Radiation Damage Effects and Operation of the LHCb Vertex Locator

K Carvalho Akiba ,J Harrison,A Pritchard,W Qian,F Marinho,A Pearce,P Collins,S Redford,A Leflat,C Parkes,E Jans,J Mylroie-Smith,S De Capua,E Rodrigues,V Volkov,M Van Beuzekom,E Dall’occo ,J J Velthuis ,M W Majewski ,G Lafferty,A D Webber ,T Latham,M Gersabeck,T Gershon,P Baladrón Rodríguez ,Shanzhen Chen ,M Smith,H M Wark ,T Hadavizadeh,Lon E Bell ,P Kopciewicz,K Dreimanis,W Hulsbergen,M Alexander,K Rinnert,C T Dean ,G A Bogdanova ,A Crocombe,T J V Bowcock ,M Schiller,M John,J Buytaert,E Buchanan,S Richards,A Poluektov,L Eklund,T Szumlak,S Borghi,D Hutchcroft,K Hennessy,G Dujany,F Dettori,P Koppenburg,A Obłąkowska-Mucha ,W Barter,T Evans,Mark Richard James Williams

doi:10.1109/tns.2018.2824618

Abstract

Vertex locator (VELO) is a silicon microstrip detector situated around the interaction point in the large Hadron Collider beauty (LHCb) spectrometer at the Large Hadron Collider. The LHCb experiment is dedicated to studying charge conjugation and parity symmetry violation in the heavy flavor sector and rare decays of B mesons. The precise reconstruction of both the primary and secondary vertices, obtained by the VELO, is crucial in the selection of signal events containing b and c quarks and lifetime measurements. VELO consists of two retractable parts that operate at 8 mm from the interaction region. Its proximity to proton beams makes the LHCb VELO a place for studying radiation damage effects in silicon detectors in proton–proton and heavy-ion collisions. The latest results from radiation damage studies and their impact on the operation of the LHCb VELO after the first data-taking period (Run I) and the ongoing Run II are presented in this paper. The main macroscopic parameters, influenced by particle fluence, are described along with selected methods of their monitoring. All the results show that VELO sustains the impact of high fluence of radiation, and its performance will not change significantly until the end of Run II.

Highlights

INTRODUCTIONT HE large Hadron Collider beauty (LHCb) detector is a single-arm forward spectrometer designed for studying heavy flavor physics at the Large Hadron Collider (LHC)
All the results show that Vertex locator (VELO) sustains the impact of high fluence of radiation, and its performance will not change significantly until the end of Run II
T HE large Hadron Collider beauty (LHCb) detector is a single-arm forward spectrometer designed for studying heavy flavor physics at the Large Hadron Collider (LHC)

Summary

INTRODUCTION

T HE large Hadron Collider beauty (LHCb) detector is a single-arm forward spectrometer designed for studying heavy flavor physics at the Large Hadron Collider (LHC). The tracking system provides a measurement of charged particle momentum with a relative uncertainty that varies from 0.5% to 1.0% at low momentum and 200 GeV, respectively. Two ring-imaging Cherenkov detectors provide efficient identification of charged particles with momenta up to 100 GeV. Up until the end of 2017, 7.63 fb−1 of integrated l√ums i=no7si−ty,13orTigeVin,atwinhgerefrosmis proton–proton the square of interactions at center-of-mass energy, has been delivered to the LHCb detector. The LHCb collecte√d data samples of ultrarelativistic protoncleoaldliscioonllsisaiot n√s sa=t sNN = 5 5 TeV. The and 8.16 TeV former sample and lead–lead corresponds to. 32.3 nb−1, whereas the latter corresponds to about 5.6 μb−1 of integrated luminosity

VERTEX LOCATOR

RADIATION ENVIRONMENT

EFFECTIVE DEPLETION VOLTAGE

CLUSTER FINDING EFFICIENCY

Findings

VIII. SUMMARY