First Direct High Precision Measurement of the Proton Magnetic Moment

In a paper just published in Nature we report on the first direct high precision measurement of the proton magnetic moment. By application of the elegant double Penning trap technique we achieved a fractional precision of 3.3 parts per billion. Our value is consistent with the currently accepted CODATA value, but 2.5 times more precise.

WELCOME

 

BASE is a multinational collaboration currently building an apparatus at the Antiproton Decelerator (AD) of CERN to make comparison measurements of antiproton and proton magnetic g-factors. Such comparisons are interesting because any measured asymmetry would hint at physics beyond the Standard Model. The experiment consists of measuring the cyclotron and Larmor frequencies of a single trapped (anti)proton. By measuring the ratio of these two frequencies the magnetic moment of the (anti)proton is obtained in units of the nuclear magneton. The BASE collaboration observed the first spin flips with a single trapped proton, measured the magnetic moment of the proton with a fractional precision at the ppm level, observed first single proton spin filps and demonstrated recently the double Penning trap technique for the first time. This opens the way towards a direct measurement of the (anti)proton magnetic moment with a precision at the ppb level and will provide one of the most sensitive tests of CPT symmetry.

Demonstration of the Double Penning Trap Technique

In a just in Physics Letters B published article we report on the first successful demonstration of the double Penning trap technique with a single proton. This is a major step towards a  measurement of the particle's magnetic moment with ppb precision. The method can be applied to the antiproton, which will enable one of the most sensitive tests of CPT symmetry with baryons.

CERN SPSC Recommends BASE Approval

The BASE technical design report was evaluated by the SPSC. The committee recommended approval of the BASE project to the research board. Our TDR contains a detailed description of our experiment and a feasibility study for implementation of BASE into the Antiproton Decelerator facility. We acknowledge the strong support of the CERN groups which contributed to to this study.Special thanks to Lajos Bojtar for the coordination.

Resolution of Single Spin Flips with a Single Proton

In a just in Physical Review Letters published article we report on the first detection of single spin-flips of a single proton. We use Bayesian analysis methods and obtain spin state detection fidelities close to 100%. This is a major step towards the application of the so-called double Penning-trap method to measure magnetic moments of both the proton and the antiproton with ppb precision.

Direct measurement of the free cyclotron frequency of a single trapped proton

Penning traps are extremely powerful and versatile tools for high precision physics. This enormous impact is mainly based on the fact that in the magnetic field B of the trap the free cyclotron frequency of a trapped particle can be measured with high fractional precision. We invented a novel method to measure the free cyclotron frequency of a single trapped proton in one shot. The method is based on double-dressed states. By application of frequency modulated sideband drives the double dressing is produced, and energy is transferred between all eigenmodes of the trapped particle.

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