antiprotons

CERN experiment takes us one step closer to discovering where all the antimatter went

New research published today by researchers from CERN has brought us a step closer to understanding where all the antimatter has gone. This matter-antimatter asymmetry is one of the greatest challenges in physics and at this moment in time the universe seems to be composed entirely of matter – the only antimatter around is created by us at places like CERN. Yet our theories predict that exactly equal amounts of matter and antimatter would have been created in the Big Bang. So where did all the antimatter go?

This new research, undertaken by the ALPHA experiment at CERN’s Antiproton Decelerator (AD) in Geneva, is the first time that the electric charge of an anti-atom has been measured to high precision. Measuring the electric charge of antihydrogen atoms is a way to study any subtle differences between matter and antimatter which could account for the lack of antimatter in the universe.

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AMS days: experiments present latest results












CERN - European Organization for Nuclear Research logo.

April 16, 2015

The Alpha Magnetic Spectrometer (AMS) collaboration will present today the latest results in its quest to understand the origin of cosmic rays and dark matter. These intriguing results will be shared and discussed during the “AMS days” starting today at CERN with many of the world’s leading theoretical physicists and principal investigators of some of the major experiments exploring the field of cosmic-ray physics. The main objective of this scientific exchange is to understand the interrelation between AMS results and those of other major cosmic-ray experiments and current theories.

“I am very pleased that so many of the world’s leading scientists are interested in AMS results and are coming to CERN for this meeting,” said AMS spokesperson Samuel Ting.


Image above: The Alpha Magnetic Spectrometer looks for dark matter, antimatter and missing matter from a module on the International Space Station (Image: NASA).

In particular, AMS is presenting unexpected new results on the antiproton/proton ratio in the cosmic rays, and on the proton and helium fluxes. Pre-existing models of ordinary cosmic rays cannot explain the AMS results. These new observations may provide important information on the understanding of cosmic-ray production and propagation. It is possible that the results may be explained by new astrophysical sources or new acceleration and propagation mechanisms, and the latest AMS results are also consistent with dark matter collisions.

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 22 Member States.

Related link:

The Alpha Magnetic Spectrometer (AMS): http://home.web.cern.ch/about/experiments/ams

Read more:

“Physics community to discuss latest results of the AMS experiment” – CERN press release: http://press.web.cern.ch/press-releases/2015/04/physics-community-discuss-latest-results-ams-experiment

Don’t miss:

- “Human Space Exploration” by NASA’s William H. Gerstenmaier, as part of the AMS days at CERN. Webcast at 6:15pm today (15 April 2015): http://webcast.web.cern.ch/webcast/play.php?event=381134

- “The Odyssey of Voyager” by Prof. Edward C. Stone, as part of the AMS days at CERN. Webcast at 6:30pm tomorrow (16 April 2015): http://webcast.web.cern.ch/webcast/play.php?event=381134

For more information about the European Organization for Nuclear Research (CERN), visit: http://home.web.cern.ch/

Image (mentioned), Text, Credits: CERN/Cian O'Luanaigh.

Greetings, Orbiter.ch
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Red's Research and Development Log, Entry 1465

The ships of our rival organization use highly destructive antiproton weaponry instead of GDI’s phasers. Their railguns are also incredibly efficient, yet devastating.

Not to mention, their SPEAR point-defenses are far superior to most GDI ships, save those in my First Fleet.

Things are going as planned, then. That’s good.

[ Authors ]
Carmelo Evoli, Daniele Gaggero, Dario Grasso
[ Abstract ]
We present a novel determination of the astrophysical uncertainties associated to the secondary antiproton flux originating from cosmic-ray spallation on the interstellar gas. We select a set of propagation models compatible with the recent B/C data from PAMELA, and find those providing minimal and maximal antiproton fluxes in different energy ranges. We use this result to determine the most conservative bounds on relevant Dark Matter (DM) annihilation channels: We find that the recent claim of a DM interpretation of a gamma-ray excess in the Galactic Center region cannot be ruled out by current antiproton data. Finally, we discuss the impact of the recently released preliminary data from AMS-02. In particular, we provide a reference model compatible with proton, helium and B/C spectra from this experiment. Remarkably, the main propagation parameters of this model are in perfect agreement with the best fit presented in our earlier statistical analyses. We also show that the antiproton-to-proton ratio does not exhibit any significant anomaly at high energy with respect to our predictions.

[ Authors ]
Hong-Bo Jin, Yue-Liang Wu, Yu-Feng Zhou
[ Abstract ]
The first measurement on the antiproton to proton ratio made by the AMS-02 collaboration agrees with the expection from conventional cosmic-ray secondaries in the kinetic energy range $\sim 10-100$ GeV, which can be turned into stringent upper limits on the dark matter (DM) annihilation cross sections above $\sim 300$ GeV. Using the GALPROP code, we derive the upper limits in various propagation models and DM profiles. We show that in the “conventional” propagation model, for the $q\bar q$, $b\bar b$, and $WW$ final states, the constraints can be more stringent than that derived from the recent Ferm-LAT gamma-ray data on the dwarf spheroidal satellite galaxies. Making use of the typical minimal, median and maximal models obtained from a previous global fit, we show that the variation of the upper limits is around a factor of five.

[ Authors ]
Henrik Stegeby, Markus Kowalewski, Konrad Piszczatowski, Hans O. Karlsson
[ Abstract ]
The problem of antiproton scattering on the molecular Hydrogen is investigated by means of wave packet dynamics. The electronically potential energy surfaces of the antiproton H2 system are presented within this work. Excitation and dissociation probabilities of the molecular Hydrogen for collision energies in the ultra low energy regime below 10 eV are computed.

Where is all that antimatter?

In particle physics, antimatter is material composed of antiparticles; which have the same mass as particles of ordinary matter but have opposite charge and other particle properties such as lepton and baryon number, quantum spin, etc. Collisions between particles and antiparticles lead to the annihilation of both, giving rise to variable proportions of intense photons (gamma rays), neutrinos, and less massive particle–antiparticle pairs. The mass of any produced neutrinos is negligible, while they contain energy that generally continues to be unavailable after the release of particle-antiparticle annihilation. The total consequence of annihilation is a release of energy available for work, proportional to the total matter and antimatter mass, in accord with the mass-energy equivalence equation, E=mc2.

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[ Authors ]
Gaëlle Giesen, Mathieu Boudaud, Yoann Genolini, Vivian Poulin, Marco Cirelli, Pierre Salati, Pasquale D. Serpico, Jie Feng, Antje Putze, Sylvie Rosier-Lees, Manuela Vecchi
[ Abstract ]
Using the updated proton and helium fluxes just released by the AMS-02 experiment we reevaluate the secondary astrophysical antiproton to proton ratio and its uncertainties, and compare it with the ratio preliminarly reported by AMS-02. We find no unambiguous evidence for a significant excess with respect to expectations. Yet, some preference for thicker halos and a flatter energy dependence of the diffusion coefficient starts to emerge. Also, we provide an assessment of the room left for exotic components such as Galactic Dark Matter annihilation or decay, deriving new stringent constraints.

“The conventional models predict that at higher energies, the amount of antimatter cosmic rays will decrease faster than the amount of matter cosmic rays,” Capell says. “But because dark matter is its own antiparticle, when two dark matter particles collide, they are just as likely to produce matter particles as they are to produce antimatter particles, so we would see an excess of antiparticles.” This new result compares the ratio of antiprotons to protons across a wide energy range and finds that this proportion does not drop down at higher energies as predicted, but stays almost constant. The scientists also found that the momentum-to-charge ratio for protons and helium nuclei is higher than predicted at greater energies. “These new results are very exciting,” says CERN theorist John Ellis. “They’re much more precise than previous data and they are really going to enable us to pin down our models of antiproton and proton production in the cosmos.”


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AMS days: experiments present latest results The Alpha Magnetic Spectrometer (AMS) collaboration will present today the latest results in its quest to understand the origin of cosmic rays and dark matter. These intriguing results will be shared and discussed during the “AMS days” starting today at CERN with many of the world’s leading theoretical physicists and principal investigators of some of the major experiments exploring the field of cosmic-ray physics. The main objective of this scientific exchange is to understand the interrelation between AMS results and those of other major cosmic-ray experiments and current theories. “I am very pleased that so many of the world’s leading scientists are interested in AMS results and are coming to CERN for this meeting,” said AMS spokesperson Samuel Ting. In particular, AMS is presenting unexpected new results on the antiproton/proton ratio in the cosmic rays, and on the proton and helium fluxes. Pre-existing models of ordinary cosmic rays cannot explain the AMS results. These new observations may provide important information on the understanding of cosmic-ray production and propagation. It is possible that the results may be explained by new astrophysical sources or new acceleration and propagation mechanisms, and the latest AMS results are also consistent with dark matter collisions.


New post from A Few Words
from http://ift.tt/1JK5Tqy