BF3 Detection in NIM equipment.

This area is for discussions involving any fusion related radiation metrology issues. Neutrons are the key signature of fusion, but other radiations are of interest to the amateur fusioneer as well.
Post Reply
guest

BF3 Detection in NIM equipment.

Post by guest »

I'm finally on my way to having a real detection capability in my lab.
I have the following gear, a scaler, an sca, linear amplifier, counter timer with alarm high and lo rates.
The only things I lack at this point are a NIM bin and high voltage supply NIM.
I have the PMT tube.
I pretty sure the type of hv NIM for a PMT setup but wonder what I would need to run a BF3 Tube?
Volts? Amps? ECT.
Also the the type of preamp needed would be helpful
Also.

My National Nuclear Alarm Module needs to have 5volts @ 1.5 amps fed to it . Any hints?

I'm using it as my counter/timer unit.
It is fairly new... was to go to the monitoring rack of a now defunct reactor unit that Entergy was building in Louisiana as an adjunct unit for Grand Gulf Nuclear.
IT sold on EBAY for two dollars.
Never used.

Thanx
Larry Leins
Physics Teacher




I
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: BF3 Detection in NIM equipment.

Post by Richard Hull »

BF3 tubes don't even start to work until 1400 volts and most of the larger tubes go up to 3800 volts, but most work in the 1600-2500 volt range with zero current needed (few microamps).

A standard Ortec 109/122 preamp is all that is needed for a BF3 tube. These are CHARGE sensitive pre-amplifiers. In all cases, the preamps are separate boxes outside of a NIM bin and must be placed as close as possible to the BF3 tube to reduce noise and or pickup in long cable runs. The preamp plugs into the rear of one of the NIM amp module's preamp power plug (9pin) and to the NIM HV supply via a SHV BNC cable. The resultant signal out of the preamp is via a normal BNC cable to a NIM spectroscopy amp or the like and then on to a NIM SCA.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
guest

Re: BF3 Detection in NIM equipment.

Post by guest »

Thanx Richard:

The preamps come in many flavors.... Thank you for spelling it out.
I read the old posting on internets on BF3.
I've decided to do both routes instead of just one.
I'm almost there... the bin is in sight.
Power supply is the final piece.
Oscilloscope is the next hill to climb.
The nim stuff is pretty availible now.
I wanted to grab some before the winter snows set in.

Thanx Again
Larry Leins
Physics Teacher
guest

Re: BF3 Detection in NIM equipment.

Post by guest »

I notice in my old lab notes ... the stuff that we did geiger experiments using a Tennelec 148a preamp.
Would that preamp work as well as the quoted one in bf3 work?
How much would be a good price for one?

Larry Leins
Phsics Teacher
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: BF3 Detection in NIM equipment.

Post by Richard Hull »

BF3 tubes require a charge sensitive preamp like a 109 ortec. This is a stand alone box and doesn't go in the NIM bin per se. It is a biased amplifier and has an SHV BNC for the bias voltage input separate from the BF3 tube input. The bias on a small BF3 tube might be 1400 volts, while on a large one, 2600 volts is about right.

The reason for the external box type preamp is that you will want to place it as close to the detector as possible. (short cable)

Richaard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Tom Dressel
Posts: 287
Joined: Fri Jun 22, 2001 4:44 pm
Real name:

Re: BF3 Detection in NIM equipment.

Post by Tom Dressel »

I have a Canberra model 2006E proportional counter preamp which is charge sensitive preamp LIKE that described by Richard, with the 9 pin connector, and the SHV BNC plugs as described.

Is this thing equivalent to the109/122 preamp, and does the BF3 counter work in the proportional region?

Tom Dressel
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: BF3 Detection in NIM equipment.

Post by Richard Hull »

Yes. Your amp is compatible. You need to check the internal capacitor off the SHV BNC. Its voltage rating will tell you the top end of the bias allowed. Figure on about 75% of the cap rating. The cap is usual a poo cushion (disk cap), although I have seen glassmikes used in a few.

Proportional preamps usually don't expect more than about 600 volts as that is the limit of most flowing gas counters regions of limited proportionality.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Post Reply

Return to “Neutrons, Radiation, and Detection (& FAQs)”