This paper reports the observation of Bose-Einstein condensation (BEC) in a gas of sodium atoms. The experiment used a novel trap combining magnetic and optical forces, and evaporative cooling increased the phase-space density by six orders of magnitude within seven seconds. The condensates contained up to 5×10⁵ atoms at densities exceeding 10¹⁴ cm⁻³. The signature of BEC was the sudden appearance of a bimodal velocity distribution below the critical temperature of ~2 μK, consisting of an isotropic thermal distribution and an elliptical core attributed to the expansion of a dense condensate. The study of BEC in weakly interacting systems holds promise for revealing new macroscopic quantum phenomena and advancing understanding of superconductivity and superfluidity. The experiment used evaporative cooling combined with laser cooling to achieve BEC in alkali atoms. The authors observed BEC in sodium, with a production rate of Bose-condensed atoms 3 orders of magnitude larger than in previous experiments. They also developed a novel atom trap that offers tight confinement and a large capture volume, enabling unprecedented densities of cold atomic gases. The experiment involved evaporative cooling using radio frequency (rf) induced evaporation, which selectively removed higher-energy atoms from the trap, decreasing the temperature of the remaining atoms. The total potential was a combination of the magnetic quadrupole trapping potential, the repulsive potential of the plug, and the effective energy shifts due to the rf. The potential barrier varied linearly with the rf frequency. The temperature and number of atoms were determined using absorption imaging. The atom cloud was imaged either while trapped or after a sudden switch-off of the trap and a delay time of 6 ms. The time-of-flight images displayed the velocity distribution of the trapped cloud. The experiment showed a bimodal velocity distribution below the critical frequency, with an elliptical core attributed to the expansion of a dense condensate. The critical number of atoms to achieve BEC was determined by the condition that the number of atoms per cubic thermal de Broglie wavelength exceeds 2.612 at the bottom of the potential. The critical peak density at 2.0 μK was 1.5×10¹⁴ cm⁻³, demonstrating that evaporative cooling is a powerful technique to obtain ultralow temperatures and extremely high densities. The internal energy of the condensate was found to be much smaller than the thermal energy at the transition point, and the width of the time-of-flight image of the condensate was expected to be about 5 times smaller than at the transition point. The lifetime of the condensate was about 1 s, likely determined by three-body recombination or heating rate. The experiment observed up to 5×10⁵ condensed atoms, with a number density of 4×10¹⁴ cm⁻³. The condensate exhibited a nonisThis paper reports the observation of Bose-Einstein condensation (BEC) in a gas of sodium atoms. The experiment used a novel trap combining magnetic and optical forces, and evaporative cooling increased the phase-space density by six orders of magnitude within seven seconds. The condensates contained up to 5×10⁵ atoms at densities exceeding 10¹⁴ cm⁻³. The signature of BEC was the sudden appearance of a bimodal velocity distribution below the critical temperature of ~2 μK, consisting of an isotropic thermal distribution and an elliptical core attributed to the expansion of a dense condensate. The study of BEC in weakly interacting systems holds promise for revealing new macroscopic quantum phenomena and advancing understanding of superconductivity and superfluidity. The experiment used evaporative cooling combined with laser cooling to achieve BEC in alkali atoms. The authors observed BEC in sodium, with a production rate of Bose-condensed atoms 3 orders of magnitude larger than in previous experiments. They also developed a novel atom trap that offers tight confinement and a large capture volume, enabling unprecedented densities of cold atomic gases. The experiment involved evaporative cooling using radio frequency (rf) induced evaporation, which selectively removed higher-energy atoms from the trap, decreasing the temperature of the remaining atoms. The total potential was a combination of the magnetic quadrupole trapping potential, the repulsive potential of the plug, and the effective energy shifts due to the rf. The potential barrier varied linearly with the rf frequency. The temperature and number of atoms were determined using absorption imaging. The atom cloud was imaged either while trapped or after a sudden switch-off of the trap and a delay time of 6 ms. The time-of-flight images displayed the velocity distribution of the trapped cloud. The experiment showed a bimodal velocity distribution below the critical frequency, with an elliptical core attributed to the expansion of a dense condensate. The critical number of atoms to achieve BEC was determined by the condition that the number of atoms per cubic thermal de Broglie wavelength exceeds 2.612 at the bottom of the potential. The critical peak density at 2.0 μK was 1.5×10¹⁴ cm⁻³, demonstrating that evaporative cooling is a powerful technique to obtain ultralow temperatures and extremely high densities. The internal energy of the condensate was found to be much smaller than the thermal energy at the transition point, and the width of the time-of-flight image of the condensate was expected to be about 5 times smaller than at the transition point. The lifetime of the condensate was about 1 s, likely determined by three-body recombination or heating rate. The experiment observed up to 5×10⁵ condensed atoms, with a number density of 4×10¹⁴ cm⁻³. The condensate exhibited a nonis