Adjusting Ludlum 2000 for Neutrons

[Steven Haid]

Thanks for the advice on getting the C-BNC cable from Ludlum. It arrived yesterday and I connected my Ludlum 2929 to the HE3 tube and it gets counts.

The Ludlum 2929 is a dual channel scaler that is generally used with an Alpha/Beta sample counter. The manual says it also works with Proportional detectors, which is what the He3 tube is.

The Ludlum 2929 has an Amplifier Output connector. I was able to connect an oscilloscope and see the pulses. My plan is to connect the Amp Out to an ADC and write software to analyze the pulses. Unfortunately the pulse widths from Amp Out are about 2 us wide, and the ADC I purchased has a sample interval of 2 us. I may need to try and make the pulses wider with a capacitor.

To test it I plan to first measure the CPM with a Uranium ore sample, and then introduce Beryllium and see what affect that has on the rate. I should first do more research on this to see if it has a chance of producing neutrons.

[Richard Hull]

I think you will be very disappointed in the proposed U-Be source. As a matter of fact even a super hot radium source like an old meter dial and Be would not be all that good. The hottest piece of U ore imaginable would never equal one WII aircraft meter. In general, for every 10,000 alphas actually entering Be you will get 1 neutron. I used a borrowed Po-Be source of 1 millicurie and got about 30 neutrons per minute over my normal 6-8 counts per minute background. A millicurie alpha source is a real blast of alphas into the Be.

Still, give your idea a shot and report back. You will be way down in the statisitcs fighting background, even with a hot radium source (which I do not recommend).
You will need an alpha source of 100,000 per second or 6,000,000 per minute to climb well out of the background. In U ore you will only get alphas from the surface U mineral as all the others within the ore are absobed in the rock.

Neutrons are tough love, no joy items. Atoms hold on to them jealously. They will spit out almost anything except one of their neutrons.

Richard Hull