Flux modulations seen by the muon veto of the Gerda experiment

E Yanovich,C Cattadori,M Hult,M Shirchenko,G Zuzel,L Baudis,A Pullia,L Bezrukov,F Ritter,M Allardt,C Wiesinger,C Schmitt,A Klimenko,M Lindner,A Kirsch,S Hemmer,M Laubenstein,D Palioselitis,H Strecker,D Zinatulina,L Pandola,J Jochum,B Majorovits,L Vanhoefer,I Lippi,A Chernogorov,A.-K Schütz,V Egorov,M Knapp,A Caldwell,D Borowicz,R Falkenstein,I Nemchenok,T Bode,A Bettini,A Wegmann,A Smolnikov,N Barros,O Kochetov,T Wester,M Heisel,S Schönert,A Lubashevskiy,W Maneschg,H Wilsenach,S Riboldi,V D’Andrea,M Agostini,V Brudanin,J Schreiner,E Medinaceli,K Von Sturm,M Stepaniuk,K Freund,A Lazzaro,W Hofmann,L Ioannucci,G Benato,M Balata,A Hegai,E Bellotti,A Domula,A Di Vacri,B Schneider,N Frodyma,C Macolino,I Barabanov,S Belogurov,N Rumyantseva,O Schulz,M Misiaszek,I Zhitnikov,G Lutter,E Doroshkevich,B Schwingenheuer,K Pelczar,A Veresnikova,N Becerici-Schmidt,H Simgen,P Grabmayr,M Salathe,A Garfagnini,C Bauer,K Gusev,B Lehnert,O Selivanenko,V Gurentsov,M Junker,R Brugnera,P Moseev,K Panas,T Kihm,A M Bakalyarov ,О В Федорова ,Κ Zuber ,A M Gangapshev ,É V Demidova ,Cinzia Sada ,Michael Walter ,V I Lebedev ,S T Belyaev ,J Janicskó Csáthy ,Б Лубсандоржиев ,V V Kuzminov ,L Stančo ,С В Жуков ,Л В Инжечик ,V N Kornoukhov ,V V Kazalov ,Victoria Wagner ,A A Vasenko ,M Wójcik ,K T Knöpfle ,I V Kirpichnikov ,Ye Shevchik ,H Liao

doi:10.1016/j.astropartphys.2016.08.002

Abstract

The Gerda experiment at Lngs of INFN is equipped with an active muon veto. The main part of the system is a water Cherenkov veto with 66 PMTs in the water tank surrounding the Gerda cryostat. The muon flux recorded by this veto shows a seasonal modulation. Two causes have been identified: (i) secondary muons from the Cngs neutrino beam (2.2%) and (ii) a temperature modulation of the atmosphere (1.4%). A mean cosmic muon rate of Iμ0=(3.477±0.002stat±0.067sys)×10−4/(s · m2) was found in good agreement with other experiments at Lngs. Combining the present result with those from previous experiments at Lngs the effective temperature coefficient αT,Lngs is determined to 0.93 ± 0.03. A fit of the temperature coefficients measured at various underground sites yields a kaon to pion ratio rK/π of 0.10 ± 0.03.

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