Radioactive Ion Beam (RIB) Facility at VECC : - Saha Institute of ...
Radioactive Ion Beam (RIB) Facility at VECC : - Saha Institute of ...
Radioactive Ion Beam (RIB) Facility at VECC : - Saha Institute of ...
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Primordial NucleosynthesisThe Universe was cre<strong>at</strong>ed about 15 billion years back by gradual expansionfrom a st<strong>at</strong>e <strong>of</strong> extremely high density (ρ~10 95 g/cc) & temper<strong>at</strong>ure (T~ 10 32 K) Big Bang Theory.Nucleosynthesis could start ~ 3 minutes after the Big Bang when Deutorium(B.E. 2.23 MeV) stable against photo-dissoci<strong>at</strong>ion <strong>at</strong> T ~ 10 9 K.Nucleosynthesis could continue for a very shorttime after the big-bang because :• All neutrons were used up for production <strong>of</strong> 4 He• No stable nuclei for A=5 and A=8• Baryon density too low for 3 body reactions• Temp. reduced due to expansion to sustainfurther nuclear reaction1H2H3He4He6Li7LiMass Fraction0.75(2.5±1.5)x10-5(4.2±2.8)x10-50.23±0.023004600+ 300 −12× 10− 150+ 4600 −12× 10− 2300
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