It has a diameter of 8cm and is very sensitive:
A quick test showed a background radiation count between 3 and 10 CPS (counts per second), compared to between 3 and 10CPM with my FHZ76V tube !! This is a 60-fold higher count rate !!
I'll do some more tests and measurements soon.
ECV 6343 II652 I COUNTER SI8B LABEL Counter Beta radiation SI8B (hereinafter counter) is used to register the soft beta-radiation in radiometric devices. Climatic performance U3.I. Solo 15170 Date of manufacture OKT 1990 Circuits connecting the electrodes with the findings Designation Name of the output electrode I Free 3 Cathode 5 Free 7 Anode Basic electrical and radiometric parameters The slope of the plateau of the counting characteristics,%, not exceeding: 0,3 Sensitivity of the counting rate, imp.s-1.A-1.kg: 1.3 * 10E12 ... 1.9 * 10E12 Sensitivity of the counting rate (imp / uR): (350 ... 500) The slope of the voltage-current characteristics,%, not more: 1,25 Amplitude voltage pulse, V, no less than: 20 Own background, imp / s, max: 2 Effectiveness of registration of beta radiation,%: 50 ... 85 Current sensitivity, uA: 8 ... 15 (at P = 12.9 * 10E-10 A / kg (5 uR / s)) Operating range voltage, V: 360 ... 440 Maximum operating speed counting, pulses / s: 3400 Maximum operating current, mA: 18.2 The maximum permissible exposure dose of gamma radiation, A / kg: 21.5 * 10E-6 (for 1 min) The maximum permissible exposure dose of gamma radiation (R / h): (300) (for 1 min) Precious metals are not contained. The content of non-ferrous metals in a counter: Nickel - 3.6 grams per 4-pin. Acceptance Information Counter SI8B meets specifications 0D0.339.388 TU. TCI Stamp At re-manufactured _________ date OPERATING INSTRUCTIONS I. After you remove the meter from the package carefully remove the protective cover and visually check to make sure that the counter has no express mechanical defects (cracks of mica, chipped enamel). The counter can be taken only at the base. Is strictly forbidden to touch mica window. 2. The inclusion of the counter is made by feeding the anode voltage 390. 3. During operation of the counter values that determine the mode of operation, should not exceed the maximum allowable value. Doing so may lead to loss of counters performance.