2–1The Nature of Matter A.Atoms B.Elements and Isotopes 1.Isotopes 2.Radioactive Isotopes
Be it doesn’t always mean that it is Be · What 7Be is used for Blake et al. (1999) Applied...
Transcript of Be it doesn’t always mean that it is Be · What 7Be is used for Blake et al. (1999) Applied...
If it looks like 7Be and says it’s 7Be it doesn’t always mean that
it is 7Be
Robert Hardy
Jackie Pates
Overview
• Context of the work
– 7Be as a environmental tracer
• Data that was recorded
– Looking good
– Wait that can’t be 7Be…
• What was really measured
– The mystery nuclide
7Be Production
7Be N2 O2
What 7Be is used for
Blake et al. (1999) Applied Radiation and Isotopes. 51, 599–605
Clean-up of Tracer
Gamma spectrum
Resin binding experiments
• Used tracer to investigate how “Be” binds under different acid concentrations
Horwitz and McAlister (2005) Solvent Extraction and Ion Exchange. 23, 611-629
“Let’s just check”
Recounted vials after ~300 day. All Be should be gone
Some 54Mn in tracer so recounted to assess 54Mn contribution to count rate
It’s not 7Be but what is it? Let’s make a model
When optimised model includes NO Be and half-life of X of ~340 days
Model Variables: Counts of Be, Counts of X, Half-life of X
Possible candidates
Searched every element with half-life 300-360 days
Element Z N Decay Half-life (days)49V 23 26 ε 330
54Mn 25 29 ε+β+, β- 312.3
145Sm 62 83 ε 340
248Cf 98 150 α, SF 333.5
249Bk 97 152 β-,α, SF 320
Back to Gamma Spectroscopy 145Sm, 61 keV, 12%
54Mn, 835 keV, 99%
7Be, 477 keV, 10%
49V no gamma
Conclusion
• 7Be not easily detected with LS
– Counting efficiency too low
• Contamination may be present
– Issues with safety
• What are you really handling/disposing of
– Calibration problems
• Counting efficiency
RH funded by studentship from NERC and ACTF Resins supplied by Steffen Happel (Triskem)