AW: [ RadSafe ] DHS Tests of Radiation Detectors Were Inconclusive, Report Says

Cheng Kit-man rhu_ic at
Fri Mar 7 00:41:00 CST 2008

There can be various ‘forms’ of calibration.  We may need to specify what
form of calibration we are referring to, i.e. whether it is a calibration
against a ‘primary’ standard by a national or international metrology
standardization laboratory, against a ‘secondary’ standard by a competent
metrology standardization laboratory, against a ‘tertiary’ standard or it is
a day-to-day operational ‘consistency’ or ‘performance’ check.  The
different levels of calibration may serve different purposes, are conducted
according to different standardization requirements and provide calibration
outcomes of different uncertainties.

Clement Cheng
Radiation Health Unit
Hong Kong SAR, China

-----Original Message-----
From: radsafe-bounces at [mailto:radsafe-bounces at] On Behalf
Of Doug Aitken
Sent: Friday, March 07, 2008 7:51 AM
To: 'Sandy Perle'; 'Franz Sch?hofer'; 'Brennan, Mike (DOH)';
radsafe at
Subject: RE: AW: [ RadSafe ] DHS Tests of Radiation Detectors
WereInconclusive,Report Says

Sandy et al:
I agree with your definition of calibration (as required, for instance, but
regulation in many instances). But in addition, I guess there is what is
(loosely) called a secondary calibration (or better referred to as a field
check or function check), where the user checks his instrument against a
known reference (normally supplied by the instrument manufacturer to the
user) to verify that it is functioning correctly.

IMHO, anything beyond the normal calibration and a field check with the
user's own references (and NOTHING supplied by the persons evaluating the
instrument performance) would be "fudging"......


-----Original Message-----
From: Sandy Perle
Your first example is how I define calibration (and NIST does as well).

-----Original Message-----
From: Franz Schönhofer <franz.schoenhofer at>
........ To make it short: "Kalibrierung" is something which
can be done in the respective laboratory, using sources provided by
institutions or companies tracing their results to some internationally
accepted standards. 
Doug Aitken     Cell phone: 713-562-8585
QHSE Advisor
D&M Operations Support           
Schlumberger Technology Corporation
300 Schlumberger Drive
Sugar Land TX 77030

Home office: 713-797-0919  Home Fax: 713-797-1757

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