Counting Results for Acid used to soak the LSU 3.33 MBq AmBe Source
Zelimir Djurcic and Andreas Piepke
University of Alabama
(Status 7/26/2002)
Results
This note is a follow-up on
a previous report published 7/23/2002.
A new round of dilute acid samples, used to soak both the 3.33 MBq and
the 1.85 MBq LSU AmBe sources (sources A and B), together with an acid blank
(sample D)
has been received at UA 7/15/2002.
Both AmBe sources have been exposed to dilute HNO3
(the concentration is not exactly know) for an unknown length of
time at Kamioka. This information can for sure be obtained but it seems,
at this point, not too relevant.
At UA most of the acid of samples A and D was transferred into 60 ml glass bottles
for counting. These were of the same type used in the previous
round of measurements. The Am activity was determined using gamma ray
spectroscopy (for more details see the
previous note).
![[link to PDF file]](source_test/ambe_6.jpg)
Figure 1
After only 0.87 days of counting sample
A showed (11.9·Sigma)
evidence for an 241Am activity. The blank showed no
peak at 59.6 keV. We determine an 241Am activity of
4.8±0.5 Bq for sample A. Figure 1 (above) shows the energy range
around the Am 59 keV peak. Both, the spectra measured for the
source sample A (red) and the blank D (blue) are shown.
The purple spectrum shows the detector background, for comparison.
The
absence of a peak in the blank demonstrates that the observed
peak is not an artifact of the detection technique.
Figure 2 shows the spectrum take with sample A, together with the
fit to the data, used derive the activity.
![[link to PDF file]](source_test/ambe_7.jpg)
Figure 2: Source A (stronger LSU source)
Conclusion
The data presented here confirms our previous observations that both LSU AmBe
sources are either leaking activity or are externally contaminated.
Right now they can therefore not be deployed into the KamLAND detector.
Careful handling is advisable to avoid spreading Am activity around in KamLAND's
clean area were in fact all the other sources are handled.
This page is maintained by A. Piepke
Last update July 26, 2002