NIMs query

[Mark Scott-Nash]

Hey all,

One of my main goals for constructing a fusor is to not only build the device itself but also put together a neutron detector.

I bought a B10 tube on ebay (from Brian McDermott it turns out) and need to put together a set of NIMs to build a detector. My question is not what modules to buy but where to find a reference for what is out there. Can anyone provide pointers?

I am sure the information is here, unfortunately I can't get the advanced search feature to behave. For example, I search for "NIM" in the neutron detection forums and get no results, which is obviously incorrect.

Any ideas on searching or a basic NIM pointer?

Thanks!

[John Futter]

Mark
Go to the ORTEC and or Canberra web sites and they (used to ) give configurations for various nuclear instrumentation setups (using their gear of course) but this will give the general idea of what you will need to hunt out.
Other Nim module makers will come out in Epay searches such as Harshaw,EEG, Lecroy, and a few others that made complimentary modules.
you will need of course a preamp and HV supply for a start followed by a Nim amplifier / discriminator

[Richard Hull]

Nim modules are a means to an end and would help, but are generally dated, electronically. (1960's technology) About the only thing to recommend them would be that they are cheap in the right framework to the normal accomplished scrounger. Most of the "cheap" modules were, indeed, manufactured in the 60's and 70's and may or may not be fully functional. There are far better electronics to be found today that are a lot simpler, smaller and better functioning. The question is, are you willing to cobble up your own electronics from scratch and do you have the skills needed to do that? For most it is a big no. Thus, the NIM route where you assemble, hopefully, functional pieces-parts ala erector set style.

Richard Hester has, in the past, posted numerous excellent circuits that he has designed and tested. The key to a functional B10, BF3 or 3He neutron detector is the charge sensitive pre-amp. This is the make or break item. After successful pre-amping, the rest is pretty easy. Check out Richard's old pre-amp and other useful circuitry if you have even passing assembly skills. You will save a good deal of money and effort.

A good amateur scientist and experimenter should have a lot of skillsets. These are acquired by the "doing". Reading is the key to knowledge here. The "doing" sets that knowledge in a context where it is useful and applicable over a lifetime. Read a lot. Do a lot.

Richard Hull

[Tom McCarthy]

From a quick first look, this website seems decent: http://www.chpconsultants.com/index.php ... w=standard

Has anybody looked at this site before?

Tom

[Nick Peskosky]

To reiterate what Richard has already put forth, NIM racks are an extremely dated means to an instrumentation end but I think there are quite a few reasons their use is advantageous for radiation detection. Many modern microcontrollers coupled with a basic instrumentation amplifier and some simple RF filters could easily replace an entire NIM rack. As an EE who possesses the background to build the individual modules from the ground up, I found it easier to just buy second hand modules off eBay and assemble my own rack because the modular aspect NIM racks was very appealing and the standards of the NIM design made working with/repairing the modules relatively straight forward. Paying any more than 20-30$ for a single module, aside from the charge sensitive preamp (this will be the hardest to track down), is IMHO ludicrous. As discussed in many of the past threads the most common issue you will run into with non-functioning modules will be a leaking/blown electrolytic capacitor on the Vsupply end of the module. With a digital multimeter and half decent oscilloscope, most of these modules can be resurrected to their past glory for pennies on the dollar. Attached is an image of my NIM set-up for use with my He3 detector and 3 links which are particularly useful for reference information on NIM design and module functionality.

http://www-bd.gsi.de/dokuwiki/lib/exe/f ... andard.pdf
http://www-esd.fnal.gov/esd/catalog/intro/intronim.htm
http://www.owlnet.rice.edu/~dodds/Files332/NIMuse.pdf

[Mark Scott-Nash]

Thanks everyone,

I have more than enough electronics experience to deal with the modules themselves. What is new to me is how a particular neutron detector is pieced together with the various types of modules available. This information is a good start.

[Richard Hull]

Carl Willis has been a big booster of the Cremat CR-110 modules.

http://cremat.com/CSP_intro.htm

These tiny charge sensitive preamps only need a bit of input conditioning to withstand the bias input voltages, yet are the latest in cool technology. At $55.00 they are a cheap, but very easily blown solution to neutron detector preamps. I personally use NIM modules like Nick. My setup is shown below.

In the image with Carl Willis, the 3He tube is set up in a tank of water for the moderator and the critcal preamp is actually directly connected to the end of the 3He detector tube. (seen in pix as silver box on top of red moderator tank) It is a salvaged Princeton GammaTech preamp from a GeLi detector and works just great with the 3He tube. The preamp output is cabled over to the NIM setup. Picture taken at an old HEAS conference during a fusor run. Carl didn't mind the radiation. I have just turned the unit down to zero volts so that Carl to turn over to brown on the other side, evenly.

Due to the nature of various NIM modules cabling to them and in between them can be done on the front panel or out of sight, in the back. Down through the years, I have used dead or ancient NIM plugins that have been stripped, to create my own custom NIM modules for specific purposes peculiar to my own needs.

Click on images to enlarge.

Richard Hull

[Carl Willis]

The NIM standard is old, but NIM remains a very popular and versatile platform that is supported by a wide array of modules in current production (Canberra, Ortec, etc.)

A good one-stop reference for learning about nuclear electronics and NIM specifically is Glenn Knoll's "Radiation Detection and Measurement" textbook.

-Carl