Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Magnetic moment of a single antiproton determined with greatest precision ever

19.01.2017

Physicists publish most accurate measurement of a fundamental property of the antiproton to date / Contribution to the matter-antimatter debate

As self-evident as it is that matter exists, its origins are just as mysterious. According to the principles of particle physics, when the universe was originally formed equal amounts of matter and antimatter would have been created, which then should have destroyed each other in a process that physicists call annihilation. But in reality, our universe shows a manifest imbalance in favor of matter.


BASE experiment using the CERN antiproton decelerator in Geneva: Visible in the image are the control equipment, the superconducting magnet that houses the Penning trap, and the antiproton transfer beam tube.

photo/©: Stefan Sellner, RIKEN

Therefore, scientists are looking for a small difference between a particle and its antiparticle that could explain why matter actually exists. The multinational Baryon Antibaryon Symmetry Experiment (BASE) collaboration at the CERN research center has set a new benchmark in this search by successfully measuring an important characteristic of the antiproton with the greatest accuracy ever achieved. The g-factor, a quantity that characterizes the magnetic moment, has been measured with a precision increased by a factor of six compared to previous results.

The idea that something like anti-matter must exist came up in the late 1920s. It was only a few years later that positrons, the antiparticles of electrons, were discovered. While positrons occur naturally on Earth, antiprotons, the antiparticles of protons, have to be artificially generated.

The Antiproton Decelerator storage ring at CERN produces cooled antiprotons in large quantities for a wide range of antimatter experiments. In the experiments carried out by the BASE group, of which Johannes Gutenberg University Mainz (JGU) is a member, single ultracold antiprotons are studied in an electromagnetic particle trap.

The system consists of three Penning traps. A reservoir trap stores a cloud of antiprotons for the experiment and supplies single particles to the co-magnetometer trap and the actual analysis trap. The purpose of the co-magnetometer trap is to continuously monitor the magnetic field. The analysis trap is surrounded by an extremely large magnetic field inhomogeneity of 300 Kilotesla per square meter.

This ultra-powerful magnetic field inhomogeneity is a fundamental requirement for detecting spin-flips, a method developed by Nobel Prize laureate Hans Georg Dehmelt in 1987 for measuring the magnetic moment of the electron and the positron. "However, the challenge in our case is much greater because the magnetic moment of the proton and the antiproton is about 660 times smaller in comparison," wrote the BASE scientists in a paper published in Nature Communications. The principle used to measure the magnetic moment of single protons was developed five years ago by a collaboration with a group at the Institute of Physics at Johannes Gutenberg University Mainz led by Professor Jochen Walz. With its high-precision measurement of the proton in 2014 the collaboration goes unchallenged as the top research team in this field.

G-factor measured with six times enhanced accuracy

The method used to analyze the antiproton employs the same principle. The g-factor was determined on the basis of six individual measurements with an uncertainty of just 0.8 parts per million. The value of 2.7928465(23) is six times more precise than the previous record achieved by another CERN research group in 2013. As recently as 2011, the magnetic moment of the antiproton was only known to an accuracy of three decimal places.

The new result is consistent with the g-factor of the proton as measured in Mainz in 2014, namely 2.792847350(9). "This means that within our experimental uncertainty, we cannot detect any difference between protons and antiprotons. At this level our measurement is consistent with the predictions of the Standard Model," stated Stefan Ulmer, coordinator of BASE at CERN and a former member of Walz' team at Mainz University.

Protons and antiprotons thus still appear to be mirror images of each other, meaning there is still no explanation of why matter actually exists at all and did not simply vaporize in the first moments of the Big Bang. The BASE collaboration intends to go a step further by increasing the precision of its measurements using a double Penning trap technique. This is a complex technique that was used for the Mainz proton measurements in 2014 and offers the potential of improving accuracy by a factor of 1,000.

"The asymmetry between matter and antimatter is so obvious that something must have happened which cannot yet be detected using the methods currently available to modern physics. So our main aim is to find approaches that can help solve this extraordinary puzzle," said Ulmer of the group's future plans. In addition to Johannes Gutenberg University Mainz, the other members involved in the research projects are the RIKEN research center in Japan, the Max Planck Institute for Nuclear Physics in Heidelberg, the Leibniz Universität Hannover and the GSI Helmholtz Center for Heavy Ion Research in Darmstadt.

Images:
http://www.uni-mainz.de/bilder_presse/08_physik_quantum_antiproton_01.jpg
BASE experiment using the CERN antiproton decelerator in Geneva: Visible in the image are the control equipment, the superconducting magnet that houses the Penning trap, and the antiproton transfer beam tube.
photo/©: Stefan Sellner, RIKEN

http://www.uni-mainz.de/bilder_presse/08_physik_quantum_antiproton_02.jpg
BASE experiment using the CERN antiproton decelerator in Geneva: Shown here are the superconducting magnet that houses the Penning trap and the antiproton transfer beam tube.
photo/©: Stefan Sellner, RIKEN

http://www.uni-mainz.de/bilder_presse/08_physik_quantum_antiproton_03.jpg
BASE Penning trap system that was used to measure the magnetic moment of the antiproton
photo/©: Georg Schneider, JGU

Publication:
Hiroki Nagahama et al.
Sixfold improved single particle measurement of the magnetic moment of the antiproton
Nature Communications, 18 January 2017
DOI: 10.1038/ncomms14084

Further information:
Prof. Dr. Jochen Walz
Quantum, Atomic, and Neutron Physics (QUANTUM)
Institute of Physics
Johannes Gutenberg University Mainz (JGU)
55099 Mainz, GERMANY
phone +49 6131 39-25976
fax +49 6131 39-25179
e-mail: Jochen.Walz@uni-mainz.de
http://www.quantum.physik.uni-mainz.de/members__ag_walz__jwalz.html.en

Dr. Stefan Ulmer
BASE spokesperson
CERN
1211 Geneva, SWITZERLAND
phone +41 75 411 9072
e-mail: stefan.ulmer@cern.ch
http://www.quantum.physik.uni-mainz.de/members__ag_walz__sulmer.html.en

Weitere Informationen:

http://www.nature.com/articles/ncomms14084 ;
http://base.web.cern.ch/ ;
http://www.quantum.physik.uni-mainz.de/ag_walz__index.html.en ;
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", 21 June 2011 ;
http://www.uni-mainz.de/presse/17364_ENG_HTML.php – press release "Magnetic moment of the proton measured with unprecedented precision", 6. June 2014

Petra Giegerich | idw - Informationsdienst Wissenschaft

More articles from Physics and Astronomy:

nachricht Smallest transistor worldwide switches current with a single atom in solid electrolyte
17.08.2018 | Karlsruher Institut für Technologie (KIT)

nachricht Protecting the power grid: Advanced plasma switch for more efficient transmission
17.08.2018 | DOE/Princeton Plasma Physics Laboratory

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: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Smallest transistor worldwide switches current with a single atom in solid electrolyte

17.08.2018 | Physics and Astronomy

Robots as Tools and Partners in Rehabilitation

17.08.2018 | Information Technology

Climate Impact Research in Hannover: Small Plants against Large Waves

17.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>