{"id":3463,"date":"2026-07-22T15:51:57","date_gmt":"2026-07-22T13:51:57","guid":{"rendered":"https:\/\/www.icone-neutron.fr\/?page_id=3463"},"modified":"2026-07-22T15:52:53","modified_gmt":"2026-07-22T13:52:53","slug":"moderer-un-neutron-libre-2","status":"publish","type":"page","link":"https:\/\/www.icone-neutron.fr\/en\/moderer-un-neutron-libre-2\/","title":{"rendered":"moderer-un-neutron-libre"},"content":{"rendered":"<div data-elementor-type=\"wp-page\" data-elementor-id=\"3463\" class=\"elementor elementor-3463\">\n\t\t\t\t<div class=\"elementor-element elementor-element-4165832b e-flex e-con-boxed e-con e-parent\" data-id=\"4165832b\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-569fe24e elementor-widget elementor-widget-text-editor\" data-id=\"569fe24e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<style>\n\n\/* =========================\n   MAIN WHITE BLOCK\n========================= *\/\n\n.neutron-container{\n\n  max-width:1000px;\n\n  margin:60px auto;\n\n  padding:60px;\n\n  background:#ffffff;\n\n  border-radius:20px;\n\n  box-shadow:0 12px 35px rgba(0,0,0,0.12);\n\n  font-family:'Inter',Arial,sans-serif;\n\n  line-height:1.8;\n\n  color:#2f2f2f;\n\n}\n\n\n\n\/* =========================\n   TITLE\n========================= *\/\n\n.neutron-title{\n\n  font-size:42px;\n\n  font-weight:900;\n\n  color:#0d5cab;\n\n  padding-left:18px;\n\n  margin-bottom:50px;\n\n  position:relative;\n\n}\n\n\n\n.neutron-title::before{\n\n  content:\"\";\n\n  position:absolute;\n\n  left:0;\n\n  top:8px;\n\n  width:6px;\n\n  height:80%;\n\n  background:linear-gradient(180deg,#0d5cab,#3a8dde);\n\n  border-radius:3px;\n\n}\n\n\n\n\/* =========================\n   SUBTITLE\n========================= *\/\n\n.neutron-subtitle{\n\n  font-size:24px;\n\n  font-weight:700;\n\n  color:#0d5cab;\n\n  margin-top:50px;\n\n  margin-bottom:20px;\n\n}\n\n\n\n\/* =========================\n   TEXT\n========================= *\/\n\n.neutron-container p{\n\n  margin-bottom:22px;\n\n  font-size:18px;\n\n  color:#444;\n\n}\n\n\n\n\/* =========================\n   FORMULA\n========================= *\/\n\n.neutron-formula{\n\n  background:#f4f7fb;\n\n  border-left:4px solid #0d5cab;\n\n  padding:18px;\n\n  font-family:\"Courier New\", monospace;\n\n  margin:25px 0;\n\n  border-radius:10px;\n\n  color:#163b68;\n\n}\n\n\n\n\/* =========================\n   IMAGE\n========================= *\/\n\n.neutron-image{\n\n  margin:30px 0;\n\n  text-align:center;\n\n}\n\n\n\n.neutron-image img{\n\n  max-width:100%;\n\n  border-radius:12px;\n\n  box-shadow:0 10px 30px rgba(0,0,0,0.12);\n\n}\n\n\n\n.neutron-caption{\n\n  font-size:14px;\n\n  color:#777;\n\n  margin-top:10px;\n\n  font-style:italic;\n\n}\n\n\n\n\/* =========================\n   RESPONSIVE\n========================= *\/\n\n@media(max-width:768px){\n\n  .neutron-container{\n\n    margin:20px;\n\n    padding:30px;\n\n  }\n\n\n\n  .neutron-title{\n\n    font-size:34px;\n\n  }\n\n\n\n  .neutron-subtitle{\n\n    font-size:22px;\n\n  }\n\n\n\n  .neutron-container p{\n\n    font-size:16px;\n\n  }\n\n}\n\n<\/style>\n\n\n\n<div class=\"neutron-container\">\n\n\n<div class=\"neutron-title\">\n    Moderating a free neutron\n<\/div>\n\n\n\n<div class=\"neutron-subtitle\">\n    Principle\n<\/div>\n\n\n<p>\nModeration is the process of reducing the kinetic energy of a neutron.\n<\/p>\n\n\n<p>\nThe initial kinetic energy of a neutron released from a nucleus is generally\nof the order of a few MeV.\n<\/p>\n\n\n<p>\nTo reduce it to a few meV (~10<sup>-3<\/sup> eV), the neutron must undergo\ncollisions with light nuclei.\n<\/p>\n\n\n<p>\nThe energy transfer depends on the mass ratio <strong>A<\/strong> between\nthe target nucleus and the neutron.\n<\/p>\n\n\n\n<div class=\"neutron-formula\">\n(\u0394E \/ E) = f(A, \u03b8)\n<\/div>\n\n\n\n<p>\nThe kinetic energy of the neutron after collision is minimal for\n<strong>\u03b8 = 180\u00b0<\/strong>.\n<\/p>\n\n\n\n<div class=\"neutron-formula\">\nE<sub>final<\/sub> = E<sub>initial<\/sub> \u00d7 ((A \u2212 1)\/(A + 1))\u00b2\n<\/div>\n\n\n\n\n<div class=\"neutron-image\">\n\n<img decoding=\"async\" src=\"IMAGE_MODERATION_NEUTRONS.jpg\" alt=\"Neutron moderation\">\n\n<div class=\"neutron-caption\">\nProgressive reduction of neutron energy through successive collisions.\n<\/div>\n\n<\/div>\n\n\n\n\n<p>\nThe closer the nucleus mass is to the neutron mass, the more efficient\nthe energy reduction is during each collision.\n<\/p>\n\n\n\n<p>\nTo moderate a neutron, it must undergo several tens of successive collisions.\n<\/p>\n\n\n\n<\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>","protected":false},"excerpt":{"rendered":"<p>Moderating a free neutron Principle Moderation is the process of reducing the kinetic energy of a neutron. The initial kinetic energy of a neutron released from a nucleus is generally of the order of a few MeV. To reduce it to a few meV (~10-3 eV), the neutron must undergo collisions with light nuclei. The [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-3463","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.icone-neutron.fr\/en\/wp-json\/wp\/v2\/pages\/3463","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.icone-neutron.fr\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.icone-neutron.fr\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.icone-neutron.fr\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.icone-neutron.fr\/en\/wp-json\/wp\/v2\/comments?post=3463"}],"version-history":[{"count":4,"href":"https:\/\/www.icone-neutron.fr\/en\/wp-json\/wp\/v2\/pages\/3463\/revisions"}],"predecessor-version":[{"id":3468,"href":"https:\/\/www.icone-neutron.fr\/en\/wp-json\/wp\/v2\/pages\/3463\/revisions\/3468"}],"wp:attachment":[{"href":"https:\/\/www.icone-neutron.fr\/en\/wp-json\/wp\/v2\/media?parent=3463"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}