Development of Flow Extraction and Detection Method of Radiocarbon for Activation Analysis of High P

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Development of Flow Extraction and Detection
Method of Radiocarbon for Activation Analysis of
High Pure Materials

• Kazuyoshi Masumoto, 1 Koji Shikano,2 Tsutomu
  Ohtsuki,3 Yutaka Ito1
• 1 Radiation Science Center, High Energy
  Accelerator Research Organization(KEK), Oho,
  Tsukuba 305-0801, Japan (E-mailkazuyoshi.masumoto
  _at_kek.jp)2 NTT Photonics Laboratory, Nippon
  Telephone and Telegraph Corporation, Tokai,
  Ibaraki, 319-1193 Japan3 Laboratory of Nuclear
  Science, Graduate School of Science, Tohoku
  University, Mikamine, Taihaku, Sendai, 982-0826,
  Japan

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Motivation

• Trace analysis of light element
• important for the characterization of high pure
  materials
• Photon and charged particle activation
• gt suitable for light element analysis
• gt Short lived positron emitters
• gt Chemical separation is necessary
• gt Rapid and simple method
• Recent advance of FIA and SIA in Anal. Chem.
• Flow method is hopeful for simultaneous
  separation and detection of radioisotopes

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Purpose of this work

• Development of sequential separation and
  detection system using flow method for
  radiocarbon analysis.
• Application to photon activation analysis of
  carbon in steel samples.
• Application to charged-particle activation
  analysis of nitrogen in silicon crystal.

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Flow extraction and detection system for 11C
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Separation condition

• Added amount of flux 4 times the amount of
  sample
• Steel sample is mixed with Tin alloy(LECOCEL II
  HP)
• Silicon sample is mixed with PbOB2O3
• Temperature control prgram of infrared furnace
• Start -gt 200? -gt 300? -gt 350? -gt 350? -gt OFF
• -3min- -2min- -3min- -3min- -1min-
• Flow rate of oxygen gas 0.3 l/min
• Extraction condition
• Glass coil with 20 turn, 20mm in diameter
• Monoaminoethanol (75)?flow rate0.25ml/min

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Carbon analysis

• Photon activation
• 12C(g,n)11C (T1/220min)
• Interference 14N(g,p2n)11C, 16O(g,an)11C
• Charged particle activation
• 12C(d,n)13N (T1/210min)
• Interference 14N(d,p2n)13N
• 12C(p,g)13N (T1/210min)
• Interference 14N(p,pn)13N
• 12C(?,n)15O (T1/22min)
• Interference 16O(a,an)15O

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Photon activation

• Nuclear reaction 12C(??, n)11C Facility
• 300MeV electron linear accelerator , Tohoku
  University
• Irradiation Condition
• ?Electron energy30MeV?Average current 100?A
• ?Bremsstrahlung is produced with 2 mm Pt
  plate?Samples are put into quartz ampoule and
  cooled with water?Irradiation time 20 min

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Extraction pattern of 11CO2 from graphite, SiC
and WC.
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The extraction curves of 11C in case of steel
samples of granular-form
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left the result obtained by extraction
curveright the measurement using Ge-detector
after separationCalibration curves show good
linearity
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The relationship between the integrated area
obtained with BGO-detector and the 511-keV peak
counts obtained with Ge-detector
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The extraction curves of 11C in case of steel
samples of disk-form
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Quantitative results obtained by the sequential
measurement using BGO-detector and the
measurement using Ge-detector after separation
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Characteristics of flow method

• Simultaneous separation and detection
• Simple and Rapid
• Small amounts of reagents
• Real time monitoring of combustion state of sample

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The results of carbon analysis

• Good recovery of 11C from steel samples
• Good linear relationship between carbon amount
  and integrated counts
• Easily detected microgram amount of carbon

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Nitrogen analysis

• Photon activation
• 14N(g,n)13N (T1/210min)
• Interference 16O(g,2pn)13N
• Charged particle activation
• 14N(p,a)11C (T1/220min)
• Interference 11B(p,n)11C, 12C(p,pn)11C
• 14N(d,n)15O (T1/22min)

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Charged particle activation

• Nuclear reaction 14N(p,?)11C
• Facility SF cyclotron , The university of Tokyo
• Irradiation Condition
• Proton energy13MeV?Average current1?A
• Samples surface is cooled with He-gas.
• Irradiation time 20 min.
• Separation
• Flux is a mixture of PbOB2O3.
• To remove 13N from 16O(p,?)13N reaction, a cobalt
  oxide trap is inserted directly before the
  extraction coil.

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The decay curves of the radioactivity of
aminoethanol solution and cobalt oxide trap.
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The comparison of analytical results of nitrogen
in siliconby CPAA and FT-IR
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The results of nitrogen analysis

• Low recovery of 11C from silicon matrix but good
  reproducibility
• -gt should be improved by the search of combustion
  condition
• Contamination of 13N in extracted solution was
  removed by the trap of Co2O3
• High sensitivity (ppb level of nitrogen)

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The application field of this method

• Activation analysis of light elements
• Sequential separation of 11C, 13N, 15O and 18F
• Nuclear chemistry
• Yield determination of low-Z nuclides induced by
  spallation reaction
• Radioactive gas analysis
• Determination of radioactive aerosol in an
  accelerator facility

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• Carbon-11, which is produced by 12C(?,n)11C,
  14N(p,?)11C and 11B(p,n)11C reactions, is a
  short-lived positron emitter. In order to
  separate 11C from irradiated samples rapidly and
  selectively, a continuous extraction and
  detection system has been developed. After an
  irradiated sample of 100mg was mixed with an
  accelerator in a quartz boat, sample was oxidized
  in a infrared furnace under oxygen stream and
  11CO2 gas was continuously extracted into 75
  monoaminoethanol solution in a coiled glass tube.
  Flow rate of oxygen gas and monoaminoethanol
  solution was adjusted 0.2 l/min and 0.2 ml/min,
  respectively. Radioactivity of 11C extracted into
  aminoethanol solution was continuously measured
  with a coincidence counting system using a pair
  of BGO-scintillation detector and a multichannel
  scaler at the down stream of the extraction coil.
  The total activity of 11C could be obtained by
  integrating extraction chromatogram after
  correction of radioactive decay. The activity of
  11C was completely recovered from iron samples.
  This method was applied to the determination of
  carbon in steel by PAA. The good linear
  relationship between the carbon amount and the
  radioactivity of 11C was obtained. The
  micro-gram amount of carbon could be easily
  determined. This method was also applied to the
  analysis of trace impurity of nitrogen in silicon
  using the 14N(p,?) 11C reaction.