Schematic illustration of PiPALS experiment using ultrashort LCS gamma-ray pulses.
Typical waveforms of PMT output.
Calculated energy spectra and measured energy spectrum. Dashed line shows the calculated energy spectrum of photons emitted from the lead target. Dashed curve shows the response of the BaF2 scintillator, which has an energy resolution of 15% (rms). Solid line shows the experimental data.
Measured positron lifetime spectrum of the lead target. Solid curve is a least-squares fitting curve of data points derived from Eq. (7) . Positron lifetime for lead is evaluated as 194 ± 15 ps. Time resolution of the photon-induced positron annihilation lifetime spectrometer is evaluated as 88 ± 6 ps (rms). The count rate is 0.54 cps.
Calculated time distribution until the annihilation gamma rays are absorbed in the BaF2 scintillator and until the scintillation light arrives at the faceplate of the PMT. σPL is the time jitter caused by σl and σa, and σTPL is the time jitter caused by σl, σa, and σs.
Parameters of electron beam, Ti:Sa laser, and ultrashort LCS gamma-ray pulses.
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