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10Be, 26Al, 36Cl, 41Ca and 1291 AMS - Internal Data Analysis Software at KIST
ELIADES, John A(일랴드스존) 한국진공학회 2021 한국진공학회 학술발표회초록집 Vol.2021 No.2
Because of their very trace natural abundances, 10Be, 26Al, 36Cl, 41Ca and 129I are measured by accelerator mass spectrometry (AMS). However, chemical pretreatment techniques produce either highly resistive materials (ex. BeO and Al<sub>2</sub>O<sub>3</sub>) or compounds that are volatile at higher temperature (CaF<sub>2</sub>, AgI, AgCI). These are therefore mixed with a second powder (ex. Ag) to aid the sputtering process, and pressed into metal cathodes. Quality varies, especially when users prepare their own cathodes. Problems can include violent ion beam instability and premature drop in current. Since cathodes are analyzed for 30 minutes in 30 s block intervals, data from poor cathodes can still be used if blocks with poor current quality are excluded. While the KIST 6MV AMS system manufacturer software produces a result file that summarizes the data for each cathode, an internal Visual Basic program run through Microsoft Excel is used to analyze the raw data from each 30 s block to determine if there was a spurious period in the data acquisition. As the radio-isotope produces only several to several thousand counts in 30 mins, the stable isotope beam currents (typically in the range 1 µA to 10 µA) are monitored for inter-block beam stability using both the high energy beam stability and the accelerator injection current to high energy current ratio stability. Isotope ratio stability and rare-isotope detector dead time are also monitored by 10 min run intervals. Finally, overall cathode current during the entire 30 min period is monitored. The program calculates averages and uncertainties both for the full data set and the data less flagged points, and provides the analyst with a quick graphical interface to plot data through a user-form. Data flagging will be discussed, along with examples of data that have been discarded based on monitoring flags.
Fabrication of Silicon-Vacancy Color Centers in Nanodiamonds by using Si-Ion Implantation
Hyeongkwon Kim,Hyeyeon Kim,Jaeyong Lee,Weon Cheol Lim,John A. Eliades,Joonkon Kim,Jonghan Song,석재권 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.5
Si ions 2.3 MeV are implanted into nanodiamonds (NDs) at doses of 11012 11015 ions/cm2. The ion implantation not only creates silicon-vacancy (SiV) color centers but also reduces the size of the NDs from 50 nm to 10 nm. As the Si dose is increased up to 1 1013 ions/cm2, the luminescence from the nitrogen-vacancy (NV) color centers in the ND initially increases. At higher dose rates, the luminescence from the NV color centers decreases. Due to the differences in the minimum ND size required for stable luminescence, the zero phonon line (ZPL) of the SiV color center appears after the luminescence from the NV center decreases dramatically. The ZPLs from both centers become almost negligible after Si ions have been implanted at doses higher than 5 1014 ions/cm2. These observations are explained by the reduced size of the NDs and the number of implanted Si ions, which is estimated based on SRIM simulations.