Computer Physics Communications 140 (2001) 172–178 www.elsevier.com/locate/cpc The HERA-B database services for detector configuration, calibration, alignment, slow control and data classification A. Amorim a,* , Vasco Amaral b , Umberto Marconi c , Stefan Steinbeck d , António Tomé e , Vincenzo Vagnoni c , Helmut Wolters f a DESY, FCUL and LIP, Campo Grande, Ed. C8, P3, 1749-016 Lisboa, Portugal b LIP Coimbra, Lisboa, Portugal c INFN, Bologna, Italy d University of Hamburg, Germany e UBI Covilhã and LIP, Lisboa, Portugal f UCP Figueira da Foz and LIP, Lisboa, Portugal For the HERA-B Collaboration Abstract The database services for the distributed application environment of the HERA-B experiment are presented. Achieving the required 10 6 trigger reduction implies that all reconstruction, including calibration and alignment procedures, must run online, making extensive usage of the database systems. The associations from the events to the database objects are carefully introduced considering efficiency and flexibility. The challenges of managing the slow control information were addressed by introducing data and update objects used in special processing on dedicated servers. The system integrates the DAQ client/server protocols with customized active database servers and relies on a high-performance database support toolkit. For applications that required complex selection mechanisms, as in the data-quality databases, the relevant data is replicated using a relational database management system.  2001 Elsevier Science B.V. All rights reserved. PACS: 07.05.K; 07.05.H; 29.40 Keywords: Information system; Databases; Slow control; Online calibration and alignment; Data quality and event tag 1. Introduction HERA-B [1,2] is an internal target experiment at DESY/Hamburg where beauty hadrons are produced by colliding 920-GeV protons, of the HERA beam * Corresponding author. E-mail address: antonio.amorim@desy.de (A. Amorim). halo, interacting with eight wire targets whose position is constantly adjusting to provide an average of 4 interactions per beam crossing each 96 ns. The experiment has a physics program is heav- ily influenced by trigger considerations. It is neces- sary, among other requirements, that the chain of on- line processing, including full reconstruction, has to achieve a 10 6 reduction of the original 40 MHz inter- action rate with good signal efficiency. 0010-4655/01/$ – see front matter  2001 Elsevier Science B.V. All rights reserved. PII:S0010-4655(01)00268-5