SI-8b (СИ8Б) Pancake Tube

Archived from radmon.org - originally posted 23/12/2022

Here are some pictures and details about the SI-8b (СИ8Б) Pancake Geiger Muller tube. The adhesive failed between the tube and the Bakelite rear case on my tube, so it would be rude not to take it apart for a look!

From what I understand this tube is designed for soft beta detection, but is also capable of alpha, hard beta and gamma, although calibration would center on soft beta particles. I did however read this from a website: 'This Geiger-Mueller tube is only sensitive to β and γ radiation. The calibration is only correct for the γ radiation (662keV) emitted from Cs-137.' I will test at some point when I get the tube back together and have the rear case sealed back on. It is a very sensitive tube with a very large surface area and thus would be good for survey purposes. Probably too sensitive for background counting.

The Bakelite case and tube rear:

The anode and cathode and glass nipple:

And some close-ups of the front:

Here is the Russian Datasheet and below a translation of the datasheet:

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.

Translated to English using Yandex: