A first level trigger approach for the CBM experiment

In view of the very heavy CBM experiment constraints on the first level trigger, no conventional trigger is obviously applicable. Hence a fast trigger algorithm with the goal of realization in reconfigurable hardware had to be developed to fulfil all requirements of the experiment. In this connection the general Hough transform, which is already utilized in several other experiments, is used as a basis. This approach constitutes further a global method for tracking, which transforms all particle interaction points with the detector stations by means of a defined formula into a parameter space corresponding to the momentum of the particle tracks. This formula is of course developed especially for the given environment of CBM and defines thus the core of the applied three dimensional Hough transform.
As the main focus of attention is furthermore on the realization of the needed data throughput, the necessary complex formula calculations give reason to outsource predefined formula results in look-up tables. This circumstance offers then collaterally the possibility to utilize any other sufficiently precise method like Runge-Kutta of fourth order for example to compute these look-up tables, because this computation can be evidently done offline without any effect on the Hough transform s processing speed.
For algorithm simulation purposes the CBMROOT framework provides the module htrack , which is written in the programming language C++. This module includes many analyses for the determination of algorithm parameters, which can be even executed automatically to some extent. In addition to this, there are of course also analyses for the measurement of the algorithm s quality as well as for the individual rating of each partial step of the algorithm. Consequently the milestone of a customizable level one tracking algorithm, which can be used without any specific knowledge, is now obtained.
Besides this, the investigated concepts are explicitly considered in