A team in Grenoble gathers in a database all cosmic-ray measurements. These data are used by many teams to model the transport of nuclei and electrons in the Galaxy, to search for dark matter in anti-proton and positron data, or to describe Solar modulation (linked to the Solar cycle). A major update of this database (CRDB v4.0) has just been published in the journal "Universe".
Since its discovery in 1912, cosmic rays (CR) have been measured by numerous ground-based and balloon-borne instruments, satellites, and more recently, from experiments on the international space station. Despite a century of progress, the CR sources and the details of the CR transport of charged particles, inside and outside the Galaxy, remain poorly understood. Any advance in the field relies on the interpretation of the energy spectrum of different species (hydrogen ions up to Uranium, anti-nuclei, electrons and positrons) over a wide range (from 106 to 1021 eV), which requires collecting data from numerous experiments.
The CRDB database (Cosmic-Ray DataBase, https://lpsc.in2p3.fr/crdb) results from a collaboration between a physicist and a computer scientist at the Laboratoire de Physique Subatomique de Grenoble (LPSC/CNRS/IN2P3/Université Grenoble Alpes). This database is based on a suite of free softwares (Linux, Apache, MySQL, PHP) and a web interface for the users. The data are presented in a contextualized manner, associated with the description of the detector, information on the data taking, links to publications. A dedicated interface allows users to view and extract various combinations of data, via several selection criteria and possible transformations (see Figure 1); a REST (Representational state transfer) interface allows this extraction without visiting the website.
Fig 1: Selection of all nuclear data published by the AMS-02 experiment, converted here in unit of kinetic energy per nucleon (Ek/n) and multiplied by Ek/n2.8 to highlight the power-law behaviour at high energy.
In the latest CRDB update, we have added (i) upper limits on anti-nuclei (anti-deuteron, anti-helium, etc., used for dark matter searches), (ii) data for super-heavy nuclei Z> 30 (whose abundances are 106 times lower than that of Fe), and (iii) ultra-high energy data (flux 1034 times lower than low energy ones!). Other improvements are related to the user interfaces, extraction criteria, and on the submission of new data by experimenters, etc. Figure 2 illustrates the reconstruction of the Solar modulation factor from neutron monitor data. This factor can be used to reconstruct Galactic CR fluxes for any period between 1950 and today (best time resolution is 10 minutes); this is for instance useful for modelling the impact of Galactic CRs on scientific missions onboard satellites.
Fig 2: Solar modulation level reconstruction from 2011 till today, colour-coded for the different neutron monitors used.
To conclude with a few figures, CRDB aggregates 44,638 data points, from nearly 400 publications, covering more than 100 experiments. CRDB is also more than a quarter million requests (since its start in 2013) mainly from Germany, USA, France, Italy, China, Switzerland, Japan, Russia, South Africa and many other countries.
Maurin, Melot et Taillet, A&A 569, 32 (2014)
Maurin, Dembinski, Gonzalez, Maris et Melot, Universe 6, 102 (2020)