Determination of the muon charge sign with the dipolar spectrometers of the OPERA experiment

N Agafonova,J Ebert,K Ozaki,T Nakano,A Zghiche,K Niwa,G Mandrioli,A Paoloni,G Giacomelli,T Ariga,P Loverre,A Hollnagel,G Shoziyoev,P Monacelli,M Roda,L Patrizii,L Votano,A Sheshukov,B Hosseini,A Bertolin,G Galati,J.H Kim,N Okateva,P Strolin,M Pozzato,C Kamiscioglu,M Chernyavsky,N Naganawa,S Zemskova,N Mauri,C Sirignano,A Lauria,N Kitagawa,A Buonaura,G Wilquet,M Dracos,T Matsuo,B Büttner,M Kamiscioglu,T Hara,M Sioli,D Goloubkov,R Brugnera,M De Serio,E Medinaceli,A Ariga,A Garfagnini,I Rostovtseva,T Dzhatdoev,S Ogawa,B.D Park,P Vilain,L Pasqualini,J Kawada,H Pessard,T Omura,A Anokhina,A Aleksandrov,S Dmitrievski,S Simone,A Chukanov,T Shchedrina,D Di Ferdinando,G De Lellis,M Spinetti,N Di Marco,D Bender,K Kodama,M.C Montesi,F Pupilli,M Stipčević ,G De Rosa ,M T Muciaccia ,Т М Роганова ,I R Shakiryanova ,N D’ambrosio ,Takashi Naka ,Simona Maria Stellacci ,Mitsuhiro Nakamura ,Hiroki Rokujo ,Shigeki Aoki ,Adam Schembri ,Yoshihiro Sato ,R A Fini ,Satoru Takahashi ,Maša Malenica ,B Kliček ,Takeshi Shiraishi ,Н И Старков ,J L Vuilleumier ,Osamu Sato ,Yu Zaitsev ,C Göllnitz ,M S Vladimirov ,Alessandro Pastore ,L Stančo ,K Jakovc̆ić ,U Köse ,A Ljubičić ,Tsutomu Fukuda ,A S Malgin ,Keisuke Morishima ,O G Ryazhskaya ,C S Yoon ,Д Подгрудков ,Hirokazu Ishida ,M Güler ,А.g Оlshevsky ,D Duchesneau,G Grella,I.G Park,H Shibuya,S Tufanli,M Komatsu,S Dusini,L Consiglio,S Buontempo,S.H Kim,J Lenkeit,B Wonsak,J Goldberg,M Meyer,V Matveev,N Polukhina,G Sirri,A Ereditato,Y Nakatsuka,S Mikado,F Terranova,I Kreslo,A Di Crescenzo,P Del Amo Sanchez,M Tenti,C Gustavino,C Jollet,V Tioukov,C Bozza,Y Gornushkin,C Pistillo,K Ishiguro,C Hagner,A Longhin,A Meregaglia

doi:10.1088/1748-0221/11/07/p07022

Abstract

The OPERA long-baseline neutrino-oscillation experiment has observed the direct appearance of ντ in the CNGS νμ beam. Two large muon magnetic spectrometers are used to identify muons produced in the τ leptonic decay and in νμ CC interactions by measuring their charge and momentum. Besides the kinematic analysis of the τ decays, background resulting from the decay of charmed particles produced in νμ CC interactions is reduced by efficiently identifying the muon track. A new method for the charge sign determination has been applied, via a weighted angular matching of the straight track-segments reconstructed in the different parts of the dipole magnets. Results obtained for Monte Carlo and real data are presented. Comparison with a method where no matching is used shows a significant reduction of up to 40% of the fraction of wrongly determined charges.

Full Text