CS257338B1 - Scintillation unit - Google Patents

Abstract

High detection efficiency radioimmunoassay scintillation unit for low energy gamma irradiation formed by a hermetic casing, photomultiplier, coupled with optical well-scintillation crystal contact wells, scintillation crystal from thali-activated sodium iodide monocrystal. Its surfaces are matted, or provided with a white reflective layer, with a polished front wall, where the space between the well and the crystal surface with a thickness not exceeding 0.25 mm is filled with either powdered magnesium oxide or air.

Description

The invention relates to a scintillation unit for radio-immunoassay.

In the measurement methods used in the radio-immunoassay, mainly the gamma radiation of radionuclide J is used. The scintillator with photomultiplier is used as the detection unit. However, the detection units used hitherto have a relatively low detection efficiency for low-energy gamma radiation.

Very high detection efficiency of low-energy gamma radiation is achieved by the scintillation unit for radio-immunoassay analysis according to the invention, consisting of a hermetized housing, a photomultiplier coupled by optical contact with a well scintillation crystal and a well based on thaliem activated sodium iodide scintillation monocrystal it has its surfaces finely matte or white reflective, the front surface is polished and the space between the well and the crystal surface does not exceed 0.25 mm in thickness and is filled either with magnesium oxide or with air.

In the following, the scintillation unit is described in more detail in conjunction with the accompanying drawing, and exemplary embodiments are given below.

In a schematic vertical section, the housing 1, the scintillation crystal 2, the photomultiplier 3, the well 4, the magnesium oxide 5, the space 6 between the well 6 and the scintillation crystal 2 are plotted, and the optical contact is indicated.

Example 1

A photomultiplier 2 connected by optical contact 2 ^{to the} well scintillation crystal 2 was fixed into the metal casing. The space between the crystal 2 and the housing 2 was filled with magnesium oxide 5, also the space 2 between the crystal 2 and the well 4, the thickness of which was 0.2 mm, was filled with the powdered magnesium oxide 5. the Cs standard in the well 2) was 70%.

Example 2

The procedure was the same as in Example 1 except that the scintillation crystal 2 of sodium iodide monocrystal activated by thallium was left to be subjected to atmospheric moisture after treatment until the surface was partially etched. It was then transferred to a nitrogen-purged reduced moisture box. In this environment, the etched layer turned into a white layer that adhered firmly to the crystal surface and acted as a reflector in the unit. The space 6 between the crystal 2 and the well 4 0.23 mm thick was filled with air in this case. The total 137 detection efficiency for gamma radiation with energy of 32 keV (Cs standard in well 2) was 65%.

Claims (1)

SUBJECT OF THE INVENTION Scintillation unit for radio-immunoassay consisting of a hermetic capsule, a photomultiplier coupled by optical contact with a well scintillation crystal and a well, characterized in that the scalillation crystal (2) of thallium activated sodium iodide monocrystal has finely matted or white reflective surfaces the space (6) between the well (4) and the crystal surface (2) to a thickness of 0.25 mm is filled either with powdered magnesium oxide (5) or with air.