Each CMS crystal is unique even though they are all made from the same material. Its physical characteristics therefore needed to be measured and recorded, not only for the construction phase but also for data collecting itself. Every crystal was labelled with a barcode to identify it and track it through the production and operation stages.
The long time-frame of producing the crystals meant that the means of production as well as the associated electronics evolved over time as improvements were made. Themethods of characterising the crystals themselves and the data formats used for storage also evolved with time. The database into which the information was to be stored would itself need to adapt to these evolving workflows. At the same time, the database must be able to fetch all of the data ever recorded –– i.e. it must be capable of handling legacy datasets –– and must be in a situation to do so in the future when the implementation might potentially be very different. It would also have to handle frequent changes, and so be flexible in design.
No such system existed in the mid-'90s, and so a consortium of scientists from CERN, CNRS (the French National Centre for Scientific Research) and UWE (the University of the West of England) set about developing their own database, giving birth to CRISTAL.
CRISTAL stands for Cooperative Repositories and Information System for Tracking Assembly Lifecycles, and was developed at CERN to manage the data of all CMS ECAL components at each stage of construction.
The CRISTAL database and its underlying technology is extremely novel, and has applications far beyond the world of tracking detector components. CRISTAL is description-driven; that is, the database structures can be modified at any time without affecting any of the collected information. The structures themselves are stored as data too, meaning they can be copied between different databases with the data they define. As a result, any large-scale project with rapidly evolving workflows can benefit from using CRISTAL. It was thus one of the first knowledge-transfer projects undertaken by CERN, and was spun-off into Agilium, a private company that handles business-process management. A second spin-off company called Technoledge is providing database solutions for e-governance, accounting firms, and more.
CRISTAL is another excellent example of technology developed in the course of particle physics research that has since found wide-spread use in industry and elsewhere.