Ngaphambi kobuciko obuthathu, okungukuthi, mayelana nokutholakala kwe-radioactivity yokufakelwa
Okuqukethwe
Ngokuhamba kwesikhathi emlandweni we-physics kuba neminyaka “emangalisayo” lapho imizamo ehlanganyelwe yabacwaningi abaningi iholela ochungechungeni lokutholwa kwempumelelo. Kwaba njalo ngo-1820, unyaka kagesi, ngo-1905, unyaka oyisimangaliso wamaphepha amane ka-Einstein, u-1913, unyaka ohlotshaniswa nokuhlolwa kwesakhiwo se-athomu, futhi ekugcineni, ngo-1932, lapho uchungechunge lokutholwa kwezobuchwepheshe kanye nentuthuko ku-athomu. amandla enuzi adaliwe. physics.
abasanda kushada
Irina, indodakazi endala kaMarie Skłodowska-Curie noPierre Curie, wazalelwa eParis ngo-1897 (1). Kuze kube yilapho eneminyaka eyishumi nambili, wakhuliswa ekhaya, "esikoleni" esincane esakhiwe ososayensi abavelele bezingane zakhe, lapho kwakukhona abafundi abangaba yishumi. Othisha kwakungalaba: UMarie Sklodowska-Curie (physics), uPaul Langevin (izibalo), uJean Perrin (wamakhemikhali), kanye nezifundo zobuntu zazifundiswa omama babafundi. Izifundo zazivame ukwenzeka emakhaya othisha, kuyilapho izingane zifunda i-physics ne-chemistry ezindaweni zokucwaninga zangempela.
Ngakho-ke, ukufundisa kwe-physics kanye ne-chemistry kwakuwukuthola ulwazi ngezenzo ezingokoqobo. Ukuhlola ngakunye okuyimpumelelo kwajabulisa abacwaningi abasebasha. Lokhu kwakuwukuhlola kwangempela okwakumelwe kuqondwe futhi kwenziwe ngokucophelela, futhi izingane zaselabhorethri kaMarie Curie kwadingeka zibe ngokulandelana okuyisibonelo. Kwadingeka ukuba kutholwe ulwazi lwethiyori. Indlela, njengesiphetho sabafundi balesi sikole, ososayensi abahle nabavelele kamuva, yabonakala iphumelela.
2. Frederic Joliot (isithombe Harcourt)
Ngaphezu kwalokho, umkhulu kayise ka-Irena, ongudokotela, wachitha isikhathi esiningi kumzukulu kayise oyintandane, ezijabulisa futhi enezela imfundo yakhe yesayensi yemvelo. Ngo-1914, u-Irene waphothula e-Collège Sévigé yokuphayona futhi wangena emkhakheni wezibalo nesayensi eSorbonne. Lokhu kwaqondana nokuqala kweMpi Yezwe Yokuqala. Ngo-1916 wajoyina unina futhi ndawonye bahlela inkonzo ye-radiological e-French Red Cross. Ngemva kwempi, wathola iziqu ze-bachelor. Ngo-1921, incwadi yakhe yokuqala yesayensi yanyatheliswa. Wayezinikele ekunqumeni kwe-athomu ye-chlorine evela kumaminerali ahlukahlukene. Emisebenzini yakhe eyengeziwe, wasebenza eduze nomama wakhe, ebhekana ne-radioactivity. Encwadini yakhe yobudokotela, eyavikelwa ngo-1925, wafunda izinhlayiya ze-alpha ezikhishwa i-polonium.
UFrederic Joliot owazalwa ngo-1900 eParis (2). Kusukela eneminyaka eyisishiyagalombili waya esikoleni e-So, ehlala esikoleni okuhlalwa kuso. Ngaleso sikhathi, wayekhetha ezemidlalo kunezifundo, ikakhulukazi ibhola. Ube eseshintshana ngokufunda ezikoleni ezimbili zamabanga aphezulu. Njengo-Irene Curie, washonelwa uyise kusenesikhathi. Ngo-1919 waphumelela ukuhlolwa e-École de Physique et de Chemie Industrielle de la Ville de Paris (Isikole Se-Industrial Physics and Industrial Chemistry yedolobha laseParis). Wathweswa iziqu ngo-1923. Uprofesa wakhe, uPaul Langevin, wafunda ngamakhono nezici ezinhle zikaFrederick. Ngemva kwezinyanga ezingu-15 enkonzweni yezempi, ngomyalo kaLangevin, waqokwa njengomsizi welabhorethri kaMarie Skłodowska-Curie eRadium Institute ngoxhaso lwe-Rockefeller Foundation. Lapho, wahlangana no-Irene Curie, futhi ngo-1926 le ntsha yashada.
UFrederick waqeda incwadi yakhe yobudokotela nge-electrochemistry of radioactive elements ngo-1930. Ngaphambidlana, wayesegxile ezithakazelweni zakhe ocwaningweni lomkakhe, futhi ngemva kokuvikela incwadi kaFrederick yobudokotela, base besebenza ndawonye. Enye yempumelelo yabo yokuqala ebalulekile kwakuwukulungiswa kwe-polonium, okuwumthombo oqinile wezinhlayiya ze-alpha, i.e. i-helium nuclei.(24Yena). Baqala besuka esikhundleni esinelungelo elingenakuphikwa, ngoba kwakungu-Marie Curie owapha indodakazi yakhe ingxenye enkulu ye-polonium. U-Lew Kowarsky, umhlanganyeli wabo wakamuva, wabachaza kanje: U-Irena "wayenguchwepheshe osezingeni eliphezulu", "wasebenza kahle kakhulu nangokucophelela", "wayekuqonda ngokujulile ayekwenza." Umyeni wakhe "wayenombono omangalisa ngokwengeziwe, okhuphuka kakhulu." "Babehambisana kahle futhi bekwazi." Ngokombono womlando wesayensi, okuthakazelisa kakhulu kubo kwakuyiminyaka emibili: 1932-34.
Bacishe bathola i-neutron
"Cishe" kubaluleke kakhulu. Basheshe bafunda ngaleli qiniso elibuhlungu. Ngo-1930 eBerlin, amaJalimane amabili - Walter Bothe i Hubert Becker - Kuphenywe ukuthi ama-athomu alula asebenza kanjani lapho ehlaselwa izinhlayiya ze-alpha. I-Beryllium Shield (49Be) lapho ishaywa ngezinhlayiya ze-alpha ezikhipha imisebe ehlabayo enamandla kakhulu futhi enamandla amakhulu. Ngokwabahlolayo, le misebe kumelwe ukuba kwakuyimisebe enamandla kagesi.
Kuleli zinga, u-Irena noFrederick babhekana nale nkinga. Umthombo wabo wezinhlayiya ze-alpha wawunamandla kunawo wonke. Basebenzise i-cloud chamber ukuze babheke imikhiqizo yokusabela. Ekupheleni kuka-January 1932, bamemezela obala ukuthi kwakuyimisebe ye-gamma eyakhipha ama-proton anamandla entweni ene-hydrogen. Babengakaqondi ukuthi yini esezandleni zabo nokuthi kwenzekani.. Ngemva kokufunda James Chadwick (3) eCambridge ngokushesha waqala ukusebenza, ecabanga ukuthi kwakungeyona nhlobo imisebe ye-gamma, kodwa ama-neutron abikezelwa uRutherford eminyakeni embalwa ngaphambili. Ngemva kochungechunge lokuhlola, waqiniseka ngokubonwa kwe-neutron futhi wathola ukuthi ubukhulu bayo bufana nobeproton. Ngo-February 17, 1932, wathumela inothi ephephabhukwini leMvelo elinesihloko esithi "Ukuba Khona Okungenzeka Kwe-Neutron."
Empeleni kwakuyineutron, nakuba uChadwick ayekholelwa ukuthi i-neutron yakhiwa iproton ne-electron. Kuphela ngo-1934 waqonda futhi wafakazela ukuthi i-neutron iyizinhlayiya eziyisisekelo. UChadwick waklonyeliswa ngeNobel Prize in Physics ngo-1935. Naphezu kokuqaphela ukuthi babephuthelwe ukutholakala okubalulekile, abakwaJoliot-Curies baqhubeka nocwaningo lwabo kule ndawo. Baqaphela ukuthi lokhu kusabela kwakhiqiza imisebe ye-gamma ngaphezu kwama-neutron, ngakho babhala ukusabela kwenuzi:
, lapho i-Ef ingamandla e-gamma-quantum. Ukuhlolwa okufanayo kwenziwa nge 919F.
Uphuthelwe ukuvula futhi
Ezinyangeni ezimbalwa ngaphambi kokutholakala kwe-positron, u-Joliot-Curie wayenezithombe, phakathi kwezinye izinto, zendlela egobile, njengokungathi i-electron, kodwa iphendukela kolunye uhlangothi lwe-electron. Izithombe zithathwe egumbini elinenkungu elisendaweni kazibuthe. Ngokusekelwe kulokhu, lo mbhangqwana ukhulume ngama-electron ahamba ngezindlela ezimbili, kusukela emthonjeni nasemthonjeni. Eqinisweni, lawo ahlotshaniswa nesiqondiso "esibheke emthonjeni" kwakungama-positron, noma ama-electron aqondile asuka kude nomthombo.
Phakathi naleso sikhathi, e-United States ngasekupheleni kwehlobo lika-1932. UCarl David Anderson (4), indodana yezifiki zaseSweden, yafunda imisebe ye-cosmic ekamelweni lamafu ngaphansi kwethonya lensimu kazibuthe. Imisebe ye-cosmic iza eMhlabeni ivela ngaphandle. U-Anderson, ukuze aqiniseke ngokuqondisa nokunyakaza kwezinhlayiya, ngaphakathi kwegumbi ladlula izinhlayiya ngepuleti lensimbi, lapho zalahlekelwa khona amandla athile. Ngo-Agasti 2, wabona umzila, ngokungangabazeki awuhumusha njenge-electron enhle.
Kuyaphawuleka ukuthi u-Dirac wayebikezele ngaphambili ubukhona bethiyori bezinhlayiyana ezinjalo. Nokho, u-Anderson akazange alandele noma yiziphi izimiso zethiyori ezifundweni zakhe zemisebe ye-cosmic. Kulo mongo, wabiza ukutholakala kwakhe ngengozi.
Nakulokhu, uJoliot-Curie kwadingeka abekezelele umsebenzi ongenakuphikwa, kodwa wenza ucwaningo olwengeziwe kule ndawo. Bathola ukuthi ama-photon e-gamma-ray anganyamalala eduze kwe-nucleus esindayo, akhe i-electron-positron pair, ngokusobala ngokuvumelana nefomula edumile ka-Einstein ethi E = mc2 kanye nomthetho wokongiwa kwamandla nomfutho. Kamuva, uFrederick ngokwakhe wafakazela ukuthi kunenqubo yokunyamalala kwepheya ye-electron-positron, okubangela ama-gamma quanta amabili. Ngokungeziwe kuma-positron asuka kumapheya e-electron-positron, ayenama-positron asuka ku-nuclear reactions.
5. Ingqungquthela yeSeventh Solvay, ngo-1933
Abahlezi phambili: u-Irene Joliot-Curie (owesibili ukusuka kwesobunxele),
U-Maria Skłodowska-Curie (wesihlanu ukusuka kwesokunxele), uLise Meitner (wesibili ukusuka kwesokudla).
i-radioactivity yokufakelwa
Ukutholakala kwe-radioactivity yokwenziwa kwakungesona isenzo esisheshayo. Ngo-February 1933, ngokuqhumisa i-aluminium, i-fluorine, kanye ne-sodium enezinhlayiya ze-alpha, uJoliot wathola ama-neutron nama-isotopes angaziwa. NgoJulayi 1933, bamemezela ukuthi, ngokukhanyisa i-aluminium ngezinhlayiya ze-alpha, ababonanga ama-neutron kuphela, kodwa nama-positron. Ngokusho kuka-Irene noFrederick, ama-positron kulokhu kusabela kwe-nuclear ayengeke akheke ngenxa yokwakhiwa kwamapheya e-electron-positron, kodwa kwakudingeka avele ku-nucleus ye-athomu.
I-Seventh Solvay Conference (5) yenzeka eBrussels ngo-Okthoba 22-29, 1933. Yayibizwa ngokuthi "Isakhiwo Nezakhiwo Ze-Atomic Nuclei". Yayihanjelwe ongoti be-physics abangu-41, kuhlanganise nochwepheshe abavelele kulo mkhakha emhlabeni. UJoliot ubike imiphumela yocwaningo lwabo, ethi i-boron ne-aluminium e-irradiating enemisebe ye-alpha ikhiqiza i-neutron ene-positron noma i-proton.. Kule ngqungquthela Lisa Meitner Uthe ekuhlolweni okufanayo nge-aluminium ne-fluorine, akazange athole umphumela ofanayo. Ekuhumusheni, akazange abe nombono wombhangqwana waseParis mayelana nemvelo yenuzi yemvelaphi ye-positrons. Kodwa-ke, lapho ebuyela emsebenzini eBerlin, waphinde wenza lezi zivivinyo, futhi ngoNovemba 18, encwadini eya kuJoliot-Curie, wavuma ukuthi manje, ngokombono wakhe, ama-positron avela ngempela ku-nucleus.
Ngaphezu kwalokho, le ngqungquthela Francis Perrin, untanga nomngane wabo omkhulu waseParis, bakhuluma ngendaba yama-positron. Kusukela ekuhloleni kwaziwa ukuthi bathola i-spectrum eqhubekayo yama-positron, afana ne-spectrum yezinhlayiya ze-beta ekuboleni kwemvelo kwe-radioactive. Ukuhlaziywa okwengeziwe kwamandla e-positrons nama-neutron u-Perrin wafinyelela esiphethweni sokuthi ukukhishwa okubili kufanele kuhlukaniswe lapha: okokuqala, ukukhishwa kwama-neutron, okuhambisana nokwakheka kwe-nucleus engazinzile, bese kuba ukukhishwa kwama-positron kule nucleus.
Ngemva kwengqungquthela u-Joliot wayeka lezi zivivinyo cishe izinyanga ezimbili. Kwathi ngo-December 1933, uPerrin washicilela umbono wakhe ngale ndaba. Ngesikhathi esifanayo, futhi ngoDisemba U-Enrico Fermi ihlongoze ithiyori yokubola kwe-beta. Lokhu kusebenze njengesisekelo sethiyori sokuchazwa kokuhlangenwe nakho. Ekuqaleni kuka-1934, umbhangqwana ovela enhloko-dolobha yaseFrance waphinde waqala ukuhlola.
Khona kanye ngoJanuwari 11, ngoLwesine ntambama, uFrédéric Joliot wathatha ucwecwe lwe-aluminium waluqhumisa ngezinhlayiya ze-alpha imizuzu engu-10. Ngokokuqala ngqa, wasebenzisa ikhawunta ye-Geiger-Muller ukuze abonwe, hhayi igumbi lenkungu, njengangaphambili. Wamangala lapho ebona ukuthi njengoba esusa umthombo wezinhlayiya ze-alpha ku-foil, ukubala kwama-positron akuzange kume, izibalo zaqhubeka ziwabonisa, kuphela inani lawo lehla ngokuphawulekayo. Unqume ukuthi uhhafu wempilo ube yimizuzu emi-3 nemizuzwana eyi-15. Wabe esenciphisa amandla ezinhlayiya ze-alpha eziwela kucwecwe ngokubeka ibhuleki lomthofu endleleni yazo. Futhi yaba nama-positron ambalwa, kodwa isigamu sempilo ayizange ishintshe.
Wabe esefaka i-boron ne-magnesium ekuhlolweni okufanayo, futhi wathola ukuphila okuyingxenye kulokhu kuhlolwa kwemizuzu engu-14 nemizuzu engu-2,5, ngokulandelana. Kamuva, ucwaningo olunjalo lwenziwa nge-hydrogen, i-lithium, i-carbon, i-beryllium, i-nitrogen, i-oxygen, i-fluorine, i-sodium, i-calcium, i-nickel nesiliva - kodwa akazange abone into efana ne-aluminium, i-boron ne-magnesium. Ikhawunta ye-Geiger-Muller ayihlukanisi phakathi kwezinhlayiya ezishajwayo ezinhle nezingezinhle, ngakho uFrédéric Joliot uphinde waqinisekisa ukuthi empeleni isebenzisana nama-electron aqondile. Isici sobuchwepheshe besibalulekile nalokhu kuhlolwa, okungukuthi, ukuba khona komthombo oqinile wezinhlayiya ze-alpha kanye nokusetshenziswa kwekhawunta yezinhlayiyana ezishajwayo ebucayi, njengekhawunta ye-Geiger-Muller.
Njengoba kuchazwe ngaphambilini ngababili be-Joliot-Curie, ama-positron nama-neutron akhululwa kanyekanye ekuguquguqukeni kwenuzi. Manje, ngemva kokusikisela kukaFrancis Perrin nokufunda nokucatshangelwa kukaFermi, lo mbhangqwana waphetha ngokuthi ukusabela kokuqala kwenuzi kwakhiqiza i-nucleus engazinzile ne-neutron, elandelwa ukubola kwe-beta plus yaleyo nucleus engazinzile. Ngakho-ke bangabhala ukusabela okulandelayo:
I-Joliots yaqaphela ukuthi ama-isotopes akhipha imisebe ane-half-life emfushane kakhulu ukuba abe khona emvelweni. Bamemezela imiphumela yabo ngoJanuwari 15, 1934, esihlokweni esithi “A New Type of Radioactivity”. Ekuqaleni kukaFebruwari, baphumelele ukuhlonza i-phosphorus ne-nitrogen ekuphenduleni kokuqala okubili okuvela ematheni amancane aqoqwe. Ngokushesha kwaba nesiprofetho sokuthi ama-isotopes amaningi anemisebe angakhiqizwa ekuphenduleni kwebhomu lenuzi, futhi ngosizo lwama-proton, ama-deuteron nama-neutron. NgoMashi, u-Enrico Fermi wenza ukubheja ukuthi ukusabela okunjalo kuzokwenziwa maduze kusetshenziswa ama-neutron. Ngokushesha wawina ukubheja ngokwakhe.
U-Irena noFrederick baklonyeliswa ngeNobel Prize in Chemistry ngo-1935 "ngokuhlanganiswa kwezinto ezintsha zomsakazo". Lokhu kutholwa kwavula indlela yokukhiqizwa kwama-isotopi akhipha imisebe yokwenziwa, athole izicelo eziningi ezibalulekile nezibalulekile ocwaningweni oluyisisekelo, ezokwelapha, nasezimbonini.
Okokugcina, kufanelekile ukusho izazi zefiziksi ezivela e-USA, U-Ernest Lawrence nozakwabo baseBerkeley kanye nabacwaningi basePasadena, phakathi kwabo kwakukhona noPole owayeqeqeshelwa umsebenzi. U-Andrzej Soltan. Ukubalwa kwama-pulses ngamakhawunta kwaqashelwa, nakuba i-accelerator yayisivele iyekile ukusebenza. Abakuthandanga lokhu kubalwa. Kodwa-ke, abazange baqaphele ukuthi babebhekene nesenzakalo esisha esibalulekile nokuthi bamane bengenakho ukutholakala kwe-radioactivity yokwenziwa ...
