I called Ludlum today to inquire as to the calibration on my PNC-1. I was soon talking with the tech doing my calibration. He noted that it was on his station as we spoke and would be done today, QC'd and shipped tomorrow. That was fast!
I reiterated what I wanted in the calibration. He went into a discussion of millirems and distances converting to events per minute as read on my meter. I stopped him somewhat short and told him that while I could with some mathematical gyrations and a couple of lookup and conversion tables back figure to what I needed with the data he and Ludlum was about to supply, what I really needed was only the simplest of raw data returned to me.
It must be remembered that surely 99.9998% of all instruments of the neutron class sent to them are survey/rate meters and are all critically cal'd for health physics concerns and issues. This means mrem!
I explained that I need to back figure simply from their istopic source to my isotropic source. This seemed to boggle his mind. I explained that I wasn't the least bit interested in my or anyone's neutron exposure or any health physics issues. (This really threw him for a loop.)
I had to explain that this was being used strictly in a simple data collection mode for absolute neutron number measurment. All I require is his source's well known isotropic emission and the energy spectrum of same. Then all he would do is move my instrument through various ranges and record off of my meter the events per minute and jot down the range at which the reading was taken. Doing this for three points on each range is their normal $70.00 calibration.
It turns out that he will now do as instructed in the letter I sent in with the unit. In addition, I will get the normal mrem/hr/event/minute lookup chart and the neutron energies associated with same, this being the normal cal that all the health physics weenies are looking for.
So.......... here we are.........A good thing I called.
Remember, they would have to interpret the mrem from the reverse RPG curve and then link to my meter with the attendant slop and analog guesstimation along the way. (albeit with skills and cal'd sources). I would then have to back convert here with all of the attendant reversing slop.
It is better to do as little conversion to nebulous health physics units as possible when all that is sought is absolute isotropic emission. I wouldn't want a normal +/- 10% sloppy thing to become a +/- 20% ultra sloppy thing by tangled conversion jumbles and unjumbles.
I think that the techs are just trained to do a rigid calibration routine (pick and place) and are not neutron metrologists by nature or training. (this might make them dangerous and or even conversant in the field).
Still, all in all, they have been helpful, very courteous, fast in action and very inexpensive. In this day and age, that is a lot to expect from any company! Thus far, I give 'em an A+, subject to final exams.
Richard Hull
Created on Wednesday, April 25, 2001 3:31 PM EDT by Richard Hull