Shower reconstruction in the CLUE experiment

AbstractTheCLUEexperimentstudiesprimarycosmicraysðE 2TeVÞ bydetectingUV(190–230nm)Cherenkovlightproducedbyatmosphericshowers.SinceatmosphericabsorptionintheUVrangeishigherthaninthevisiblerange,CLUEcannotapplyalgorithmsnormallyusedinIACT 1 experimentstodetermineprimarycosmic-raydirection.Inthispaper,wepresentanewmethoddevelopedbyCLUE.Thealgorithmperformanceswereevaluatedusingsimulatedshowers.Preliminaryresultsofthesourceanalysisusingthisnewmethodareshown.# 2001ElsevierScienceB.V.Allrightsreserved. PACS:95.75.PqKeywords:Cosmicray;Reconstructionalgorithm 1. IntroductionIn the past, CLUE [1,2] used a maximumlikelihood method approach [3] to determineprimarycosmic-raydirectioncomparingobserveddistributions of Cherenkov photons in CLUEchamberswithsimulatedones.Thebestangularresolutiononshowerdirectionis0:88 forenergyE> 2TeVandthereconstructedangleisaffectedbyalargesystematicerrorforoff-axisshowers(18 systematicerrorforshowerswith28 off-axisangle).Recently,CLUEdevelopedanewrecon-struction algorithm, called Thrust, adapting a