Investigation of the activity of the β-radioactive source
Fizikos laboratorinis darbas. Investigation of the activity of the β-radioactive source. Purpose. Determination of the β-radioactive source. Apparatus. The main formulas. Procedure. Calculations. Conclusions. We determined the β-radioactive source and calculated the absorption of β-particles coefficient which are for thick plastic μ=1316 1/m, for clear plastic μ=1778 1/m and for cardboard μ=1864 1/m. References.
The low-background device together with the pulse counter are used for the determination of the activity of β-radioactive source. The low-background device (Fig 1) consist of the detector 1 for the registration of radioactive particles emitted from the radioactive source, detector 2 mounted on a cylinder block which take into account an external radiation, triggers 3, cascade 4 connected into anticoincidence with respect to detectors 1 and 2 to eliminate the external radiation and amplifier 5. The leaden protective shell of the low-background device has a movable part.
The detectors used in the low-background device are Geiger-Muller counters. The Geiger-Muller counter (Fig 58) consists of a cylinder (cathode) and a thin wire (anode) fixed on insulators. The potential difference of 1.0-1.2 kV is set up between the electrodes. The chamber of the counter is filled with Ar gas at the pressure of 90 mm Hg.