Fig. 3: Temporal and spatial distribution of detected events.
From: Observation of the 1S–2P Lyman-α transition in antihydrogen
a, Temporal distribution of detected signals between −2 ms and 10 ms with respect to the laser pulse. The laser frequency was at the resonance of the 1S–2P transition (detuning 0 GHz). The black trace shows the raw detector triggers. The red trace shows events after background suppression due to an MVA-based machine-learning algorithm. The y axis is the total number of counts (bin size, 50 μs) for 24,000 pulses at the resonant frequency. b, Same as a, but the laser frequency was off-resonance; the detuning was −2.47 GHz. c, The axial position of the annihilation events is plotted versus the TOF. The detuning was 0 GHz. d, Same as c, but the detuning was −2.47 GHz. Events within the dashed box for each laser frequency were selected for the spectral shape determination (Fig. 4a).
