The Thin Gap Chambers database experience in test beam and preparations for ATLAS

Thin gap chambers (TGCs) are used for the muon trigger system in the forward region of the LHC experiment ATLAS. The TGCs are expected to provide a trigger signal within 25 ns of the bunch spacing. An extensive system test of the ATLAS muon spectrometer has been performed in the H8 beam line at the CERN SPS during the last few years. A relational database was used for storing the conditions of the tests as well as the configuration of the system. This database has provided the detector control system with the information needed for configuration of the front end electronics. The database is used to assist the online operation and maintenance. The same database is used to store the non event condition and configuration parameters needed later for the offline reconstruction software. A larger scale of the database has been produced to support the whole TGC system. It integrates all the production, QA tests and assembly information. A 1/12th model of the whole TGC system is currently in use for testing the performance of this database in configuring and tracking the condition of the system. A prototype of the database was first implemented during the H8 test beams. This paper describes the database structure, its interface to other systems and its operational performance.Comment: Proceedings IEEE, Nuclear Science Symposium 2005, Stockholm, Sweeden, May 200

Semantic Event Model and Its Implication on Situation Detection

Events are at the core of reactive applications, which have become popular in many domains. Contemporary modeling tools lack the capability express the event semantics and relationships to other entities. This research is aimed at providing the system designer a tool to define and describe events and their relationships to other events, object and tasks. It follows the semantic data modeling approach, and applies it to events, by using the classification, aggregation, generalization and association abstractions in the event world. The model employs conditional generalizations that are specific to the event domain, and determine conditions in which an event that is classified to lower level class, is considered as a member of a higher-level event class, for the sake of reaction to the event. The paper describes the event model, its knowledge representation scheme and its properties, and demonstrates these properties through a comprehensive example

Using a neural network approach for muon reconstruction and triggering

The extremely high rate of events that will be produced in the future Large Hadron Collider requires the triggering mechanism to take precise decisions in a few nano-seconds. We present a study which used an artificial neural network triggering algorithm and compared it to the performance of a dedicated electronic muon triggering system. Relatively simple architecture was used to solve a complicated inverse problem. A comparison with a realistic example of the ATLAS first level trigger simulation was in favour of the neural network. A similar architecture trained after the simulation of the electronics first trigger stage showed a further background rejection.Comment: A talk given at ACAT03, KEK, Japan, November 2003. Submitted to Nuclear Instruments and Methods in Physics Research, Section

A Complete Characterization of Irreducible Cyclic Orbit Codes and their Pl\"ucker Embedding

Constant dimension codes are subsets of the finite Grassmann variety. The study of these codes is a central topic in random linear network coding theory. Orbit codes represent a subclass of constant dimension codes. They are defined as orbits of a subgroup of the general linear group on the Grassmannian. This paper gives a complete characterization of orbit codes that are generated by an irreducible cyclic group, i.e. a group having one generator that has no non-trivial invariant subspace. We show how some of the basic properties of these codes, the cardinality and the minimum distance, can be derived using the isomorphism of the vector space and the extension field. Furthermore, we investigate the Pl\"ucker embedding of these codes and show how the orbit structure is preserved in the embedding.Comment: submitted to Designs, Codes and Cryptograph

Modeling the origin of parkinsonian tremor

poster abstractEven though much is known about the biophysics, anatomy and physiology of basal ganglia networks, the cellular and network basis of parkinsonian tremor remains an open question. Multiple experimental data suggest that the physiological origin of parkinsonian tremor is different from the physiological origin of other parkinsonian motor symptoms. However, the exact origin of the tremor genesis in Parkinson’s disease remains unknown. A large body of experimental evidence supports the hypothesis, that the tremor arises due to pathological interaction of potentially oscillatory cells within the loop formed by basal ganglia and thalamocortical circuits. We suggest a model of this circuitry, which helps to clarify this potential mechanism of tremor genesis

Semantic Event Model and its Implication on Situation Detection

Abstract -Events are at the core of reactive applications, which have become popular in many domains. Contemporary modeling tools lack the capability express the event semantics and relationships to other entities. This research is aimed at providing the system designer a tool to define and describe events and their relationships to other events, object and tasks. It follows the semantic data modeling approach, and applies it to events, by using the classification, aggregation, generalization and association abstractions in the event world. The model employs conditional generalizations that are specific to the event domain, and determine conditions in which an event that is classified to lower level class, is considered as a member of a higher-level event class, for the sake of reaction to the event. The paper describes the event model, its knowledge representation scheme and its properties, and demonstrates these properties through a comprehensive example

Asymptotic bounds for the sizes of constant dimension codes and an improved lower bound

We study asymptotic lower and upper bounds for the sizes of constant dimension codes with respect to the subspace or injection distance, which is used in random linear network coding. In this context we review known upper bounds and show relations between them. A slightly improved version of the so-called linkage construction is presented which is e.g. used to construct constant dimension codes with subspace distance $d=4$, dimension $k=3$ of the codewords for all field sizes $q$, and sufficiently large dimensions $v$ of the ambient space, that exceed the MRD bound, for codes containing a lifted MRD code, by Etzion and Silberstein.Comment: 30 pages, 3 table

The Certification of ATLAS Thin Gap Chambers Produced in Israel and China

Thin gap chambers (TGCs) are used for the muon trigger system in the forward region of the LHC experiment ATLAS. A TGC consists of a plane of closely spaced wires maintained at positive high voltage, sandwiched between resistive grounded cathode planes with an anode wire to cathode plane gap distance smaller than the wire-to-wire spacing. The TGCs are expected to provide a trigger signal within 25 ns of the bunch spacing of the LHC accelerator, with an efficiency exceeding 95%, while exposed to an effective photon and neutron background ranging from 30 to 500 Hz/cm2. About 2,500 out of the 3,600 ATLAS TGCs are being produced at the Weizmann institute in Israel, and in Shandong University in China. Once installed in the ATLAS detector the TGCs will be inaccessible. A vigorous production quality control program is therefore implemented at the production sites. Furthermore, after chamber completion, a thorough program of quality assurance is implemented to ensure the efficient performance of the chambers during more than ten years of operation in the LHC high rate environment. This program consists of a detailed mapping of the detectors response using cosmic rays, as well as checking the chambers behavior using a high rate radiation source. An aging test performed on five chambers in a serial gas connection is presented. Finally the results of the chambers certification tests performed at CERN before the installation in ATLAS are described.Comment: Presented at 2004 IEEE Nuclear Science Symposium 2004, Rome, Oct 200