The high data rates at the LHC necessitate the use of biasing selections already at the trigger level. Consequently, the correction of the biases induced by these selections becomes one of the main ...challenges for analyses. This paper presents the LHCb implementation of a data driven method for extracting such biases which entirely avoids uncertainties associated with detector simulation. Its novelty lies in the LHCb trigger which is implemented entirely in software, allowing its decisions to be reproduced in an exact manner offline. It is demonstrated that this method allows the control of selection biases to better than 0.1%, and that it greatly enhances the range of physics which can be performed by the LHCb experiment. The implications of trigger and software architectures on the long term viability of this method, in particular with respect to the reproducibility of trigger decisions when running the same code on different underlying hardware or compilers, is discussed.
The LCG Persistency Framework consists of three software packages (CORAL, COOL and POOL) that address the data access requirements of the LHC experiments in several different areas. The project is ...the result of the collaboration between the CERN IT Department and the three experiments (ATLAS, CMS and LHCb) that are using some or all of the Persistency Framework components to access their data. POOL is a hybrid technology store for C++ objects, using a mixture of streaming and relational technologies to implement both object persistency and object metadata catalogs and collections. CORAL is an abstraction layer with an SQL-free API for accessing data stored using relational database technologies. COOL provides specific software components and tools for the handling of the time variation and versioning of the experiment conditions data. This presentation reports on the status and outlook in each of the three sub-projects at the time of the CHEP2012 conference, reviewing the usage of each package in the three LHC experiments.
The Persistency Framework consists of three software packages (CORAL, COOL and POOL) addressing the data access requirements of the LHC experiments in different areas. It is the result of the ...collaboration between the CERN IT Department and the three experiments (ATLAS, CMS and LHCb) that use this software to access their data. POOL is a hybrid technology store for C++ objects, metadata catalogs and collections. CORAL is a relational database abstraction layer with an SQL-free API. COOL provides specific software tools and components for the handling of conditions data. This paper reports on the status and outlook of the project and reviews in detail the usage of each package in the three experiments.
The beam and detector, used for the NA48 experiment, devoted to the measurement of
Re
(
ε
′
/
ε
)
, and for the NA48/1 experiment on rare
K
S
and neutral hyperon decays, are described.
Abstract The NA48/2 experiment at CERN reports the first observation of the K ± → π 0 π 0 μ ± ν decay based on a sample of 2437 candidates with 15% background contamination collected in 2003–2004. ...The decay branching ratio in the kinematic region of the squared dilepton mass above 0.03 GeV2/c 4 is measured to be (0.65 ± 0.03) × 10 −6. The extrapolation to the full kinematic space, using a specific model, is found to be (3.45 ± 0.16) × 10 −6, in agreement with chiral perturbation theory predictions.
After ten years from its first version, the Gaudi software framework underwent many changes and improvements with a subsequent increase of the code base. Those changes were almost always introduced ...preserving the backward compatibility and reducing as much as possible changes in the framework itself; obsolete code has been removed only rarely. After a release of Gaudi targeted to the data taking of 2008, it has been decided to have a review of the code of the framework with the aim of a general consolidation in view of the data taking of 2009. We also decided to take the occasion to introduce those improvements never implemented because of the big impact they have on the rest of the code, and those changes of the framework needed to solve some intrinsic problems of the implementation, but never made because they were considered too disruptive. With this contribution we want to describe which are the problems we addressed and the improvements we made to the framework during this review.
The drift chamber electronics for the NA48 experiment Arcidiacono, R.; Cartiglia, N.; Chiozzi, S. ...
IEEE transactions on nuclear science,
2004-Aug., 2004-08-00, 20040801, Letnik:
51, Številka:
4
Journal Article
Recenzirano
Drift chamber readout electronics for over 8000 channels with concurrent data recording and readout have been developed to update the NA48 experiment existing system. Drift times are measured in bins ...of 1.56 ns with respect to the continuously running 40 MHz experiment clock. The architecture is based on commercially available hardware for cost effectiveness and flexibility. The design of the electronics is described, and results from data-taking runs are presented.
A new read-out for the drift chambers (DCH) (8192 channels) of the NA48 experiment at CERN has been developed and realized by the Ferrara and Torino INFN sites and has taken data during the 2002 run. ...The core of the system is a set of 32 VME-9U Time-to-Digital-Converter boards (NA48-TDC). The NA48-TDCs record the time of arrival of signals from the DCH and store them in 40
MHz pipelined ring memories pending the trigger supervisor's decision. Dual memories and data extraction resources allow independent and simultaneous processing of level-1 and level-2 trigger requests. Time measurements are performed by the TDC-F1 commercial ASICs, having an intrinsic time resolution of 120
ps and multi-hit capabilities. The NA48-TDC board features a maximum sustained rate of 500
kHz per channel.
Abstract A combination of measurements sensitive to the CKM angle γ from LHCb is performed. The inputs are from analyses of time-integrated B + arrow right DK +, B 0 arrow right DK 0, B 0 arrow right ...DK +pi- and B + arrow right DK +pi+pi- tree-level decays. In addition, results from a time-dependent analysis of B s 0 arrow rightD s K ± decays are included. The combination yields γ=(72.2 -7.3 +6.8 )°, where the uncertainty includes systematic effects. The 95.5% confidence level interval is determined to be γ 55.9, 85.2°. A second combination is investigated, also including measurements from B + arrow right Dpi+ and B + arrow right Dpi+pi-pi+ decays, which yields compatible results. Figure not available: see fulltext.
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