranov, S.P.; Behnke, O.; Bracinfk, J.; Cacciari,M.; Corradi, M. et al.
Partner: UNT Libraries Government Documents Department

SIMULATION OF E-CLOUD DRIVEN INSTABILITY AND ITS ATTENUATION USING A FEEDBACK SYSTEM IN THE CERN SPS

Description: Electron clouds have been shown to trigger fast growing instabilities on proton beams circulating in the SPS [1], and a feedback system to control the instabilities is under active development [2]. We present the latest improvements to the Warp-Posinst simulation framework and feedback model, and its application to the self-consistent simulations of two consecutive bunches interacting with an electron cloud in the SPS.
Date: May 3, 2010
Creator: Vay, J.-L.; Byrd, J. M.; Furman, M. A.; Secondo, R.; Venturini, M.; Fox, J. D. et al.
Partner: UNT Libraries Government Documents Department

Present and future high-energy accelerators for neutrino experiments

Description: There is an active neutrino program making use of the high-energy (larger than 50 GeV) accelerators both in USA at Fermilab with NuMI and at CERN in Europe with CNGS. In this paper we will review the prospects for high intensity high energy beams in those two locations during the next decade.
Date: June 1, 2007
Creator: Kourbanis, I.
Partner: UNT Libraries Government Documents Department

From Neutrino Factory to Muon Collider

Description: Both Muon Colliders and Neutrino Factories require a muon source capable of producing and capturing {Omicron}(10{sup 21}) muons/year. This paper reviews the similarities and differences between Neutrino Factory and Muon Collider accelerator complexes, the ongoing R&D needed for a Muon Collider that goes beyond Neutrino Factory R&D, and some thoughts about how a Neutrino Factory on the CERN site might eventually be upgraded to a Muon Collider.
Date: January 1, 2010
Creator: Geer, S.
Partner: UNT Libraries Government Documents Department

The cryogenics of the LHC interaction region final focus superconducting magnets

Description: The LHC interaction region final focus magnets will include four superconducting quadrupoles cooled with pressurized, static superfluid helium at 1.9 K. The heat absorbed in pressurized He II, which may be more than 10 Watts per meter due to dynamic heating from the particle beam halo, will be transported to saturated He II at 1.8 K and removed by the 16 mbar vapor. This paper discusses the conceptual design for the cryogenics of the interaction region final focus superconducting magnets and the integration of this magnet system into the overall LHC cryogenic system.
Date: August 1, 1998
Creator: Byrns, R. & et al., FNAL
Partner: UNT Libraries Government Documents Department

Magnetic design of a high gradient quadrupole for the LHC low-{beta} insertions

Description: Fermilab, Lawrence Berkeley National Laboratory and Brookhaven National Laboratory have formed a consortium to provide components for the Large Hadron Collider (LHC) to be built at CERN. The U.S. contribution includes half of the high gradient quadrupoles (HGQ) for the inner focusing triplets. In this paper a description of the HGQ magnetic design is given, including short sample limit for field gradient, sources and expected values of systematic and random field errors, and possible strategies for field quality correction.
Date: June 1, 1997
Creator: Sabbi, G.; Gourlay, S. A.; Kerby, J.; Limon, P. J.; Nobrega, F.; Novitski, I. et al.
Partner: UNT Libraries Government Documents Department

Design of a High Gradient Quadrupole for the LHC Interaction Regions

Description: A collaboration of Fermilab, Lawrence Berkeley National Laboratory and Brookhaven National Laboratory is currently engaged in the design of a high gradient quadrupole suitable for use in the LHC interaction regions. The cold iron design incorporates a two-shell, cos2{theta} coil geometry with a 70 mm aperture. This paper summarizes the progress on a magnetic and mechanical design that meets the requirements of maximum gradient {>=}250 T/m, operation at 1.8K, high field quality and provision for adequate cooling in a high radiation environment.
Date: March 1, 1997
Creator: Bossert, R.; Gourlay, S.A.; Heger, T.; Huang, Y.; Kerby, J.; Lamm, M.J. et al.
Partner: UNT Libraries Government Documents Department

Perturbation of the periodic dispersion under beam crossing optics in LHC

Description: Beam crossing and separation schemes in the LHC interaction regions impose non-zero closed orbit in the low-{beta} triplets. The related perturbative dispersion is derived ; propagation, multi-crossing interference, perturbative effects around the ring are investigated and quantified. Horizontal and vertical compensation schemes are presented.
Date: May 1, 1997
Creator: Meot, F.
Partner: UNT Libraries Government Documents Department

On transverse mode coupling instability in the VLHC

Description: We present the results of calculation of transverse mode coupling instability (TMCI) thresholds for Very Large Hadron Collider (VLHC). The estimates are done with use of conventional approach and more sophisticated mode dynamics analysis. We found the RF system parameters which allows to get appropriate TMCI threshold number of particles per bunch and attain high luminosity of the collider. Alternative ways to raise the threshold are briefly discussed.
Date: January 1, 1998
Creator: Danilov, V.V. & Shiltsev, V.D.
Partner: UNT Libraries Government Documents Department

Correction of vertical crossing induced dispersion in LHC

Description: Beam crossing schemes in the LHC interaction regions impose non-zero vertical closed orbit in the low-{beta} triplets, which excite a perturbative periodic dispersion ; the phenomenon is described and quantified in detail. It is shown that this dispersion reaches values at the limit of tolerances in the nominal optics of Version 5.0 of the LHC ring, and prohibitively large values in particular in the low- {beta} quadrupoles and interaction regions in the foreseen extreme {beta}-squeeze case ({beta}{sup *} = 0.25 m). Such behaviour justifies including a local correction in the LHC design, in order to damp the effect and confine it as much as possible in the vicinity of the excitation sources (the low-{beta} triplets). An optical compensation scheme based on the use of skew quadrupoles is described in detail, as well as the entailed residual dispersion.
Date: November 1, 1997
Creator: Meot, F.
Partner: UNT Libraries Government Documents Department

Analysis of magnetic measurements of short model quadrupoles for the LHC low-b insertions

Description: The first two short models of the MQXB quadrupole magnets for the LHC interaction regions have been built and tested at Fermilab. In this paper we present the magnetic field measurement results and compare them with expectations based on as-built dimensional parameters and with a preliminary table of field quality requirements.
Date: July 1, 1998
Creator: Bossert, R. & others, and
Partner: UNT Libraries Government Documents Department