[ RadSafe ] RE:exploranium GR-135 question

[Geo>K0FF]

The question was:"Hello from Australia!

Could someone who's got this monitor (or used it before) let me know if it's
worth the $$$...?
I'm thinking of getting myself one but I'm not too sure as to easiness of
use, which radionuclides are in the library, calibration etc.
Replies will be very much appreciated.

Kind regards
Nick Tsurikov
Eneabba, Western Australia"A: Nick, Yes of course they are worth the money.Only you can determine "is it worth the $$ TO ME?" and that would depend on your particular requirements.The Exploranium GR-135 does isotope identification based on proprietary software that compares Gamma Energy peaks against an internal library. Ideally, it looks for peak pairs that are unique to that isotope, in some cases only one unique peak will suffice. This process takes time, 30 seconds is not usual for reliable results. That time parameter is adjustable by the operator, but once set is fixed for the duration of testing.Another instrument, the Quantrad Ranger and Ranger Plus ( designed by LANL) by Veridt Inc.,has a similar function but a different approach to statistical reliability. Using a take off of Canberra's "time to count" protocol, the Ranger can make a positive ID in as few as one or two seconds under favorable doserate conditions. Either the Ranger or GR-135 may be equipped with optional neutron detectors.Base price on a GR-135 is about $10,000 USD, and the Ranger is right at $20,000.00 USD with the neutron detectors.GR-135 uses a solid state neutron sensor , Ranger uses a pair of high pressure (20 atm) He3 tubes. I own and have used both of these, and after extensive field tests, usually deploy them both and the same time!Each has it's strong points.Please refer to the review entitled "Evaluation of Commercial Detectors" at:http://www.ortec-online.com/papers/la_ur_03_4020.pdfThe report compares the GR-130, GR-135, SAM 935, Ranger, SAIC Radsmart, and Bicron Fieldspec.Also check out Canberras InSpector series on their website.http://www.canberra.com/products/639.aspThere are other approaches to isotope ID in the field, such as using an URSA II with a laptop. These are not nearly as "handy", nor are they automatic.So bottom line: determine you actual needs, then consult with someone who can recommend a cost effective solution.My personal solution is to use the handheld "point-and-shoot" in the field forpreliminary survey and ID, but to bring sample back to the Home Lab for detailed analysis. Failing being able to remove samples, at least we can bring home the scans storedin the handhelds, download and further analyze them in the Home Lab computers.Libraries can be obtained from the manufacturers, or I can forward that infoby eMail.George DowellNLNLNew London Nucleonics Lab56791 Rivere Au Sel Pl.New London, MO 63459GEOelectronics at Netscape.com573-221-3418