The current study aimed to identify the role of school principals in building professional learning communities public schools Ajloun Governorate from point view teachers. used descriptive survey approach, and a questionnaire was prepared collect information applied sample (367) They were selected stratified cluster method, consisted three axes measure results concluded that there is (high) for...

Introduction: 238U decays with alpha particles emission into 234Th and the series ends with 206Pb. The unstable nucleus loses the energy with emitting ionizing alpha particles for reaching a stable state. It is undergoing alpha decay with decay energy (4.679 MeV). Alpha particles enter the human and animal bodies through inhalation of air or ingestion of contaminated food and water. This study ...