RE: Measuring pulsed fields

["Marco Caceci" <chemitech@chemitech.com>]

My grain of salt:



GM´s are not adequate if you have or suspect pulsed field with

instantaneous strength reaching higher than GM´s stated max rate (say

10-100 k counts/sec, depending on circuitry).

Some GM systems are better than others: the time-to-count technology in

an expired patent by NRC (the company, not the commission: they

deservedly went down the drain, have been bought by the French) and also

used in some other products provides better linerity in high fields.

The logical tool is ionization chamber: a DC current is measured, you

get in practice an analog signal smoothed by the time constant of the

circuitry.

You being at NASA, you might want to look at a design that Jay Lowell

(Jr) put in Apollo in the 60's: the simplest of concepts: ionization

chamber and a counter circuit giving a pulse every so many pC

(picoCoulombs): the lightest load on the systems recorder.



marco caceci 





> >>Kim D. Merritt wrote:

> >>

> >>

> >>

> >>>Is the Bicron 2000 w/ HP270 or the RO2 adequate for measuring 

> >>>pulsed x-ray fields with microsecond pulsewidths?  I don't have the



> >>>manuals for these instruments.  Alternately, can anyone recommend 

> >>>an instrument that is good for measuring these kinds of fields.

> >>>

> >>>Kim Merritt

> >>>Radiation/Laser Safety Officer

> >>>HazMed, Inc.

> >>>NASA Langley Research Center

> >>>

> >>>



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