RE: Survey inst.

[Wes <vanpelt@ios.com>]

Hi Les and Radsafers,

I agree that with microprocessor controlled survey meters, lots more functions, checks and readings can and should be incorporated.

I have one example of a really poorly done electronic read-out:  the Victoreen 450.  When near background or very low dose rate readings are being taken, the output can swing to negative numbers, but the display reads POSITIVE.  There is no ability to display a minus sign or other indication of a negative output.  If the instrument is slightly mis-calibrated, it can appear to read  +x  when in fact it is detecting  -x .  I have mentioned this deficiency many times over many years to Victoreen.

This is not a total flame of Victoreen, I use my Model 450 ion chamber ratemeter a lot.

Cheers, Wes Van Pelt
vanpelt@ios.com

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From: 	Slaback@micf.nist.gov[SMTP:Slaback@micf.nist.gov]
Sent: 	Monday, April 22, 1996 2:19 PM
To: 	Multiple recipients of list
Subject: 	Survey inst.

Thought I would elict some comments on features of portable
survey instruments, likes, dislikes, wishes, etc.

While I like and appreciate the added 'power' of the new digital
based instruments I get frustrated at the non-intuitive controls. 
And for our researchers (non-expert users) I really need simple
(i.e., old fashioned) instruments. [Why cannot sticker notes be
affixed with help info for the more obscure operating features?]

I am very attracted to the Victoreen 450's, but with the
autoranging design there is no way to simply look at the
instrument to identify its upper range.  We have some that go to
50 R/h, and others that go to 500 R/h.  [How about a label?]
Similarly, the Eberline ASP-1 meter displays its unhappiness when
overranged by irratic meter movement [how about a warning
label?].

I also dearly love the check feature on the Eberline ASP-1 where
it displays a result reflective of all the cal settings.  It is a
great Q.A. check to see that nothing has changed (but it cannot
check the detector).

On the subject of Q.A. checks, why do we not have more in these
modern instruments?  Like...
 -next due cal date (in an Eberline instrument)
 -most recent date any changes were made in operating settings
 -selective display of important settings (in the field, not on
the computer in your cal lab).
 -is it an unreachable dream that an instrument will be able to
self diagnose well enough that calibration and performance checks
will not be needed?

We still need simple instruments.  Victoreen stopped making the
rugged Model 400 (which had some nice features like an off scale
alarm on the selected range) but the replacement does not do the
same job.  The basic Tech Associate TSM (pancake tube, analog
ratemeter, inexpensive) and similar products (Ludlum, Johnson)
still have a place on my shelf (despite liking the new, high-tech
digital items).

While it is tough to come up with a new detector (I would guess
that Bicron's energy compensated plastic scintillator is the most
recent in a portable survey instrument) the new electronic
technolgy lets more be done.  The Eberline sealed alpha/beta
probe and the Victoreen ion chamber technology are good examples.
It will be nice when the LET spectroscopy systems achieve an
adequate dose rate and energy threshold sensitivity.
More?

Reliability, performance to spec's, etc is another topic.
Interesting times for portable instruments.

Obviously, my opinion only.
Food for thought on a slow spring day.
slaback@MICF.NIST.gov