25 research outputs found
Direct Measurement of the Proton Magnetic Moment
The proton magnetic moment in nuclear magnetons is measured to be
, a 2.5 ppm (parts per
million) uncertainty. The direct determination, using a single proton in a
Penning trap, demonstrates the first method that should work as well with an
antiproton as with a proton. This opens the way to measuring the antiproton
magnetic moment (whose uncertainty has essentially not been reduced for 20
years) at least times more precisely
Resolving an Individual One-Proton Spin Flip to Determine a Proton Spin State
Previous measurements with a single trapped proton or antiproton detected
spin resonance from the increased scatter of frequency measurements caused by
many spin flips. Here a measured correlation confirms that individual spin
transitions and states are detected instead. The high fidelity suggests that it
may be possible to use quantum jump spectroscopy to measure the p and \pbar
magnetic moments much more precisely.Comment: 4 pages, 7 figure
Self-Excitation and Feedback Cooling of an Isolated Proton
The first one-proton self-excited oscillator (SEO) and one-proton feedback
cooling are demonstrated. In a Penning trap with a large magnetic gradient, the
SEO frequency is resolved to the high precision needed to detect a one-proton
spin flip. This is after undamped magnetron motion is sideband-cooled to a 14
mK theoretical limit, and despite random frequency shifts (larger than those
from a spin flip) that take place every time sideband cooling is applied in the
gradient. The observations open a possible path towards a million-fold improved
comparison of the antiproton and proton magnetic moments
Direct high-precision measurement of the magnetic moment of the proton
The spin-magnetic moment of the proton is a fundamental property of
this particle. So far has only been measured indirectly, analysing the
spectrum of an atomic hydrogen maser in a magnetic field. Here, we report the
direct high-precision measurement of the magnetic moment of a single proton
using the double Penning-trap technique. We drive proton-spin quantum jumps by
a magnetic radio-frequency field in a Penning trap with a homogeneous magnetic
field. The induced spin-transitions are detected in a second trap with a strong
superimposed magnetic inhomogeneity. This enables the measurement of the
spin-flip probability as a function of the drive frequency. In each measurement
the proton's cyclotron frequency is used to determine the magnetic field of the
trap. From the normalized resonance curve, we extract the particle's magnetic
moment in units of the nuclear magneton . This
measurement outperforms previous Penning trap measurements in terms of
precision by a factor of about 760. It improves the precision of the forty year
old indirect measurement, in which significant theoretical bound state
corrections were required to obtain , by a factor of 3. By application
of this method to the antiproton magnetic moment the fractional
precision of the recently reported value can be improved by a factor of at
least 1000. Combined with the present result, this will provide a stringent
test of matter/antimatter symmetry with baryons.Comment: published in Natur
One-Particle Measurement of the Antiproton Magnetic Moment
\DeclareRobustCommand{\pbar}{\HepAntiParticle{p}{}{}\xspace}
\DeclareRobustCommand{\p}{\HepParticle{p}{}{}\xspace}
\DeclareRobustCommand{\mup}{{}{}\xspace}
\DeclareRobustCommand{\mupbar}{\mu_{\pbar}{}{}\xspace}
\DeclareRobustCommand{\muN}{{}{}\xspace
For the first time a single trapped \pbar is used to measure the \pbar
magnetic moment {\bm\mu}_{\pbar}. The moment {\bm\mu}_{\pbar} = \mu_{\pbar}
{\bm S}/(\hbar/2) is given in terms of its spin and the nuclear
magneton (\muN) by \mu_{\pbar}/\mu_N = -2.792\,845 \pm 0.000\,012. The 4.4
parts per million (ppm) uncertainty is 680 times smaller than previously
realized. Comparing to the proton moment measured using the same method and
trap electrodes gives \mu_{\pbar}/\mu_p = -1.000\,000 \pm 0.000\,005 to 5
ppm, for a proton moment ,
consistent with the prediction of the CPT theorem.Comment: 4 pages, 4 figures. arXiv admin note: substantial text overlap with
arXiv:1201.303
Studies on Antihydrogen Atoms with the ATRAP Experiment at CERN
The CPT theorem predicts the same properties of matter and anti- matter, however, in the nearby Universe, we observe a huge imbalance of matter and antimatter. Therefore, it is intriguing to measure the proper- ties of particles and antiparticles in order to contribute to an explanation of this phenomena. In this article, we will describe the experimental ef- forts of the ATRAP Collaboration in order to test the CPT theorem using antihydrogen atom