The LBA (low activity laboratory) is capable of measuring very low levels of radioactivity. It is a member of the Réseau Becquerel of the IN2P3. This laboratory, located inside the LPSC, is equipped with two hyper-pure geranium detectors. Different kinds of samples can be analyzed (ore, water, raw material)
The LBA is equipped with two germanium detectors made of high purity quality, one is 100 cc, the other is 122 cc, for the low activity measurements and X ray energies. These measurements are made for the needs of the laboratory and also for outside requests.
Both detectors are surrounded by two cm of lead exempt of natural radioactivity (archeological lead), and by 15 cm of purified lead. The two detectors and the lead plate are placed at the center of a two meter high cube; each face of this cube is made with a liquid sparkle detector. These detectors prevent pollution of the acquisition due to the cosmic muons and cosmic neutrons.
The detector is located in an underground room of the laboratory. Protection from possible dust is obtained by the using air filters.
The data acquisition and analysis use two PCs equipped with the "Interwinner" (ITECH-instruments) software.
The LBA uses the LPSC hot chemical laboratory for packaging samples.
Residual rates of counting are 3 rounds/mn for the 100 cc detector, and 1.5 rounds/mn for the other one.
The following limits of detection, calculated for a 100 g sample are:
Uranium and Thorium family: 0.01 Bq/Kg (That is 1 in 2 parts by one billion).
Olivier Méplan et Mourad Ramdhane
Tel : +33 4 76 28 40 57 et +33 4 76 28 40 27
Tel : +33 4 76 28 40 23