SPEKTRA Volume 8 issue 1 contains six papers: 1) Combined Method of Bulk Material Shielding Evaluation For 200 MeV High Energy Neutron Source Using Phits Modelling and Partial Density, 2) Characterization of Energy Band Gap Thin Film BaTiO₃ – BaZr_0.5Ti_0.5O₃ Using Difusion Reflectance Spectroscopy (DRS) Method, 3) Exploring The Interconnectedness of Cosmological Parameters and Observations: Insights Into The Properties and Evolution of The Universe, 4) A Combined Method of 1D And 2D Resistivity for Groundwater Layer Estimation at A Farming Area in Rejomulyo Village, 5) High Strength Mango Leaf Waste/Polyurethane Composite Reinforcement Using Quartz Material, and 6) The Correlation Between Electric Current Produced and The Light Source Distance in Photoelectric Effect Experiments.

The articles in this issue from 2 countries: Indonesia and Malaysia. We are grateful for all the contributions of the authors. We also appreciate the professional reviewers who are an essential part of this issue.