{"product_id":"helicita-goldhaber-neutrino-helicity","title":"Helicita – Neutrino Helicity \/ h = −1 Physics Sticker","description":"\u003cp\u003eHelicita, a curly-haired spiral-weaver, draws a twisting violet ribbon of light.\u003c\/p\u003e\u003ch3\u003eThe Physics\u003c\/h3\u003e\u003cp\u003eIn 1958 Maurice Goldhaber, Lee Grodzins and Andrew Sunyar measured the handedness of the neutrino (“Helicity of Neutrinos”, Phys. Rev. 109, 1015). Europium-152m captures an electron and emits a neutrino; the daughter nucleus recoils and then emits a gamma ray. Selecting gammas emitted against the recoil and measuring their circular polarisation with magnetised iron tied the neutrino's spin to its motion. Neutrinos turned out left-handed: spin opposite to motion.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eh = −1\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\u003cli\u003eh: helicity, the spin component along the direction of motion, in units of the maximum\u003c\/li\u003e\u003c\/ul\u003e\u003cp\u003eThe result fits the V−A theory of the weak force, which acts only on left-handed particles, part of the story of parity violation after Wu's 1957 experiment.\u003c\/p\u003e\u003cp\u003e\u003cem\u003eHonest caveat:\u003c\/em\u003e Helicity −1 is exact only for massless neutrinos; with their tiny masses it is very nearly −1 at the energies measured.\u003c\/p\u003e\u003ch3\u003eOn the sticker\u003c\/h3\u003e\u003cp\u003eHelicita holds up a glowing violet spiral ribbon beside her. Printed text: \u003cstrong\u003eHELICITA\u003c\/strong\u003e with the line \u003cstrong\u003eh = −1\u003c\/strong\u003e. Pixel-art kiss-cut vinyl sticker, white, in 2″, 3″, 4″ and 6″ sizes.\u003c\/p\u003e","brand":"Printify","offers":[{"title":"2\" × 2\" \/ White","offer_id":50964064534631,"sku":"27307329389365592478","price":4.99,"currency_code":"USD","in_stock":true},{"title":"3\" × 3\" \/ White","offer_id":50964064567399,"sku":"27459613636259166035","price":6.99,"currency_code":"USD","in_stock":true},{"title":"4\" × 4\" \/ White","offer_id":50964064600167,"sku":"26538671231183439278","price":8.99,"currency_code":"USD","in_stock":true},{"title":"6\" × 6\" \/ White","offer_id":50964064632935,"sku":"16561053651749768892","price":11.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0596\/8746\/9159\/files\/7571813505522410671_1200.jpg?v=1793659114","url":"https:\/\/pixelatedphysics.com\/ko\/products\/helicita-goldhaber-neutrino-helicity","provider":"Pixelated Physics","version":"1.0","type":"link"}