Research ArticlePHYSICS

First demonstration of antimatter wave interferometry

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Science Advances  03 May 2019:
Vol. 5, no. 5, eaav7610
DOI: 10.1126/sciadv.aav7610
  • Fig. 1 Schematics of the Talbot-Lau interferometer.

    Positrons traverse two circular 2-mm-wide collimators 10.2 cm apart. The interferometer is composed of two SiN diffraction gratings with periodicity d1 and d2, respectively, separated by L1 = (118.1 ± 0.2) mm. Interference fringes with d3 periodicity are expected at L2 = (576 ± 5) mm. The emulsion is tilted so that the Y axis in the reference frame of the emulsion surface (X, Y) forms a 45° angle with the y axis of the laboratory. Gamma rays (511 keV) from positron annihilation in the emulsion are monitored with a high-purity germanium (HpGe) detector for rate measurement.

  • Fig. 2 Representative example of view analysis.

    All panels refer to the highest contrast view for E = 14 keV. (A) Three-dimensional distribution of the reconstructed clusters limited to a 100-μm-wide region along X. A hint of the periodic fringes is even appreciable by visual inspection. (B) Raw microscope image cropped to a region of 250 × 160 μm2. (C) Histogram of the Z position of the clusters and Gaussian fit used to determine the analysis region.

  • Fig. 3 Optimal angle and period found via the Rayleigh test.

    Scatter plot and profile histograms of the optimal period and angle (α*,d3*)for 14 keV. A total of 1620 views covering a surface of about 10 × 14 mm2 were analyzed. Histograms are fit with a Gaussian function plus a constant background. The black ellipse indicates the corresponding 99.7% confidence level region. The corresponding plots for the other energy points are shown in fig. S2.

  • Fig. 4 Contrast on the emulsion surface.

    (A) Contrast C as a function of Y for views in the region delimited by the dashed lines in (B). The origin of the Y axis is set to coincide with the center of the beam intensity profile, estimated for each energy with a Gaussian fit. Errors on the contrast come from the sinusoidal least-squares fit. The result of a Gaussian fit with constant background is superimposed to the data. The inset shows a histogram of Xj(α*) mod 3d* and a sinusoidal fit for the highest contrast view; error bars represent Poissonian counting uncertainties. (B) Contrast heatmaps for the four energies considered. The contrast of views excluded from the analysis was set to zero.

  • Fig. 5 Contrast as a function of energy.

    Measured contrast normalized to the resonance value, defined as C/Cmax(E). The 68% confidence interval uncertainties are obtained by standard error propagation. The solid line is the quantum-mechanical prediction, while the classical prediction is indicated by the dashed line.

  • Table 1 Summary of the results at different energies.

    Measured fringe period d3, contrast C, and peak contrast position Y0, as discussed in the text.

    E (keV)d3 (μm)C (%)Y0 (mm)
    165.853 ± 0.001stat ± 0.050syst45.8 ± 1.5−2.9 ± 0.6
    145.851 ± 0.001stat ± 0.050syst49.1 ± 0.5−2.3 ± 0.6
    115.852 ± 0.001stat ± 0.050syst43.6 ± 0.8−2.2 ± 0.6
    95.852 ± 0.001stat ± 0.050syst26.7 ± 0.8−2.3 ± 0.6
    85.850 ± 0.001stat ± 0.050syst14.4 ± 0.8−2.2 ± 0.6

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/5/eaav7610/DC1

    Fig. S1. Picture of two emulsion detectors after exposure to the beam and chemical development.

    Fig. S2. Optimal angle and period found via the Rayleigh test.

    Fig. S3. Picture of the apparatus.

    Fig. S4. Picture of the interferometer.

    Fig. S5. Schematics of the rotational alignment procedure.

    Movie S1. Animation based on actual data from the scanned emulsion film showing the buildup of the interference pattern.

  • Supplementary Materials

    The PDF file includes:

    • Fig. S1. Picture of two emulsion detectors after exposure to the beam and chemical development.
    • Fig. S2. Optimal angle and period found via the Rayleigh test.
    • Fig. S3. Picture of the apparatus.
    • Fig. S4. Picture of the interferometer.
    • Fig. S5. Schematics of the rotational alignment procedure.
    • Legend for movie S1

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    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.mp4 format). Animation based on actual data from the scanned emulsion film showing the buildup of the interference pattern.

    Files in this Data Supplement:

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