Re: Survey inst.

[Alex Zapantis <a.zapantis@qut.edu.au>]

At 01:20 PM 22/4/96 -0500, you wrote:
>Thought I would elict some comments on features of portable
>survey instruments, likes, dislikes, wishes, etc.

A couple of years ago when I took up this position which was new, I had to
start from scratch. We had no radiation monitoring equipment at all. I spent
a lot of time looking at various monitors, comparing costs etc and ended up
buying a Rotem Ram DA-3 which I can recommend. Its a digital unit to which
an assortment of probes may be attached. It also has two GM tubes within the
unit (so it can be used without ancilliary probes), one for low dose rates
and one for high.

It is autoranging, has an "anologue style bar" (a series of LCDs in a line)
as well as digital readout. It also reads accumulated dose (resettable) and
has a "freeze" mode which reads the highest dose rate measured (since
reset). This is particularly useful when determining TIs for packages
(non-fissionable). My only complaint is that it is not as easy to calibrate
as the older style analogue units.

The real beauty if this unit is it's versatilility. I also have a pancake
probe for it. Once the probe is connected, you turn the unit on and it is
ready to go. The HV is set automatically and checked and the Unit "knows"
which probe is connected. When the pancake probe is connected, it reads in
CPM or CPS and you can set it to do a 100 or 1000 second count, which is
great for quick and nasty wipes!!

I also have a low energy response ionisation chamber for it (it reads in
Sieverts, both doserate and accumulated dose). Once again, all you do is
connect the chamber and it "knows" what to do. It immediately checks for
leakage and sets an offset (if required). Every 10minutes (I think) it does
another offset check or you can do one on demand. I have compared its
accuracy/precision with a Farmer ionisation chamber in the primary beam of
an x-ray unit from 60 - 100kV and its right on the money (taking into
account the difference between Roentgen and Sieverts in tissue at these
energies). At higher kVs, the doserate is too high and it alarms. (I bought
the low doserate ionisation chamber)

There are a multitude of other types of probes for it - you name it, they
got it!!

And its well priced. For less than the cost of a Bicron MicroRem, I
purchased the Ram DA-3 and the pancake probe. 

Regards
 
  Alex Zapantis                                         
  Radiation Safety Officer                                     
  Queensland University of Technology 
  Acting Manager       
  Health & Safety Section                             
  Locked Bag No.2                    Ph     : 61 7 3864 3566
  Red Hill Qld 4059                    fax     : 61 7 3864 3993
  AUSTRALIA                           Email  : a.zapantis@qut.edu.au    

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       "If I could remember the names of all those particles
        I would have become a botanist."
                                                            Enrico Fermi

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