Radioactive decay

**Radioactive decay** (jiske **nuclear decay**, **radioactivity**, **radioactive disintegration**, nai to **nuclear disintegration** ke naam se bhi jaana jaawe hae), uu process hae jisse ek unstable atomic nucleus,  radiation se shakti kamti kare hae. Ek chij jiske  unstable nucleus hae ke   *radioactive* maana jaawe hae. Sab se jaana maana rakam ke  decay hae alpha, beta, aur gamma decay. Weak force uu mechanism hae jisse beta decay hoe hae, jab baaki duuno  electromagnetic aur nuclear force se hoe hae.

Radioactive decay ek random process hae jon ek atom ke level pe kaam kare hae.  Quantum theory ke anusaar, ii nai bataawa jaawe sake hae ki kab ek atom decay hoi, aur ii decay atom ke umar ke uppar nai nirbhar hae. Lekin, dher atom jon ekke rakam ke hae ke decay rate ke ek decay constant me express karaa jaawe sake hae, nai to ek  half-life me. Radioactive atom ke half-life ke barraa range rahe hae range: jon lagbhag instantaneous se lae ke   universe ke umar talak rahe sake hae.

Jon nucleus decay hoe hae, ke  parent radionuclide (nai to parent radioisotope) bola jaawe hae, aur ii  process se kamti-se-kamti ek daughter nuclide bane hae.  Gamma decay nai to internal conversion ek nuclear excited state se, jiske decay ek  nuclear transmutation hae aur isse ek  daughter atom bane hae jisme  different number of proton nai to neutron (nai to duuno) rahe hae. Jab number of protons badle hae tab ek duusra chemical element ke atom bane hae.

Dunia ke 28 naturally occurring chemical elements  radioactive hae, jisme se  35 radionuclides (saat elements ke dui different radionuclides each rahe hae) jon Solar System ke bane se pahile ke hae. Ii 35 ke primordial radionuclides bola jaawe hae. Isme se kuchh jaana-maana hae, uranium aur thorium, lekin isme kuch naturally occurring long-lived radioisotopes bhi hae, jaise potassium-40.  primordial radionuclides me se har ek four decay chain reaction me se ek me bhagg le hae.

## Radioactivity ke paawa jaawe ke itihaas

Henri Poincaré, radioactivity ke paawa jaawe ke kaaran rahaa, kaaheki uu  X-ray ke adhyan karis rahaa, jiske khaas asar,  physicist Henri Becquerel pr rashaa. 1896 me radioactivity ke duuno  Becquerel aur Marie Curie paae rahin, jab uu logan aapan aapan kaam  phosphorescent materials me karat rahin. Ii chij andhera me  glow hoe hae jab ispe light chamkaawa jaawe hae,  aur Becquerel ke ii sandhay rahaa ki cathode-ray tube ke gloww  ke kaaran  X-rays hae. Uu ek kaiyaa paper me photographic plate ke lapetis aur iske dher phosphorescent salts ke uppar rakkhis. Sab natija negative rahaa, uranium salts ke chhorr ke.  Uranium salts ke kaaran  plate kariyaa hoe gais rahaa,  plate ke kariyaa paper me lapete ke baawajuut. Curie ii radiation ke naam *rayons de Becquerel*, "Becquerel Rays" diis rahaa aur ii dekhais ki ii  rays atoms ke property rahaa.

Jab X-rays ke electrical energy produce kare hae, radiation ke taagat ke nahi samjhaa jaawat rahaa. 1899 me, Julius Elster aur Hans Geitel  experiments karin ii jaane ke khaatir ki  radioactivity ke shakti kahaan se aawe hae. Ii experiment ke vacuum me karaa gais rahaa jisse shakti hawaa me se nai aawe aur ek 300m gahiraa mine me jisse shakti space se nai aawe. Agar atoms apne shaki dewat rahin, tab iske matlab hae ki atoms apne badalte hoi  jab uu ray ke emit kare hae. 1900 me Curie summarize karis, the puzzle of radioactivity as a choice between two equally unlikely possibilities: either energy was not conserved or chemical elements could be transmuted.

Rutherford pahila jan rahaa jon ii  realize karis rahaa ki sab ii rakam ke   elements decay hoe hae koi mathematical exponential formula ke anusaar. Rutherford aur uske  student, Frederick Soddy pahila jan rahin jon ii  realize kare rahin kidher decay processes ke natija rahaa ek element se duusra element ka bananaa.  Iske baad radioactive displacement law of Fajans and Soddy ke banaawa gais rahaa jon alpha aur beta decay ke product ke describe kare hae.

Pahila researchers ii bhi paain ki dher aur  chemical element,  uranium ke alaawa, ke radioactive isotopes hae. Ek systematic khoj, uranium me puura  radioactivity ke samay  Pierre aur Marie Curie dui nawaa  element ke isolate kare rahin: polonium aur radium. Radium ke  radioactivity ke chhorr ke, radium aur  barium ke chemical similarity ke kaaran ii duuno two elements ke biich ke antar nai paawa jaawe sakat rahaa.

Marie aur Pierre Curie ke  radioactivity ke adhyan, science and medicine aur medicine me  ek khaas factor hae. UUlog ke Becquerel's rays ke research se uulog duuno  radium aur polonium ke paain aur , "radioactivity" sabd ke banain emission of ionizing radiation by some heavy elements ke  define kare ke khaatir. (Baad me ii term ke generalize kar ke sab element ke apply karaa gais rahaa.) Uulog ke research  penetrating rays in uranium me aur   radium ke paawe ke kaaran  radium ke cancer ke treatment me kaam me laawe jaae lagaa. Uulog ke exploration of radium ke dekha jaawe hae  pahila dafe  nuclear energy ke modern nuclear medicine me kaam me laana.

## Pajila health pe khatraa

 Ionizing radiation  radioactivity aur X-rays ke kaaran je khatraa  ke pahile nai jaana jaawat rahaa. 

### X-rays

## References