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 Hubble sees Neptune's mysterious shrinking storm
16.02.2018 | NASA/Goddard Space Flight Center

nachricht Supermassive black hole model predicts characteristic light signals at cusp of collision
15.02.2018 | Rochester Institute of Technology

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: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

Im Focus: Autonomous 3D scanner supports individual manufacturing processes

Let’s say the armrest is broken in your vintage car. As things stand, you would need a lot of luck and persistence to find the right spare part. But in the world of Industrie 4.0 and production with batch sizes of one, you can simply scan the armrest and print it out. This is made possible by the first ever 3D scanner capable of working autonomously and in real time. The autonomous scanning system will be on display at the Hannover Messe Preview on February 6 and at the Hannover Messe proper from April 23 to 27, 2018 (Hall 6, Booth A30).

Part of the charm of vintage cars is that they stopped making them long ago, so it is special when you do see one out on the roads. If something breaks or...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Fingerprints of quantum entanglement

16.02.2018 | Information Technology

'Living bandages': NUST MISIS scientists develop biocompatible anti-burn nanofibers

16.02.2018 | Health and Medicine

Hubble sees Neptune's mysterious shrinking storm

16.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>