The DarkSide-50 outer detectors

S Westerdale ,M Cadeddu ,S Davini ,K Fomenko ,D Montanari ,M Gromov ,S Perasso ,B R Hackett ,K Biery ,M Orsini ,W Sands ,N Canci ,A Devoto ,G Korga ,S D Rountree ,A Mandarano ,M E Monzani ,M Dskorokhvatov,B J Mount ,C Stanford ,Ianni Andrea,B Bottino ,J Wilhelmi ,A Tonazzo ,J Maricic ,K J Keeter ,M De Vincenzi ,A Monte ,F Budano ,F Di Eusanio ,C Savarese ,Y Guardincerri ,S Luitz ,P Cavalcante ,L Grandi ,A Zec ,K Arisaka ,Mariano Cadoni ,K Pelczar ,G Fiorillo ,E Segreto ,M Bossa ,R Saldanha ,A Razeto ,M De Deo ,D Franco ,O Smirnov ,N Rossi ,D Sablone ,B Vogelaar ,J Napolitano ,S Catalanotti ,S De Cecco ,B Reinhold ,P Agnes ,R Tartaglia ,E Pantic ,A S Kubankin ,K Herner ,L Agostino ,P Trinchese ,A Fan ,G Bonfini ,M Carlini ,A Vishneva ,A Alton ,C Giganti ,Y Suvorov ,C J Martoff ,L Marini ,C Jollet ,A Meregaglia ,G Koh ,A G Cocco ,T Miletic ,S Pordes ,E Edkins ,J Tatarowicz ,G Testera ,A Sotnikov ,K Randle ,G Di Pietro ,A Pocar ,P Lombardi ,M Wada ,Y Ma ,F Ortica ,Hua Cao ,A Watson ,E Hungerford ,A Renshaw ,C Zhu ,E Unzhakov ,P Mosteiro ,D Korablëv ,M Pallavicini ,X Li ,Weili Zhong ,E Shields ,C Galbiati ,Hao Qian ,T Alexander ,A Chepurnov ,Y Wang ,P D Meyers ,D D’angelo ,I Machulin ,G Covone ,V Muratova ,L Cadonati ,S Bussino ,G Ranucci ,J Yoo ,M Wójcik ,L Pagani ,Mengyun Guan ,S Sangiorgio ,H Wang ,I F M Albuquerque ,A Brigatti ,M Montuschi ,J Brodsky ,M Lissia ,A Derbin ,V Kobychev ,Paolo Saggese ,R Milinčić ,A Candela ,M D׳Incecco ,X Xiang ,I James ,F Calaprice ,A Empl ,P Musico ,Stefano Maria Mari ,N Pelliccia ,B Rossi ,D Semenov ,A Romani ,Chao Yang ,S Zavatarelli ,Susan Walker ,J Xu ,A Goretti ,Prabhjot Singh ,C L Kendziora ,F Gabriele ,H O Back ,F Granato ,D A Pugachev ,M Cariello ,S Parmeggiano ,G W Foster ,B Baldin ,G Zuzel

doi:10.1088/1742-6596/718/4/042062

Abstract

DarkSide-50 is a dark matter detection experiment searching for Weakly Interacting Massive Particles (WIMPs), in Gran Sasso National Laboratory. For experiments like DarkSide-50, neutrons are one of the primary backgrounds that can mimic WIMP signals.The experiment consists of three nested detectors: a liquid argon time projection chamber surrounded by two outer detectors. The outermost detector is a 10 m by 11 m cylindrical water Cherenkov detector with 80 PMTs, designed to provide shielding and muon vetoing.Inside the water Cherenkov detector is the 4 m diameter spherical boron-loaded liquid scintillator veto, with a cocktail of pseudocumene, trimethyl borate, and PPO wavelength shifter, designed to provide shielding, neutron vetoing, and in situ measurements of the TPC backgrounds. We present design and performance details of the DarkSide-50 outer detectors.

Highlights

The experiment consists of three nested detectors: a liquid argon tim e projection chamber surrounded by two outer detectors
We considered using 1,4-Bis(2-methylstyryl) benzene or 1,4-bis(5-phenyloxazol-2-yl) benzene (PO PO P) as secondary wavelength shifters, but found th at they did not increase the light yield enough to w arrant their use
We decided to use Lum irror in the liquid scintillator veto (LSV). It should be noted th a t while we found the bulk of the Lum irror m aintained a high reflectance when submerged in P C and trim ethyl borate (TM B) for an extended period of tim e, a slow degradation was observed around the edges, where the reflectance dropped to a peak reflectance of ~83% at a rate of about 1 cm every nine m onths

Summary

Introduction

The experiment consists of three nested detectors: a liquid argon tim e projection chamber surrounded by two outer detectors. The lower wavelength cutoff for Lum irror m eant th a t we could get a high light yield w ithout the use of a secondary wavelength shifter, while we would need one w ith Tyvek 4077D.

Results

Conclusion