We show that the energy gap for BCS equation is $ \Xi = \mu \left( 8 e^{-2} + o(1)\right) \exp\left( \frac{\pi}{2\sqrt{\mu} a}\right) in low density limit $\mu \to 0$. Together with similar result critical temperature [arXiv:0803.3324] this shows that, limit, ratio of and a universal constant independent interaction potential $V$. The results hold class potentials negative scattering length $a$...

Borosilicate BK7 glasses doped with different amounts of CeO2 (0.5,1,1.5%) were prepared by the convenient melting process in this work. DTA analysis proved that 0.5-1% CeO2 has a network modifier role and then up to 1.5% it shows network former role.For structural studies, FT-IR and Raman spectroscopy were carried out. Fermi energy level, direct/ indirect optical band gap and Urbach energy wer...