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This Resource Letter provides a guide to literature concerning the development of accelerators for the future of high-energy physics. Research articles, books, and Internet resources are cited for the following topics: motivation for future accelerators, present accelerators for high-energy physics, possible future machine, and laboratory and collaboration websites. [ABSTRACT FROM AUTHOR]

Some risks have extremely high stakes. For example, a worldwide pandemic or asteroid impact could potentially kill more than a billion people. Comfortingly, scientific calcultions often put very low probabilities on the occurrence of such catastrophes. In this paper, we argue that there are important new methodological problems which arise when assessing global catastrophic risks and we focus on a problem regarding probability estimation. When an expert provides a calculation of the probability of an outcome, they are really providing the probability of the outcome occurring, given that their argument is watertight. However, their argument may fail for a number of reasons, such as a flaw in the underlying theory, a flaw in the modelling of the problem or a mistake in the calculations. If the probability estimate given by an argument is dwarfed by the chance that the argument itself is flawed, then the estimate is suspect. We develop this idea formally, explaining how it differs from the related distinction between model and parameter uncertainty. Using the risk estimates from the Large Hadron Collider as a test case, we show how serious the problem can be when it comes to catastrophic risks and how best to address it. [ABSTRACT FROM AUTHOR]

Superconducting magnets can exhibit training quenches during successive powering to reaching nominal performance. The slip–stick motion of the conductors is considered to be one of the mechanisms of training. In this paper, we present a simple quantitative model where the training is described as a discrete dynamical system matching the equilibrium between the energy margin of the superconducting cable and the frictional energy released during the conductor motion. The model can be explicitly solved in the linearized case, showing that the short sample limit is reached via a power law. Training phenomena have a large random component. A large set of data of the large hadron collider magnet tests is postprocessed according to previously defined methods to extract an average training curve for dipoles and quadrupoles. These curves show the asymptotic power law predicted by the model. The curves are then fit through the model, which has two free parameters. The model shows good agreement over a large range, but it fails to describe the very initial part of the training. [ABSTRACT FROM AUTHOR]

The Facility for Anti-proton and Ion Research (FAIR), under development at GSI, includes the synchrotron SIS300, so called because the magnetic rigidity is 300 Tm. In order to reach the required high intensities of proton and heavy ions beams, the bending dipole magnets have to be pulsed from the injection magnetic field of 1.5 T up to 4.5 T maximum field at the rate of 1 T/s. These 7.8 m long magnets have \cos\theta shaped coils with a 100 mm bore and the particular characteristic to be geometrically curved, with a sagitta of 112.9 mm. These challenging requirements triggered R&D activities, aimed at the development of suitable construction technologies for fast ramped curved coils. The heart of the R&D program is the construction of a 3.9 m long model. The paper discusses the main problems faced during the design and the construction of the cold mass, mainly covering the aspects related to the manufacture. [ABSTRACT FROM AUTHOR]

Particle accelerators have many important uses in scientific experiments, in industry and in medicine. This paper reviews the variety of technologies which are used to accelerate charged particles to high energies. It aims to show how the capabilities and limitations of these technologies are related to underlying physical principles. The paper emphasises the way in which different technologies are used together to convey energy from the electrical supply to the accelerated particles. [ABSTRACT FROM AUTHOR]

The project presented in this paper, the CMS muon detector, is fully described in Ref. 1. It was designed from 1991 to 19945 by a community of physicists and engineers from universities and institutes of several countries. The details of the design were fixed in 1997 with the submission of the CMS Muon Technical Design Report.4 This paper reflects the views, the memoirs and the understanding of the author, who is responsible for the choice of the subjects and for any omission or error. [ABSTRACT FROM AUTHOR]

At CERNs Large Hadron Collider, a unique possibility to study central exclusive processes such as the production of low mass resonances, charmonium states and jets, as well as to search for missing mass or momentum signatures opens up by the detection of both leading protons with the special β* = 90 optics. At with that optics the leading proton acceptance of the TOTEM Roman Pots covers all diffractive masses, provided that the proton four-momentum transfer |t| ≳ 0.04 2. This paper describes the physics potential with an integrated luminosity of 10 pb-1 and 100 pb-1 for common CMS and TOTEM data taking at β* = 90 optics. [ABSTRACT FROM AUTHOR]

In this paper the information loss for fermionic superstrings 'superstring balls' in mini black holes at LHC by extending the Gottesman and Preskill method to string theory and calculate the information transformation from the collapsing matter to the state of outgoing Hawking radiation is calculated. It is found that for all finite values of ω, all information from all string emission processes experiences some degree of loss. It means that the string model is not sufficient to solve the information-loss problem. Then the fermionic superstring states at corresponding point are considered. The correspondence principle offered a unique opportunity to test the Horowitz and Maldacena mechanism at correspondence point 'the centre of mass energies around ( M/( g))'. To consider the super string states, a copy of the original Hilbert space is constructed with a set of operators of creation/annihilation that have the same anticommutation properties as the original ones. The total Hilbert space is the tensor product of the two spaces H⊗ H, where in this case H denotes the physical quantum states space of the fermionic string. It is shown that fermionic string states can be represented by a maximally entangled two-mode squeezed state of the physical and unphysical spaces of fermionic string. Also, the entropy for these string states is calculated. It is observed that black hole entropy matches the fermionic superstring entropy at transition point. This means that our result is consistent with correspondence principle and thus HM mechanism in string theory works. Finally the signature of fermionic string ball at LHC is studied. When superstring balls produce at LHC, they evaporate to Massive particles like Higgs boson. In fact string balls act as a factory for Higgs production. Then Higgs bosons decay to QCD matter. Thus an enhancement of QCD matter can be a signature of fermionic superstring ball at LHC. [ABSTRACT FROM AUTHOR]

In this paper we discuss the production of a heavy scalar MSSM Higgs boson H and its subsequent decays into pairs of electroweak gauge bosons WW and ZZ. We perform a scan over the relevant MSSM parameters, using constraints from direct Higgs searches and several low-energy observables. We then compare the possible size of the pp→ H→ WW, ZZ cross sections with corresponding Standard Model cross sections. We also include the full MSSM vertex corrections to the H→ WW, ZZ decay and combine them with the Higgs propagator corrections, paying special attention to the IR-divergent contributions. We find that the vertex corrections can be as large as −30 % in MSSM parameter space regions which are currently probed by Higgs searches at the LHC. Once the sensitivity of these searches reaches two percent of the SM signal strength the vertex corrections can be numerically as important as the leading order and Higgs self-energy corrections and have to be considered when setting limits on MSSM parameters. [ABSTRACT FROM AUTHOR]

In this paper, we investigate how a sizeable width-to-mass ratio for a gluino, as is for example realized in GMSB scenarios, could affect the discovery potential of gluinos at the LHC. More importantly, the influence of the gluino being 'fat' on the standard mass and spin determination methods at the LHC are investigated. For this purpose, we focus on gluino production at the LHC, where we do not factorize the first step in the gluino decay cascade, but treat the following decay cascade steps in factorization, including full spin correlations. The effects of sizeable width-to-mass ratios from a few up to 15-20 per cent on the endpoint of several mass determination methods as well as on means for discrimination between BSM spin paradigms like SUSY and UED are studied. [ABSTRACT FROM AUTHOR]

Abstract: The VErtex LOcator (VELO) is a vital piece of apparatus providing tracking, triggering and vertexing to the LHCb experiment. Its superb impact parameter resolution and high efficiency enable LHCb to make precision measurements and searches for New Physics in the flavour sector. These proceedings focus on the R&D for the future LHCb VELO detector to be installed in the upgraded LHCb experiment. In order to increase hadronic yields and to be able to run at higher luminosities LHCb plans to upgrade the front end electronics, currently limited by a first level hardware trigger. For the silicon vertex detector this implies a complete rebuild of the modules and electronics, with improved cooling capability to cope with the high voltages and currents expected after significant radiation damage has been accrued. This paper presents the design considerations for the vertex detector upgrade together with the two proposed options for the sensor layout, based on strips or pixels. As part of the R&D programme a pixel based tracking telescope has been developed for use in testbeams, to gain experience with pixel tracking and to evaluate the technologies under consideration. This paper presents results from the last years running of the TimePix telescope and describes the integration of various test devices. [Copyright &y& Elsevier]

The scale, complexity and worldwide geographical spread of the Large Hadron Collider (LHC) computing and data analysis problems are unprecedented in scientific research. The complexity of processing and accessing this data is increased substantially by the size and global span of the major experiments, combined with the limited wide-area network bandwidth available. This paper discusses the latest generation of the MONARC (MOdels of Networked Analysis at Regional Centers) simulation framework, as a design and modeling tool for large-scale distributed systems applied to high-energy physics experiments. We present a simulation study designed to evaluate the capabilities of the current real-world distributed infrastructures deployed to support existing LHC physics analysis processes and the means by which the experiments band together to meet the technical challenges posed by the storage, access and computing requirements of LHC data analysis. The Compact Muon Solenoid (CMS) experiment, in particular, uses a general-purpose detector to investigate a wide range of physics. We present a simulation study designed to evaluate the capability of its underlying distributed processing infrastructure to support the physics analysis processes. The results, made possible by the MONARC model, demonstrate that the LHC infrastructures are well suited to support the data processes envisioned by the CMS computing model. [ABSTRACT FROM PUBLISHER]

This paper presents options for high-energy colliders at the energy frontier for the years to come. The immediate plans include the exploitation of the LHC at its design luminosity and energy as well as upgrades to the LHC (luminosity and energy) and to its injectors. This may be complemented by a linear electron-positron collider, based on the technology being developed by the Compact Linear Collider and by the International Linear Collider, by a high-energy electron-proton machine, the LHeC, and/or by a muon collider. This contribution describes the various future directions, all of which have a unique value to add to experimental particle physics, and concludes by outlining the key messages for the way forward. [ABSTRACT FROM AUTHOR]

In this paper, developments presented at the Lepton-Photon 2011 Conference are summarized and a perspective on the current situation in high-energy physics is given. [ABSTRACT FROM AUTHOR]

In this paper we study the H+ γ ( H= J/ Ψ and ϒ) production in coherent hadron-hadron interactions at LHC energies. Considering the ultrarelativistic protons as a source of photons, we estimate the γ+ p→ H+ γ+ X cross section using the non-relativistic QCD (NRQCD) factorization formalism and considering different sets of values for the matrix elements. Our results for the total p+ p→ p+ H+ γ+ X cross sections and rapidity distributions at $\sqrt{s} = 7\ \mbox{and}\ 14\ \mbox{TeV}$ demonstrate that the experimental analysis of the J/ Ψ+ γ production at LHC is feasible. [ABSTRACT FROM AUTHOR]

Abstract: The readout strategy of the LHCb experiment is based on complete event readout at 1MHz. A set of 320 sub-detector readout boards transmit event fragments at total rate of 24.6MHz at a bandwidth usage of up to 70GB/s over a commercial switching network based on Gigabit Ethernet to a distributed event building and high-level trigger processing farm with 1470 individual multi-core computer nodes. In the original specifications, the readout was based on a pure push protocol. This paper describes the proposal, implementation, and experience of a non-conventional mixture of a push and a pull protocol, akin to credit-based flow control. An FPGA-based central master module, partly operating at the LHC bunch clock frequency of 40.08MHz and partly at a double clock speed, is in charge of the entire trigger and readout control from the front-end electronics up to the high-level trigger farm. One FPGA is dedicated to controlling the event fragment packing in the readout boards, the assignment of the farm node destination for each event, and controls the farm load based on an asynchronous pull mechanism from each farm node. This dynamic readout scheme relies on generic event requests and the concept of node credit allowing load control and trigger rate regulation as a function of the global farm load. It also allows the vital task of fast central monitoring and automatic recovery in-flight of failing nodes while maintaining dead-time and event loss at a minimum. This paper demonstrates the strength and suitability of implementing this real-time task for a very large distributed system in an FPGA where no random delays are introduced, and where extreme reliability and accurate event accounting are fundamental requirements. It was in use during the entire commissioning phase of LHCb and has been in faultless operation during the first two years of physics luminosity data taking. [Copyright &y& Elsevier]

Hadron physics represents the study of strongly interacting matter in all its manifestations and understanding its properties and interactions. The interest in this field has been revitalized by the discovery of new light hadrons, charmonium- and bottomonium-like states. In this paper, the most recent experimental results from different experiments are reviewed. [ABSTRACT FROM AUTHOR]

Diboson production in proton-proton collisions presents an opportunity to study the self-interaction between gauge bosons via anomalous trilinear gauge couplings (aTGC). The values of these couplings are fully fixed in the SM by the gauge structure. Thus, any deviation of the observed strength of the TGC from the SM prediction would indicate new physics. This paper presents the limits on anomalous WWγ, ZZγ and Zγ γ trilinear gauge couplings in proton-proton collisions at the centre of mass energy of 7 TeV with the CMS detector. [ABSTRACT FROM AUTHOR]

Charged lepton transverse momenta in the Drell--Yan processes play an important role at the LHC in precision measurements of the Standard Model parameters, such as the W-boson mass and width, their charge asymmetries and sin² ϑW. Therefore, their distributions should be described as accurately as possible by the Monte Carlo event generators. In this paper, we discuss the problem of matching the hard-process kinematics of the Monte Carlo generator WINHAC with the parton-shower kinematics of the PYTHIA 6.4 generator while interfacing these two programs. We show that improper assignment of the quark and antiquark effective momenta in the LO matrix element computations may affect considerably the predicted lepton transverse momenta and even completely reverse their charge asymmetries at the LHC. We propose two matching schemes in which the NLO QCD distributions of the leptonic kinematical variables can be well reproduced by the LO WINHAC generator. [ABSTRACT FROM AUTHOR]

This paper studies the multiplicity distribution of hadrons produced in p-p collisions at 0.9 and 2.36 TeV using ALICE as a detector. The multiplicity distribution exhibits enhanced void probability. They are also found to satisfy the void probability scaling. The scaling of &b.chi; with &nmacr;&kmacr;2 is studied using the generalized hypergeometric model. The variation of the parameter "a" of the hyper geometric model with energy and type of events is also studied. The parameter "a" distinguishes between various theoretical models, e.g. Lorentz/Catalan, negative binomial, geometric distribution etc. Finally a comparison is made with the p-&pmacr; collisions at 200, 546 and 900 GeV. It is observed both for p-&pmacr; and p-&pmacr; data, the value of "a" decreases with increase in collision energy and approach towards the upper bound or the NB model of the void probability scaling. [ABSTRACT FROM AUTHOR]

In this paper, the measurement of the fragmentation factor ratio ƒs/ƒd in the LHCb experiment using hadronic decay modes is presented. The relative yields of the three channels B0 → D- π+, B0 → D-K+, B0s → D-S π+ selected from 35pb-1 of data collected in 2010 are used for the analysis. The fragmentation fraction ratio is determined to be ƒs/ƒd = 0.245 ± 0.017stat ± 0.018syst ± 0.018theor. [ABSTRACT FROM AUTHOR]

During 2011, LHCb has collected an integrated luminosity of 1.1 fb-1, giving rise to a large variety of measurements. Amongst these, measurements of CP violation in B decays play a central role. Three highlights are presented in this paper. The evidence for b → u transitions in B± → DK± is obtained, confirming recent BELLE results. The first evidence for direct CP violation in the B0S system is presented and CP violation is observed in the B0 system, using respectively B0S → K- π+ and B0 → K+ π- decays. An unambiguous world leading measurement of the mixing phase φs of the B0S system is obtained by looking at b → cᶜ̄s transitions. [ABSTRACT FROM AUTHOR]

The LHCb experiment at the LHC has collected more than 1 fb-1 of physics data during the first two years of operation at the LHC, reaching one of its most important milestones. This has allowed the experiment to already perform extensive world-class measurements in b and c-physics, in order to probe New Physics Beyond the Standard Model. In this paper, the status and excellent performance of the LHCb experiment are reviewed, focusing the attention on the most important aspects of the operation of the experiment. Moreover, several important physics results are highlighted together with their impact for the full physics program at the LHC. Finally, a description of the upgrade of the detector to collect more than 50 fb -1 starting in 2018 will be also given. [ABSTRACT FROM AUTHOR]

In this paper, a measurement of ? polarization in W? ?? decays is presented. It is measured from the energies of the decay products in hadronic ? decays with a single final state charged particle. The data, corresponding to an integrated luminosity of 24 pb, were collected by the ATLAS experiment at the Large Hadron Collider in 2010. The measured value of the ? polarization is ${P_{\tau}}= -1.06 \pm0.04\ (\mathrm{stat})\;^{+0.05}_{-0.07}\ (\mathrm{syst})$, in agreement with the Standard Model prediction, and is consistent with a physically allowed 95 % CL interval [?1,?0.91]. Measurements of ? polarization have not previously been made at hadron colliders. [ABSTRACT FROM AUTHOR]

A particle scattered off by a rotating black hole can be amplified when the system is in the superradiant regime. If the system is surrounded by a mirror which reflects the particle back to the black hole the whole system forms a black-hole bomb, amplifying the original field exponentially. We show in this paper that higher-dimensional black holes can also form black-hole bombs at the LHC. For a pion the e-folding time for the field amplification is tc ~ 10-23-10-24sec. If the lifetime of the black hole is long enough compared with tc, we can observe severely amplified fields. [ABSTRACT FROM AUTHOR]

For almost a quarter of a century, the Tevatron proton-antiproton collider was the centerpiece of the world's high energy physics program - since it began operation in December of 1985, until it was overtaken by LHC in 2011. The aim of this unique scientific instrument was to explore the elementary particle physics reactions with center of mass collision energies of up to 1.96 TeV. The initial design luminosity of the Tevatron was 1030cm-2s-1, however as a result of two decades of upgrades, the accelerator has been able to deliver 430 times higher luminosities to each of two high luminosity experiments, CDF and D0. The Tevatron has been shut off since September 30, 2011. The collider was arguably one of the most complex research instruments ever to reach the operation stage and is widely recognized for many technological breakthroughs and numerous physics discoveries. In this paper, we briefly present the history of the Tevatron, major advances in accelerator physics, technology implemented during the long quest for better and better performance, and the lessons learned from our experience. [ABSTRACT FROM AUTHOR]

The hardware commissioning of the Large Hadron Collider required the testing and the qualification of the cryogenic and vacuum system, as well as the electrical systems for the powering of more than 10 000 superconducting magnets. Nonconformities had to be resolved within a tight schedule. In this paper, we focus on the role that electromagnetic-field computation has played during hardware commissioning in terms of the analysis of a magnet quench and electromagnetic-force calculations in busbars and splices, as well as field-quality prediction for the optimization of powering cycles. [ABSTRACT FROM AUTHOR]

The ALICE High Level Trigger comprises a large computing cluster, dedicated interfaces and software applications. It allows on-line event reconstruction of the full data stream of the ALICE experiment at up to 25 GByte/s. The commissioning campaign has passed an important phase since the startup of the Large Hadron Collider in November 2009. The system has been transferred into continuous operation with focus on the event reconstruction and first simple trigger applications. The paper reports for the first time on the achieved event reconstruction performance in the ALICE central barrel region. [ABSTRACT FROM PUBLISHER]

ALICE at the CERN LHC will investigate the physics of strongly interacting matter at extreme energy densities where the formation of the Quark Gluon Plasma is expected. Its properties can be studied from observations like the production of mesons with charm and beauty quarks. These signals have to be studied as a function of energy density, which is determined by the centrality of collisions. One of the physics observables that is closely related with the centrality of the collision is the number of spectator nucleons that can be measured by the Zero Degree Calorimeters (ZDC). Having a direct geometric interpretation allows to extract the impact parameter with minimal model assumptions. This paper describes the readout system of the ZDC. The ZDC readout consists of a VME system with a ZDC Readout Card, a VME Processor, Discriminators, a ZDC Trigger Card, scalers, QDCs and TDCs. The system was successfully tested during the 2009 ALICE data taking and is currently operational at the LHC. [ABSTRACT FROM PUBLISHER]

The present paper discusses recent advances on a Passive Optical Network inspired Timing-Trigger and Control scheme for the future upgrade of the TTC system installed in the LHC experiments' and more specifically the currently known as TTCex to TTCrx link. The timing PON is implemented with commercially available FPGAs and 1-Gigabit Ethernet PON transceivers and provides a fixed latency gigabit downlink that can carry level-1 trigger accept decisions and commands as well as an upstream link for feedback from the front-end electronics. [ABSTRACT FROM PUBLISHER]

This paper describes the performance of low energy electron reconstruction and identification at ATLAS with proton-proton collisions at a centre of mass energy of 7 TeV produced by the Large Hadron Collider. This study was performed with a sample collected from April to June 2010, corresponding to an integrated luminosity of 78 nb-1. We present the reconstruction of prompt J/ψ mesons decaying into e+e- pairs. These electrons can be used to study the detector performance at low energy, as a complement of higher energy electrons coming from W and Z decays. A sample of ~ 220 J/ψ events can be selected. Their mass values reconstructed with different inputs agree with the values expected from the initial calibration of the ATLAS detector. The kinematics and shower shape distributions (used for identification purpose) have been extracted from the J/ψ data sample and show a good agreement with the simulation. [ABSTRACT FROM AUTHOR]

CP symmetry violation in Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. mixing can be measured in Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. decays to vector-(pseudo)scalar final state. Example of such decay is the Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. which has never been observed so far. The CP symmetry breaking phase of Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. mixing, βs, can be directly extracted from the CP asymmetry observable since the final state is the CP eigenstate. This measurement can complement the one coming from the analysis of the Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. decay. Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. decay is expected to provide the best sensitivity for the βs but the angular distribution analysis is needed to disentangle the admixture of different CP eigenstates of the vector-vector final state. In this paper the CP violation in Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. mesons decays is briefly introduced, the status of current state of βs measurement is presented and finally the analysis of the Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed., as a case study of Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. decay to vector-(pseudo)scalar decay in LHCb experiment, is described. [ABSTRACT FROM AUTHOR]

The year 2010 was the first full year of operation of the Large Hadron Collider (LHC). The Compact Muon Solenoid (CMS) experiment has recorded integrated luminosity of over 43 pb-1 of proton--proton data at center-of-mass energy √s = 7 TeV and 8 μb-1 of lead--lead data at √sNN = 2:76 TeV. In this paper the CMS detector is briefly introduced. Its initial readiness for data taking and status of operation in 2010 is given. The performance of CMS subsystems is shown. Selected measurements from proton--proton and lead--lead runs are described. [ABSTRACT FROM AUTHOR]

This article discusses the recent tests of the Standard Model using pp-collision events at √s = 7 TeV collected with the ATLAS detector at the Large Hadron Collider (LHC) during 2010 data taking period. The paper focuses on measurements of hard and soft sectors of quantum chromodynamics (QCD), a theory describing interactions of quarks and gluons. [ABSTRACT FROM AUTHOR]

Superconducting cables for power transmission usually contain two conductors for DC application, or three conductors for AC, with high voltage insulation. In contrast, for some applications related to accelerators it is convenient to transfer high currents via superconducting links feeding a number of circuits at relatively low voltage, of the order of a kilovolt, over distances of up to a few hundred meters. For power transmission applications based on cooling via sub-cooled liquid nitrogen, suitable HTS conductors are only available in the form of tape, and a multi-layer variant can be envisaged for the multi-circuit links. However, where cooling to temperatures of the order of 20 K is feasible, MgB2 conductor, available in the form of both tape and wire, can also be envisaged and in the latter case used to assemble round cables. There are, therefore, two distinct topologies—based on the use of wires or tapes—that can be envisaged for use in applications to multi-circuit link systems. In this paper the merits of the two approaches are compared, and case studies related to applications to the LHC are presented. [ABSTRACT FROM AUTHOR]

Future upgrades of the Large Hadron Collider (LHC) will require large aperture and high gradient quadrupoles. Nb3Sn is the most viable option for this application but is also known for its strain sensitivity. In high field magnets, with magnetic fields above 12 T, the Lorentz forces will generate mechanical stresses that may exceed 200 MPa in the windings. The existing measurements of critical current versus strain of Nb3Sn strands or cables are not easily applicable to magnets. In order to investigate the impact of high mechanical stress on the quench performance, a series of tests was carried out within a LBNL/CERN collaboration using the magnet TQS03 (a LHC Accelerator Research Program (LARP) 1-meter long, 90-mm aperture Nb3Sn quadrupole). The magnet was tested four times at CERN under various pre-stress conditions. The average mechanical compressive azimuthal pre-stress on the coil at 4.2 K ranged from 120 MPa to 200 MPa. This paper reports on the magnet performance during the four tests focusing on the relation between pre-stress conditions and the training plateau. [ABSTRACT FROM AUTHOR]

The accident in the LHC in September 2008 occurred in an interconnection between two magnets of the 13 kA dipole circuit. Successive measurements of the resistance of other interconnects revealed other defective joints, even though the SC cables were properly connected. These defective joints are characterized by a poor bonding between the SC cable and the copper stabilizer in combination with an electrical discontinuity in the copper stabilizer. A quench at the 7–13 kA level in such a joint can lead to a fast and unprotected thermal run-away and hence opening of the circuit. It has therefore been decided to operate the LHC at a reduced and safe current of 6 kA corresponding to 3.5 TeV beam energy until all defective joints are repaired. A task force is reviewing the status of all electrical joints in the magnet circuits and preparing for the necessary repairs. The principle solution is to resolder the worst defective joints and, in addition, to apply an electrical shunt made of copper across all joints with sufficient cross-section to guarantee safe 12-13 kA operation at 7–7.5 TeV. In this paper the various actions that have lead to this solution are presented. [ABSTRACT FROM AUTHOR]

Complex scientific workflows can process large amounts of data using thousands of tasks. The turnaround times of these workflows are often affected by various latencies such as the resource discovery, scheduling and data access latencies for the individual workflow processes or actors. Minimizing these latencies will improve the overall execution time of a workflow and thus lead to a more efficient and robust processing environment. In this paper, we propose a pilot job concept that has intelligent data reuse and job execution strategies to minimize the scheduling, queuing, execution and data access latencies. The results have shown that significant improvements in the overall turnaround time of a workflow can be achieved with this approach. The proposed approach has been evaluated, first using the CMS Tier0 data processing workflow, and then simulating the workflows to evaluate its effectiveness in a controlled environment. [ABSTRACT FROM AUTHOR]

The fabrication of 3D detectors which requires bulk micromachining of columnar electrodes has been realized with advancements in MEMS technology. Since the fabrication of the first 3D prototype in Stanford Nanofabrication Facility in 1997, a significant effort has been put forth to transfer the 3D detector technology to large scale manufacturing for future high luminosity collider experiments, in which the radiation hardness will be the primary concern, and other applications such as medical imaging and X-ray imaging for molecular biology. First, alternative 3D structures, single type column (STC) and double-side double type column (DDTC) 3D detectors, were produced at FBK-irst (Trento, Italy) and CNM-Barcelona (Spain), and assessed thoroughly to improve the production technology towards the standard full-3D detectors. The 3D collaboration has been extended to include SINTEF (Norway), which is committed to small to medium scale production of active edge full-3D silicon sensors. This paper focuses on p-type 3D detectors compatible with the CMS pixel front end electronics from the second run of fabrication at SINTEF clean room facilities. The sensors that passed the wafer level electrical characterization have been bump-bonded at IZM (Germany), assembled into modules and wire-bonded for functional characterization at Purdue University. We report the leakage current characteristics, bump-bond quality, threshold, noise, and gain measurement results of these 3D modules as well as the preliminary beam test data taken at Fermi National Accelerator Laboratory. [ABSTRACT FROM AUTHOR]

Abstract: We report the first results of the ALICE experiment on heavy-flavour measurements at forward 1 [1] In this paper “forward” means in the LHC clockwise stream with respect to the interaction point. rapidity in the muonic decay channel. The data have been collected during the proton-proton collisions at . In the ALICE program, the heavy-flavour detection in nucleon-nucleon interactions has a central role both as a test of perturbative QCD and as a baseline for the study of matter at high energy densities in heavy-ion collisions. The extraction of the heavy-flavour signal in the inclusive muon spectra requires the subtraction of the contribution from the decay-in-flight of light hadrons and from particles produced in the absorption elements. The details of the analysis and the main results will be discussed in this paper. [Copyright &y& Elsevier]

The paper deals with an approach to the model-independent searching for the Z' gauge boson as a virtual state in scattering processes. The relations between the Z' couplings to fermions covering a wide class of models beyond the Standard Model are found and used. They reduce in an essential way the number of parameters to be fitted in experiments. Special observables which uniquely pick out the Z' at energies of LEP and ILC colliders in different leptonic processes are introduced and the data of LEP experiments are analyzed. The Z' couplings to leptons and quarks are estimated at 95% confidence level. At this level, the LEP data are compatible with the existence of the Z' with the mass mZ′ ~ 1-1.2 TeV. These estimates may serve as a guide for experiments at the Tevatron and/or LHC. A comparison with other approaches and results is given. [ABSTRACT FROM AUTHOR]

The heavy T-quark is one of the most crucial ingredients in the left-right twin Higgs model, which is introduced to cancel the largest contribution of the Standard Model top quark to the Higgs boson mass at one-loop level. In this paper, we study the relevant single heavy T-quark production processes, the 2 → 2 partonic processes of qb → q'T and $qq^\prime \rightarrow \bar{b}T$, the 2 → 3 partonic processes of $q\bar{q}^\prime\rightarrow g\bar{b}T$ and $qg\rightarrow q^\prime\bar{b}T$ at the CERN LHC. Our numerical results show that the 2 → 3 process can be quite important, as its cross-section is about 60% of that for the 2 → 2 process at the LHC. We also show the pT distribution and the rapidity distributions for out-going particles. For the 2 → 3 process, the production rate of the $l^{+}\bar{\nu}_{l}bb\bar{b}\bar{b}j$ final state can be larger than 100 fb with reasonable values of the free parameters. The possible signatures of the heavy T-quark might be detected via the process $pp\rightarrow T\bar{b}+{\rm jet}+X$ at the LHC. [ABSTRACT FROM AUTHOR]

In this paper we find information loss in mini black holes at LHC by extending the Horowitz and Maldacena mechanism to gluons and calculate the information transformation from the collapsing matter to the state of outgoing Hawking radiation for gluons, quarks, and mesons. Next, we calculate the total cross-section for mesons produced from black holes at LHC. We conclude that the more the mass of the quark within the hadrons, the lower is the cross-section. Then, we consider the effect of quarks inside the black hole on the density matrix of individual quarks within the meson outside of a black hole. At the end, we show that information is not lost in black holes if we ignore interactions between particles inside the event horizon in comparison with the effect of a black hole on particles. However, we observe that the unstable condition of excited black holes causes information loss in them. After that, we anticipate quantum black hole production by using electron-positron annihilation modeling at TeV centre of mass energies and compare the corresponding cross-sections calculated, at this stage, for different black hole states. Finally, we calculate the dependence of gluon tree level amplitudes to their thermal distributions near mini black holes at LHC. Nous étudions ici la perte d'information dans les mini trous noirs au LHC en étendant le mécanisme de Horowitz et Maldacena aux gluons et calculons la transformation d'information de l'effondrement de la matière jusqu'à la radiation sortante de Hawking, pour les gluons, les quarks et les gluons. Nous calculons ensuite la section efficace totale pour les mésons produits par les trous noirs au LHC. Nous trouvons que plus la masse du quark dans le hadron est élevée, plus la section efficace est faible. Nous considérons ensuite l'effet du de la présence du quark dans le trou noir sur la matrice de densité des quarks individuels à l'intérieur du méson hors du trou noir. Enfin, nous montrons que l'information n'est pas perdue dans les trous noirs si nous ignorons les interactions entre les particules à l'intérieur de l'horizon, en comparant avec l'effet du trou noir sur les particules. Cependant, nous constatons que l'instabilité des trous noirs excités cause une perte d'information. Par la suite, nous prévoyons la production de trous noirs quantiques en utilisant un modèle d'annihilation électron-posiron à l'échelle des TeV dans le centre de masse et comparons les sections efficaces calculées à ce point-ci pour différents états finals du trou noir. Pour finir, nous calculons la dépendance des amplitudes de gluons au niveau des arbres sur les distributions thermiques près des mini trous noirs au LHC. [ABSTRACT FROM AUTHOR]

The Precautionary Principle is a guide to coping with scientific uncertainties in the assessment and management of risks. In recent years, it has moved to the forefront of debates in policy and applied ethics, becoming a key normative tool in policy discussions in such diverse areas as medical and scientific research, health and safety regulation, environmental regulation, product development, international trade, and even judicial review. The principle has attracted critics who claim that it is fundamentally incoherent, too vague to guide policy, and makes demands that are logically and scientifically impossible. In this paper we will answer these criticisms by formulating guidelines for its application that ensure its coherence as a useful normative guide in applied and policy ethics debates. We will also provide analyses of cases that demonstrate how our version of the principle functions in practice. [ABSTRACT FROM AUTHOR]

Following an outline of the Large Hadron Collider, this paper will analyze CERNs scientific plans for highenergy colliders for the years to come. The immediate plans include the upgrades to the Large Hadron Collider and its injectors. This may be followed by a linear electronpositron collider, the Compact Linear Collider. This paper describes the design of these future colliders at CERN, all of which have a unique value to add to experimental particle physics [ABSTRACT FROM AUTHOR]

The aim of this paper is to review the recent developments in the phenomenology of quantum gravity at the Large Hadron Collider. We shall pay special attention to four-dimensional models which are able to lower the reduced Planck mass to the TeV region and compare them to models with a large extra-dimensional volume. We then turn our attention to reviewing the emission of gravitons (massless or massive) at the LHC and to the production of small quantum black holes. [ABSTRACT FROM AUTHOR]

The test of the first LARP(LHC Accelerator Research Program) Long Quadrupole is a significant milestone toward the development of Nb3Sn quadrupoles for LHC (Large Hadron Collider) Luminosity Upgrades. These 3.7-m long magnets, scaled from the 1-m long Technological Quadrupoles, are used to develop our capabilities to fabricate and assemble Nb3Sn coils and structures with lengths comparable to accelerator magnet dimensions. The long quadruples have a target gradient of 200 T/m in a 90-mm aperture. Pre-stress and support are provided by an Al-shell-based structure pre-loaded using bladders and keys. The coils were fabricated at BNL and FNAL, the shell-based structure was designed and assembled at LBNL, the test is performed at FNAL. In this paper we present the final steps of the development of the first model (LQS01), several upgrades to the test facility, the test results of witness cables, and the short sample limit. [ABSTRACT FROM AUTHOR]

In the framework of the US LHC Accelerator Program (LARP), three US laboratories BNL, FNAL and LBNL are developing Nb3Sn quadrupole magnets for the Large Hadron Collider (LHC) luminosity upgrade. At present CERN is supporting this activity by testing some of the LARP 1 m long 90 mm aperture magnets. Recently two magnets using a shell based key and bladder technology (TQS) have been tested at CERN. These magnets (TQS02c, TQS03a) share the same mechanical structure and use a 27 strand Rutherford cable based on the 0.7 mm RRP strand. The main difference between the two magnets is the strand sub-element layout (54/61 in TQS02c versus 108/127 in TQS03a) and the strand critical current. The TQS03a wire has a lower (18%) critical current, a larger amount of copper stabilizer, and a larger number of superconducting sub-elements with respect to the TQS02c strand. The tests show that TQS02c was stable between 4.3 K and 2.7 K while it was limited by the self-field instability at lower temperatures. TQS03a was not limited by magneto-thermal instabilities and reached 93% of the short sample limit both at 4.3 K and 1.9 K. In this paper the results are summarized and compared with the stability measurements performed at CERN on individual strands. [ABSTRACT FROM AUTHOR]

Abstract: LHCb is the dedicated b-physics experiment of the LHC. Its vertex detector, the VErtex LOcator (VELO), will operate in a harsh radiation environment with limited access due to its proximity to the LHC beam. To ensure the long term operation and performance, every module was required to pass a set of quality assurance tests. These were specifically developed for the VELO modules to take into account their operational environment and assembly steps. Each VELO module was rigorously inspected, tested and thermally cycled in the Glasgow module burn-in procedures. This paper provides details of the burn-in procedures and summarises the main results that were found. Some of the major results presented in this paper are: the full characterisation of the leakage currents; identification of bad channels; and signal to noise measurements. A few minor problems were identified through visual inspections of the modules and the feedback into the production process proved critical. As a result of the electrical and thermal tests, one module out of the 45 that were tested was rejected due to its thermal performance. Studies are also reported, based on individual modules, characterising the front end read out chip pulse shape. [Copyright &y& Elsevier]

In this paper, we calculate the branching ratio and direct CP asymmetry parameter of B→ D0 K± in the framework of a perturbative QCD approach based on k T factorization. Besides the usual factorizable diagrams, both nonfactorizable and annihilation type contributions are taken into account. We find that (a) the branching ratio is at the order of 10−5; (b) the tree annihilation diagrams and the penguin diagrams dominate the total contribution; and (c) the direct CP asymmetry is about 7%, which can be tested in the Large Hadron Collider beauty experiments (LHC-b) at CERN. [ABSTRACT FROM AUTHOR]