New method for measuring ultralow levels of radioactivity

Since more than two years the so-called Counting Test Facility (CTF), the prototype of the BOREXINO solar neutrino experiment, is taking data at the underground laboratories of the LNGS. During its construction and the period of data taking a new method for measuring radioactivity at ultralow levels has been developed. This method is based on a well known type of detector, on miniaturized proportional counters. It is used for measuring the concentrations of 222Rn and 226Ra in various materials (gases, liquids). The sensitivity levels which have actually been reached are competitive with other methods developed in different experiments.