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##### How are cone jets reconstructed ?

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**Modification in cone jets reconstruction**Preclustering with Simple Cone algo Clustering with cone algorithm Emmanuel Busato How are cone jets reconstructed ? Vishnu's proposal to improve reconstruction : At preclustering level : not let a CH cell become a seed if it's energy is less than some sigma**List of towers (pT ordered)**Take the highest pT tower in the list « T » ? pT > seedET =500MeV yes no Go to clustering around T (with R=coneSize=0.3). Remove progressively towers from the list. Stop preclustering Current preclustering (Simple Cone)**List of towers (pT ordered)**Take the highest pT tower in the list « T » ? pT > seedET =500MeV yes Take highest ET cell in T : « C » if C is CH or ECMG and if C has E < n * sigma pT = pT ETC no pT > seedET =500MeV ? yes Stop preclustering no Go to clustering around T (with R=coneSize=0.3). Remove progressively towers from the list. Modified preclustering**Implementation**Everything is on coco-clued0 : /work/coco-clued0/busato/jetanalyze_p13.06.01 - Major modifications are in SconeClusterAlgo.hpp - Needed to create a class (ReadNoiseFile) to read in the noise file (energycluster/energycluster/ReadNoiseFile.hpp) ReadNoiseFile uses official cal_nlc and em_util packages methods to . convert channel (0 55295) (ieta, iphi, layer) . convert ADC GeV (problem with GeV rawADC) Current algo works with linearized ADCs gain 8, should we work with raw ADCs and/or gain 1 ? - 3 new parameters in the rcps.**CalPreSCILCone05(07,03).rcp**string PackageName = "CalClusterReco" string data_type = "MC" string algo_type = "PreSCilcone" bool drop_negative_mass2 = true // preclustering parameters float coneSize = 0.3 float seedET = 0.5 float pTmin = 1.0 int minItems = 2 bool dropCHseed = false float dropCHseedsigma = 3.5 string offline_zero_supp_file = "/work/coco- clued0/busato/jetanalyze_p13.06.01/cal_zsup_noise.dat" // cone clustering parameters float Item_ET_threshold = 0. float Radius_of_Cone= 0.5 float Min_Jet_ET= 8.0 float ET_Split_Frac= 0.5 float Far_ratio = 0.5 float ET_min_ratio = 0.5 bool Kill_duplicate = true float Duplicate_dR = 0.005 float Duplicate_dPT = 0.01 // if useMCvertex is true: use Monte Carlo vertex // if useD0vertex is true: use reconstructed vertex // if both true use Monte Carlo vertex if there is no reconstructed vertex bool useMCvertex = false bool useD0vertex = true To run the algo with modified preclustering, set dropCHseed to true**Status**- This modification was first made to reduce the number of fake jets, but - good jets can have high f90 - Apparently number of fake jets with 2.5 sigma ZS small More to come to confirm this (jets in dijet events study). - Could be used instead to reduce the effect of noise on good jets MC study done by Vishnu