Re: cpm conversion to mrem/hr

[Rahim Ghanooni <rahim@inav.net>]

Few years ago, one of the instrument company in US, was using 3600 cpm per
mr ratio as a rule of thumb for their GM tubes. This is a very good estimate
while you are in the field.





At 03:53 PM 8/28/96 -0500, you wrote:
>Actually, one does see such conversions from time to time.  They are generally 
>treated as "rules of thumb."  Examples can be found in IAEA #152, "Evaluation 
>of Radiation Emergencies and Accidents."  Granted, such relationships are not 
>scientifically rigorous, but they are very handy to get a feel for what one is 
>dealing with.
>
>Your comments regarding calibration are correct.  How does one equate two 
>measurements that use different geometries (i.e., calibration setups vs. 
>"field" measurements).  CPM to mr/hr can be done, but one must be very careful 
>to ensure that the field measurement duplicates the geometry of the
calibration 
>setup.
>
>As to your comment regarding sarcasm. . . .we have a saying in the U.S. that 
>there is no "stupid" question.  Given that we all use various thumb rules in 
>day to day health physics, I don't think that the question was all that 
>off-base.  Are you possibly just laying on the flame button a little heavily?
>
>
>Jim Barnes, CHP
>Radiation Safety Officer
>Rocketdyne Division; Rockwell Aerospace
>
>    > At 13:49 28.08.1996 -0500, you wrote:
>    > >I was looking through some x-ray diffraction reports and ran across
>    > >some conversion figure converting cpm from a GM to mR/hr or mrem/hr.  I
>    > >can't remember where I saw it.  Anyone no what it is?
>    > >
>    > >David Harrison
>    > >DHARRISON@DOE.LANL.GOV
>    >
>=========================================================================
>    > =
>    > 
>    > I cannot believe that you saw anything like this, because the conversion 
>    > is
>    > dependent on your GM, on the energy of the radiation and probably a
couple
>    > of other conditions. In fact calibration would have to be done 
>    > individually. 
>    > 
>    > Is this the expertise which DOE employees have?
>    > 
>    > Anybody who wants to accuse me of the typical European arrogancy is
>    > requested to refrain from it. I had so many positive responses on my
>    > sometimes sarcastic comments to my private e-mail that I do not care for 
>    > the
>    > one or two who do not like it. 
>    > 
>    > Instead I would recommend that you Americans would do something to rise 
>    > the
>    > average scientific level of your health physics people. I know that you 
>    > have
>    > a large number of excellent experts, which are among the best in the
world
>    > and I am honoured to know some of these personally. But this is not
enough
>    > for everyday life. 
>    > 
>    > Franz Schoenhofer
>    > Schoenhofer
>    > Habichergasse 31/7
>    > A-1160 WIEN
>    > AUSTRIA/EUROPE
>    > Tel./Fax: +43-1-4955308
>    > Tel.:     +43-664-3380333
>    > e-mail:       schoenho@via.at
>    > 
>    > 
>
>
>
Mr. Rahim Ghanooni
Sr. Health Physicist
Certified Hazardous Material Manager (CHMM)
319-851-7133
rahim@inav.net

My opinion only.