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Heating adjustment of Panasonic UD710 readers
We operate Panasonic UD710 readers with UD802 badges.
Doing heating adjustment on our readers we have come accross some
anomalies with the accepted practice of heating adjustment in the
Panasonic users manual (chapter 8 - heating adjustment).
These anomalies only appeared since we started using G-series lamps.
1. We have problems getting short term LiBO fading down to less than 6 %
(15 min compared to 24 hours) and still getting acceptable glow curves.
If we go lower than about 10%, the glow curves indicate too strong
heating with big shoulders in the first part of the main glow peak.
2. There does not seem to be a problem for the CaSO elements.
When the heating is adjusted with the focus on properly shaped glow
curves, the short term fading is normally about 15 %.
We investigated the effects of different fading on: ECFs, %CV of readout
values, shape of glow curves and long term fading.
The disagreement with the accepted theory in the heating adjustment
chapter of the User's Manual:
1. We could not find a noticeable difference between ECFs generated at 5%
and 15% short term fading.
2. There is not a statistically significant difference between %CV
values for readout at 5% and 15% short term fading.
3. The long term fading studies we have done so far (10 days and 30 days)
show that the LiBO fading is about 4 to 8 % when the short term fading is
15%. This is essentially the same as the fading determined previously at
about 5% short term fading. This is certainly acceptable, and will be
further verified with a 60 day fading study.
4. The differences in responses between old and new badges (different
heat capacities) at the different values of short term fading (5 and 15%)
cannot statistically be proven to be different.
According to the User's Manual, I would have expected a significant
difference between the results for 5 and 15% short term fading, as well
as higher long term fading at 15% fading.
Our experiments indicate that it would be acceptable to adjust all our
readers with G-series lamps to 15% short term fading for LiBO. They also
indicate that the relationship between short term and long term fading is
not so clear cut as has been claimed. It appears that the short term
fading criteria are more valid for alignment of different readers and
having a standard setting for readers.
I am just wondering whether we overlooked something? Any comments /
experience / etc in this regard would be appreciated.
Du Toit Volschenk
Radiation Protection Service
South African Bureau of Standards
Tel: 012 428 6882 (international: 27 12 428 6882)
Fax: 012 344 1568 (international: 27 12 344 1568)