• Applied Science and Convergence Technology
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• 제25권5호
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• pp.85-87
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• 2016

Coincidence Doppler broadening and positron lifetime methods in positron annihilation spectroscopy has been used to analyze defect structures in metal, semiconductor and polycrystal, respectively. The S parameter and the lifetime (${\tau}$) value show that the defects were strongly related with vacancies. A positive relationship existed between the scanning electron microscope (SEM) images and the positron annihilation spectroscopy (PAS). According to the SEM images and PAS results, measurements of the defects with PAS indicate that it was more affected by the defect than the purity.

• Journal of the Korean Physical Society
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• 제73권12호
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• pp.1895-1898
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• 2018

The mechanical properties of Al, Ti, Fe, and Cu metals p-type Si, and n-type Si were investigated by using coincidence Doppler broadening (CDB) positron annihilation spectroscopy. The samples in this experiment were irradiated by using X-rays at generating powers for up to 9 kW. The data taken after the irradiation showed all the characteristic features predicted from defects with vacancies. The S parameter values of the metals were generally less than those of semiconductors such as p-type Si and n-type Si. The relationship between n-type Si and p-type Si were more affected when n-type Si rather than p-type Si was irradiated with X-rays.

• 한국재료학회지
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• 제20권6호
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• pp.307-311
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• 2010

Positron annihilation lifetime spectroscopy is applied to BaSrFBr : Eu film which is used for the phosphore layer, and afterwards the reliability and self-consistency of source corrections in the positron lifetime spectroscopy is investigated using a $^{22}Na$ positron emitter covered by thin foils. The positron lifetime showed no significant change through the various proton irradiation energies. It is unusual that the measurements of the defects indicate that most of the defects were likely to have been generated by X-ray radiation. This may have resulted from the Bragg peaks of the proton characteristics. The Bragg peak does not affect the defect signals enough to distinguish the lifetimes and intensities in a material that is includes multi-grains. The lifetime ($\tau_1$) associated with positron annihilations in the Ba, Br, and Eu of the sample was about 250 ps, and due to the annihilations at F-centers or defects from the irradiated protons in sample, the lifetime ($\tau_2$) was about 500 ps.

• 한국방사선학회논문지
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• 제6권6호
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• pp.489-493
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• 2012

양전자소멸법은 양전자와 전자가 만나 소멸하면서 발생하는 광자로부터 물질의 상태를 간접적으로 파악하는 실험 방법이다. 본 연구에서는 다양한 분야에서 널리 사용되고 있는 폴리머인 CR, EPDM, NBR에 대하여 양전자소멸법을 통해 양전자 소멸시간을 측정하였다. 한국원자력연구원의 Na-22 선원을 이용한 양전자소멸시간측정장치를 통해 양전자소멸시간의 세가지 수명과 세기를 측정하였다. 이중 세 번째 수명성분은 폴리머의 자유부피와 직접적으로 관계된다. Tao-Eldrup 모델을 이용하여 3가지 폴리머에 대한 자유부피를 측정하였다. 그 결과 CR, EPDM, NBR의 자유부피와 상대비율은 각각 $0.1217nm^3$(1.910%), $0.1478nm^3$(5.315%), $0.1216nm^3$(2.638%)로 나타났다. 이를 통해 양전자소멸법의 폴리머에 대한 적용성을 확인할 수 있었으며 향후 비파괴적으로 폴리머의 특성변화를 분석하는 자료로 활용될 수 있을 것이다.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 춘계 총회 및 학술발표회
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• pp.82-85
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• 2004

Flux-enhancement mechanism of thin-film-composite (TFC) membranes for the reverse comosis (RO) process was newly explained by positron annihilation lifetime spectroscopy (PALS) that has been found to be applied for detecting molecular vacancies or pores having sizes that are equivalent to salt or hydrate ions in RO membrane.(omitted)

• Journal of Astronomy and Space Sciences
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• 제36권3호
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• pp.115-119
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• 2019

This paper is a part of the series on positron annihilation spectroscopy of two-phase diffuse gas-and-dust aggregates, such as interstellar medium and the young remnants of type II supernovae. The results obtained from prior studies were applied here to detect the relationship between the processes of the annihilation of the K-shell electrons and incident positrons, and the effects of these processes on the optical spectra of their respective atoms. Particular attention was paid to the Doppler broadening of their optical lines. The relationship between the atomic mass of the elements and the Doppler broadening, ${\Delta}{\lambda}_D$ (${\AA}$), of their emission lines as produced in these processes was established. This relationship is also illustrated for isotope sets of light elements, namely $^3_2He$, $^6_3Li$, $^7_3Be$, $^{10}_5B$ and $^{11}_5B$. A direct correlation between the ${\gamma}-line$ luminosity ( $E_{\gamma}=1.022MeV$) and ${\Delta}{\lambda}_D$ (${\AA}$) was proved virtually. Qualitative estimates of the structure of such lines depending on the positron velocity distribution function, f(E), were made. The results are presented in tabular form and can be used to set up the objectives of further studies on active galactic nuclei and young remnants of type II supernovae.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1995년도 제8회 학술발표회 논문개요집
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• pp.116-116
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• 1995

• 한국진공학회지
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• 제21권5호
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• pp.225-232
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• 2012

수명 측정법과 동시 계수 도플러 넓어짐 양전자 소멸 분광법으로 p형과 n형 실리콘 시료에 3.98 MeV 에너지를 가진 $0.0{\sim}20.0{\times}10^{13}\;protons/cm^2$ 양성자 빔 조사에 의한 결함을 측정하여 실리콘 결함 특성에 대하여 조사하였다. 양전자와 전자의 쌍소멸로 발생하는 감마선 스펙트럼의 전자 밀도 에너지를 수리적 해석 방법인 S-변수와 열린 부피 결함에 대한 측정법으로서 양전자 수명 ${\tau}_1$과 ${\tau}_2$, 이에 따른 밀도 $I_1$과 $I_2$를 사용하여, 시료의 구조 변화를 측정하였다. 본 연구에서 측정된 S-변수와 양전자 수명은 시료에 조사된 양성자 조사량의 변화에 따라 결함이 증가하였으며, 양전자 수명 측정과 같은 경향을 보여준다. SRIM의 결과로써, 양성자 조사 에너지에 따른 Bragg 피크 때문에 양성자는 시료의 특정 깊이에 주로 결함을 형성하여 시료 전체에는 결함으로 잘 나타나지 않기 때문이다. 빔의 조사량에 따른 결함의 영향이 더 큰 것으로 나타났다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1996년도 재료학회 추계학술발표회
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• pp.146-146
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• 1996

• 한국진공학회:학술대회논문집
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• 한국진공학회 2008년도 제34회 동계학술대회 초록집
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• pp.169-169
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• 2008