Re: GM Counters in High Backgrounds

[Kurt <kurtd@locomp.net>]

Hey Bob or who ever. Will this help:

eff = cpm/dpm, therefore dpm = cpm/eff.
Standard eff = 10 %
Notice background had no mention of /100cm2. We can do this. It's simple math. A
tech in the field understands this even if we do not use this terminology.

As far as the 50 cpm. Hey man, let us make up our own numbers for the sake of an
sample situation.

OK every one, lighten up.

                                Kurt

Bob Flood wrote:

> At 09:13 AM 10/13/1999 -0500, you wrote:
> >It's a standing joke in Containment during Outages
> >when a person gets a 12kdpm/100cm2 count in a 10kdpm background and calls it
> >"2k" that the individual is stuck with that name for the whole Outage until
> >he/she counts the smear in a much lower background and find it reading
> >between 12k and 15kdpm/100cm2.
>
> I have to admit to some confusion over units in this discussion. In the
> above example, background is compared in units of dpm to a smear exhibiting
> radioactivity in dpm/100cm2. Hopefully the background count rate isn't due
> to beta-emitting contamination inside the HP-210 probe. It would be due to
> the incident photon field, and thus should not be converted to dpm. The
> conversion that was made assumes some efficiency not given.
>
> Can we see this case again where we deal only in insrument readings in cpm?
> Are we dealing with a 1,000 cpm background or a 10,000 cpm background? And
> what is the gross reading on the 15,000 DPM smear? If the GM isn't giving
> you what you consider an accurate assessment of the activity on the smear,
> how did you arrive at the 15,000 value?
>
> ===================================
> Bob Flood
> Dosimetry Group Leader
> Stanford Linear Accelerator Center
> (650) 926-3793
> bflood@slac.stanford.edu
> ************************************************************************
> The RADSAFE Frequently Asked Questions list, archives and subscription
> information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html

************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html