Detector identification by waveform shape analysis for effective data acquisition: Improvements in time resolution and count rate for positron annihilation age–momentum correlation measurement

Hirade, Tetsuya; Ando, Hirokazu; Manabe, K.; Ueda, Daisuke

doi:10.1016/j.nima.2019.04.047

Cited by 10 publications

(4 citation statements)

References 8 publications

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“…We used a newly introduced method to enhance the counting rate. The detail of the method can be found in [17]. We used the same apparatus here for AMOC measurements.…”

Section: Methodsmentioning

confidence: 99%

Positron annihilation study of tungsten exposed to low-energy deuterium plasma

et al. 2023

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Positron annihilation lifetime spectroscopy (PALS) measurements by use of a positron source of 22 Na were performed for the polycrystalline tungsten samples that were exposed to low-energy deuterium (D) plasma. The energy of D plasma was low and then it was expected that it would affect just the near-surface region. However, we obtained the longer mean positron annihilation lifetime in the tungsten samples exposed to the low-energy D plasma than the virgin tungsten sample. Moreover, the same longer values were obtained even on the other (no exposed) side of the samples, although the thickness of the samples was 1 mm or 2 mm. The elongation of the positron lifetime probably indicates defects formation in W. Ohsawa, et al. predicted that the high concentration hydrogen creates high concentration vacancy-hydrogen clusters by the first-principles calculations. We also performed positron annihilation age-momentum correlation (AMOC) measurements to know if there are some D's at the positron trapping sites such as vacancies and found that some of the positrons annihilate with electrons in D.

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“…We used a newly introduced method to enhance the counting rate. The detail of the method can be found in [17]. We used the same apparatus here for AMOC measurements.…”

Section: Methodsmentioning

confidence: 99%

Positron annihilation study of tungsten exposed to low-energy deuterium plasma

et al. 2023

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“…Different energy windows are set for the two γ-ray detectors, so that Detector_1 does not measure the 0.511 MeV annihilation γ-ray, and Detector_2 does not measure the 1.27 MeV decay γ-ray. [11][12][13] If lifetime measurements from the 1.27 MeV decay γ-ray detected by Detector_1 and the 0.511 MeV γ-ray detected by Detector_2 are made simultaneously with lifetime measurement from the 0.511 MeV annihilation γ-ray by Detector_1 and the 1.27 MeV annihilation γ-ray by Detector_2 (dual start/stop data acquisition), two positron lifetime spectra can be obtained simultaneously. In this paper, we call this measurement method dual acquisition and the conventional method single acquisition.…”

Section: Background Of Researchmentioning

confidence: 99%

Drift compensation in dual start/stop data acquisition positron lifetime measurements

Yamawaki

Uesugi²,

Ando

et al. 2020

Jpn. J. Appl. Phys.

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When analyzing positron annihilation lifetime spectra with multiple components using an exponential function with a single component, there is a difference between the experimental data and the fitted spectrum. Compensating for this difference causes a shift in the starting time (T 0) in the fitted spectrum. Previously, we applied single-component analysis to the positron lifetime spectrum of a defect-containing metal and confirmed the effectiveness of the shift in T 0 (ΔT 0) for defect analysis. To optimally use the T 0 variation for defect analysis, however, it is necessary to minimize the drift in the positron lifetime spectrum due to the temporal instability of the photomultiplier tube and high-voltage power supply. In this study, we report significant suppression of the drift by using dual start/stop data acquisition (dual acquisition), which employs each of the two γ-ray detectors to acquire start and stop signals.

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“…Pulse shape discrimination-like the clustering method described here-can aid in γ-ray tracking experiments with high-volume, segmented HPGe detectors [25,28]. An improvement in the HPGe time resolution can also greatly enhance positron annihilation spectroscopies that involve timing with these detectors, such as the Age-Momentum Correlation (AMOC) technique or the measurement of the all three momentum components of the annihilating positron-electron pair [29][30][31].…”

Section: Introductionmentioning

confidence: 99%