CSC2003 Programme Track Description



AL:  Algorithms

Rudi Frühwirth, Andreas Pfeiffer


The objective of this track is to make the students familiar with state-of-the-art algorithms used for event selection and event reconstruction. At LHC, event selection is a very important topic, because of the high event rate and the small signal to background ratio. An efficient and powerful selection procedure has to rely on an at least partial reconstruction of the event; reconstruction algorithms therefore play an important role already at this stage. The first lecture series explains the principles of event selection and gives an overview of the algorithms that are used in this context. The details of some of these algorithms are explored in the exercises.  If an event is selected, full reconstruction is launched.   In this stage the emphasis is on the best possible precision that can be obtained. It has recently been shown that adaptive algorithms of track reconstruction can cope very well with the high background that is present in the LHC track detectors. The second lecture series explains the concept of adaptive methods, explores their relation to general combinatorial optimization problems, and shows that they can be implemented as iterated classical (least-squares) estimators. The most important features of adaptive methods are demonstrated by solving some basic problems in combinatorial optimization in the exercises. The third lecture series deals with the task of vertex reconstruction, which consists of assigning tracks to common production points (vertices) and of finding optimal estimates of vertex and track parameters. After an exposition of the traditional methods, applications in several experiments are presented and discussed critically.  Finally, it is shown that robust and adaptive methods are important also in vertex reconstruction. The adaptive method is extended to deal with several vertices concurrently, allowing dynamical swapping of tracks between vertices.


Lectures Algorithms for online Event Selection at the LHC N.Neumeister, T.Todorov 4
  AL-ES-L-1 Introduction to online event selection at the LHC  N.Neumeister  
  AL-ES-L-2 Regional and partial event reconstruction T.Todorov  
  AL-ES-L-3 Reconstruction of physics objects N.Neumeister  
  AL-ES-L-4 Algorithms for track reconstruction T.Todorov  
Adaptive methods, with application to track reconstruction A.Strandlie 2
  AL-AM-L-1 Introduction to adaptive methods A.Strandlie  
  AL-AM-L-2 Adaptive methods in track reconstruction at LHC A.Strandlie  
Vertex reconstruction M.Regler 2
  AL-VR-L-1 Basic algorithms for vertex reconstruction, experimental applications M.Regler
  AL-VR-L-2 Robust and adaptive algorithms for vertex reconstruction M.Regler




Algorithms for online Event Selection at the LHC N.Neumeister,T.Todorov 2
Adaptive methods, with application to track reconstruction A.Strandlie 2


Total hours   10+2

 Italics: Optional lectures 

Last edited: 26-May-03 .