Measurement of the longitudinal diffusion of ionization electrons in the MicroBooNE detector

P Abratenko,Z Williams,T Bolton,R Fine,M Murphy,S Söldner-Rembold,A Bhat,O Benevides Rodrigues,C James,L Mora Lepin,M Del Tutto,I Caro Terrazas,K Terao,W Wu,A Blake,J Sinclair,W Van De Pontseele,K Miller,J Mills,C Mariani,J St John,S Gardiner,C Barnes,X Luo,Y Chen,S Prince,P Green,A Lister,T Strauss,D Caratelli,P Hamilton,D Cianci,M Mooney,T Usher,D Marsden,P Spentzouris,K Duffy,A Papadopoulou,E Hall,J Rodriguez Rondon,Y.-T Tsai,X Ji,K Li,R Guénette ,L C J Rice ,J Mousseau,A Rafique,V Papavassiliou,M Soares Nunes ,R K Neely ,M H Shaevitz ,V Radeka,S Balasubramanian,D Schmitz ,K Sutton,A Ashkenazi,B R Littlejohn ,J Anthony,T Kobilarcik,M Ross-Lonergan,J Moon,G B Cerati ,R Diurba,W Tang,O Hen,M Rosenberg,R Itay,J Spitz,D García-Gámez ,N Kaneshige,B Viren,A Schukraft,S A Dytman ,M Stancari,E Church,M Weber,H E Rogers ,C D Moore ,J I Crespo-Anadón ,L Bathe-Peters,M A Uchida ,J Zennamo,S F Pate ,A M Szelc ,M Soderberg,J Asaadi,A C Smith ,O Goodwin,R Lazur,N Mcconkey,Y Li,B T Fleming ,J L Raaf ,I Kreslo,R S Fitzpatrick ,Lu Ren ,N Wright,T Yang,X Qian,R Dorrill,W C Louis ,G A Horton-Smith ,V Paolone,L Jiang,V Meddage,E Piasetzky,C Zhang,S Berkman,Ž Pavlović ,A Hourlier,G P Zeller ,T Mohayai,G A Fiorentini Aguirre ,M Wospakrik,A Navrer-Agasson,C Thorpe,W Seligman,S Gollapinni,N Foppiani,T Mettler,Lynn Rochester ,E L Snider ,R An,D A Martínez Caicedo ,I Lepetic,L Hagaman,A Mastbaum,M Toups,I D Ponce-Pinto ,F Cavanna,J Nowak,A P Furmanski ,B Eberly,V Basque,S Wolbers,Y.-J Jwa,K Mason,N Kamp,R Sharankova,E Yandel,H Greenlee,G Yarbrough,K Mistry,J H Jo ,A F Moor ,A Bhanderi,Justin J Evans ,A Paudel,M Kirby,A Ereditato,L Cooper-Troendle,S Sword-Fehlberg,B Baller,T Wongjirad,K Manivannan,N Tagg,R Castillo Fernández ,L E Yates ,D Naples,A Mogan,R A Johnson ,H Wei,O Palamara,J M Conrad ,L Camilleri,M R Convery ,M Reggiani-Guzzo,E Gramellini,D Devitt,M Bishai,S R Dennis ,G Barr,D Totani,P Guzowski,J Marshall,W Ketchum,D Franco,G Ge,W Gu,G Karagiorgi,K Lin,G Scanavini

doi:10.1088/1748-0221/16/09/p09025

Abstract

Accurate knowledge of electron transport properties is vital to understanding the information provided by liquid argon time projection chambers (LArTPCs). Ionization electron drift-lifetime, local electric field distortions caused by positive ion accumulation, and electron diffusion can all significantly impact the measured signal waveforms. This paper presents a measurement of the effective longitudinal electron diffusion coefficient, DL, in MicroBooNE at the nominal electric field strength of 273.9 V/cm. Historically, this measurement has been made in LArTPC prototype detectors. This represents the first measurement in a large-scale (85 tonne active volume) LArTPC operating in a neutrino beam. This is the largest dataset ever used for this measurement. Using a sample of ∼70,000 through-going cosmic ray muon tracks tagged with MicroBooNE's cosmic ray tagger system, we measure DL = 3.74+0.28 -0.29 cm2/s.

Highlights

Accurate knowledge of electron transport properties in liquid argon is vital to understanding collected signals in liquid argon time projection chambers (LArTPCs)
Due to the abundant cosmic ray flux in MicroBooNE caused by its location near the surface, the electric field varies as a function of position in the detector due to Space Charge Effect (SCE)
We report a measurement of the effective longitudinal electron diffusion coefficient of = 3.74+−00..2289 cm2/s at an electric field (E-field) of 273.9 V/cm

Summary

Introduction

Accurate knowledge of electron transport properties in liquid argon is vital to understanding collected signals in liquid argon time projection chambers (LArTPCs). In LArTPCs, charged particles traversing the detector volume liberate a cloud of ionization electrons from the argon atoms that drift toward the anode readout plane under the influence of an applied electric field (figure 1). Ionization electrons may recombine with argon atoms (“recombination”), a process which depends on both the local density of ionization electrons and the local E-field strength and results in an attenuated signal. Ionization electrons can attach to electronegative contaminants such as O2 and H2O, attenuating the collected signal as a function of drift time. Electron diffusion acts to spread the ionization clouds as a function of drift time

Methods

Results

Discussion

Conclusion