Stefan Ulmer, a particle physicist at RIKEN in Wako, Japan, and colleagues analyzed antiprotons and negative hydrogen ions (a proton plus two electrons) one by one inside an instrument called a Penning trap.
They found that as particles circled inside the Penning trap, gravity acted on protons and antiprotons with the same strength, just as Einstein's theory predicts.
Developed by Biercuk and colleagues, the device consists of a few dozen beryllium ions in a device called a Penning trap
Ulmer and his team used a device called a Penning trap to improve on previous magnetic moment measurements for the proton.
He says the work's most significant contribution is the Penning trap setup: It should also be able to measure the magnetic moment of the antiproton.
To make the mass measurement, the team used a device called a Penning trap
, which employs electric and magnetic fields to confine atoms.
The so-called Paul trap and its cousin, the Penning trap
, play an important role in modern spectroscopy.
Such a crystal, confined in a Penning trap
with its rotation locked to a rotating electric field, has potential applications in atomic frequency standards and quantum logic.
One experiment aimed at doing that at the CERN laboratory in Geneva, Switzerland, has managed to capture antiprotons in a device called a Penning trap
and hold them for periods of up to 10 minutes.