Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Magnetic moment of the proton measured with unprecedented precision

06.06.2014

Physicists succeeded in the first direct high-precision measurement of a fundamental property of the proton / Results will contribute to a better understanding of the matter/antimatter asymmetry

One of the biggest riddles in physics is the apparent imbalance between matter and antimatter in our universe. To date, there is no explanation as to why matter and antimatter failed to completely annihilate one another immediately after the big bang and how the surplus matter was created that went on to form the universe as we know it. Experiments conducted at Johannes Gutenberg University Mainz (JGU) have contributed towards a resolution of this problem.


Double Penning trap used to measure the magnetic moment of the proton. The double Penning trap is made of gold-plated cylindrical trap electrodes; the individual trap electrodes are isolated from one another using sapphire rings. During measurements the trap is in an ultra-high vacuum. To the right of the image is the outer housing of a detection instrument which allows for the observation of single protons. The entire structure is about 20 centimeters long.

photo: Andreas Mooser, JGU


The oscillating proton (red) generates a tiny current which is recorded using highly sensitive electronic detectors. The red arrow represents the magnetic moment of the proton; the green lines indicate the magnetic field in the trap.

Ill.: Georg Schneider, JGU

For the first time a direct and high-precision measurement of the magnetic moment of the proton has been conducted successfully. The magnetic moment is one of the fundamental properties of protons, which combine with neutrons to form the nucleus of atoms.

In principal, the method can also be used to measure the magnetic moment of an antiproton with a similarly high precision, making it possible to investigate matter/antimatter asymmetry. Related experiments are now being set up at the CERN research center in Geneva, Switzerland.

Years of preparation were necessary before the measurements were possible and the results obtained have far exceeded those of all previous attempts. In addition to Mainz University, the GSI Helmholtz Center for Heavy Ion Research in Darmstadt, the Max Planck Institute of Nuclear Physics in Heidelberg, and the Japanese RIKEN research facility all took part in the experiment. 

Using a double Penning trap, the researchers were able to determine the relevant parameter, the so-called 'g-factor,' with a precision of 3.3 x 10ˆ9. The result is 760 times more precise than all the results documented independently at Mainz University and Harvard University in 2012, and three-times more precise than the result obtained by an indirect measurement in 1972.

"Protons are like tiny rod magnets. They have a magnetic moment 24 magnitudes – equal to one millionth of a billionth of a billionth – weaker than a typical compass needle. This is the first time we have been able to measure anything on this scale," said Andreas Mooser, primary author of the study and a member of Professor Jochen Walz's research team at Mainz University.

The key to success proved to be the use of a double Penning trap, i.e., an electromagnetic particle trap, to isolate and evaluate a single free proton. An analysis trap serves to detect spin-quantum jumps of the proton, while in a precision trap precise frequency measurements are conducted.

It has proved possible in the past to use Penning traps to directly measure the magnetic moment of individual particles such as electrons and their antiparticle counterparts, positrons. But adapting this approach for use with protons is an enormous challenge as the magnetic moment of a proton is 660 times smaller than that of an electron.

The apparatus for the experiment needed to be far more sensitive. The collaborating partners were able to develop such a highly sensitive double Penning trap so that they could undertake the long-planned measurements.

Apart from the direct measurement performed in Mainz, the previous most precise measurements were obtained by means of an indirect method in 1972, where the hyper-fine structure of atomic hydrogen was measured and subsequently theoretical corrections were applied.

The principle of a direct measurement in a double Penning trap can also be used for the antiproton. "We can then compare the two results and test these against the fundamental predictions of the standard model," explained Stefan Ulmer, coordinator of the BASE joint project, which is currently setting up a corresponding experiment at CERN in Geneva.

Using the double Penning trap technique for the antiproton could enhance the precision of results obtained during the ATRAP project in 2013 by a factor of at least 1,000. Assuming that the measured values differ, this would represent an important step forward with regard to understanding the matter/antimatter asymmetry of our universe.

Publication:
Andreas Mooser et al.
Direct high-precision measurement of the magnetic moment of the proton
Nature, 29 May 2014
DOI: 10.1038/nature13388

Andreas Mooser et al.
Resolution of Single Spin Flips of a Single Proton
Physical Review Letters, 4 April 2013
DOI: 10.1103/PhysRevLett.110.140405

Further information:
Dr. Andreas Mooser
Quantum, Atomic and Neutron Physics (QUANTUM)
Institute of Physics
Johannes Gutenberg University Mainz (JGU)
D 55099 Mainz, GERMANY
phone +49 6131 39-25953
fax +49 6131 39-23438
e-mail: mooser@uni-mainz.de
http://www.quantum.physik.uni-mainz.de/members__ag_walz__mooser.html.en

Weitere Informationen:

http://www.quantum.physik.uni-mainz.de/ag_walz__index.html.en ;
http://www.nature.com/nature/journal/v509/n7502/full/nature13388.html (Abstract) ;
http://www.uni-mainz.de/presse/14236_ENG_HTML.php (press release „Quantum leap: Magnetic properties of a single proton directly observed for the first time”) ;
http://base.web.cern.ch/

Ergänzung vom 06.06.2014

CORRECTION - 2nd paragraph, 3rd sentence:

Using a double Penning trap, the researchers were able to determine the relevant parameter, the so-called 'g-factor,' with a precision of 3.3 x 10ˆ9.

Petra Giegerich | idw - Informationsdienst Wissenschaft

Further reports about: CERN Magnetic Physics asymmetry fundamental measure measurement measurements method protons trap

More articles from Physics and Astronomy:

nachricht Spiral arms: not just in galaxies
30.09.2016 | Max-Planck-Institut für Radioastronomie

nachricht Discovery of an Extragalactic Hot Molecular Core
29.09.2016 | National Astronomical Observatory of Japan

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First-Ever 3D Printed Excavator Project Advances Large-Scale Additive Manufacturing R&D

Heavy construction machinery is the focus of Oak Ridge National Laboratory’s latest advance in additive manufacturing research. With industry partners and university students, ORNL researchers are designing and producing the world’s first 3D printed excavator, a prototype that will leverage large-scale AM technologies and explore the feasibility of printing with metal alloys.

Increasing the size and speed of metal-based 3D printing techniques, using low-cost alloys like steel and aluminum, could create new industrial applications...

Im Focus: New welding process joins dissimilar sheets better

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of light metals.
Scientists at the University of Stuttgart have now developed two new process variants that will considerably expand the areas of application for friction stir welding.
Technologie-Lizenz-Büro (TLB) GmbH supports the University of Stuttgart in patenting and marketing its innovations.

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of...

Im Focus: First quantum photonic circuit with electrically driven light source

Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.

Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Paper – Panacea Green Infrastructure?

30.09.2016 | Event News

HLF: From an experiment to an establishment

29.09.2016 | Event News

European Health Forum Gastein 2016 kicks off today

28.09.2016 | Event News

 
Latest News

First-Ever 3D Printed Excavator Project Advances Large-Scale Additive Manufacturing R&D

30.09.2016 | Materials Sciences

New Technique for Finding Weakness in Earth’s Crust

30.09.2016 | Earth Sciences

Cells migrate collectively by intermittent bursts of activity

30.09.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>