61569699
The RTC-a software support system for the control of the CERN SPS
The RTC (Run Time Coordinator) is described. It is a software support system designed for the SPS (Super Proton Synchrotron) control system to provide a run time environment for application software. It coordinates the execution of individual programs or processes and supervises the process control, i.e. process synchronization, interprocess communication, data transfer, and operator I/O (input/output). This supervision includes the control of processes distributed on a Unix-based network. A standard language independent data interface is part of the system. The system includes tools for data presentation, error logging, and contention resolution. Separating system-dependent features for the body of the application programs leads to high flexibility and simplifies the software development. The basic philosophy of the RTC is discussed and its implementation is described.<<ETX>>
56290660
The Software for the CERN Detector Safety System
The CERN Detector Safety System (DSS) has been developed to monitor the state of the LHC detectors and protect their components against emer gency situations which other less reliable systems could possibly fail to handle, or which were not co vered by any other system. The DSS consists of two main components: a PLC-based Front-End and a supervisor Back-End. The two parts communicate via the OPC mechanism. The Front-End is the core of the DSS, to which all the runtime safety-critical actions are delegated. These are encoded in an "Alarm-Action Matrix", that can be seen as a set of user-defined rules relating the Input Channels (analogue and digital senso rs) to the Output Channels (actuators, typically on/off interlock switches). One of the user requireme nts is the possibility of modifying these rules at any time, without stopping the system. New Input and Output Channels can also be incrementally added to the system without perturbing the prev iously existing part. To fulfil these requirements without detriment to the safety-critical part, the PLC software has been designed in a completely datadriven way. This approach allowed the PLC code to be kept as simple as possible and independent from the user-defined rules. The rules, as well as the parameteri zation for the Input and Output Channels, are stored into PLC "datablocks", whose contents drive the execution of the PLC code. The supervisor Back-End, based on the CERN-chosen PVSS SCADA system, represents both the “Configuration Interface” and the “Operator Display” for the DSS. The User is able to define and parameterize Input and Output Channels and to modify the set of rules defining the Alarm-Action Matrix. These modifications, after passing some c onsistency checks, are accepted by the Back-End, permanently stored in PVSS "datapoints", and finally mirrored into the PLC datablocks via the OPC mechanism. In addition to this, the Back-End is constantly informed, again through OPC, of any changes in the status of the monitored system . The Back-End then displays all the relevant information to the User, both via an alarm screen and via an interactive synoptic system. This paper describes in greater details some of the ideas behind the design and the implementation of this system.
62825805
THE CLIC MACHINE PROTECTION
INTRODUCTION The proposed Compact Linear Collider (CLIC) [1, 2] is based on a two-beam acceleration scheme. The energy of two high-intensity, low-energy drive beams is extracted and transferred to the two low-intensity, high-energy main beams. The machine protection has to cope with a wide variety of failures, from real-time failures (RF breakdowns, kicker misfiring), to slow equipment failures, to beam instabilities (caused by e.g. temperature drifts, slow ground motions). Due to the many different types of accelerator components and the beams of various characteristics throughout the entire complex, the CLIC machine protection is an extensive subject. The machine protection has the mission to protect the various machine components from damage caused by ill controlled beams. The severity of the damage is given by the financial impact of the damage and the reduction in the operational availability of the facility. The risk equivalent is given by the product of the fault rate and the impact of the fault (i.e. in statistical terms: risk is the expectation value of the fault impact). This concept is illustrated by some examples for downtime in Table 1.
10489447
LEP OPERATION AND PERFORMANCE WITH 100 GEV COLLIDING BEAMS
Luminosity production in LEP was extended to 101 GeV beam energy in 1999 and 104.4 GeV in 2000. The performance was continually optimised, resulting in 1999 peak and integrated luminosities higher than in any previous year of LEP operation. In particular, the beambeam tune shift reached 0.083 per interaction point. This was achieved with the help of a faster luminosity monitoring, a new tune working point, a reduced design vertical dispersion and new dispersion and coupling optimisation tools. A higher beam rate from the injectors, a better injection efficiency, a faster ramp and a newly automated control of the horizontal damping partition number J x maximised the time available for physics and thus contributed to the higher integrated luminosity.
12798237
Overview of LEP operation in 1998
After the installation of 32 additional RF cavities in the 1997-1998 shutdown LEP was operated at a beam energy of 94.5 GeV. The total integrated luminosity for the year 1998 clearly surpassed its target and reached 198 pb/sup -1/. Vertical beam-beam tuneshifts of more than 0.07 were obtained. The performance did not seem to be beam-beam limited, but the total beam current was limited by power dissipation problems to around 6 mA. A high phase advance optics (102/spl deg/, 90/spl deg/), with a smaller natural emittance, was used for regular operation in 1998. This contributed to the excellent performance of LEP, together with the further reduction of both the horizontal and vertical beta function at the interaction points. No dynamic aperture problems were encountered.
115464633
Do We Understand the Luminosity Imbalance
12690675
The general QCD parametrization and the large Nc description: Some remarks
Stimulated by a recent paper of Buchmann and Lebed,a comparison is presented of the two methods mentioned in the title for treating hadron properties in QCD.Doubts arise on the equivalence of the large Nc description to real QCD. (PACS: 12.38.Aw; 11.15.Pg; 13.40.Dk)
118006705
Parametrizing the baryon magnetic moments
14665617
Comment on "Chiral symmetry and the intrinsic structure of the nucleon"- by D.B.Leinweber,A.W.Thomas and R.D.Young
Some remarks are presented on a recent paper (Leinweber,Thomas and Young, Phys.Rev.Lett. 86, 5011, 2001). In particular a statement of the above paper on the fact that the ratio between the magnetic moments of proton and neutron should remain constant at -3/2, independent of the change of the quark mass is discussed on the basis of the general parameterization.
124048429
Non equivalence of QCD and effective Lagrangians with pions : the example of the $\Delta$'s magnetic moments
120069504
A description of the ferromagnetic levitation electrometer used in the search of quarks in matter
Abstract We describe the main features of the ferromagnetic levitation electrometer and give the basic parameters and construction data.