RE: Measuring pulsed fields

["Gerry Blackwood" <gpblackwood@justice.com>]

On Mon, 8 Dec 2003 08:54:35 +0100, "Marco Caceci" wrote:



> 

> 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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