(Update 2011-06-07 22:30 CEDST): more measurement results and photos added.
- Background radiation, indoor..
90-126cpm, average 105cpm (with or without aluminium Beta-shield on probe).
- Fertilizer (N-P-K), 100grams of granulars in a zip-bag laid on top of the probe:
with Beta-shield: 134-149cpm, average 141cpm.
without Beta-shield: 475-548cpm, average 505cpm.
- Am-241 Source from Smoke detector:
with Beta-shield: 7-12cps (420-720cpm).
without Beta-shield, just a piece of paper between Am-241 source and probe (blocking alpha): 13-25cps (780-1500cpm).
without any shielding: 150-450cps (9000-27000+ cpm).
- Wolfram-Thorium (red color band, 2% Thorium, 2.4mm thickness) Tungsten welding electrode:
A length (8cm) of WT20 electrode positioned across the SI-8B window:
with Beta-shield: 253-280cpm, 268cpm average.
without Beta-shield: 521-543cpm, 530cpm average.
with Beta-shield: 239-285cpm, 261cpm average.
without Beta-shield: 536-556cpm, 544cpm average.
Both lengths of WT20 electrode positioned side-by-side across the SI-8B window:
with Beta-shield: 356-427cpm, 389cpm average.
without Beta-shield: 941-983cpm, 963cpm average.
- 14C 60µC test source (Beta radiation, 0.156476MeV), in TTL6109a
"Strahlenspurgerat". Measured with the SI-8B held close to the mica window of the ionisation chamber, with the mode switch in the "R" position (so the 14C test source is exposed into TTL6109A's ionisation chamber).
with Beta-shield: 102-143cpm, 116cpm average
without Beta-shield: 3924-4360cpm, 4142cpm average
cpm = counts per minute
cps = counts per second
Photo's of experimental counter setup with SI8B, my HV inverter circuit and my Pulse-Counter / RS232- interface / LCD:
|Test setup with SI8B, HV inverter and PIC pulse counter / LCD, powered by 4 NiMh coin cells|
|Close-up of the SI-8B mounted on a Pringles can.|