Recommendations for Geiger Counter or Scintillation Detector

if you doing some prospecting you might want the scintillation type they are more sensitive to gamma ray as Ozone pointed out, and most uranium and thorium ore have gamma emission .
this one is very simple yet rugged, perfect for carrying around ...



for radio chemistry and isotopes identification you`ll need a gamma spectrometer and a alpha spectrometer but thats a different range of prices..

A good scintillator (at proper voltage for the PMT) will detect (decent) Uranium ore easily 1-2 away. So...yes.

Background counts are higher, too, though, so you might want to make sure you can mute the audio output (it's cool at first, but gets old quickly).

edit: Ugh, I just noticed the one you are looking at is a GM...Regardless, it will be more than enough to get you started (presuming it works).

O3

[Edited on 17-7-2015 by Ozone]



[Edited on 18-7-2015 by Ozone]

to Careysub

use 0.1uF for C and 100Kohm for R
runs at about 2000V DC

Scintillation Probes

On my comment about the PM circuit values posted previously, I suggest this image be studied.



Source:

http://www.rhelectronics.net/store/simple-homemade-diy-gamma...

Quote: Originally posted by careysub

What is the recommended procedure for coating the scintillation block/PM tube interface? I have experience doing oil separated achromatic lenses - there you just put a drop of oil in the concave lens surface, place the second lens on top and wait a day or so for the film to migrate to the edge. If it does not, you can always separate them and try again (and it is easy to see). With the thicker optical "grease" and the fact that you can't see how even the the coat is, thinks look a little trickier. My plan was to make a ~quarter sized smear on the PM tube (as even as I can), heat the plastic block up to maybe 60 C, and place the tube on top with a bean bag weight, and wait for the stuff to migrate to the edge. I am not using this probe for spectroscopy, just pulse counting, so I imagine the requirements aren't as stringent.

Quote: Originally posted by zts16

I've been considering purchasing some kind of radiation detecting device for doing some future uranium ore hunting and radiochemistry. I went to Google and began looking at various Geiger counters and scintillation detectors, and was very overwhelmed by the sheer number of different ones and the wide range of prices. I honestly have no idea how to determine what kind I should buy. In fact, I don't even know whether a Geiger counter or a scintillation detector would be better for what I need. I was hoping that some of the resident radiochemistry enthusiasts would be able to help me out.

Radiation detector for minerals on a budget

Well, I wrote one for an arduino a long while ago.

I ran the arduino off a 9 volt battery, and cannabilised an old camera with flash to get a cheap and highly efficient hv supply (cost 50 cents at Vinnies - aka a thrift store for those not of the great southern land).
I put a 1uF capacitor and 4 x 100v zener in series then fed a sbm20 russian tube in series with a 10 meg ohm resistor. I coupled the junction of the tube and the resistor to an optocoupler via a small capacitor (100pF I think) and used the output photodiode to trigger one of the digital pins on the arduino. Something like this:

It works well, and is able to "see"a uranium glass button I have at over 4 times background.

Code: (Some pinched, some my own)
/* Geiger Counter Interface Example BroHogan 1/26/10
* A very simple example of interfacing to the Geiger Counter circuit and counting
* the events / min. It triggers an LED and piezo for each event but this is not
* necessary since these are included in the circuit.
* *INT from circuit is connected to PIN 2 and triggered as FALLING.
*
* Keypad LCD notes: The keypad uses a single a/d line (A0) and it reads the
* resistance. The keys are aranged as a "resistance ladder", so you can tell by the
* resistance on A0 which key is pressed. Pin 13 generated the voltage at the top of
* the ladder, so to poll the keys you must both set pin 13 high and read A0

* Circuit notes:
* This works with the following:
*
*
* 4N25 optocoupler
*
*<--------| /-------/\/\/\-----+ve 5v
* | ^ |/
* V / |
* --- / |\ ____________/\/\/\_____> int pin 3
* | v |
*<--------- ------|-->|----|
* to gm circuit |
*LED Led1 |
* white V gnd
* 3.9v bandgap
*/
//#include <LCD4Bit_mod.h> // 4 bit lcd keypad shield
//#include <Tone.h> // used for non-blocking tone
#include <TimedAction.h> // THIS LIB MODIFIED - now uses long & public interval


#define PIEZO_PIN 13
#define LED_PIN 11 // pin 11 is led to flash in time with counts
#define PERIOD 10000 // collect counts in 10 seconds
#define DISP_FREQ 5000 // how often to display counts
#define TONE_FREQ 4000
//Tone tone;
TimedAction cntDisp = TimedAction(DISP_FREQ,displayCount); // instanciate timed action for display

//LCD4Bit_mod lcd = LCD4Bit_mod(2); // make an lcd object

volatile boolean newEvent = false; // indicates a new event was caught by ISR
unsigned long startTime, startPeriod;
unsigned long cpmCnt, dispCnt, totalCnt, totalCPM, totalPeriods;
char countstring [15];


void setup(){
cpmCnt = 0;
dispCnt =0;
totalCnt = 0;
totalCPM =0;

Serial.begin(9600);
pinMode(LED_PIN,OUTPUT);
//pinMode(3,OUTPUT); //put geiger pin into low impedence state
//attachInterrupt(0,GetEvent,FALLING); // Geiger event on pin 2 triggers interrupt
attachInterrupt(1,GetEvent,FALLING); // Geiger event on pin 3 triggers interrupt
// tone.begin(PIEZO_PIN);
startTime = millis();
startPeriod = startTime;

pinMode(13, OUTPUT); //we'll use the debug LED to output a heartbeat to drive keypad
//lcd.init();
//optionally, now set up our application-specific display settings, overriding whatever the lcd did in lcd.init()
//lcd.commandWrite(0x0F);//cursor on, display on, blink on. (nasty!)
// lcd.clear();
//lcd.printIn("Geiger counter");
//lcd.cursorTo(2, 0); //line=2, x=0
//lcd.printIn("V1.0 by L Harris");
//delay(500);
//lcd.clear();

memset(countstring, 0, sizeof(countstring)); // fill LCD message with nulls
}

void loop(){
cntDisp.check(); // check if should display the counts
if (millis() > startPeriod + PERIOD) Reset_Counter();
if (newEvent){
updateCount();
//tone.play(TONE_FREQ,100); // short non-blocking tone
digitalWrite(LED_PIN,HIGH); // indicate an event
delay(25);
newEvent = false;
digitalWrite(LED_PIN,LOW);
}
}

void Reset_Counter(){ // aggragate totals and reset counters for each period
totalPeriods ++;
dispCnt = cpmCnt;
totalCPM += cpmCnt;
cpmCnt = 0;
startPeriod = millis(); // reset time
}


void updateCount(){
totalCnt++; // update total count since startup
cpmCnt++;
}

void displayCount(){
Serial.print(dispCnt * 6,DEC);
//lcd.cursorTo(2, 0); //line=2, x=0

//snprintf(countstring, 17, " "); // clear out the old garbage
//lcd.printIn(countstring);
//lcd.cursorTo(2, 0); //line=2, x=0
//snprintf(countstring, 15, "%i CPM", dispCnt);

// lcd.printIn(countstring);
Serial.print(" CPM ");
Serial.print(dispCnt * 4,DEC); // I've read that counts in 40 sec = uR/H
Serial.print(" uR/H ");
Serial.print("Avg CPM: ");
Serial.print((totalCPM * 6) / totalPeriods,DEC);
Serial.print(" Avg uR/H: ");
Serial.print((totalCPM * 4) / totalPeriods,DEC);
Serial.print(" Total Count: ");
Serial.println(totalCnt,DEC);
}

void GetEvent(){ // triggered for each new event
newEvent = true;
}

I made my own counters from kits and vintage Russian pancake GM tubes from ebay. I'm lazy so I purchased counter kits from RHelectronics http://www.rhelectronics.net/store/diy-geiger-counter-kit.ht... particularly the one named
"ARDUINO IDE GEIGER COUNTER DIY KIT VER.2 WITH LCD; W/O GM TUBE"
They work well with the Russian pancake counters, though the dose calculator needs to be adjusted for each tube if you want some semblance of accuracy. You need to change a variable in the software then recompile in the Arduino IDE and reupload to the counter.
The particular tubes I use with those are:
Si-22G large tube, tubular not pancake, quite sensitive but not for alpha, only beta/bgamma
SBT11A - small pancake tube, very portable, decent sensitivity
SBT10A - large pancake tube, about 4x the size of the above, very sensitive but a bit cumbersome
Si-8B - large circular pancake tube, even more sensitive than the SBT10A in my experience.

The last 3 can detect alpha.

I mounted the above tubes+counter combinations on sticks of wood, so that I can test stuff at a distance. About a 1m long stick, 5cm wide and 1cm thick was used for this. The detector is mounted at one end of the stick, high voltage wires (rated for 1000V) connect it to the detector which is mounted about 10cm from the other end together with a battery holder. I call them my GeigerSticks. I had some pictures somewhere but can't find them now.

More information on tubes https://sites.google.com/site/diygeigercounter/gm-tubes-supp...

(edit) note that you can only detect alpha radiation up to distances about 3-4cm away from the source, no matter how sensitive the tube is. That's because the free path of alpha particles in the air is no longer than 5cm.


[Edited on 16-6-2018 by stamasd]

Quote: Originally posted by VSEPR_VOID

Its an old survey meter from the cold war.

Geiger counter advice please

I want to buy a Geiger counter and I am looking at one listed on eBay with the following link:
https://www.ebay.com.au/itm/Geiger-Counter-Beta-Gamma-X-ray-...

Picture of the listing below. I have no experience with Geiger counters. The reason I want one is to check the radioactivity of my uranyl acetate before I use it and then to check the glassware and so on afterwards. Maybe overkill but just to be sure, and something else to learn about.

If there are members on here knowledgeable about Geiger counter use, can you please comment and tell me if this one will be suitable, or if you perhaps can suggest another model from experience?

Thanks in advance.

Quote: Originally posted by draculic acid69

How much depleted uranium acetate would one need to invest to die? How many milligrammes/grams/Oz would it take? Would you die from heavy metal toxicity or from radiation?

A gamma/beta detector isn't ideal for use with uranium salts. Uranium salts contain (almost) only uranium isotopes (238, 235, 234), which are alpha emitters, with little beta and gamma from the small quantities of decay products that have accumulated since manufacture.

Uranium ore on the other hand also contains all the decay products of uranium in secular equilibrium, each of which has an activity equal to that of the uranium isotope it came from. At secular equilibrium, the isotopes are produced as fast as they decay, so their amount doesn't change much over time, and they each contribute equal amounts to the radioactivity (in number of particles emitted per second).

So uranium ore is much more radioactive than pure uranium and we can estimate by how much from the decay chain below.
There are a total of 8 alpha decays and 6 beta decays per uranium 238 atom to reach stable Lead-206. Uranium-238 makes up most of natural uranium and has, by itself, an activity of about 12.5 kBq/mg. That's 12500 decomposition events per second per gram not only for U-238 but also for each decay product, for a combined total of 8x12.5 = 100 kBq/g as alpha particles and 6x12.5 = 75 kBq as beta particles. Almost as much beta as alpha activity!

There's a nice website that explains the principle of secular equilibrium, from which I took the activity plot below. You can see that soon after purification uranium has mostly U-238 and U-234 alpha emission. After years, you start to get beta decays from Th-234 and Pa-234m. And after millions of years you are at equilibrium, hence why this kind of thing only happens in uranium minerals!

(The contribution of the U-235 decay chain is negligible in comparison to U-238, as U-235 has an activity of only about 5% that of U-238 in natural ores)

Additionally, beta particles (which are simply electrons with high energies) can interact with the nuclei of atoms (especially heavy ones such as uranium) to produce x-rays. A phenomenon known as Bremsstrahlung which is used in x-ray tubes for that exact purpose. X-rays are high energy photons, same as gamma rays. The yield of x-rays is low but not zero. So uranium ore produces both beta particles and x-rays in addition to alphas, which is why it can be easily be detected by beta- and gamma-only geiger counters.

If you want to use a geiger counter for safety reasons when using uranium, you should really get one which is sensitive to alpha particles. Especially since uranium chemistry involves purification steps, such that you cannot count on the decay products to make the uranium "visible" to a beta/gamma detector.

Last year I finally got around to buying a device. I went with an old CD V-700 from eBay. It previously belonged to the state of Nebraska and had been serviced/inspected a couple years before, so I figured that there was a good chance of it actually working, and it would appear that it does. It was a good deal, and it came in the original box with the original manual, a couple dosimeter pens, and a charger for the pens. Those probably don't work, but they're cool antiques nonetheless. The whole lot was about $200. Here's some pictures. I was able to get a faint response from a banana with the beta shield open, and a stronger response from an americium source out of a smoke detector. Wanted to post these because I wasn't able to find much info on what these models are capable of detecting without modification.





Given that it responds well to the weak gamma from the americium source, is it safe to say that this meter could work well for identifying hot rocks out in the desert? I don't currently own any ore to test it with.

Quote: Originally posted by Texium

Last year I finally got around to buying a device. I went with an old CD V-700 from eBay. It previously belonged to the state of Nebraska and had been serviced/inspected a couple years before, so I figured that there was a good chance of it actually working, and it would appear that it does. It was a good deal, and it came in the original box with the original manual, a couple dosimeter pens, and a charger for the pens. Those probably don't work, but they're cool antiques nonetheless. The whole lot was about $200. Here's some pictures. I was able to get a faint response from a banana with the beta shield open, and a stronger response from an americium source out of a smoke detector. Wanted to post these because I wasn't able to find much info on what these models are capable of detecting without modification. Given that it responds well to the weak gamma from the americium source, is it safe to say that this meter could work well for identifying hot rocks out in the desert? I don't currently own any ore to test it with.

Late January I got an SBT10A based counter from Lithuania (eBay) unfortunately it ceased functioning after a couple of days...
I first thought it was the battery since I had been playing forensics in my appartment for most of the weekend. I'll have to contact the seller and see if he cares that his unit broke down merely after days of usage.

But boy... that was scary and enlightening !

Three tritium vials put together: 92cpm 0.07µSv/h
The bottom of my bathtub: 294cpm 0.24µsV/h
"Cool" Uranium glass: 204cpm 0.16µSv/h
"Hot" Uranium glass: 6933 cpm 5.55µSv/h

The SBT10A tube is apparently very sensitive. I cant really explain the readings in my bathtub. I ended up in my bathroom looking for a place with the least background radiation. Imagine my surprise (and disbelief!) when I realized my bathtub is more radioactive than tritium vials !
I hope I can get this Geiger counter fixed easily, next place I'm taking it is 20 meters below Pierre and Marie Curie's old lab. I know they had a well where they would dump pechblende waste. I has been depoluted since but I'm curious how well the job was done