Detecting filaments in the ultra-high energy cosmic ray distribution
  We propose and test new statistical tools to study the distribution of cosmic rays based on the use of the Minimal Spanning Tree. The method described is particularly sensitive to filamentary structures, as those expected to arise from strong sources of charged cosmic rays which get deflected by intervening magnetic fields. We also test the method with data available from the AGASA and SUGAR surface detector arrays. 
Diego Harari, Silvia Mollerach and Esteban Roulet