Prestudy for APMP Comparison of C14 Activity Measurement

1
Prestudy for APMP Comparison of C-14 Activity
Measurement
Korea Research Institute of Standards and
Science Ionizing Radiation Group K.B. Lee
lee_at_kriss.re.kr
2
C-14 APMP Comparison Status

• Last TCRI meeting, KRISS proposed to have an APMP
  comparison for activity measurement of C-14
  solution.
• NMIJ asked to have pre-bilateral-comparison
  between KRISS and NMIJ and, if all is fine, to
  extend the comparison into a KC.
• Five member states currently express an intent of
  participation.
• Pre-study stability, impurity and absorption
  test

3
Source Preparation

• Purchased from Amersham plc
• Chemical composition
• (1g glucose1g formaldehyde)/liter in
  water
• Total activity 200 kBq for 5 g
• 2.5 g shipped to NMIJ for comparison
• 10 LSC sources prepared using gravimetric
  sampling method ( 5 sources with Hionic Fluor
  and 5 sources with Ultima Gold)
• 3 point sources for ? spectrometry

4
Impurity Check with LSC
No spectra other than that of C-14 are observed.
5
Impurity Check with HPGe
C-14 point source
Background
No Gamma Impurity
6
Absorption Test
Test the possibility of absorption of
radioactivity in the walls of the ampoules using
water-immiscible cocktail (UG-F)

• LSC count rate 186 counts/s
• Activity 186/0.5/0.9 413 Bq
• 10 mg equivalent sol.
• ltlt 50 mg
• No significant absorption observed.

7
C-14 Measurement with TDCR
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Stability Test
C-14 measurements are stable within the
statistical uncertainty and show no dependence on
LSC cocktail used.
9
Tentative schedule

• On Sept., 2004 Source shipped to NMIJ for
  bilateral comparison
• By Feb., 2005 Results received NMIJ
• By April, 2005 Source distributed to
  participating NMI states
• By Oct. 2005 Measurement results received
• By Dec. 2005 Comparison results published