3.33 Sspd_chapter 1_part 13_ constituent particles of solid state  (Page 12/14)

In the time interval of 1second to 180 seconds after the Big Bang:

p : n = 7: 1 or p : n = 14: 2 combine to give deuterium and hydrogen nuclei. Deuterium( ² D ₁ = 1 p + 1 n) is an isotope of hydrogen ( ¹ H ₁ ).

p + n → 2 D 1

2 D 1 + 2 D 1 → 4 He 2 …………………………………………….. 1.133

At the Deuterium stage there are 12 ( ¹ H ₁ ) hydrogen nuclei and 1( ⁴ He ₂ ) helium nucleus.

(p : n = 14:2) → (12 × ¹ H ₁ ) + (1× ⁴ He ₂ )

Therefore weight ratio is :

H: He = 12 Atomic Weight : 4 Atomic Weight=75% : 25% ……………………………………………… 1.134

Therefore 3 minutes after the Big Bang, the primordial matter in Universe is in elemental form and most primitive form. The evolved form of matter come about by nucleosynthesis in the interior of stars up to Iron. Heavier elements are synthesized during Super nova explosion when a star beyond 1.44M 0 collapses into a neutron star or in a black hole.

(1/10,000) of the primordial matter is residual Deuterium. (1/100,000) of the primordial matter is He-3. A still smaller fraction (1/10×10 9 ) fused to Lithium.[Reference “The Evolution of the Universe” by Peebles, Schramn, Turner&Kron, Scientific American, October 1994].

η = baryonic number/photon number is the fraction which determines the percentage composition of primordial matter in terms of H, He, D&Li.

Presently there are 411 photons/cm ³ and 0.4 baryons/m ³ . This gives η= 1/10 ⁹ . [Reference “Primordial Deuterium and the Big Bang” by Craig J. Hogan, Scientific American , December 1996].

1.13.3. 300,000 YEARS AFTER THE BIG BANG

In band theory chapter we have seen that ionization energy of hydrogen atom is 13.6eV.

Therefore as Universe cools from 10 ¹³ K to 1.6×10 ⁵ K, matter remains in plasma state.

As temperature of the Universe falls below 10 ¹³ K, quarks undergo confinement. They either confine as Hadrons which are Fermions or as Gluons which are Bosons. Protons and Neutrons belong to hadrons group of nuclear particles and Mesons belong to gluon group of nuclear particles.

At 10 ^-4 second after the Big-Bang, temperature falls to 10 ¹² K and energy equivalent is 100MeV. At this time and temperature, atomic nuclii come into existence. The matter density of the Universe is 10 ¹⁴ gm/(cm) ³ which is the density of atomic nucleus also.

At the quark-nucleon phase transition ,10 ^-6 second after the Big Bang, the quarks which got decoupled should be there as relic or residual quarks and their mass abundance should be as high as gold. But till date no relic quark has been detected.

From 10 ^-6 second to 10 ¹³ second (300,000 yrs after the Big Bang), temperature fell from 10 ¹³ K to 4000K.

4000K per se corresponds to photon energy of 0.3eV. But there are sufficient high energy photons in the tail of Black Body Radiation at 4000K which keep the hydrogen atoms ionized. Hence above 4000K and upto 4000K all hydrogen atoms arte ionized plasma bathed in black body radiation flux.

Below 4000K, the energy is insufficient to cause the ionization of Hydrogen and Helium. Hence the hot plasma deionizes to form neutral H ₂ 77% by weight and neutral He 23% by weight.

At quark to nucleon phase transition, the nuclii of H ₂ and He namely proton and neutron had been formed in the ratio 75% and 25%. After deionization, neutral H ₂ and He form in the ratio 77% and 23%.