D. S. Akerib, X. Bai, S. Bedikian, E. Bernard, A. Bernstein, A. Bradley, S. B. Cahn, M. C. Carmona-Benitez, D. Carr, J. J. Chapman, K. Clark, T. Classen, T. Coffey, A. Curioni, S. Dazeley, L. deViveiros, M. Dragowsky, E. Druszkiewicz, C. H. Faham, S. Fiorucci, R. J. Gaitskell, K. R. Gibson, C. Hall, M. Hanhardt, B. Holbrook, M. Ihm, R. G. Jacobsen, L. Kastens, K. Kazkaz, R. Lander, N. Larsen, C. Lee, D. Leonard, K. Lesko, A. Lyashenko, D. C. Malling, R. Mannino, D. N. McKinsey, D. Mei, J. Mock, M. Morii, H. Nelson, J. A. Nikkel, M. Pangilinan, P. Phelps, T. Shutt, W. Skulski, P. Sorensen, J. Spaans, T. Stiegler, R. Svoboda, M. Sweany, M. Szydagis, J. Thomson, M. Tripathi, J. R. Verbus, N. Walsh, R. Webb, J. T. White, M. Wlasenko, F. L. H. Wolfs, M. Woods, C. Zhang
LUX is a two-phase (liquid/gas) xenon time projection chamber designed to detect nuclear recoils from interactions with dark matter particles. Signals from the LUX detector are processed by custom-built analog electronics which provide properly shaped signals for the trigger and data acquisition (DAQ) systems. The DAQ is comprised of commercial digitizers with firmware customized for the LUX experiment. Data acquisition systems in rare-event searches must accommodate high rate and large dynamic range during precision calibrations involving radioactive sources, while also delivering low threshold for maximum sensitivity. The LUX DAQ meets these challenges using real-time baseline sup- pression that allows for a maximum event acquisition rate in excess of 1.5 kHz with virtually no deadtime. This paper describes the LUX DAQ and the novel acquisition techniques employed in the LUX experiment.
The LZ Collaboration, D. S. Akerib, C. W. Akerlof, D. Yu. Akimov, A. Alquahtani, S. K. Alsum, T. J. Anderson, N. Angelides, H. M. Araújo, A. Arbuckle, J. E. Armstrong, M. Arthurs, H. Auyeung, X. Bai, A. J. Bailey, J. Balajthy, S. Balashov, J. Bang, M. J. Barry, J. Barthel, D. Bauer, P. Bauer, A. Baxter, J. Belle, P. Beltrame, J. Bensinger, T. Benson, E. P. Bernard, A. Bernstein, A. Bhatti, A. Biekert, T. P. Biesiadzinski, B. Birrittella, K. E. Boast, A. I. Bolozdynya, E. M. Boulton, B. Boxer, R. Bramante, S. Branson, P. Brás, M. Breidenbach, J. H. Buckley, V. V. Bugaev, R. Bunker, S. Burdin, J. K. Busenitz, J. S. Campbell, C. Carels, D. L. Carlsmith, B. Carlson, M. C. Carmona-Benitez, M. Cascella, C. Chan, J. J. Cherwinka, A. A. Chiller, C. Chiller, N. I. Chott, A. Cole, J. Coleman, D. Colling, R. A. Conley, A. Cottle, R. Coughlen, W. W. Craddock, D. Curran, A. Currie, J. E. Cutter, J. P. da Cunha, C. E. Dahl, S. Dardin, S. Dasu, J. Davis, T. J. R. Davison, L. de Viveiros, N. Decheine, A. Dobi, J. E. Y. Dobson, E. Druszkiewicz, A. Dushkin, T. K. Edberg, W. R. Edwards, B. N. Edwards, J. Edwards, M. M. Elnimr, W. T. Emmet, S. R. Eriksen, C. H. Faham, A. Fan, S. Fayer, S. Fiorucci, H. Flaecher, I. M. Fogarty Florang, P. Ford, V. B. Francis, F. Froborg, T. Fruth, R. J. Gaitskell, N. J. Gantos, D. Garcia, A. Geffre, V. M. Gehman, R. Gelfand, J. Genovesi, R. M. Gerhard, C. Ghag, E. Gibson, M. G. D. Gilchriese, S. Gokhale, B. Gomber, T. G. Gonda, A. Greenall, S. Greenwood, G. Gregerson, M. G. D. van der Grinten, C. B. Gwilliam, C. R. Hall, D. Hamilton, S. Hans, K. Hanzel, T. Harrington, A. Harrison, C. Hasselkus, S. J. Haselschwardt, D. Hemer, S. A. Hertel, J. Heise, S. Hillbrand, O. Hitchcock, C. Hjemfelt, M. D. Hoff, B. Holbrook, E. Holtom, J. Y-K. Hor, M. Horn, D. Q. Huang, T. W. Hurteau, C. M. Ignarra, M. N. Irving, R. G. Jacobsen, O. Jahangir, S. N. Jeffery, W. Ji, M. Johnson, J. Johnson, P. Johnson, W. G. Jones, A. C. Kaboth, A. Kamaha, K. Kamdin, V. Kasey, K. Kazkaz, J. Keefner, D. Khaitan, M. Khaleeq, A. Khazov, A. V. Khromov, I. Khurana, Y. D. Kim, W. T. Kim, C. D. Kocher, A. M. Konovalov, L. Korley, E. V. Korolkova, M. Koyuncu, J. Kras, H. Kraus, S. W. Kravitz, H. J. Krebs, L. Kreczko, B. Krikler, V. A. Kudryavtsev, A. V. Kumpan, S. Kyre, A. R. Lambert, B. Landerud, N. A. Larsen, A. Laundrie, E. A. Leason, H. S. Lee, J. Lee, C. Lee, B. G. Lenardo, D. S. Leonard, R. Leonard, K. T. Lesko, C. Levy, J. Li, Y. Liu, J. Liao, F. -T. Liao, J. Lin, A. Lindote, R. Linehan, W. H. Lippincott, R. Liu, X. Liu, C. Loniewski, M. I. Lopes, B. López Paredes, W. Lorenzon, D. Lucero, S. Luitz, J. M. Lyle, C. Lynch, P. A. Majewski, J. Makkinje, D. C. Malling, A. Manalaysay, L. Manenti, R. L. Mannino, N. Marangou, D. J. Markley, P. MarrLaundrie, T. J. Martin, M. F. Marzioni, C. Maupin, C. T. McConnell, D. N. McKinsey, J. McLaughlin, D. -M. Mei, Y. Meng, E. H. Miller, Z. J. Minaker, E. Mizrachi, J. Mock, D. Molash, A. Monte, M. E. Monzani, J. A. Morad, E. Morrison, B. J. Mount, A. St. J. Murphy, D. Naim, A. Naylor, C. Nedlik, C. Nehrkorn, H. N. Nelson, J. Nesbit, F. Neves, J. A. Nikkel, J. A. Nikoleyczik, A. Nilima, J. O'Dell, H. Oh, F. G. O'Neill, K. O'Sullivan, I. Olcina, M. A. Olevitch, K. C. Oliver-Mallory, L. Oxborough, A. Pagac, D. Pagenkopf, S. Pal, K. J. Palladino, V. M. Palmaccio, J. Palmer, M. Pangilinan, S. J. Patton, E. K. Pease, B. P. Penning, G. Pereira, C. Pereira, I. B. Peterson, A. Piepke, S. Pierson, S. Powell, R. M. Preece, K. Pushkin, Y. Qie, M. Racine, B. N. Ratcliff, J. Reichenbacher, L. Reichhart, C. A. Rhyne, A. Richards, Q. Riffard, G. R. C. Rischbieter, J. P. Rodrigues, H. J. Rose, R. Rosero, P. Rossiter, R. Rucinski, G. Rutherford, D. Rynders, J. S. Saba, L. Sabarots, D. Santone, M. Sarychev, A. B. M. R. Sazzad, R. W. Schnee, M. Schubnell, P. R. Scovell, M. Severson, D. Seymour, S. Shaw, G. W. Shutt, T. A. Shutt, J. J. Silk, C. Silva, K. Skarpaas, W. Skulski, A. R. Smith, R. J. Smith, R. E. Smith, J. So, M. Solmaz, V. N. Solovov, P. Sorensen, V. V. Sosnovtsev, I. Stancu, M. R. Stark, S. Stephenson, N. Stern, A. Stevens, T. M. Stiegler, K. Stifter, R. Studley, T. J. Sumner, K. Sundarnath, P. Sutcliffe, N. Swanson, M. Szydagis, M. Tan, W. C. Taylor, R. Taylor, D. J. Taylor, D. Temples, B. P. Tennyson, P. A. Terman, K. J. Thomas, J. A. Thomson, D. R. Tiedt, M. Timalsina, W. H. To, A. Tomás, T. E. Tope, M. Tripathi, D. R. Tronstad, C. E. Tull, W. Turner, L. Tvrznikova, M. Utes, U. Utku, S. Uvarov, J. Va'vra, A. Vacheret, A. Vaitkus, J. R. Verbus, T. Vietanen, E. Voirin, C. O. Vuosalo, S. Walcott, W. L. Waldron, K. Walker, J. J. Wang, R. Wang, L. Wang, Y. Wang, J. R. Watson, J. Migneault, S. Weatherly, R. C. Webb, W. -Z. Wei, M. While, R. G. White, J. T. White, D. T. White, T. J. Whitis, W. J. Wisniewski, K. Wilson, M. S. Witherell, F. L. H. Wolfs, J. D. Wolfs, D. Woodward, S. D. Worm, X. Xiang, Q. Xiao, J. Xu, M. Yeh, J. Yin, I. Young, C. Zhang
We describe the design and assembly of the LUX-ZEPLIN experiment, a direct detection search for cosmic WIMP dark matter particles. The centerpiece of the experiment is a large liquid xenon time projection chamber sensitive to low energy nuclear recoils. Rejection of backgrounds is enhanced by a Xe skin veto detector and by a liquid scintillator Outer Detector loaded with gadolinium for efficient neutron capture and tagging. LZ is located in the Davis Cavern at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. We describe the major subsystems of the experiment and its key design features and requirements.
J. R. Verbus, C. A. Rhyne, D. C. Malling, M. Genecov, S. Ghosh, A. G. Moskowitz, S. Chan, J. J. Chapman, L. de Viveiros, C. H. Faham, S. Fiorucci, D. Q. Huang, M. Pangilinan, W. C. Taylor, R. J. Gaitskell
We propose a new technique for the calibration of nuclear recoils in large noble element dual-phase time projection chambers used to search for WIMP dark matter in the local galactic halo. This technique provides an $\textit{in situ}$ measurement of the low-energy nuclear recoil response of the target media using the measured scattering angle between multiple neutron interactions within the detector volume. The low-energy reach and reduced systematics of this calibration have particular significance for the low-mass WIMP sensitivity of several leading dark matter experiments. Multiple strategies for improving this calibration technique are discussed, including the creation of a new type of quasi-monoenergetic 272 keV neutron source. We report results from a time-of-flight based measurement of the neutron energy spectrum produced by an Adelphi Technology, Inc. DD108 neutron generator, confirming its suitability for the proposed nuclear recoil calibration.
B. J. Mount, S. Hans, R. Rosero, M. Yeh, C. Chan, R. J. Gaitskell, D. Q. Huang, J. Makkinje, D. C. Malling, M. Pangilinan, C. A. Rhyne, W. C. Taylor, J. R. Verbus, Y. D. Kim, H. S. Lee, J. Lee, D. S. Leonard, J. Li, J. Belle, A. Cottle, W. H. Lippincott, D. J. Markley, T. J. Martin, M. Sarychev, T. E. Tope, M. Utes, R. Wang, I. Young, H. M. Araújo, A. J. Bailey, D. Bauer, D. Colling, A. Currie, S. Fayer, F. Froborg, S. Greenwood, W. G. Jones, V. Kasey, M. Khaleeq, I. Olcina, B. López Paredes, A. Richards, T. J. Sumner, A. Tomás, A. Vacheret, P. Brás, A. Lindote, M. I. Lopes, F. Neves, J. P. Rodrigues, C. Silva, V. N. Solovov, M. J. Barry, A. Cole, A. Dobi, W. R. Edwards, C. H. Faham, S. Fiorucci, N. J. Gantos, V. M. Gehman, M. G. D. Gilchriese, K. Hanzel, M. D. Hoff, K. Kamdin, K. T. Lesko, C. T. McConnell, K. O'Sullivan, K. C. Oliver-Mallory, S. J. Patton, J. S. Saba, P. Sorensen, K. J. Thomas, C. E. Tull, W. L. Waldron, M. S. Witherell, A. Bernstein, K. Kazkaz, J. Xu, D. Yu. Akimov, A. I. Bolozdynya, A. V. Khromov, A. M. Konovalov, A. V. Kumpan, V. V. Sosnovtsev, C. E. Dahl, D. Temples, M. C. Carmona-Benitez, L. de Viveiros, D. S. Akerib, H. Auyeung, T. P. Biesiadzinski, M. Breidenbach, R. Bramante, R. Conley, W. W. Craddock, A. Fan, A. Hau, C. M. Ignarra, W. Ji, H. J. Krebs, R. Linehan, C. Lee, S. Luitz, E. Mizrachi, M. E. Monzani, F. G. O'Neill, S. Pierson, M. Racine, B. N. Ratcliff, G. W. Shutt, T. A. Shutt, K. Skarpaas, K. Stifter, W. H. To, J. Va'vra, T. J. Whitis, W. J. Wisniewski, X. Bai, R. Bunker, R. Coughlen, C. Hjemfelt, R. Leonard, E. H. Miller, E. Morrison, J. Reichenbacher, R. W. Schnee, M. R. Stark, K. Sundarnath, D. R. Tiedt, M. Timalsina, P. Bauer, B. Carlson, M. Horn, M. Johnson, J. Keefner, C. Maupin, D. J. Taylor, S. Balashov, P. Ford, V. Francis, E. Holtom, A. Khazov, A. Kaboth, P. Majewski, J. A. Nikkel, J. O'Dell, R. M. Preece, M. G. D. van der Grinten, S. D. Worm, R. L. Mannino, T. M. Stiegler, P. A. Terman, R. C. Webb, C. Levy, J. Mock, M. Szydagis, J. K. Busenitz, M. Elnimr, J. Y-K. Hor, Y. Meng, A. Piepke, I. Stancu, L. Kreczko, B. Krikler, B. Penning, E. P. Bernard, R. G. Jacobsen, D. N. McKinsey, R. Watson, J. E. Cutter, S. El-Jurf, R. M. Gerhard, D. Hemer, S. Hillbrand, B. Holbrook, B. G. Lenardo, A. G. Manalaysay, J. A. Morad, S. Stephenson, J. A. Thomson, M. Tripathi, S. Uvarov, S. J. Haselschwardt, S. Kyre, C. Nehrkorn, H. N. Nelson, M. Solmaz, D. T. White, M. Cascella, J. E. Y. Dobson, C. Ghag, X. Liu, L. Manenti, L. Reichhart, S. Shaw, U. Utku, P. Beltrame, T. J. R. Davison, M. F. Marzioni, A. St. J. Murphy, A. Nilima, B. Boxer, S. Burdin, A. Greenall, S. Powell, H. J. Rose, P. Sutcliffe, J. Balajthy, T. K. Edberg, C. R. Hall, J. S. Silk, S. Hertel, C. W. Akerlof, M. Arthurs, W. Lorenzon, K. Pushkin, M. Schubnell, K. E. Boast, C. Carels, T. Fruth, H. Kraus, F. -T. Liao, J. Lin, P. R. Scovell, E. Druszkiewicz, D. Khaitan, M. Koyuncu, W. Skulski, F. L. H. Wolfs, J. Yin, E. V. Korolkova, V. A. Kudryavtsev, P. Rossiter, D. Woodward, A. A. Chiller, C. Chiller, D. -M. Mei, L. Wang, W. -Z. Wei, M. While, C. Zhang, S. K. Alsum, T. Benson, D. L. Carlsmith, J. J. Cherwinka, S. Dasu, G. Gregerson, B. Gomber, A. Pagac, K. J. Palladino, C. O. Vuosalo, Q. Xiao, J. H. Buckley, V. V. Bugaev, M. A. Olevitch, E. M. Boulton, W. T. Emmet, T. W. Hurteau, N. A. Larsen, E. K. Pease, B. P. Tennyson, L. Tvrznikova
J. Aalbers, D. S. Akerib, C. W. Akerlof, A. K. Al Musalhi, F. Alder, A. Alqahtani, S. K. Alsum, C. S. Amarasinghe, A. Ames, T. J. Anderson, N. Angelides, H. M. Araújo, J. E. Armstrong, M. Arthurs, S. Azadi, A. J. Bailey, A. Baker, J. Balajthy, S. Balashov, J. Bang, J. W. Bargemann, M. J. Barry, J. Barthel, D. Bauer, A. Baxter, K. Beattie, J. Belle, P. Beltrame, J. Bensinger, T. Benson, E. P. Bernard, A. Bhatti, A. Biekert, T. P. Biesiadzinski, H. J. Birch, B. Birrittella, G. M. Blockinger, K. E. Boast, B. Boxer, R. Bramante, C. A. J. Brew, P. Brás, J. H. Buckley, V. V. Bugaev, S. Burdin, J. K. Busenitz, M. Buuck, R. Cabrita, C. Carels, D. L. Carlsmith, B. Carlson, M. C. Carmona-Benitez, M. Cascella, C. Chan, A. Chawla, H. Chen, J. J. Cherwinka, N. I. Chott, A. Cole, J. Coleman, M. V. Converse, A. Cottle, G. Cox, W. W. Craddock, O. Creaner, D. Curran, A. Currie, J. E. Cutter, C. E. Dahl, A. David, J. Davis, T. J. R. Davison, J. Delgaudio, S. Dey, L. de Viveiros, A. Dobi, J. E. Y. Dobson, E. Druszkiewicz, A. Dushkin, T. K. Edberg, W. R. Edwards, M. M. Elnimr, W. T. Emmet, S. R. Eriksen, C. H. Faham, A. Fan, S. Fayer, N. M. Fearon, S. Fiorucci, H. Flaecher, P. Ford, V. B. Francis, E. D. Fraser, T. Fruth, R. J. Gaitskell, N. J. Gantos, D. Garcia, A. Geffre, V. M. Gehman, J. Genovesi, C. Ghag, R. Gibbons, E. Gibson, M. G. D. Gilchriese, S. Gokhale, B. Gomber, J. Green, A. Greenall, S. Greenwood, M. G. D. van der Grinten, C. B. Gwilliam, C. R. Hall, S. Hans, K. Hanzel, A. Harrison, E. Hartigan-O'Connor, S. J. Haselschwardt, S. A. Hertel, G. Heuermann, C. Hjemfelt, M. D. Hoff, E. Holtom, J. Y-K. Hor, M. Horn, D. Q. Huang, D. Hunt, C. M. Ignarra, R. G. Jacobsen, O. Jahangir, R. S. James, S. N. Jeffery, W. Ji, J. Johnson, A. C. Kaboth, A. C. Kamaha, K. Kamdin, V. Kasey, K. Kazkaz, J. Keefner, D. Khaitan, M. Khaleeq, A. Khazov, I. Khurana, Y. D. Kim, C. D. Kocher, D. Kodroff, L. Korley, E. V. Korolkova, J. Kras, H. Kraus, S. Kravitz, H. J. Krebs, L. Kreczko, B. Krikler, V. A. Kudryavtsev, S. Kyre, B. Landerud, E. A. Leason, C. Lee, J. Lee, D. S. Leonard, R. Leonard, K. T. Lesko, C. Levy, J. Li, F. -T. Liao, J. Liao, J. Lin, A. Lindote, R. Linehan, W. H. Lippincott, R. Liu, X. Liu, Y. Liu, C. Loniewski, M. I. Lopes, E. Lopez Asamar, B. López Paredes, W. Lorenzon, D. Lucero, S. Luitz, J. M. Lyle, P. A. Majewski, J. Makkinje, D. C. Malling, A. Manalaysay, L. Manenti, R. L. Mannino, N. Marangou, M. F. Marzioni, C. Maupin, M. E. McCarthy, C. T. McConnell, D. N. McKinsey, J. McLaughlin, Y. Meng, J. Migneault, E. H. Miller, E. Mizrachi, J. A. Mock, A. Monte, M. E. Monzani, J. A. Morad, J. D. Morales Mendoza, E. Morrison, B. J. Mount, M. Murdy, A. St. J. Murphy, D. Naim, A. Naylor, C. Nedlik, C. Nehrkorn, F. Neves, A. Nguyen, J. A. Nikoleyczik, A. Nilima, J. O'Dell, F. G. O'Neill, K. O'Sullivan, I. Olcina, M. A. Olevitch, K. C. Oliver-Mallory, J. Orpwood, D. Pagenkopf, S. Pal, K. J. Palladino, J. Palmer, M. Pangilinan, N. Parveen, S. J. Patton, E. K. Pease, B. Penning, C. Pereira, G. Pereira, E. Perry, T. Pershing, I. B. Peterson, A. Piepke, J. Podczerwinski, D. Porzio, S. Powell, R. M. Preece, K. Pushkin, Y. Qie, B. N. Ratcliff, J. Reichenbacher, L. Reichhart, C. A. Rhyne, A. Richards, Q. Riffard, G. R. C. Rischbieter, J. P. Rodrigues, A. Rodriguez, H. J. Rose, R. Rosero, P. Rossiter, T. Rushton, G. Rutherford, D. Rynders, J. S. Saba, D. Santone, A. B. M. R. Sazzad, R. W. Schnee, P. R. Scovell, D. Seymour, S. Shaw, T. Shutt, J. J. Silk, C. Silva, G. Sinev, K. Skarpaas, W. Skulski, R. Smith, M. Solmaz, V. N. Solovov, P. Sorensen, J. Soria, I. Stancu, M. R. Stark, A. Stevens, T. M. Stiegler, K. Stifter, R. Studley, B. Suerfu, T. J. Sumner, P. Sutcliffe, N. Swanson, M. Szydagis, M. Tan, D. J. Taylor, R. Taylor, W. C. Taylor, D. J. Temples, B. P. Tennyson, P. A. Terman, K. J. Thomas, D. R. Tiedt, M. Timalsina, W. H. To, A. Tomás, Z. Tong, D. R. Tovey, J. Tranter, M. Trask, M. Tripathi, D. R. Tronstad, C. E. Tull, W. Turner, L. Tvrznikova, U. Utku, J. Va'vra, A. Vacheret, A. C. Vaitkus, J. R. Verbus, E. Voirin, W. L. Waldron, A. Wang, B. Wang, J. J. Wang, W. Wang, Y. Wang, J. R. Watson, R. C. Webb, A. White, D. T. White, J. T. White, R. G. White, T. J. Whitis, M. Williams, W. J. Wisniewski, M. S. Witherell, F. L. H. Wolfs, J. D. Wolfs, S. Woodford, D. Woodward, S. D. Worm, C. J. Wright, Q. Xia, X. Xiang, Q. Xiao, J. Xu, M. Yeh, J. Yin, I. Young, P. Zarzhitsky, A. Zuckerman, E. A. Zweig
LUX Collaboration, D. S. Akerib, X. Bai, E. Bernard, A. Bernstein, A. Bradley, D. Byram, S. B. Cahn, M. C. Carmona-Benitez, J. J. Chapman, T. Coffey, A. Dobi, E. Dragowsky, E. Druszkiewicz, B. Edwards, C. H. Faham, S. Fiorucci, R. J. Gaitskell, K. R. Gibson, M. Gilchriese, C. Hall, M. Hanhardt, M. Ihm, R. G. Jacobsen, L. Kastens, K. Kazkaz, R. Knoche, N. Larsen, C. Lee, K. T. Lesko, A. Lindote, M. I. Lopes, A. Lyashenko, D. C. Malling, R. Mannino, D. N. McKinsey, D. Mei, J. Mock, M. Moongweluwan, M. Morii, H. Nelson, F. Neves, J. A. Nikkel, M. Pangilinan, K. Pech, P. Phelps, A. Rodionov, T. Shutt, C. Silva, W. Skulski, V. N. Solovov, P. Sorensen, T. Stiegler, M. Sweany, M. Szydagis, D. Taylor, M. Tripathi, S. Uvarov, J. R. Verbus, L. de Viveiros, N. Walsh, R. Webb, J. T. White, M. Wlasenko, F. L. H. Wolfs, M. Woods, C. Zhang
Oct 16, 2012·astro-ph.IM·PDF We present the results of the three-month above-ground commissioning run of the Large Underground Xenon (LUX) experiment at the Sanford Underground Research Facility located in Lead, South Dakota, USA. LUX is a 370 kg liquid xenon detector that will search for cold dark matter in the form of Weakly Interacting Massive Particles (WIMPs). The commissioning run, conducted with the detector immersed in a water tank, validated the integration of the various sub-systems in preparation of the underground deployment. Using the data collected, we report excellent light collection properties, achieving 8.4 photoelectrons per keV for 662 keV electron recoils without an applied electric field, measured in the center of the WIMP target. We also find good energy and position resolution in relatively high-energy interactions from a variety of internal and external sources. Finally, we have used the commissioning data to tune the optical properties of our simulation and report updated sensitivity projections for spin-independent WIMP-nucleon scattering.
LUX Collaboration, D. S. Akerib, H. M. Araujo, X. Bai, A. J. Bailey, J. Balajthy, S. Bedikian, E. Bernard, A. Bernstein, A. Bolozdynya, A. Bradley, D. Byram, S. B. Cahn, M. C. Carmona-Benitez, C. Chan, J. J. Chapman, A. A. Chiller, C. Chiller, K. Clark, T. Coffey, A. Currie, A. Curioni, S. Dazeley, L. de Viveiros, A. Dobi, J. Dobson, E. M. Dragowsky, E. Druszkiewicz, B. Edwards, C. H. Faham, S. Fiorucci, C. Flores, R. J. Gaitskell, V. M. Gehman, C. Ghag, K. R. Gibson, M. G. D. Gilchriese, C. Hall, M. Hanhardt, S. A. Hertel, M. Horn, D. Q. Huang, M. Ihm, R. G. Jacobsen, L. Kastens, K. Kazkaz, R. Knoche, S. Kyre, R. Lander, N. A. Larsen, C. Lee, D. S. Leonard, K. T. Lesko, A. Lindote, M. I. Lopes, A. Lyashenko, D. C. Malling, R. Mannino, D. N. McKinsey, D. -M. Mei, J. Mock, M. Moongweluwan, J. Morad, M. Morii, A. St. J. Murphy, C. Nehrkorn, H. Nelson, F. Neves, J. A. Nikkel, R. A. Ott, M. Pangilinan, P. D. Parker, E. K. Pease, K. Pech, P. Phelps, L. Reichhart, T. Shutt, C. Silva, W. Skulski, C. J. Sofka, V. N. Solovov, P. Sorensen, T. Stiegler, K. O`Sullivan, T. J. Sumner, R. Svoboda, M. Sweany, M. Szydagis, D. Taylor, B. Tennyson, D. R. Tiedt, M. Tripathi, S. Uvarov, J. R. Verbus, N. Walsh, R. Webb, J. T. White, D. White, M. S. Witherell, M. Wlasenko, F. L. H. Wolfs, M. Woods, C. Zhang
Oct 30, 2013·astro-ph.CO·PDF The Large Underground Xenon (LUX) experiment, a dual-phase xenon time-projection chamber operating at the Sanford Underground Research Facility (Lead, South Dakota), was cooled and filled in February 2013. We report results of the first WIMP search dataset, taken during the period April to August 2013, presenting the analysis of 85.3 live-days of data with a fiducial volume of 118 kg. A profile-likelihood analysis technique shows our data to be consistent with the background-only hypothesis, allowing 90% confidence limits to be set on spin-independent WIMP-nucleon elastic scattering with a minimum upper limit on the cross section of $7.6 \times 10^{-46}$ cm$^{2}$ at a WIMP mass of 33 GeV/c$^2$. We find that the LUX data are in strong disagreement with low-mass WIMP signal interpretations of the results from several recent direct detection experiments.
D. S. Akerib, X. Bai, S. Bedikian, E. Bernard, A. Bernstein, A. Bradley, S. B. Cahn, M. C. Carmona-Benitez, D. Carr, J. J. Chapman, K. Clark, T. Classen, T. Coffey, S. Dazeley, L. de Viveiros, M. Dragowsky, E. Druszkiewicz, C. H. Faham, S. Fiorucci, R. J. Gaitskell, K. R. Gibson, C. Hall, M. Hanhardt, B. Holbrook, M. Ihm, R. G. Jacobsen, L. Kastens, K. Kazkaz, R. Lander, N. Larsen, C. Lee, D. Leonard, K. Lesko, A. Lyashenko, D. C. Malling, R. Mannino, D. N. McKinsey, D. -M Mei, J. Mock, M. Morii, H. Nelson, J. A. Nikkel, M. Pangilinan, P. D. Parker, P. Phelps, T. Shutt, W. Skulski, P. Sorensen, J. Spaans, T. Stiegler, R. Svoboda, M. Sweany, M. Szydagis, J. Thomson, M. Tripathi, J. R. Verbus, N. Walsh, R. Webb, J. T. White, M. Wlasenko, F. L. H. Wolfs, M. Woods, C. Zhang
Geant4 has been used throughout the nuclear and high-energy physics community to simulate energy depositions in various detectors and materials. These simulations have mostly been run with a source beam outside the detector. In the case of low-background physics, however, a primary concern is the effect on the detector from radioactivity inherent in the detector parts themselves. From this standpoint, there is no single source or beam, but rather a collection of sources with potentially complicated spatial extent. LUXSim is a simulation framework used by the LUX collaboration that takes a component-centric approach to event generation and recording. A new set of classes allows for multiple radioactive sources to be set within any number of components at run time, with the entire collection of sources handled within a single simulation run. Various levels of information can also be recorded from the individual components, with these record levels also being set at runtime. This flexibility in both source generation and information recording is possible without the need to recompile, reducing the complexity of code management and the proliferation of versions. Within the code itself, casting geometry objects within this new set of classes rather than as the default Geant4 classes automatically extends this flexibility to every individual component. No additional work is required on the part of the developer, reducing development time and increasing confidence in the results. We describe the guiding principles behind LUXSim, detail some of its unique classes and methods, and give examples of usage. * Corresponding author, kareem@llnl.gov
V. M. Abazov, B. Abbott, M. Abolins, B. S. Acharya, M. Adams, T. Adams, G. D. Alexeev, G. Alkhazov, A. Altona, G. Alverson, G. A. Alves, L. S. Ancu, M. Aoki, Y. Arnoud, M. Arov, A. Askew, B. Åsman, O. Atramentov, C. Avila, J. BackusMayes, F. Badaud, L. Bagby, B. Baldin, D. V. Bandurin, S. Banerjee, E. Barberis, P. Baringer, J. Barreto, J. F. Bartlett, U. Bassler, V. Bazterra, S. Beale, A. Bean, M. Begalli, M. Begel, C. Belanger-Champagne, L. Bellantoni, S. B. Beri, G. Bernardi, R. Bernhard, I. Bertram, M. Besançon, R. Beuselinck, V. A. Bezzubov, P. C. Bhat, V. Bhatnagar, G. Blazey, S. Blessing, K. Bloom, A. Boehnlein, D. Boline, T. A. Bolton, E. E. Boos, G. Borissov, T. Bose, A. Brandt, O. Brandt, R. Brock, G. Brooijmans, A. Bross, D. Brown, J. Brown, X. B. Bu, D. Buchholz, M. Buehler, V. Buescher, V. Bunichev, S. Burdinb, T. H. Burnett, C. P. Buszello, B. Calpas, E. Camacho-Pérez, M. A. Carrasco-Lizarraga, B. C. K. Casey, H. Castilla-Valdez, S. Chakrabarti, D. Chakraborty, K. M. Chan, A. Chandra, G. Chen, S. Chevalier-Théry, D. K. Cho, S. W. Cho, S. Choi, B. Choudhary, T. Christoudias, S. Cihangir, D. Claes, J. Clutter, M. Cooke, W. E. Cooper, M. Corcoran, F. Couderc, M. -C. Cousinou, A. Croc, D. Cutts, M. Ćwiok, A. Das, G. Davies, K. De, S. J. de Jong, E. De La Cruz-Burelo, F. Déliot, M. Demarteau, R. Demina, D. Denisov, S. P. Denisov, S. Desai, K. DeVaughan, H. T. Diehl, M. Diesburg, A. Dominguez, T. Dorland, A. Dubey, L. V. Dudko, D. Duggan, A. Duperrin, S. Dutt, A. Dyshkant, M. Eads, D. Edmunds, J. Ellison, V. D. Elvira, Y. Enari, S. Eno, H. Evans, A. Evdokimov, V. N. Evdokimov, G. Facini, T. Ferbel, F. Fiedler, F. Filthaut, W. Fisher, H. E. Fisk, M. Fortner, H. Fox, S. Fuess, T. Gadfort, A. Garcia-Bellido, V. Gavrilov, P. Gay, W. Geist, W. Geng, D. Gerbaudo, C. E. Gerber, Y. Gershtein, G. Ginther, G. Golovanov, A. Goussiou, P. D. Grannis, S. Greder, H. Greenlee, Z. D. Greenwood, E. M. Gregores, G. Grenier, Ph. Gris, J. -F. Grivaz, A. Grohsjean, S. Grnendahl, M. W. Grünewald, F. Guo, J. Guo, G. Gutierrez, P. Gutierrez, A. Haasc, S. Hagopian, J. Haley, L. Han, K. Harder, A. Harel, J. M. Hauptman, J. Hays, T. Head, T. Hebbeker, D. Hedin, H. Hegab, A. P. Heinson, U. Heintz, C. Hensel, I. Heredia-De La Cruz, K. Herner, G. Hesketh, M. D. Hildreth, R. Hirosky, T. Hoang, J. D. Hobbs, B. Hoeneisen, M. Hohlfeld, S. Hossain, Z. Hubacek, N. Huske, V. Hynek, I. Iashvili, R. Illingworth, A. S. Ito, S. Jabeen, M. Jaffré, S. Jain, D. Jamin, R. Jesik, K. Johns, M. Johnson, D. Johnston, A. Jonckheere, P. Jonsson, J. Joshi, A. Justed, K. Kaadze, E. Kajfasz, D. Karmanov, P. A. Kasper, I. Katsanos, R. Kehoe, S. Kermiche, N. Khalatyan, A. Khanov, A. Kharchilava, Y. N. Kharzheev, D. Khatidze, M. H. Kirby, J. M. Kohli, A. V. Kozelov, J. Kraus, A. Kumar, A. Kupco, T. Kurča, V. A. Kuzmin, J. Kvita, S. Lammers, G. Landsberg, P. Lebrun, H. S. Lee, S. W. Lee, W. M. Lee, J. Lellouch, L. Li, Q. Z. Li, S. M. Lietti, J. K. Lim, D. Lincoln, J. Linnemann, V. V. Lipaev, R. Lipton, Y. Liu, Z. Liu, A. Lobodenko, M. Lokajicek, P. Love, H. J. Lubatti, R. Luna-Garciae, A. L. Lyon, A. K. A. Maciel, D. Mackin, R. Madar, R. Magaña-Villalba, S. Malik, V. L. Malyshev, Y. Maravin, J. Martínez-Ortega, R. McCarthy, C. L. McGivern, M. M. Meijer, A. Melnitchouk, D. Menezes, P. G. Mercadante, M. Merkin, A. Meyer, J. Meyer, N. K. Mondal, G. S. Muanza, M. Mulhearn, E. Nagy, M. Naimuddin, M. Narain, R. Nayyar, H. A. Neal, J. P. Negret, P. Neustroev, S. F. Novaes, T. Nunnemann, G. Obrant, J. Orduna, N. Osman, J. Osta, G. J. Otero y Garzón, M. Owen, M. Padilla, M. Pangilinan, N. Parashar, V. Parihar, S. K. Park, J. Parsons, R. Partridgec, N. Parua, A. Patwa, B. Penning, M. Perfilov, K. Peters, Y. Peters, G. Petrillo, P. Pétroff, R. Piegaia, J. Piper, M. -A. Pleier, P. L. M. Podesta-Lermaf, V. M. Podstavkov, M. -E. Pol, P. Polozov, A. V. Popov, M. Prewitt, D. Price, S. Protopopescu, J. Qian, A. Quadt, B. Quinn, M. S. Rangel, K. Ranjan, P. N. Ratoff, I. Razumov, P. Renkel, P. Rich, M. Rijssenbeek, I. Ripp-Baudot, F. Rizatdinova, M. Rominsky, C. Royon, P. Rubinov, R. Ruchti, G. Safronov, G. Sajot, A. Sánchez-Hernández, M. P. Sanders, B. Sanghi, A. S. Santos, G. Savage, L. Sawyer, T. Scanlon, R. D. Schamberger, Y. Scheglov, H. Schellman, T. Schliephake, S. Schlobohm, C. Schwanenberger, R. Schwienhorst, J. Sekaric, H. Severini, E. Shabalina, V. Shary, A. A. Shchukin, R. K. Shivpuri, V. Simak, V. Sirotenko, P. Skubic, P. Slattery, D. Smirnov, K. J. Smith, G. R. Snow, J. Snow, S. Snyder, S. Söldner-Rembold, L. Sonnenschein, A. Sopczak, M. Sosebee, K. Soustruznik, B. Spurlock, J. Stark, V. Stolin, D. A. Stoyanova, E. Strauss, M. Strauss, D. Strom, L. Stutte, P. Svoisky, M. Takahashi, A. Tanasijczuk, W. Taylor, M. Titov, V. V. Tokmenin, D. Tsybychev, B. Tuchming, C. Tully, P. M. Tuts, L. Uvarov, S. Uvarov S. Uzunyan, R. Van Kooten, W. M. van Leeuwen, N. Varelas, E. W. Varnes, I. A. Vasilyev, P. Verdier, L. S. Vertogradov, M. Verzocchi, M. Vesterinen, D. Vilanova, P. Vint, P. Vokac, H. D. Wahl, M. H. L. S. Wang, J. Warchol, G. Watts, M. Wayne, M. Weberg, L. Welty-Rieger, M. Wetstein, A. White, D. Wicke M. R. J. Williams, G. W. Wilson, S. J. Wimpenny, M. Wobisch, D. R. Wood, T. R. Wyatt, Y. Xie, C. Xu, S. Yacoob, R. Yamada, W. -C. Yang, T. Yasuda, Y. A. Yatsunenko, Z. Ye, H. Yin, K. Yip, H. D. Yoo, S. W. Youn, J. Yu, S. Zelitch, T. Zhao, B. Zhou, J. Zhu, M. Zielinski, D. Zieminska, L. Zivkovic
V. M. Abazov, B. Abbott, B. S. Acharya, M. Adams, T. Adams, G. D. Alexeev, G. Alkhazov, A. Altona, G. Alverson, G. A. Alves, L. S. Ancu, M. Aoki, Y. Arnoud, M. Arov, A. Askew, B. Asman, O. Atramentov, C. Avila, J. BackusMayes, F. Badaud, L. Bagby, B. Baldin, D. V. Bandurin, S. Banerjee, E. Barberis, P. Baringer, J. Barreto, J. F. Bartlett, U. Bassler, V. Bazterra, S. Beale, A. Bean, M. Begalli, M. Begel, C. Belanger-Champagne, L. Bellantoni, S. B. Beri, G. Bernardi, R. Bernhard, I. Bertram, M. Besancon, R. Beuselinck, V. A. Bezzubov, P. C. Bhat, V. Bhatnagar, G. Blazey, S. Blessing, K. Bloom, A. Boehnlein, D. Boline, T. A. Bolton, E. E. Boos, G. Borissov, T. Bose, A. Brandt, O. Brandt, R. Brock, G. Brooijmans, A. Bross, D. Brown, J. Brown, X. B. Bu, M. Buehler, V. Buescher, V. Bunichev, S. Burdinb, T. H. Burnett, C. P. Buszello, B. Calpas, E. Camacho-Perez, M. A. Carrasco-Lizarraga, B. C. K. Casey, H. Castilla-Valdez, S. Chakrabarti, D. Chakraborty, K. M. Chan, A. Chandra, G. Chen, S. Chevalier-Thery, D. K. Cho, S. W. Cho, S. Choi, B. Choudhary, T. Christoudias, S. Cihangir, D. Claes, J. Clutter, M. Cooke, W. E. Cooper, M. Corcoran, F. Couderc, M. -C. Cousinou, A. Croc, D. Cutts, M. Cwiok, A. Das, G. Davies, K. De, S. J. de Jong, E. De La Cruz-Burelo, F. Deliot, M. Demarteau, R. Demina, D. Denisov, S. P. Denisov, S. Desai, K. DeVaughan, H. T. Diehl, M. Diesburg, A. Dominguez, T. Dorland, A. Dubey, L. V. Dudko, D. Duggan, A. Duperrin, S. Dutt, A. Dyshkant, M. Eads, D. Edmunds, J. Ellison, V. D. Elvira, Y. Enari, H. Evans, A. Evdokimov, V. N. Evdokimov, G. Facini, T. Ferbel, F. Fiedler, F. Filthaut, W. Fisher, H. E. Fisk, M. Fortner, H. Fox, S. Fuess, T. Gadfort, A. Garcia-Bellido, V. Gavrilov, P. Gay, W. Geist, W. Geng, D. Gerbaudo, C. E. Gerber, Y. Gershtein, G. Ginther, G. Golovanov, A. Goussiou, P. D. Grannis, S. Greder, H. Greenlee, Z. D. Greenwood, E. M. Gregores, G. Grenier, Ph. Gris, J. -F. Grivaz, A. Grohsjean, S. Grunendahl, M. W. Grunewald, F. Guo, G. Gutierrez, P. Gutierrez, A. Haasc, S. Hagopian, J. Haley, L. Han, K. Harder, A. Harel, J. M. Hauptman, J. Hays, T. Head, T. Hebbeker, D. Hedin, H. Hegab, A. P. Heinson, U. Heintz, C. Hensel, I. Heredia-De La Cruz, K. Herner, G. Hesketh, M. D. Hildreth, R. Hirosky, T. Hoang, J. D. Hobbs, B. Hoeneisen, M. Hohlfeld, S. Hossain, Z. Hubacek, N. Huske, V. Hynek, I. Iashvili, R. Illingworth, A. S. Ito, S. Jabeen, M. Jaffre, S. Jain, D. Jamin, R. Jesik, K. Johns, M. Johnson, D. Johnston, A. Jonckheere, P. Jonsson, J. Joshi, A. Juste, K. Kaadze, E. Kajfasz, D. Karmanov, P. A. Kasper, I. Katsanos, R. Kehoe, S. Kermiche, N. Khalatyan, A. Khanov, A. Kharchilava, Y. N. Kharzheev, D. Khatidze, M. H. Kirby, J. M. Kohli, A. V. Kozelov, J. Kraus, A. Kumar, A. Kupco, T. Kurca, V. A. Kuzmin, J. Kvita, S. Lammers, G. Landsberg, P. Lebrun, H. S. Lee, S. W. Lee, W. M. Lee, J. Lellouch, L. Li, Q. Z. Li, S. M. Lietti, J. K. Lim, D. Lincoln, J. Linnemann, V. V. Lipaev, R. Lipton, Y. Liu, Z. Liu, A. Lobodenko, M. Lokajicek, P. Love, H. J. Lubatti, R. Luna-Garciae, A. L. Lyon, A. K. A. Maciel, D. Mackin, R. Madar, R. Magana-Villalba, S. Malik, V. L. Malyshev, Y. Maravin, J. Martinez-Ortega, R. McCarthy, C. L. McGivern, M. M. Meijer, A. Melnitchouk, D. Menezes, P. G. Mercadante, M. Merkin, A. Meyer, J. Meyer, N. K. Mondal, G. S. Muanza, M. Mulhearn, E. Nagy, M. Naimuddin, M. Narain, R. Nayyar, H. A. Neal, J. P. Negret, P. Neustroev, S. F. Novaes, T. Nunnemann, G. Obrant, J. Orduna, N. Osman, J. Osta, G. J. Otero y Garzon, M. Owen, M. Padilla, M. Pangilinan, N. Parashar, V. Parihar, S. K. Park, J. Parsons, R. Partridge, N. Parua, A. Patwa, B. Penning, M. Perfilov, K. Peters, Y. Peters, G. Petrillo, P. Petroff, R. Piegaia, J. Piper, M. -A. Pleier, P. L. M. Podesta-Lerma, V. M. Podstavkov, M. -E. Pol, P. Polozov, A. V. Popov, M. Prewitt, D. Price, S. Protopopescu, J. Qian, A. Quadt, B. Quinn, M. S. Rangel, K. Ranjan, P. N. Ratoff, I. Razumov, P. Renkel, P. Rich, M. Rijssenbeek, I. Ripp-Baudot, F. Rizatdinova, M. Rominsky, C. Royon, P. Rubinov, R. Ruchti, G. Safronov, G. Sajot, A. Sanchez-Hernandez, M. P. Sanders, B. Sanghi, A. S. Santos, G. Savage, L. Sawyer, T. Scanlon, R. D. Schamberger, Y. Scheglov, H. Schellman, T. Schliephake, S. Schlobohm, C. Schwanenberger, R. Schwienhorst, J. Sekaric, H. Severini, E. Shabalina, V. Shary, A. A. Shchukin, R. K. Shivpuri, V. Simak, V. Sirotenko, P. Skubic, P. Slattery, D. Smirnov, K. J. Smith, G. R. Snow, J. Snow, S. Snyder, S. Soldner-Rembold, L. Sonnenschein, A. Sopczak, M. Sosebee, K. Soustruznik, B. Spurlock, J. Stark, V. Stolin, D. A. Stoyanova, M. Strauss, D. Strom, L. Stutte, L. Suter, P. Svoisky, M. Takahashi, A. Tanasijczuk, W. Taylor, M. Titov, V. V. Tokmenin, Y. -T. Tsai, D. Tsybychev, B. Tuchming, C. Tully, P. M. Tuts, L. Uvarov, S. Uvarov, S. Uzunyan, R. Van Kooten, W. M. van Leeuwen, N. Varelas, E. W. Varnes, I. A. Vasilyev, P. Verdier, L. S. Vertogradov, M. Verzocchi, M. Vesterinen, D. Vilanova, P. Vint, P. Vokac, H. D. Wahl, M. H. L. S. Wang, J. Warchol, G. Watts, M. Wayne, M. Weberg, L. Welty-Rieger, A. White, D. Wicke, M. R. J. Williams, G. W. Wilson, S. J. Wimpenny, M. Wobisch, D. R. Wood, T. R. Wyatt, Y. Xie, C. Xu, S. Yacoob, R. Yamada, W. -C. Yang, T. Yasuda, Y. A. Yatsunenko, Z. Ye, H. Yin, K. Yip, S. W. Youn, J. Yu, S. Zelitch, T. Zhao, B. Zhou, J. Zhu, M. Zielinski, D. Zieminska, L. Zivkovic
D. S. Akerib, X. Bai, S. Bedikian, E. Bernard, A. Bernstein, A. Bradley, S. B. Cahn, M. C. Carmona-Benitez, D. Carr, J. J. Chapman, Y-D. Chan, K. Clark, T. Classen, T. Coffey, S. Dazeley, L. deViveiros, M. Dragowsky, E. Druszkiewicz, C. H. Faham, S. Fiorucci, R. J. Gaitskell, K. R. Gibson, C. Hall, M. Hanhardt, B. Holbrook, M. Ihm, R. G. Jacobsen, L. Kastens, K. Kazkaz, R. Lander, N. Larsen, C. Lee, D. Leonard, K. Lesko, A. Lyashenko, D. C. Malling, R. Mannino, D. McKinsey, D. Mei, J. Mock, M. Morii, H. Nelson, J. A. Nikkel, M. Pangilinan, P. D. Parker, P. Phelps, T. Shutt, W. Skulski, P. Sorensen, J. Spaans, T. Stiegler, R. Svoboda, A. Smith, M. Sweany, M. Szydagis, J. Thomson, M. Tripathi, J. R. Verbus, N. Walsh, R. Webb, J. T. White, M. Wlasenko, F. L. H. Wolfs, M. Woods, S. Uvarov, C. Zhang
We report on the screening of samples of titanium metal for their radio-purity. The screening process described in this work led to the selection of materials used in the construction of the cryostats for the Large Underground Xenon (LUX) dark matter experiment. Our measurements establish titanium as a highly desirable material for low background experiments searching for rare events. The sample with the lowest total long-lived activity was measured to contain <0.25 mBq/kg of U-238, <0.2 mBq/kg of Th-232, and <1.2 mBq/kg of K-40. Measurements of several samples also indicated the presence of short-lived (84 day half life) Sc-46, likely produced cosmogenically via muon initiated (n,p) reactions.
D. S. Akerib, H. M. Araujo, X. Bai, A. J. Bailey, J. Balajthy, E. Bernard, A. Bernstein, A. Bradley, D. Byram, S. B. Cahn, M. C. Carmona-Benitez, C. Chan, J. J. Chapman, A. A. Chiller, C. Chiller, T. Coffey, A. Currie, L. de Viveiros, A. Dobi, J. Dobson, E. Druszkiewicz, B. Edwards, C. H. Faham, S. Fiorucci, C. Flores, R. J. Gaitskell, V. M. Gehman, C. Ghag, K. R. Gibson, M. G. D. Gilchriese, C. Hall, S. A. Hertel, M. Horn, D. Q. Huang, M. Ihm, R. G. Jacobsen, K. Kazkaz, R. Knoche, N. A. Larsen, C. Lee, A. Lindote, M. I. Lopes, D. C. Malling, R. Mannino, D. N. McKinsey, D. -M. Mei, J. Mock, M. Moongweluwan, J. Morad, A. St. J. Murphy, C. Nehrkorn, H. Nelson, F. Neves, R. A. Ott, M. Pangilinan, P. D. Parker, E. K. Pease, K. Pech, P. Phelps, L. Reichhart, T. Shutt, C. Silva, V. N. Solovov, P. Sorensen, K. O'Sullivan, T. J. Sumner, M. Szydagis, D. Taylor, B. Tennyson, D. R. Tiedt, M. Tripathi, S. Uvarov, J. R. Verbus, N. Walsh, R. Webb, J. T. White, M. S. Witherell, F. L. H. Wolfs, M. Woods, C. Zhang
The Large Underground Xenon (LUX) dark matter experiment aims to detect rare low-energy interactions from Weakly Interacting Massive Particles (WIMPs). The radiogenic backgrounds in the LUX detector have been measured and compared with Monte Carlo simulation. Measurements of LUX high-energy data have provided direct constraints on all background sources contributing to the background model. The expected background rate from the background model for the 85.3 day WIMP search run is $(2.6\pm0.2_{\textrm{stat}}\pm0.4_{\textrm{sys}})\times10^{-3}$~events~keV$_{ee}^{-1}$~kg$^{-1}$~day$^{-1}$ in a 118~kg fiducial volume. The observed background rate is $(3.6\pm0.4_{\textrm{stat}})\times10^{-3}$~events~keV$_{ee}^{-1}$~kg$^{-1}$~day$^{-1}$, consistent with model projections. The expectation for the radiogenic background in a subsequent one-year run is presented.
M. Szydagis, D. S. Akerib, H. M. Araujo, X. Bai, A. J. Bailey, J. Balajthy, E. Bernard, A. Bernstein, A. Bradley, D. Byram, S. B. Cahn, M. C. Carmona-Benitez, C. Chan, J. J. Chapman, A. A. Chiller, C. Chiller, T. Coffey, A. Currie, L. de Viveiros, A. Dobi, J. Dobson, E. Druszkiewicz, B. Edwards, C. H. Faham, S. Fiorucci, C. Flores, R. J. Gaitskell, V. M. Gehman, C. Ghag, K. R. Gibson, M. G. D. Gilchriese, C. Hall, S. A. Hertel, M. Horn, D. Q. Huang, M. Ihm, R. G. Jacobsen, K. Kazkaz, R. Knoche, N. A. Larsen, C. Lee, A. Lindote, M. I. Lopes, D. C. Malling, R. Mannino, D. N. McKinsey, D. -M. Mei, J. Mock, M. Moongweluwan, J. Morad, A. St. J. Murphy, C. Nehrkorn, H. Nelson, F. Neves, R. A. Ott, M. Pangilinan, P. D. Parker, E. K. Pease, K. Pech, P. Phelps, L. Reichhart, T. Shutt, C. Silva, V. N. Solovov, P. Sorensen, K. O'Sullivan, T. Sumner, D. Taylor, B. Tennyson, D. R. Tiedt, M. Tripathi, S. Uvarov, J. R. Verbus, N. Walsh, R. Webb, J. T. White, M. S. Witherell, F. L. H. Wolfs, M. Woods, C. Zhang
LUX, the world's largest dual-phase xenon time-projection chamber, with a fiducial target mass of 118 kg and 10,091 kg-days of exposure thus far, is currently the most sensitive direct dark matter search experiment. The initial null-result limit on the spin-independent WIMP-nucleon scattering cross-section was released in October 2013, with a primary scintillation threshold of 2 phe, roughly 3 keVnr for LUX. The detector has been deployed at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, and is the first experiment to achieve a limit on the WIMP cross-section lower than $10^{-45}$ cm$^{2}$. Here we present a more in-depth discussion of the novel energy scale employed to better understand the nuclear recoil light and charge yields, and of the calibration sources, including the new internal tritium source. We found the LUX data to be in conflict with low-mass WIMP signal interpretations of other results.
LUX Collaboration, D. S. Akerib, S. Alsum, H. M. Araújo, X. Bai, A. J. Bailey, J. Balajthy, P. Beltrame, E. P. Bernard, A. Bernstein, T. P. Biesiadzinski, E. M. Boulton, A. Bradley, R. Bramante, P. Brás, D. Byram, S. B. Cahn, M. C. Carmona-Benitez, C. Chan, J. J. Chapman, A. A. Chiller, C. Chiller, A. Currie, J. E. Cutter, T. J. R. Davison, L. de Viveiros, A. Dobi, J. E. Y. Dobson, E. Druszkiewicz, B. N. Edwards, C. H. Faham, S. Fiorucci, R. J. Gaitskell, V. M. Gehman, C. Ghag, K. R. Gibson, M. G. D. Gilchriese, C. R. Hall, M. Hanhardt, S. J. Haselschwardt, S. A. Hertel, D. P. Hogan, M. Horn, D. Q. Huang, C. M. Ignarra, M. Ihm, R. G. Jacobsen, W. Ji, K. Kamdin, K. Kazkaz, D. Khaitan, R. Knoche, N. A. Larsen, C. Lee, B. G. Lenardo, K. T. Lesko, A. Lindote, M. I. Lopes, D. C. Malling, A. Manalaysay, R. L. Mannino, M. F. Marzioni, D. N. McKinsey, D. M. Mei, J. Mock, M. Moongweluwan, J. A. Morad, A. St. J. Murphy, C. Nehrkorn, H. N. Nelson, F. Neves, K. O'Sullivan, K. C. Oliver-Mallory, K. J. Palladino, M. Pangilinan, E. K. Pease, P. Phelps, L. Reichhart, C. A. Rhyne, S. Shaw, T. A. Shutt, C. Silva, M. Solmaz, V. N. Solovov, P. Sorensen, S. Stephenson, T. J. Sumner, M. Szydagis, D. J. Taylor, W. C. Taylor, B. P. Tennyson, P. A. Terman, D. R. Tiedt, W. H. To, M. Tripathi, L. Tvrznikova, S. Uvarov, J. R. Verbus, R. C. Webb, J. T. White, T. J. Whitis, M. S. Witherell, F. L. H. Wolfs, J. Xu, K. Yazdani, S. K. Young, C. Zhang
The Large Underground Xenon (LUX) experiment is a dual-phase liquid xenon time projection chamber (TPC) operating at the Sanford Underground Research Facility in Lead, South Dakota. A calibration of nuclear recoils in liquid xenon was performed $\textit{in situ}$ in the LUX detector using a collimated beam of mono-energetic 2.45 MeV neutrons produced by a deuterium-deuterium (D-D) fusion source. The nuclear recoil energy from the first neutron scatter in the TPC was reconstructed using the measured scattering angle defined by double-scatter neutron events within the active xenon volume. We measured the absolute charge ($Q_{y}$) and light ($L_{y}$) yields at an average electric field of 180 V/cm for nuclear recoil energies spanning 0.7 to 74 keV and 1.1 to 74 keV, respectively. This calibration of the nuclear recoil signal yields will permit the further refinement of liquid xenon nuclear recoil signal models and, importantly for dark matter searches, clearly demonstrates measured ionization and scintillation signals in this medium at recoil energies down to $\mathcal{O}$(1 keV).
LUX Collaboration, D. S. Akerib, H. M. Araújo, X. Bai, A. J. Bailey, J. Balajthy, P. Beltrame, E. P. Bernard, A. Bernstein, T. P. Biesiadzinski, E. M. Boulton, A. Bradley, R. Bramante, S. B. Cahn, M. C. Carmona-Benitez, C. Chan, J. J. Chapman, A. A. Chiller, C. Chiller, A. Currie, J. E. Cutter, T. J. R. Davison, L. de Viveiros, A. Dobi, J. E. Y. Dobson, E. Druszkiewicz, B. N. Edwards, C. H. Faham, S. Fiorucci, R. J. Gaitskell, V. M. Gehman, C. Ghag, K. R. Gibson, M. G. D. Gilchriese, C. R. Hall, M. Hanhardt, S. J. Haselschwardt, S. A. Hertel, D. P. Hogan, M. Horn, D. Q. Huang, C. M. Ignarra, M. Ihm, R. G. Jacobsen, W. Ji, K. Kazkaz, D. Khaitan, R. Knoche, N. A. Larsen, C. Lee, B. G. Lenardo, K. T. Lesko, A. Lindote, M. I. Lopes, D. C. Malling, A. G. Manalaysay, R. L. Mannino, M. F. Marzioni, D. N. McKinsey, D. M. Mei, J. Mock, M. Moongweluwan, J. A. Morad, A. St. J. Murphy, C. Nehrkorn, H. N. Nelson, F. Neves, K. O`Sullivan, K. C. Oliver-Mallory, R. A. Ott, K. J. Palladino, M. Pangilinan, E. K. Pease, P. Phelps, L. Reichhart, C. Rhyne, S. Shaw, T. A. Shutt, C. Silva, V. N. Solovov, P. Sorensen, S. Stephenson, T. J. Sumner, M. Szydagis, D. J. Taylor, W. Taylor, B. P. Tennyson, P. A. Terman, D. R. Tiedt, W. H. To, M. Tripathi, L. Tvrznikova, S. Uvarov, J. R. Verbus, R. C. Webb, J. T. White, T. J. Whitis, M. S. Witherell, F. L. H. Wolfs, S. K. Young, C. Zhang
We present measurements of the electron-recoil (ER) response of the LUX dark matter detector based upon 170,000 highly pure and spatially-uniform tritium decays. We reconstruct the tritium energy spectrum using the combined energy model and find good agreement with expectations. We report the average charge and light yields of ER events in liquid xenon at 180 V/cm and 105 V/cm and compare the results to the NEST model. We also measure the mean charge recombination fraction and its fluctuations, and we investigate the location and width of the LUX ER band. These results provide input to a re-analysis of the LUX Run3 WIMP search.
D. S. Akerib, X. Bai, S. Bedikian, E. Bernard, A. Bernstein, A. Bolozdynya, A. Bradley, D. Byram, S. B. Cahn, C. Camp, M. C. Carmona-Benitez, D. Carr, J. J. Chapman, A. Chiller, C. Chiller, K. Clark, T. Classen, T. Coffey, A. Curioni, E. Dahl, S. Dazeley, L. de Viveiros, A. Dobi, E. Dragowsky, E. Druszkiewicz, B. Edwards, C. H. Faham, S. Fiorucci, R. J. Gaitskell, K. R. Gibson, M. Gilchriese, C. Hall, M. Hanhardt, B. Holbrook, M. Ihm, R. G. Jacobsen, L. Kastens, K. Kazkaz, R. Knoche, S. Kyre, J. Kwong, R. Lander, N. A. Larsen, C. Lee, D. S. Leonard, K. T. Lesko, A. Lindote, M. I. Lopes, A. Lyashenko, D. C. Malling, R. Mannino, Z. Marquez, D. N. McKinsey, D. -M. Mei, J. Mock, M. Moongweluwan, M. Morii, H. Nelson, F. Neves, J. A. Nikkel, M. Pangilinan, P. D. Parker, E. K. Pease, K. Pech, P. Phelps, A. Rodionov, P. Roberts, A. Shei, T. Shutt, C. Silva, W. Skulski, V. N. Solovov, C. J. Sofka, P. Sorensen, J. Spaans, T. Stiegler, D. Stolp, R. Svoboda, M. Sweany, M. Szydagis, D. Taylor, J. Thomson, M. Tripathi, S. Uvarov, J. R. Verbus, N. Walsh, R. Webb, D. White, J. T. White, T. J. Whitis, M. Wlasenko, F. L. H. Wolfs, M. Woods, C. Zhang
The Large Underground Xenon (LUX) collaboration has designed and constructed a dual-phase xenon detector, in order to conduct a search for Weakly Interacting Massive Particles(WIMPs), a leading dark matter candidate. The goal of the LUX detector is to clearly detect (or exclude) WIMPS with a spin independent cross section per nucleon of $2\times 10^{-46}$ cm$^{2}$, equivalent to $\sim$1 event/100 kg/month in the inner 100-kg fiducial volume (FV) of the 370-kg detector. The overall background goals are set to have $<$1 background events characterized as possible WIMPs in the FV in 300 days of running. This paper describes the design and construction of the LUX detector.
V. M. Abazov, B. Abbott, M. Abolins, B. S. Acharya, M. Adams, T. Adams, G. D. Alexeev, G. Alkhazov, A. Altona, G. Alverson, G. A. Alves, L. S. Ancu, M. Aoki, Y. Arnoud, M. Arov, A. Askew, B. Åsman, O. Atramentov, C. Avila, J. BackusMayes, F. Badaud, L. Bagby, B. Baldin, D. V. Bandurin, S. Banerjee, E. Barberis, P. Baringer, J. Barreto, J. F. Bartlett, U. Bassler, V. Bazterra, S. Beale, A. Bean, M. Begalli, M. Begel, C. Belanger-Champagne, L. Bellantoni, S. B. Beri, G. Bernardi, R. Bernhard, I. Bertram, M. Besançon, R. Beuselinck, V. A. Bezzubov, P. C. Bhat, V. Bhatnagar, G. Blazey, S. Blessing, K. Bloom, A. Boehnlein, D. Boline, T. A. Bolton, E. E. Boos, G. Borissov, T. Bose, A. Brandt, O. Brandt, R. Brock, G. Brooijmans, A. Bross, D. Brown, J. Brown, X. B. Bu, D. Buchholz, M. Buehler, V. Buescher, V. Bunichev, S. Burdinb, T. H. Burnett, C. P. Buszello, B. Calpas, E. Camacho-Pérez, M. A. Carrasco-Lizarraga, B. C. K. Casey, H. Castilla-Valdez, S. Chakrabarti, D. Chakraborty, K. M. Chan, A. Chandra, G. Chen, S. Chevalier-Théry, D. K. Cho, S. W. Cho, S. Choi, B. Choudhary, T. Christoudias, S. Cihangir, D. Claes, J. Clutter, M. Cooke, W. E. Cooper, M. Corcoran, F. Couderc, M. -C. Cousinou, A. Croc, D. Cutts, M. Ćwiok, A. Das, G. Davies, K. De, S. J. de Jong, E. De La Cruz-Burelo, F. Déliot, M. Demarteau, 47 R. Demina, D. Denisov, S. P. Denisov, S. Desai, K. DeVaughan, H. T. Diehl, M. Diesburg, A. Dominguez, T. Dorland, A. Dubey, L. V. Dudko, D. Duggan, A. Duperrin, S. Dutt, A. Dyshkant, M. Eads, D. Edmunds, J. Ellison, V. D. Elvira, Y. Enari, S. Eno, H. Evans, A. Evdokimov, V. N. Evdokimov, G. Facini, T. Ferbel, F. Fiedler, F. Filthaut, W. Fisher, H. E. Fisk, M. Fortner, H. Fox, S. Fuess, T. Gadfort, A. Garcia-Bellido, V. Gavrilov, P. Gay, W. Geist, W. Geng, D. Gerbaudo, C. E. Gerber, Y. Gershtein, G. Ginther, G. Golovanov, A. Goussiou, P. D. Grannis, S. Greder, H. Greenlee, Z. D. Greenwood, E. M. Gregores, G. Grenier, Ph. Gris, J. -F. Grivaz, A. Grohsjean, S. Grünendahl, M. W. Grünewald, F. Guo, J. Guo, G. Gutierrez, P. Gutierrez, A. Haasc, S. Hagopian, J. Haley, L. Han, K. Harder, A. Harel, J. M. Hauptman, J. Hays, T. Head, T. Hebbeker, D. Hedin, H. Hegab, A. P. Heinson, U. Heintz, C. Hensel, I. Heredia-De La Cruz, K. Herner, G. Hesketh, M. D. Hildreth, R. Hirosky, T. Hoang, J. D. Hobbs, B. Hoeneisen, M. Hohlfeld, S. Hossain, Z. Hubacek, N. Huske, V. Hynek, I. Iashvili, R. Illingworth, A. S. Ito, S. Jabeen, M. Jaffré, S. Jain, D. Jamin, R. Jesik, K. Johns, M. Johnson, D. Johnston, A. Jonckheere, P. Jonsson, J. Joshi, A. Justed, K. Kaadze, E. Kajfasz, D. Karmanov, P. A. Kasper, I. Katsanos, R. Kehoe, S. Kermiche, N. Khalatyan, A. Khanov, A. Kharchilava, Y. N. Kharzheev, D. Khatidze, M. H. Kirby, J. M. Kohli, A. V. Kozelov, J. Kraus, A. Kumar, A. Kupco, T. Kurča, V. A. Kuzmin, J. Kvita, S. Lammers, G. Landsberg, P. Lebrun, H. S. Lee, S. W. Lee, W. M. Lee, J. Lellouch, L. Li, Q. Z. Li, S. M. Lietti, J. K. Lim, D. Lincoln, J. Linnemann, V. V. Lipaev, R. Lipton, Y. Liu, Z. Liu, A. Lobodenko, M. Lokajicek, P. Love, H. J. Lubatti, R. Luna-Garciae, A. L. Lyon, A. K. A. Maciel, D. Mackin, R. Madar, R. Magaña-Villalba, S. Malik, V. L. Malyshev, Y. Maravin, J. Martínez-Ortega, R. McCarthy, C. L. McGivern, M. M. Meijer, A. Melnitchouk, D. Menezes, P. G. Mercadante, M. Merkin, A. Meyer, J. Meyer, N. K. Mondal, G. S. Muanza, M. Mulhearn, E. Nagy, M. Naimuddin, M. Narain, R. Nayyar, H. A. Neal, J. P. Negret, P. Neustroev, S. F. Novaes, T. Nunnemann, G. Obrant, J. Orduna, N. Osman, J. Osta, G. J. Otero y Garzón, M. Owen, M. Padilla, M. Pangilinan, N. Parashar, V. Parihar, S. K. Park, J. Parsons, R. Partridgec, N. Parua, A. Patwa, B. Penning, M. Perfilov, K. Peters, Y. Peters, G. Petrillo, P. Pétroff, R. Piegaia, J. Piper, M. -A. Pleier, P. L. M. Podesta-Lermaf, V. M. Podstavkov, M. -E. Pol, P. Polozov, A. V. Popov, M. Prewitt, D. Price, S. Protopopescu, J. Qian, A. Quadt, B. Quinn, M. S. Rangel, K. Ranjan, P. N. Ratoff, I. Razumov, P. Renkel, P. Rich, M. Rijssenbeek, I. Ripp-Baudot, F. Rizatdinova, M. Rominsky, C. Royon, P. Rubinov, R. Ruchti, G. Safronov, G. Sajot, A. Sánchez-Hernández, M. P. Sanders, B. Sanghi, A. S. Santos, G. Savage, L. Sawyer, T. Scanlon, R. D. Schamberger, Y. Scheglov, H. Schellman, T. Schliephake, S. Schlobohm, C. Schwanenberger, R. Schwienhorst, J. Sekaric, H. Severini, E. Shabalina, V. Shary, A. A. Shchukin, R. K. Shivpuri, V. Simak, V. Sirotenko, P. Skubic, P. Slattery, D. Smirnov, K. J. Smith, G. R. Snow, J. Snow, S. Snyder, S. Söldner-Rembold, L. Sonnenschein, A. Sopczak, M. Sosebee, K. Soustruznik, B. Spurlock, J. Stark, V. Stolin, D. A. Stoyanova, E. Strauss, M. Strauss, D. Strom, L. Stutte, P. Svoisky, M. Takahashi, A. Tanasijczuk, W. Taylor, M. Titov, V. V. Tokmenin, D. Tsybychev, B. Tuchming, C. Tully, P. M. Tuts, L. Uvarov, S. Uvarov S. Uzunyan, R. Van Kooten, W. M. van Leeuwen, N. Varelas, E. W. Varnes, I. A. Vasilyev, P. Verdier, L. S. Vertogradov, M. Verzocchi, M. Vesterinen, D. Vilanova, P. Vint, P. Vokac, H. D. Wahl, M. H. L. S. Wang, J. Warchol, G. Watts, M. Wayne, M. Weberg, L. Welty-Rieger, M. Wetstein, A. White, D. Wicke M. R. J. Williams, G. W. Wilson, S. J. Wimpenny, M. Wobisch, D. R. Wood, T. R. Wyatt, Y. Xie, C. Xu, S. Yacoob, R. Yamada, W. -C. Yang, T. Yasuda, Y. A. Yatsunenko, Z. Ye, H. Yin, K. Yip, H. D. Yoo, S. W. Youn, J. Yu, S. Zelitch, T. Zhao, B. Zhou, J. Zhu, M. Zielinski, D. Zieminska, L. Zivkovic
D. C. Malling, D. S. Akerib, H. M. Araujo, X. Bai, S. Bedikian, E. Bernard, A. Bernstein, A. Bradley, S. B. Cahn, M. C. Carmona-Benitez, D. Carr, J. J. Chapman, K. Clark, T. Classen, T. Coffey, A. Curioni, A. Currie, S. Dazeley, L. de Viveiros, M. Dragowsky, E. Druszkiewicz, C. H. Faham, S. Fiorucci, R. J. Gaitskell, K. R. Gibson, C. Hall, M. Hanhardt, B. Holbrook, M. Ihm, R. G. Jacobsen, L. Kastens, K. Kazkaz, R. Lander, N. Larsen, C. Lee, D. Leonard, K. Lesko, A. Lindote, M. I. Lopes, A. Lyashenko, P. Majewski, R. Mannino, D. N. McKinsey, D. -M. Mei, J. Mock, M. Morii, A. St J. Murphy, H. Nelson, F. Neves, J. A. Nikkel, M. Pangilinan, P. Phelps, L. Reichhart, T. Shutt, C. Silva, W. Skulski, V. Solovov, P. Sorensen, J. Spaans, T. Stiegler, T. J. Sumner, R. Svoboda, M. Sweany, M. Szydagis, J. Thomson, M. Tripathi, J. R. Verbus, N. Walsh, R. Webb, J. T. White, M. Wlasenko, F. L. H. Wolfs, M. Woods, C. Zhang
The LZ program consists of two stages of direct dark matter searches using liquid Xe detectors. The first stage will be a 1.5-3 tonne detector, while the last stage will be a 20 tonne detector. Both devices will benefit tremendously from research and development performed for the LUX experiment, a 350 kg liquid Xe dark matter detector currently operating at the Sanford Underground Laboratory. In particular, the technology used for cryogenics and electrical feedthroughs, circulation and purification, low-background materials and shielding techniques, electronics, calibrations, and automated control and recovery systems are all directly scalable from LUX to the LZ detectors. Extensive searches for potential background sources have been performed, with an emphasis on previously undiscovered background sources that may have a significant impact on tonne-scale detectors. The LZ detectors will probe spin-independent interaction cross sections as low as 5E-49 cm2 for 100 GeV WIMPs, which represents the ultimate limit for dark matter detection with liquid xenon technology.
D. C. Malling, S. Fiorucci, M. Pangilinan, J. J. Chapman, C. H. Faham, J. R. Verbus, R. J. Gaitskell
May 22, 2013·astro-ph.IM·PDF Dark matter direct-detection searches for weakly interacting massive particles (WIMPs) are commonly limited in sensitivity by neutron and gamma backgrounds from the decay of radioactive isotopes. Several common radioisotopes in detector construction materials are found in long decay chains, notably those headed by 238U, 235U, and 232Th. Gamma radioassay using Ge detectors identifies decay rates of a few of the radioisotopes in each chain, and typically assumes that the chain is in secular equilibrium. If the chains are out of equilibrium, detector background rates can be elevated significantly above expectation. In this work we quantify the increase in neutron and gamma production rates from an excess of various sub-chains of the 238U decay chain. We find that the 226Ra sub-chain generates x10 higher neutron flux per decay than the 238U early sub-chain and 210Pb sub-chain, in materials with high (alpha,n) neutron yields. Typical gamma screening results limit potential 238U early sub-chain activity to x20-60 higher than 226Ra sub-chain activity. Monte Carlo simulation is used to quantify the contribution of the sub-chains of 238U to low-energy nuclear recoil (NR) and electron recoil (ER) backgrounds in simplified one tonne liquid Ar and liquid Xe detectors. NR and ER rates generated by 238U sub-chains in the Ar and Xe detectors are found after comparable fiducial and multiple-scatter cuts. The Xe detector is found to have x12 higher signal-to-background for 100 GeV WIMPs over neutrons than the Ar detector. ER backgrounds in both detectors are found to increase weakly for excesses of 238U early sub-chain and 210Pb sub-chain relative to 226Ra sub-chain. Experiments in which backgrounds are NR-dominated are sensitive to undetected excesses of 238U early sub-chain and 210Pb sub-chain concentrations. Experiments with ER-dominated backgrounds are relatively insensitive to these excesses.
D. S. Akerib, X. Bai, E. Bernard, A. Bernstein, A. Bradley, D. Byram, S. B. Cahn, M. C. Carmona-Benitez, D. Carr, J. J. Chapman, Y-D. Chan, K. Clark, T. Coffey, L. deViveiros, M. Dragowsky, E. Druszkiewicz, B. Edwards, C. H. Faham, S. Fiorucci, R. J. Gaitskell, K. R. Gibson, C. Hall, M. Hanhardt, B. Holbrook, M. Ihm, R. G. Jacobsen, L. Kastens, K. Kazkaz, N. Larsen, C. Lee, K. Lesko, A. Lindote, M. I. Lopes, A. Lyashenko, D. C. Malling, R. Mannino, D. McKinsey, D. Mei, J. Mock, M. Morii, H. Nelson, F. Neves, J. A. Nikkel, M. Pangilinan, K. Pech, P. Phelps, T. Shutt, C. Silva, W. Skulski, V. N. Solovov, P. Sorensen, J. Spaans, T. Stiegler, M. Sweany, M. Szydagis, D. Taylor, J. Thomson, M. Tripathi, S. Uvarov, J. R. Verbus, N. Walsh, R. Webb, J. T. White, M. Wlasenko, F. L. H. Wolfs, M. Woods, C. Zhang
Results are presented from radioactivity screening of two models of photomultiplier tubes designed for use in current and future liquid xenon experiments. The Hamamatsu 5.6 cm diameter R8778 PMT, used in the LUX dark matter experiment, has yielded a positive detection of four common radioactive isotopes: 238U, 232Th, 40K, and 60Co. Screening of LUX materials has rendered backgrounds from other detector materials subdominant to the R8778 contribution. A prototype Hamamatsu 7.6 cm diameter R11410 MOD PMT has also been screened, with benchmark isotope counts measured at <0.4 238U / <0.3 232Th / <8.3 40K / 2.0+-0.2 60Co mBq/PMT. This represents a large reduction, equal to a change of \times 1/24 238U / \times 1/9 232Th / \times 1/8 40K per PMT, between R8778 and R11410 MOD, concurrent with a doubling of the photocathode surface area (4.5 cm to 6.4 cm diameter). 60Co measurements are comparable between the PMTs, but can be significantly reduced in future R11410 MOD units through further material selection. Assuming PMT activity equal to the measured 90% upper limits, Monte Carlo estimates indicate that replacement of R8778 PMTs with R11410 MOD PMTs will change LUX PMT electron recoil background contributions by a factor of \times1/25 after further material selection for 60Co reduction, and nuclear recoil backgrounds by a factor of \times 1/36. The strong reduction in backgrounds below the measured R8778 levels makes the R11410 MOD a very competitive technology for use in large-scale liquid xenon detectors.