120919376
The Durham air shower array - III: Evaluation of the array's response to showers
Abstract A Monte Carlo investigation of the Durham air shower array is described in which the systematic biases introduced into air shower data recorded by the experiment are evaluated.
5729393
High-Speed Data-Injection for Data-Flow Verification at LHCb
The High Level Trigger (HLT) and Data Acquisition System select about 2 kHz of events out of the 40 MHz of beam crossings. The selected events are consolidated into files in onsite storage and then sent to permanent storage for subsequent analysis on the Grid. For local and full-chain tests a method to exercise the data-flow through the High Level Trigger is needed in the absence of real data. In order to test the system as much as possible under identical conditions as for data-taking, the solution would be to inject data at the input of the HLT at a minimum rate of 2 kHz. This is done via a software implementation of the trigger system which sends data to the HLT. The application has to simulate that the data it sends come from real LHCb readout-boards. Data can come from several input streams, which are selected according to probabilities or frequencies. Therefore the emulator offers runs which are not only identical data-flows coming from a sequence on tape, but physics-like pseudo-indeterministic data-flow, including lumi events and candidate b-quark events. Both simulation data and previously recorded real data can be re-played through the system in this manner. As the data rate is high (100 MB/s), care has been taken to optimize the emulator for throughput from the Storage Area Network. The emulator can be run in stand-alone mode, but even more interesting is that it can emulate any partition of LHCb in parallel with the real hardware partition. In this mode it is fully integrated into the standard run-control. The architecture, implementation, and performance results of the emulator and full tests will be presented. This emulator is a crucial part of the ongoing data-challenges in LHCb. Results from these Full System Integration Tests (FEST) will be presented, which helped to verify and benchmark the entire LHCb data-flow.
178787319
Determining the Arrival Directions of Extensive Air Showers from Fast Timing Measurements
121598426
High-energy muons in extensive air showers
SummaryA study has been made of the density of high-energy muons (10<Eμ<300 GeV) as a function of the distance from the axis of extensive air showers in the size range 2·105<Ne<3·106,i.e. showers produced by primary cosmic rays in a decade of energy centered on 5·1015 eV. The results for muons above 50 GeV agree with those from the Lodz-Moscow group, but those for muons above 200 GeV are a little different from the only other experimental results: those of Acharyaet al. Comparison with predictions favours a CKP-type model with a «normal» comparison. The simple scaling model with any composition does not give a good fit to the data, but no doubt modifications could be made, principally an increase in the mean transverse momentum, which would restore agreement.RiassuntoSi è effettuato uno studio della densità dei muoni (10<Eμ<300 GeV) in funzione della distanza dall’asse di sciami d’aria estesi nell’intervallo di grandezza 2·105<Ne<<3·106, cioè sciami prodotti da raggi cosmici del primario in un decadimento di energia centrato su 5 · 1015 eV. I risultati per muoni al di sopra di 50 GeV sono in accordo con quelli del gruppo di Lodz-Moscow, ma quelle per muoni al di sopra di 200 GeV sono un po’ differenti dagli unici altri risultati sperimentali: quelli di Acharyaet al. Confronti con produzioni sono a favore del modello del tipo CKP con una composizione « normale ». Il modello a variazione di scala semplice con qualsiasi composizione non dà un buon adattamento ai dati, ma, senza dubbio, modificazioni potrebbero essere fatte, principalmente un aumento nell’impulso trasversale medio, che ripristinerebbero l’accordo.
129617632
The Durham Extensive Air Shower Array
5719579
DIRAC: A Community Grid Solution
The DIRAC system was developed in order to provide a complete solution for using the distributed computing resources of the LHCb experiment at CERN for data production and analysis. It allows a concurrent use of over 10K CPUs and 10M file replicas distributed over many tens of sites. The sites can be part of a Computing Grid such as WLCG or standalone computing clusters all integrated in a single management structure. DIRAC is a generic system with the LHCb specific functionality incorporated through a number of plug-in modules. It can be easily adapted to the needs of other communities. Special attention is paid to the resilience of the DIRAC components to allow an efficient use of non-reliable resources. The DIRAC production management components provide a framework for building highly automated data production systems including data distribution and data driven workload scheduling. In this paper we give an overview of the DIRAC system architecture and design choices. We show how different components are put together to compose an integrated data processing system including all the aspects of the LHCb experiment - from the MC production and raw data reconstruction to the final user analysis.
117019037
The Lyman-alpha signature of the first galaxies
120136815
A lead-glass cherenkov detector for electrons and photons
Abstract An apparatus for the detection of high-energy electrons and photons is described. Lead-glass Cherenkov counters measure the energies, and charged particle tracks are reconstructed using an array of wire spark chambers. The mode of operation, calibration, and stability of the system are described, and details are given of the ability to discriminate electrons from hadrons.
119945983
πp elastic scattering from 88 to 292 MeV
Abstract Differential cross sections for π + p and π − p elastic scattering have been measured with an accuracy of typically ±2% at 10 and 9 energies respectively in the range 88 to 292 MeV of lab kinetic energy.
119595431
A wire-spark-chamber system with on-line computers
Abstract We describe the performance of a system of wire spark chambers and 2 on-line computers (one being time-shared) used in an experiment at the Brookhaven A.G.S. to study the decay of K± mesons via the τ mode (K±→ π ± π ± π ∓).
118694154
Production of Dimuons by Pions and Protons at Fermilab
In this lecture I shall describe an experiment in progress1 at the Fermi National Accelerator Laboratory (FNAL) to study the production of μ+μ− pairs in hadron-hadron collisions. So far, we have used beams of 225 — GeV π+, π− and protons incident on carbon and tin targets for most of the data. In an earlier run, a 150 GeV positive beam was used with a beryllium target. The results I report of the 150 GeV run are final; those at 225 GeV are preliminary.