I added enough hot glue to the terminals of the GM tube to put an end to the corona discharge. I also ran a test of the Aware Electronics RM-60 beside the Electronics Goldmine Geiger counter. The Goldmine detector picked up six times as much radiation.
Here's what the current detector looks like.
That tube is the Russian made SBM-20. According to the maker it has a sensitivity to Cobolt 60 of 22 CPS/mR/hr.
ReplyDeleteThe RM-60 sensitivity to Cobolt 60 is 21.3 CPS/mR/hr. Maybe you are getting six pulses from that counter circuit per Geiger pulse. The circuit might do this so you can see the LED flash and hear the click i.e. the pulse from the tube would not be long enough to allow one to see the LED flash or hear the click or perhaps that tube is old and is ringing.
Elsewhere I noticed you stated the RM-60 deadtime is 20 ms. The deadtime of the RM-60 is ~ 50 to 90 microseconds not 20000 micro seconds (20 ms). The deadtime of the RM-60 decreases with higher radiation count rates and will generate 33,000 CPS with a radiation field of 2 Roentgens/hr as tested by a government agency, ~1000 times higher then your 20 ms deadtime implies.