@article{615c929dde5e447abbb8ed5f65b50abe,
title = "Identification of radiopure titanium for the LZ dark matter experiment and future rare event searches",
abstract = "The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a detector containing a total of 10 tonnes of liquid xenon within a double-vessel cryostat. The large mass and proximity of the cryostat to the active detector volume demand the use of material with extremely low intrinsic radioactivity. We report on the radioassay campaign conducted to identify suitable metals, the determination of factors limiting radiopure production, and the selection of titanium for construction of the LZ cryostat and other detector components. This titanium has been measured with activities of 238Ue < 1.6 mBq/kg, 238Ul < 0.09 mBq/kg, 232The=0.28±0.03 mBq/kg, 232Thl=0.25±0.02 mBq/kg, 40K < 0.54 mBq/kg, and 60Co < 0.02 mBq/kg (68% CL). Such low intrinsic activities, which are some of the lowest ever reported for titanium, enable its use for future dark matter and other rare event searches. Monte Carlo simulations have been performed to assess the expected background contribution from the LZ cryostat with this radioactivity. In 1,000 days of WIMP search exposure of a 5.6-tonne fiducial mass, the cryostat will contribute only a mean background of 0.160 ± 0.001(stat) ± 0.030(sys) counts.",
author = "{The LUX-ZEPLIN (LZ) Collaboration} and Akerib, {D. S.} and Akerlof, {C. W.} and Akimov, {D. Yu} and Alsum, {S. K.} and Ara{\'u}jo, {H. M.} and Arnquist, {I. J.} and M. Arthurs and X. Bai and Bailey, {A. J.} and J. Balajthy and S. Balashov and Barry, {M. J.} and J. Belle and P. Beltrame and T. Benson and Bernard, {E. P.} and A. Bernstein and Biesiadzinski, {T. P.} and Boast, {K. E.} and A. Bolozdynya and B. Boxer and R. Bramante and P. Br{\'a}s and Buckley, {J. H.} and Bugaev, {V. V.} and R. Bunker and S. Burdin and Busenitz, {J. K.} and C. Carels and Carlsmith, {D. L.} and B. Carlson and Carmona-Benitez, {M. C.} and C. Chan and Cherwinka, {J. J.} and Chiller, {A. A.} and C. Chiller and A. Cottle and R. Coughlen and Craddock, {W. W.} and A. Currie and Dahl, {C. E.} and Davison, {T. J.R.} and A. Dobi and Dobson, {J. E.Y.} and E. Druszkiewicz and Edberg, {T. K.} and Edwards, {W. R.} and Emmet, {W. T.} and Faham, {C. H.} and S. Fiorucci",
note = "Funding Information: We acknowledge many types of support provided to us by the South Dakota Science and Technology Authority, which developed the Sanford Underground Research Facility (SURF) with an important philanthropic donation from T. Denny Sanford as well as support from the State of South Dakota. SURF is operated by Lawrence Berkeley National Laboratory for the DOE, Office of High Energy Physics. The University of Edinburgh is a charitable body, registered in Scotland, with the registration number SC005336 . Funding Information: We acknowledge additional support from the Boulby Underground Laboratory in the U.K., the University of Wisconsin for grant UW PRJ82AJ and the GridPP Collaboration, in particular at Imperial College London . Part of the research described in this Letter was conducted under the Ultra Sensitive Nuclear Measurements Initiative at Pacific Northwest National Laboratory, which is operated by Battelle for the U.S. Department of Energy under Contract No. DE-AC05-76RL01830 . Funding Information: This work was partially supported by the U.S. Department of Energy ( DOE ) under award numbers DESC0012704 , DE-SC0010010 , DE-AC02-05CH11231 , DE-SC0012161 , DE-SC0014223 , DE-FG02- 13ER42020 , DE-FG02-91ER40674 , DE-NA0000979 , DE-SC0011702 , DESC0006572 , DESC0012034 , DE-SC0006605 , and DE-FG02-10ER46709 ; by the U.S. National Science Foundation (NSF) under award numbers NSF PHY-110447 , NSF PHY-1506068 , NSF PHY-1312561 , NSF PHY-1406943 and NSF PHY-1642619 ; by the U.K. Science and Technology Facilities Council under award numbers ST/K006428/1 , ST/M003655/1 , ST/M003981/1 , ST/M003744/1 , ST/M003639/1 , ST/M003604/1 , and ST/M003469/1 ; and by the Portuguese Foundation for Science and Technology (FCT) under award numbers CERN/FP/123610/2011 and PTDC/FIS-NUC/1525/2014 . University College London and Lawrence Berkeley National Laboratory thank the U.K. Royal Society for travel funds under the International Exchange Scheme ( IE141517 ). Publisher Copyright: {\textcopyright} 2017 Elsevier B.V.",
year = "2017",
month = nov,
doi = "10.1016/j.astropartphys.2017.09.002",
language = "English (US)",
volume = "96",
pages = "1--10",
journal = "Astroparticle Physics",
issn = "0927-6505",
publisher = "Elsevier",
}