Instrumentation

Liquid Scintillation Analyzer Tri-Carb 3170TR/SL

The Liquid Scintillation Analyzer (LSA) Tri-Carb 3170TR/SL (by Perkinelmer Ltd) is capable inmeasuring in super low count mode, which is necessary for radiocarbon and tritium dating. The LSA is equipped with a passive lead shield that surrounds the measuring area (sample vial with the two photomultipliers). The super low background counting conditions are meet with the use of the time-resolved technique and the addition of a ring of Bismuth Germanium Oxide (BGO crystal) that surrounds the vial with the sample during measurement. The BGO ring is in coincidence with the two photo multipliers of the LSA and this assures the distinguish of background events. Data acquisition is supported by a specially designed software (QuantaSmart) and a build-in computer system, running NT windows. The counter can calculate theconcentration of up to three beta emitting isotopes from the same sample using the technique ofspectrum unfolding. It is also capable to discriminate alpha and beta emitting radioisotopes in thesame sample using the technique of pulse shape analysis. Alpha and beta counts can be stored in separately files which can accessed for further analysis.

It performs continuous measurements for more than 400 samples (20 ml vials) with unlimitedprotocol and assay combination for up to 60 different users of the counter.

TL/OSL Reader DA-20 (Risø)

The Risø TL/OSL Reader DA-20 was purchased from Risø National Laboratory (DTU-Denmark) and was installed at the facilities of the UoIAC in 2008. The TL/OSL automatic measurementsystem enables measurements of both thermoluminescence and optically stimulated luminescence. The system allows up to 48 samples to be 1) individually heated to any temperature between room temperature and 700°C, 2) optically stimulated using various light sources (blue LEDs array and IR LEDs array) in continuous wave (CW), linearly modulated OSL (LM-OSL) and pulsed OSL (POSL) mode, 3) individually irradiated by radioactive beta source(⁹⁰Sr/⁹⁰Y ).

The emitted luminescence is measured by a light detection system comprising a photomultiplier tube and suitable detection filters. The sample chamber can be programmed to be evacuated (vacuum) or have a nitrogen atmosphere maintained by a nitrogen flow. The TL/OSL Reader is equipped with a radioactive beta source. The system performs any combination of protocols.

Specially designed programs (Sequence Editor, Control, Analyst) are used to control the system and to acquire and analyze data. A separate unit, the controller, controls the hardware of the system.

Integrated system for γ-spectroscopy

The system consists of a Broad Energy HPGe Detector (BE3825) installed in a passive shield system (Lead Shield M747). Data aquisition is performed using an MCA connected to a PC and the Genie 2000 gamma spectroscopy software. The detector has a relative efficiency more than 26% and FWHM resolution at 5.9 keV energy 0.45 keV, at 122 keV energy 0.75 keV and at 1332 keV energy 2.10 keV. Spectra are analysed to determine the radioactivity of each sample in various radioisotopes with photopeak energies from 3keV to 3MeV. The system is used for measuring environmental radioactivity in various kinds of substances: soils, liquids (e.g. water, milk) and air filters. Various geometries are used for sample quantities from 10-500 gr. The system is calibrated for efficiency using standard multi-isotope or ¹⁵²Eu solutions or standard soils and sediments. The Archaeometry Center of the University of Ioannina have participated to internatinal intercalibration tests organized by IAEA with very good results.