pojeetraun

paajeetron (e+) ya pojeetiv ilektron (dhan aavesh yukt ilektron) parmaanu mein paaya jaane wala ek maulik kan hai. yeh dhan aavesh yukt ilektron hai. iske gun ilektron ke samaan hote kintu dono mein antar yeh hai ki ilektron rin aavesh yukt kan hai tatha pojeetron dhan aavesh yukt kan hai. iska dravyamaan ilektron ke dravyamaan ke samaan hota hai. iski khoj san 1932 mein kaarl di Anderson ne ki thi. iska vidyut aavesh +1.602176487(40)×a10−19 koolaamb hota hai. iski ghoornan gati aadhi hoti hai. pojitron ko β+ chinh se bhi darshaate hai. jab pojitron tatha ilektron ki takkar hoti hai to dono nasht ho jaate hain aur do gaama kiran fotaan utpann hoti hai.

chikitsaalaya mein upayog hone vaale ex kiran mein nyootron, gaama kiran, proton, nyootrino, ke saath pojitron bhi shaamil rahata hai.

itihaas

paujitraun ka prayogaatmak aavishkaar 1932 E. mein hua. aindarsan ne dekha ki Wilson abhrakoshth (Wilson's cloud chamber) mein chunbakeeya kshetr lagaakar yadi antariksh kirnon ke photo lein, to praaya: ilektraun jaise do path (tracks) drushti mein aate hain, jinki vakrata ulti dishaaon mein hoti hai. vakrata kan ke aavesh par nirbhar karti hai. isaliye in prayogon se spasht hai ki in kanon ka aavesh ulta hoga. ab paujitraun ka astitv anya pareekshanon se bhi sthaapit ho chuka hai.

paujitraun ke prayogaatmak aavishkaar se chaar varsh pehle diraik ne ek sameekaran diya tha, jisse ilektraun ke sab gyaat gunadharmon ka varnan ho jaata tha, kintu saath hi iske anusaar ek aise kan ka maanana bhi anivaarya tha jiski sanhati aur oorja rinaatmak hon. yeh baat ajeeb thi. is avaanchhaneeya sthiti se bachane ke liye diraik ne prastaav rakha ki saadhaaranataya rinaatmak oorja ki sab avasthaaeain ilektraunon se bhari rahati hain. at: ham dhanaatmak oorja ki avasthaaon (arthaat saadhaaran ilektraunon) ko hi dekh paate hain. par kabhi kabhi jab vidyutachchunbakeeya kshetr dvaara prabal, paraspar kriyaaeain (interactions) hoti hain tab rinaatmak oorja ki avasthaaon mein se ek ilektraun baahar nikal aata hai tatha baahar aakar aise vyavahaar karta hai jaise dhan oorja ilektraun karte hain. par saath hi rin oorjaavaali ek avastha khaali ho jaati hai. ise ham rin oorja ke samudra mein ek chhidr (hole) se chitrit kar sakte hain. yeh chhidr aise hi aacharan karta hai jaise dhan aaveshavaala kan, jiski sanhati ilektraun ke baraabar ho. pahile diraik ne is kan ko protaun maanane ka prayatn kiya, par aindarsan ke parinaam ka pata chalne par unhonne is kan ko protaun naheen, parantu paujitraun maana.

diraik ka chhidr siddhaant (hole theory) bahut santoshajanak naheen hai. ilektraun aur paujitraun ka aadhunik siddhaant diraik sameekaran ke dviteeya kvaanteekaran (Second quantisation) par nirbhar hai. ismein paujitraun ke gunadharm praakrutik vidhi se nikal aate hain. ilektraun aur paujitraun ko 'kan' aur 'pratikn' (antiparticle) kah sakte hain. yeh vichaaradhaara bhautiki mein atyant upayogi siddh hui hai.