Confine first, count without touching

Two fields form the bottle; a tiny induced current reveals how many particles remain.

1. Keep the particles away from matter

Penning-trap confinementA magnetic field confines antiprotons radially while electrostatic end electrodes confine them along the field axis.magnetic fieldradial confinementelectrostatic end electrodes92 antiprotons

Magnetic and electrostatic fields provide confinement without physical walls.

2. Count them non-destructively

Image-current detector and noise-spectrum dipOscillating antiprotons induce a tiny image current in a resonant detector, producing a dip whose width is proportional to particle count.resonant detectorabout 453 kHzimage currentelectrical noise spectrumdip width ∝ count

The particles’ shared oscillation creates a measurable dip in the detector’s noise.

Before → after transport334.08(8) → 333.92(6) Hz
Absolute difference: 0.16 Hz
Signal expected if one were lost3.633(16) Hz
More than 20 times the observed difference

Schematic only; geometry and spectrum shape are illustrative. The reported dip widths and one-particle calibration exclude the loss of even one antiproton during transport.