Search

The Compressed Baryonic Matter experiment (CBM) will investigate strongly interacting matter at high net-baryon densities by measuring nucleus-nucleus collisions at the FAIR research centre in Darmstadt, Germany. Its ambitious aim is to measure at very high interaction rates, unprecedented in the field of experimental heavy-ion physics so far. This goal will be reached with fast and radiation-hard detectors, self-triggered read-out electronics and streaming data acquisition without any hardware trigger. Collision events will be reconstructed and selected in real-time exclusively in software. This puts severe requirements to the algorithms for event reconstruction and their implementation. We will discuss some facets of our approaches to event reconstruction in the main tracking device of CBM, the Silicon Tracking System, covering local reconstruction (cluster and hit finding) as well as track finding and event definition.

This paper is dedicated to the current state of the Geometry Database (Geometry DB) for the CBM experiment. The geometry DB is an information system that supports the CBM geometry. The main aims of Geometry DB are to provide storage of the CBM geometry, convenient tools for managing the geometry modules, assembling various versions of the CBM setup as a combination of geometry modules and additional files, providing support of various versions of the CBM setup. The development is based on the analysed users’ requirements (which were formulated in User Requirements Document) and takes into account peculiarities of the workflow for simulation of particle transport through the setup. Both the Graphical User Interface (GUI) and the Application Programming Interface (API) are available for the members of the CBM collaboration.

In position-sensitive detectors with segmented readout (pixels or strips), charged particles activate in general several adjacent read-out channels. The first step in the reconstruction of the hit position is thus to identify clusters of active channels associated to one particle crossing the detector. In conventionally triggered systems, where the association of raw data to events is given by a hardware trigger, this is an easy-to-solve problem. It, however, becomes more involved in untriggered, free-streaming read-out systems like the one employed by the CBM experiment. Here, the time coordinate of the single-channel measurement must be taken into account to decider whether neighbouring active channels belong to a cluster. A simple extension of well-known cluster finding algorithms is not satisfactory because of involving increasing combinatorics, which are prohibitive for reconstruction in real-time. In this article, a cluster-finding solution for the Silicon Tracking System of the CBM experiment is presented which avoids any combinatorics or loops over detector channels. Its execution time is thus independent on the size of the data packages (time slices) delivered by the data acquisition, making it suitable for being used in online reconstruction.

The paper describes the approaches, implemented by the authors, for the track reconstruction in data, subdivided to time slices, in the CBM experiment.

Since the early days of heavy-ion physics, strangeness has been considered a sensitive probe of the state of matter created in nuclear collisions. This assessment still holds today, where we are witnessing renewed interest in collisions at moderate energies, manifested in the running or projected experimental programmes at RHIC, SPS, FAIR, and NICA. In this article, we will review the current understanding of strangeness production at lower energies and discuss how far future measurement of strange particles can contribute to understanding the properties of dense QCD matter and to the search for the onset of deconfinement.

Currently, several experimental programmes, both at existing and at future accelerator facilities, aim at investigating strongly interacting matter with nuclear collisions at energies below top SPS energy. These activities complement the heavy-ion experiments conducted at the highest available energies at the RHIC and LHC accelerators. In this report, we discuss the motivation for and prospects of the low-energy heavy-ion programmes.

Currently, several experimental programmes, both at existing and at future accelerator facilities, aim at investigating strongly interacting matter with nuclear collisions at energies below top SPS energy. These activities complement the heavy-ion experiments conducted at the highest available energies at the RHIC and LHC accelerators. In this report, we discuss the motivation for and prospects of the low-energy heavy-ion programmes.