{"id":3023,"date":"2010-12-25T06:56:40","date_gmt":"2010-12-25T04:56:40","guid":{"rendered":"http:\/\/localhost\/azgad\/wordpress\/?p=3023"},"modified":"2010-12-25T07:01:12","modified_gmt":"2010-12-25T05:01:12","slug":"when-matter-meets-antimatter","status":"publish","type":"post","link":"https:\/\/azgad.com\/?p=3023","title":{"rendered":"When matter meets antimatter"},"content":{"rendered":"

.
\n\u05dc\u05e7\u05e8\u05d9\u05d0\u05d4 \u05e0\u05d5\u05e1\u05e4\u05ea: \u05de\u05d0\u05de\u05e8 \u05de\u05e7\u05d9\u05e3 \u05d1\u05e2\u05d1\u05e8\u05d9\u05ea \u05e2\u05dc \u05d7\u05d5\u05de\u05e8 \u05d5\u05d0\u05e0\u05d8\u05d9-\u05d7\u05d5\u05de\u05e8<\/a><\/strong>
\n.
\nAntimatter, a substance that often features in science fiction, is routinely created at the CERN particle
\nphysics laboratory in Geneva, Switzerland, to provide us with a better understanding of atoms and
\nmolecules. Now, RIKEN scientists, as part of a collaborative team with researchers from Denmark,
\nJapan, the United Kingdom and Hungary, have shown that antiprotons\u2014particles with the same
\nmass as a proton but negatively charged\u2014collide with molecules in a very different way from
\ntheir interaction with atoms1. The result sets an important benchmark for testing future
\natomic-collision theories.
\n.
\nRIKEN scientist Yasunori Yamazaki explains that to assess such collisions: \u201cWe shot the simplest
\n negatively charged particles, slow antiprotons, at the simplest molecular target, molecular hydrogen.\u201d
\nSlow antiprotons are a unique probe of atoms and molecules because their negative charge does
\nnot attract electrons\u2014thereby simplifying theoretical modelling. Further, slower projectile speeds
\nmean longer-lasting, stronger interactions and avoid the need for complicated relativistic
\ncalculations.
\n.
\nThe scientists at CERN created antiprotons by firing a beam of high-speed protons into a block of the
\nmetal iridium. Then, in a facility known as the Antiproton Decelerator, they used magnets to focus the
\n antiprotons before applying strong electric fields to slow them down to approximately 10% of the speed
\n of light. Yamazaki and his colleagues trapped and cooled these antiprotons to 0.01% of the velocity
\nof light before accelerating them one by one to the desired velocity (Fig. 1). They then slammed
\nantiprotons into a gas of molecular deuterium\u2014a pair of bound hydrogen atoms each with a nucleus
\ncomprising one proton and one neutron\u2014and used sensitive equipment to detect the remnants of
\n the collision.
\n.
\n\"\"<\/a><\/p>\n

.
\nFigure 1:<\/strong> A schematic diagram of the antiproton decelerator at CERN that is used to smash antiprotons
\nand molecular hydrogen molecules to together so that the remaining particles can be analyzed to
\n provide insight to their interactions.
\n.<\/em><\/p>\n

Yamazaki and the team found that the likelihood of the ionization of the deuterium molecules scales
\nlinearly with the antiproton velocity. This is contrary to what is expected for the atomic target, hydrogen.
\n\u201cThis was a big surprise, and it infers that our understanding of atomic collision dynamics, even at a
\nqualitative level, is still in its infancy,\u201d says Yamazaki. The team suggests that molecular targets provide
\na mechanism for suppressing the ionization process. As an antiproton approaches one of the protons in
\n the molecule, the presence of the second proton shifts the orbiting electron cloud. The slower the
\n antiproton, the more time the electron has to adjust, and hence the smaller the chance of ionization.
\n.
\nThe team now hopes to investigate how ionization depends on the antiproton\u2013target distance and the
\norientation at the moment of collision.
\n.<\/p>\n","protected":false},"excerpt":{"rendered":"

. \u05dc\u05e7\u05e8\u05d9\u05d0\u05d4 \u05e0\u05d5\u05e1\u05e4\u05ea: \u05de\u05d0\u05de\u05e8 \u05de\u05e7\u05d9\u05e3 \u05d1\u05e2\u05d1\u05e8\u05d9\u05ea \u05e2\u05dc \u05d7\u05d5\u05de\u05e8 \u05d5\u05d0\u05e0\u05d8\u05d9-\u05d7\u05d5\u05de\u05e8 . Antimatter, a substance that often features in science fiction, is routinely created at the CERN particle physics laboratory in Geneva, Switzerland, to provide us with a better understanding of atoms and molecules. Now, RIKEN scientists, as part of a collaborative team with researchers from Denmark, … <\/p>\n

\u05d4\u05de\u05e9\u05d9\u05db\u05d5 \u05d1\u05e7\u05e8\u05d9\u05d0\u05d4<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[10],"tags":[513,49],"class_list":["post-3023","post","type-post","status-publish","format-standard","hentry","category-10","tag-513","tag-49","nodate","item-wrap"],"_links":{"self":[{"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/posts\/3023","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/azgad.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3023"}],"version-history":[{"count":6,"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/posts\/3023\/revisions"}],"predecessor-version":[{"id":3031,"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/posts\/3023\/revisions\/3031"}],"wp:attachment":[{"href":"https:\/\/azgad.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3023"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/azgad.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3023"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/azgad.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3023"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}