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Geiger counter

Discussion of the Cumulusutils tool and website generator.

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HansR
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Re: Geiger counter

Post by HansR »

Cortmalaw wrote: Sat 19 Mar 2022 12:59 am Well, I bought this board and it arrived in 3 days as promised.
https://www.ebay.co.uk/itm/373937539723
Whahaha.... There I go with 8 weeks waiting time. Used Amazon to avoid AliExpress but that clearly did not help. The €27 I payed is cheap, but a bit faster may cost something ;)
Anyway, I'll sit it out. Congrats with the quick buy. Good to hear it works.

Thanks for the observations and the code. I found it here for reference and maybe for some who wish to use an Arduino, ESP32 or whatever remotely.

I will probably come back on the code with some modified - but still very simple - procedure to write output to a file and move it to the CMX machine or even the website directly where it can be picked up by CumulusUtils (at least, that will be the idea) as an extra sensor. This will require some modification of CumulusUtils itself as well. I don't expect CMX to start handling any wild piece of equipment.
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Re: Geiger counter

Post by Cortmalaw »

Further update.

The detector works fine powered from Raspberry Pi GPIO pins as expected.

However, the Raspberry Pi data connection didn't work as expected; no counts counted despite the detector clicking away.
I decided to add a simple decoupling capacitor - 100 nF in between the VIN output pin and the GPIO pin. Still no success when looking for either falling or rising edges. I thought the 'clicks' were likely being swamped by the software 'pull up' - and as soon as I disabled that it counts correctly.

An improved version of the program is below.

I also looked at the "Geiger Bot" iPad/iPhone program. It runs on an old iPad I had lying around, but not on current models. It has some excellent features which I will adapt for future Raspberry Pi programming, but a big downside that it does NOT use the audio cable even when plugged in - it just relies on the iPad microphone picking up the clicking noise, and will not cope with very fast rates. I need to experiment with decoupling and a correct cable (the device outputs a mono signal on L and R channels of a headphone socket; need to decouple that to the 2nd ring (microphone) of iPad input connector, I think.

My next problem is that I have reasonable indoor counts (eg 30/min), but outdoors I'm getting an outrageously high 100,000 counts/min. Explanation awaited but I'm bothered about that nearby recently disturbed ex-radioactive waste dump site. Maybe there's a correlation with wind direction and dust particle counts. Luckily I'm acquiring all the monitoring gear!

Code: Select all

# Raspberry Pi connection:
# Maybe the code can be optimized but it works and that's good. 
#     VIN = INT connected to pin#12 via a 100nF decoupling capacitor
#     5V to pin#2
#     GND to pin#6

import time
from datetime import datetime
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BOARD) # use RaspPi board layout pin numbering
GPIO.setup(12, GPIO.IN) # Only works if do NOT have a pull up or down

counter = 0

def tube_impulse_callback(channel): # threaded callback -- falling edge detected
    global counter # make counter global to be able to increment it
    counter+=1
    # print("Click",counter,"!") # disabled to hide display of individual clicks

# when a falling edge is detected on pin#12, regardless of whatever 
# else is happening in the program, the tube_impulse_callback will be run
GPIO.add_event_detect(12, GPIO.FALLING, callback=tube_impulse_callback)

try:
    while True:
        currentMinute = datetime.now().minute
        while datetime.now().minute == currentMinute: # this minute..
            time.sleep(1) # .. wait while add_event_detect detects pulses
        print("Minute",currentMinute, ":", counter,"/min")
        counter=0 # reset counter
except KeyboardInterrupt:
    GPIO.cleanup() # clean up GPIO on CTRL+C exit
except:
    GPIO.cleanup() # clean up GPIO on normal exit

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Re: Geiger counter

Post by HansR »

Cortmalaw wrote: Sun 20 Mar 2022 6:27 pm However, the Raspberry Pi data connection didn't work as expected; no counts counted despite the detector clicking away.
I decided to add a simple decoupling capacitor - 100 nF in between the VIN output pin and the GPIO pin. Still no success when looking for either falling or rising edges. I thought the 'clicks' were likely being swamped by the software 'pull up' - and as soon as I disabled that it counts correctly.

An improved version of the program is below.
Great thanks!
Cortmalaw wrote: Sun 20 Mar 2022 6:27 pm My next problem is that I have reasonable indoor counts (eg 30/min), but outdoors I'm getting an outrageously high 100,000 counts/min. Explanation awaited but I'm bothered about that nearby recently disturbed ex-radioactive waste dump site. Maybe there's a correlation with wind direction and dust particle counts. Luckily I'm acquiring all the monitoring gear!
That is interesting. The counter pays apparently. I would calculate it to µSv/h (see link above).

100.000 cpm = 812 µSv/h
For a day that would be 19.488 µSv which, according to the link above, would be 40% of the Maximum allowable yearly occupational dose in the USA.

Either there is an error somewhere, you should get worried or something happened 5000 miles east of us (the wind is E to SE).

Can't wait to get my device :roll:
Hans

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Re: Geiger counter

Post by mcrossley »

Aren't these tubes UV sensitive, so they need to be in a light tight container out doors?
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Re: Geiger counter

Post by HansR »

Paper or other darkening material would also reduce penetrating power of lower energy particle/radiation.
And I am not sure UV has enough energy to excite the gas in the tube.

But anyway, easy enough to try I guess: cover the tube with paper and see what happens shine with a uv light source or see how the tube behaves outside at night.
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Re: Geiger counter

Post by Cortmalaw »

mcrossley wrote: Sun 20 Mar 2022 7:50 pm Aren't these tubes UV sensitive, so they need to be in a light tight container out doors?
I think Mark has it: the counts were normal at the front of my house (more shaded) and later on became low at the back as well. I didn't associate it with 'getting dark', but it seems very likely that's the cause.

If we need to put something in place to block the light, the purpose of the measurements is somewhat defeated as the material would stop low energy particles. More experimentation needed, but it may be that only BRIGHT sunlight causes the problem. The last 2 days have been the brightest days seen in Glasgow so far this year - very unseasonal.

My "luxometer" is currently inoperative after high winds lifted the lid and allowed rain into my EnviroMonitor housing (a bird box!). The PiZero was destroyed and the BME280 Temperature/Pressure/Humidity sensors now report stupid values ( minus 280C !) - luckily I have those from my Vantage Pro.
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Re: Geiger counter

Post by mcrossley »

HansR wrote: Sun 20 Mar 2022 8:30 pm Paper or other darkening material would also reduce penetrating power of lower energy particle/radiation.
From what I understand (and remember from university about 100 years ago!) unless you buy a tube with a special (thin mica?) window then they are only really sensitive to gamma rays. Almost all alpha and beta radiation will be blocked by the glass walls of the tube, neutrons get through to some extent but I'm not sure if these tubes will register them anyway? Gamma radiation will penetrate a thin solar shield easily.
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Re: Geiger counter

Post by HansR »

mcrossley wrote: Mon 21 Mar 2022 1:09 pm From what I understand (and remember from university about 100 years ago!) unless you buy a tube with a special (thin mica?) window then they are only really sensitive to gamma rays. Almost all alpha and beta radiation will be blocked by the glass walls of the tube, neutrons get through to some extent but I'm not sure if these tubes will register them anyway? Gamma radiation will penetrate a thin solar shield easily.
Mine is 200 yrs ago :lol:
But anyway, I guess you are right. I have been looking at devices with smaller tube with a mica window but those are about 6 times more expensive and professional geiger tubes are beyond that.

The good thing though is that a lot of different tubes - many not glass - can be bought (in Russia :shock: ; probably no more) at low prices so experimentation is possible. The only thing to do is regulate the working voltage for the tube which I think is possible on this device. Anyway, as a toy it is great and will give an indication. If we really want to detect a second Chernobyl we will probably need another device.

The other good thing is that this device may drive me to a general extra sensor plotting technique to plot anything which can generate date/value combinations in a csv file. So anything logable will be plotable in or out CMX context with CUtils.
Hans

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Re: Geiger counter

Post by Cortmalaw »

A further progress report.

The tube supplied with my board was a J305. I believe this is a clone/similar to SMB-20. There are details on the Canadian Walmart page https://www.walmart.ca/en/ip/J305-Geige ... WELGV7259G which suggest that it detects Gamma and soft Beta.

The board does indeed have a mini trim pot to allow adjustment of the tube voltage (but note there are special instructions on adding a high series resistance based on your meter's input impedance as the board cannot deliver sufficient current even for a 1MegOhm/Volt digital meter).

The background count rate decreases from 30/min to 20/min if I put the tube inside a length of black heatshrink tubing (unshrunk), similar to when the room is dark overnight.

I now have the detector running on my RPi ZeroW alongside a Pimoroni Enviro+ (measures air particles, noxious gases and Lux), with the Geiger counter connected to pin 22 (GPIO 25) via a 10nF blocking capacitor, detection set to 'falling edge'. I had to change GPIO pin to find one that did not conflict with the Enviro+ or other RPi usage.

I have disconnected Jumper 1 to silence the 'click' speaker, and not connected P100 which would turn on the audio output (3.5mm socket for earpiece). I also disconnected R1 to disable the 'power-on' LED

The data are available for you to see at https://io.adafruit.com/Cortmalaw/dashboards/cortmalaw .

Presently the sensors are all indoors, but I plan on returning them to the garden tomorrow [now done]. I'll add a photo of everything squeezed inside a bird box if I can!
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Re: Geiger counter

Post by HansR »

Nice and thanks for the update. Useful info for when I get my device eventually ;)
And a nice board that Pimoroni Enviro+ btw. I presume you all integrated it in one Python program?

I am curious why the RPi internal pull up/down resistors do not work and I don't really understand the blocking capacitor. But I'll dive into it when I get my own.

So far I did finish my charting exercise for my CumulusUtils (now in beta) and it now should be possible to chart the counts on a website. But that's another story :) I see the adafruit thing does a fine job :clap:
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Re: Geiger counter

Post by zoomx »

Phil23 wrote: Sun 13 Mar 2022 8:00 am [Edit 14/3/22 HR:] This thread has been moved from the Stevenson Screen thread in General as it became a subject in itself.

I know this is a bit extreme, but @ $33, it would be fun to play with a module like this in an screen now more so than after an event we'd rather not have.

https://www.aliexpress.com/item/1005002590519046.html

Both Esp32 & Pi seems to have software solutions.
There is a cheaper version without the geiger tube (I have one, bought in ebay from Ukraine some years ago!)
https://www.aliexpress.com/item/1005002590475171.html

Since there is no shipping option to Italy it cannot be ordered.
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Re: Geiger counter

Post by zoomx »

mcrossley wrote: Mon 21 Mar 2022 1:09 pm
HansR wrote: Sun 20 Mar 2022 8:30 pm Paper or other darkening material would also reduce penetrating power of lower energy particle/radiation.
From what I understand (and remember from university about 100 years ago!) unless you buy a tube with a special (thin mica?) window then they are only really sensitive to gamma rays. Almost all alpha and beta radiation will be blocked by the glass walls of the tube, neutrons get through to some extent but I'm not sure if these tubes will register them anyway? Gamma radiation will penetrate a thin solar shield easily.
Correct.
Soviet tube SMB-20 is covered by metal, usually. I don't believe that UV is capable to raise the counts.
They all are calibrate to a Cesium 137 source so if it get radiation from other sources it gives a bad value because geiger doesn't react differently at different gamma photon energy, you have only a pulse. You have to use a scintillator to have energy measured but they are not as cheap as geiger counters.
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Re: Geiger counter

Post by Cortmalaw »

2 photos attached.
The metal box attached with staples and gaffer tape is theparticle counter with its opening attached at the "bird entry hiole".
The third photo showing the Enviro+ screen visible through the aperture in the box bottom didn't come out.
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Re: Geiger counter

Post by Cortmalaw »

Further update:

The Geiger tube is installed outdoors in the birdbox. It will be dark inside, though I did not take special effort to make it light-tight.

There is a small but definite increase in count rate in parallel to increased light intensity. Same pattern each day, as can be seen at https://io.adafruit.com/Cortmalaw/dashboards/cortmalaw

Geiger vs Lux.jpg
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Re: Geiger counter

Post by HansR »

This is taking some time :o :lol:

My first order never arrived so I asked (and received) my money back and ordered a second time. This time I apparently pushed the wrong button and got a kit. Oh god, it is just a jigsaw puzzle with codes on a sheet of paper and all parts unlabeled. Hope I am not missing anything.

Shall I send it back or order .... nah, I want to do this. :mrgreen:
Don't expect this to be ready tomorrow, Christmas is fine :roll:
This seems a project under a strange star.
    20220627_170537.jpg
    20220627_173939.jpg
    20220627_170611.jpg
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