R. Agnese, A. J. Anderson, D. Balakishiyeva, R. Basu Thakur, D. A. Bauer, A. Borgland, D. Brandt, P. L. Brink, R. Bunker, B. Cabrera, D. O. Caldwell, D. G. Cerdeno, H. Chagani, M. Cherry, J. Cooley, B. Cornell, C. H. Crewdson, P. Cushman, M. Daal, P. C. F. Di Stefano, E. Do Couto E Silva, T. Doughty, L. Esteban, S. Fallows, E. Figueroa-Feliciano, J. Fox, M. Fritts, G. L. Godfrey, S. R. Golwala, J. Hall, H. R. Harris, J. Hasi, S. A. Hertel, B. A. Hines, T. Hofer, D. Holmgren, L. Hsu, M. E. Huber, A. Jastram, O. Kamaev, B. Kara, M. H. Kelsey, S. A. Kenany, A. Kennedy, C. J. Kenney, M. Kiveni, K. Koch, B. Loer, E. Lopez Asamar, R. Mahapatra, V. Mandic, C. Martinez, K. A. McCarthy, N. Mirabolfathi, R. A. Moffatt, D. C. Moore, P. Nadeau, R. H. Nelson, L. Novak, K. Page, R. Partridge, M. Pepin, A. Phipps, K. Prasad, M. Pyle, H. Qiu, R. Radpour, W. Rau, P. Redl, A. Reisetter, R. W. Resch, Y. Ricci, T. Saab, B. Sadoulet, J. Sander, R. Schmitt, K. Schneck, R. W. Schnee, S. Scorza, D. Seitz, B. Serfass, B. Shank, D. Speller, A. Tomada, A. N. Villano, B. Welliver, D. H. Wright, S. Yellin, J. J. Yen, B. A. Young, J. Zhang
The SuperCDMS experiment in the Soudan Underground Laboratory searches for dark matter with a 9-kg array of cryogenic germanium detectors. Symmetric sensors on opposite sides measure both charge and phonons from each particle interaction, providing excellent discrimination between electron and nuclear recoils, and between surface and interior events. Surface event rejection capabilities were tested with two $^{210}$Pb sources producing $\sim$130 beta decays/hr. In $\sim$800 live hours, no events leaked into the 8--115 keV signal region, giving upper limit leakage fraction $1.7 \times 10^{-5}$ at 90% C.L., corresponding to $< 0.6$ surface event background in the future 200-kg SuperCDMS SNOLAB experiment.
R. Agnese, A. J. Anderson, D. Balakishiyeva, R. Basu Thakur, D. A. Bauer, J. Billard, A. Borgland, M. A. Bowles, D. Brandt, P. L. Brink, R. Bunker, B. Cabrera, D. O. Caldwell, D. G. Cerdeno, H. Chagani, Y. Chen, J. Cooley, B. Cornell, C. H. Crewdson, P. Cushman, M. Daal, P. C. F. Di Stefano, T. Doughty, L. Esteban, S. Fallows, E. Figueroa-Feliciano, G. L. Godfrey, S. R. Golwala, J. Hall, H. R. Harris, S. A. Hertel, T. Hofer, D. Holmgren, L. Hsu, M. E. Huber, A. Jastram, O. Kamaev, B. Kara, M. H. Kelsey, A. Kennedy, M. Kiveni, K. Koch, A. Leder, B. Loer, E. Lopez Asamar, R. Mahapatra, V. Mandic, C. Martinez, K. A. McCarthy, N. Mirabolfathi, R. A. Moffatt, D. C. Moore, H. Nelson, R. H. Nelson, R. W. Ogburn, K. Page, W. A. Page, R. Partridge, M. Pepin, A. Phipps, K. Prasad, M. Pyle, H. Qiu, W. Rau, P. Redl, A. Reisetter, Y. Ricci, H. E. Rogers, T. Saab, B. Sadoulet, J. Sander, K. Schneck, R. W. Schnee, S. Scorza, B. Serfass, B. Shank, D. Speller, S. Upadhyayula, A. N. Villano, B. Welliver, D. H. Wright, S. Yellin, J. J. Yen, B. A. Young, J. Zhang
While the Standard Model of particle physics does not include free particles with fractional charge, experimental searches have not ruled out their existence. We report results from the Cryogenic Dark Matter Search (CDMS II) experiment that give the first direct-detection limits for cosmogenically-produced relativistic particles with electric charge lower than $e$/6. A search for tracks in the six stacked detectors of each of two of the CDMS II towers found no candidates, thereby excluding new parameter space for particles with electric charges between $e$/6 and $e$/200.
SuperCDMS Collaboration, R. Agnese, T. Aramaki, I. J. Arnquist, W. Baker, D. Balakishiyeva, S. Banik, D. Barker, R. Basu Thakur, D. A. Bauer, T. Binder, M. A. Bowles, P. L. Brink, R. Bunker, B. Cabrera, D. O. Caldwell, R. Calkins, C. Cartaro, D. G. Cerdeño, Y. Chang, Y. Chen, J. Cooley, B. Cornell, P. Cushman, M. Daal, P. C. F. Di Stefano, T. Doughty, E. Fascione, E. Figueroa-Feliciano, M. Fritts, G. Gerbier, R. Germond, M. Ghaith, G. L. Godfrey, S. R. Golwala, J. Hall, H. R. Harris, Z. Hong, E. W. Hoppe, L. Hsu, M. E. Huber, V. Iyer, D. Jardin, A. Jastram, C. Jena, M. H. Kelsey, A. Kennedy, A. Kubik, N. A. Kurinsky, B. Loer, E. Lopez Asamar, P. Lukens, D. MacDonell, R. Mahapatra, V. Mandic, N. Mast, E. H. Miller, N. Mirabolfathi, B. Mohanty, J. D. Morales Mendoza, J. Nelson, J. L. Orrell, S. M. Oser, K. Page, W. A. Page, R. Partridge, M. Penalver Martinez, M. Pepin, A. Phipps, S. Poudel, M. Pyle, H. Qiu, W. Rau, P. Redl, A. Reisetter, T. Reynolds, A. Roberts, A. E. Robinson, H. E. Rogers, T. Saab, B. Sadoulet, J. Sander, K. Schneck, R. W. Schnee, S. Scorza, K. Senapati, B. Serfass, D. Speller, M. Stein, J. Street, H. A. Tanaka, D. Toback, R. Underwood, A. N. Villano, B. von Krosigk, B. Welliver, J. S. Wilson, M. J. Wilson, D. H. Wright, S. Yellin, J. J. Yen, B. A. Young, X. Zhang, X. Zhao
We report the result of a blinded search for Weakly Interacting Massive Particles (WIMPs) using the majority of the SuperCDMS Soudan dataset. With an exposure of 1690 kg days, a single candidate event is observed, consistent with expected backgrounds. This analysis (combined with previous Ge results) sets an upper limit on the spin-independent WIMP--nucleon cross section of $1.4 \times 10^{-44}$ ($1.0 \times 10^{-44}$) cm$^2$ at 46 GeV/$c^2$. These results set the strongest limits for WIMP--germanium-nucleus interactions for masses $>$12 GeV/$c^2$.
SuperCDMS Collaboration, R. Agnese, A. J. Anderson, T. Aralis, T. Aramaki, I. J. Arnquist, W. Baker, D. Balakishiyeva, D. Barker, R. Basu Thakur, D. A. Bauer, T. Binder, M. A. Bowles, P. L. Brink, R. Bunker, B. Cabrera, D. O. Caldwell, R. Calkins, C. Cartaro, D. G. Cerdeno, Y. Chang, H. Chagani, Y. Chen, J. Cooley, B. Cornell, P. Cushman, M. Daal, P. C. F. Di Stefano, T. Doughty, L. Esteban, E. Fascione, E. Figueroa-Feliciano, M. Fritts, G. Gerbier, M. Ghaith, G. L. Godfrey, S. R. Golwala, J. Hall, H. R. Harris, Z. Hong, E. W. Hoppe, L. Hsu, M. E. Huber, V. Iyer, D. Jardin, A. Jastram, C. Jena, M. H. Kelsey, A. Kennedy, A. Kubik, N. A. Kurinsky, A. Leder, B. Loer, E. Lopez Asamar, P. Lukens, D. MacDonell, R. Mahapatra, V. Mandic, N. Mast, E. H. Miller, N. Mirabolfathi, R. A. Moffatt, B. Mohanty, J. D. Morales Mendoza, J. Nelson, J. L. Orrell, S. M. Oser, K. Page, W. A. Page, R. Partridge, M. Pepin, M. Penalver Martinez, A. Phipps, S. Poudel, M. Pyle, H. Qiu, W. Rau, P. Redl, A. Reisetter, T. Reynolds, A. Roberts, A. E. Robinson, H. E. Rogers, T. Saab, B. Sadoulet, J. Sander, K. Schneck, R. W. Schnee, S. Scorza, K. Senapati, B. Serfass, D. Speller, M. Stein, J. Street, H. A. Tanaka, D. Toback, R. Underwood, A. N. Villano, B. von Krosigk, B. Welliver, J. S. Wilson, M. J Wilson, D. H. Wright, S. Yellin, J. J. Yen, B. A. Young, X. Zhang, X. Zhao
The SuperCDMS experiment is designed to directly detect weakly interacting massive particles (WIMPs) that may constitute the dark matter in our Galaxy. During its operation at the Soudan Underground Laboratory, germanium detectors were run in the CDMSlite mode to gather data sets with sensitivity specifically for WIMPs with masses ${<}$10 GeV/$c^2$. In this mode, a higher detector-bias voltage is applied to amplify the phonon signals produced by drifting charges. This paper presents studies of the experimental noise and its effect on the achievable energy threshold, which is demonstrated to be as low as 56 eV$_{\text{ee}}$ (electron equivalent energy). The detector-biasing configuration is described in detail, with analysis corrections for voltage variations to the level of a few percent. Detailed studies of the electric-field geometry, and the resulting successful development of a fiducial parameter, eliminate poorly measured events, yielding an energy resolution ranging from ${\sim}$9 eV$_{\text{ee}}$ at 0 keV to 101 eV$_{\text{ee}}$ at ${\sim}$10 eV$_{\text{ee}}$. New results are derived for astrophysical uncertainties relevant to the WIMP-search limits, specifically examining how they are affected by variations in the most probable WIMP velocity and the Galactic escape velocity. These variations become more important for WIMP masses below 10 GeV/$c^2$. Finally, new limits on spin-dependent low-mass WIMP-nucleon interactions are derived, with new parameter space excluded for WIMP masses $\lesssim$3 GeV/$c^2$
SuperCDMS Collaboration, R. Agnese, A. J. Anderson, T. Aramaki, M. Asai, W. Baker, D. Balakishiyeva, D. Barker, R. Basu Thakur, D. A. Bauer, J. Billard, A. Borgland, M. A. Bowles, P. L. Brink, R. Bunker, B. Cabrera, D. O. Caldwell, R. Calkins, D. G. Cerdeno, H. Chagani, Y. Chen, J. Cooley, B. Cornell, P. Cushman, M. Daal, P. C. F. Di Stefano, T. Doughty, L. Esteban, S. Fallows, E. Figueroa-Feliciano, M. Ghaith, G. L. Godfrey, S. R. Golwala, J. Hall, H. R. Harris, T. Hofer, D. Holmgren, L. Hsu, M. E. Huber, D. Jardin, A. Jastram, O. Kamaev, B. Kara, M. H. Kelsey, A. Kennedy, A. Leder, B. Loer, E. Lopez Asamar, P. Lukens, R. Mahapatra, V. Mandic, N. Mast, N. Mirabolfathi, R. A. Moffatt, J. D. Morales Mendoza, S. M. Oser, K. Page, W. A. Page, R. Partridge, M. Pepin, A. Phipps, K. Prasad, M. Pyle, H. Qiu, W. Rau, P. Redl, A. Reisetter, Y. Ricci, A. Roberts, H. E. Rogers, T. Saab, B. Sadoulet, J. Sander, K. Schneck, R. W. Schnee, S. Scorza, B. Serfass, B. Shank, D. Speller, D. Toback, R. Underwood, S. Upadhyayula, A. N. Villano, B. Welliver, J. S. Wilson, D. H. Wright, S. Yellin, J. J. Yen, B. A. Young, J. Zhang
The CDMS low ionization threshold experiment (CDMSlite) uses cryogenic germanium detectors operated at a relatively high bias voltage to amplify the phonon signal in the search for weakly interacting massive particles (WIMPs). Results are presented from the second CDMSlite run with an exposure of 70 kg days, which reached an energy threshold for electron recoils as low as 56 eV. A fiducialization cut reduces backgrounds below those previously reported by CDMSlite. New parameter space for the WIMP-nucleon spin-independent cross section is excluded for WIMP masses between 1.6 and 5.5 GeV/$c^2$.
R. Agnese, A. J. Anderson, T. Aramaki, W. Baker, D. Balakishiyeva, S. Banik, D. Barker, R. Basu Thakur, D. A. Bauer, T. Binder, A. Borgland, M. A. Bowles, P. L. Brink, R. Bunker, B. Cabrera, D. O. Caldwell, R. Calkins, C. Cartaro, D. G. Cerdeno, H. Chagani, Y. -Y. Chang, Y. Chen, J. Cooley, B. Cornell, P. Cushman, M. Daal, T. Doughty, E. M. Dragowsky, L. Esteban, S. Fallows, E. Fascione, E. Figueroa-Feliciano, M. Fritts, G. Gerbier, R. Germond, M. Ghaith, G. L. Godfrey, S. R. Golwala, J. Hall, H. R. Harris, D. Holmgren, Z. Hong, L. Hsu, M. E. Huber, V. Iyer, D. Jardin, A. Jastram, C. Jena, M. H. Kelsey, A. Kennedy, A. Kubik, N. A. Kurinsky, A. Leder, E. Lopez Asamar, P. Lukens, D. MacDonell, R. Mahapatra, V. Mandic, N. Mast, K. A. McCarthy, E. H. Miller, N. Mirabolfathi, R. A. Moffatt, B. Mohanty, D. Moore, J. D. Morales Mendoza, J. Nelson, S. M. Oser, K. Page, W. A. Page, R. Partridge, M. Penalver Martinez, M. Pepin, A. Phipps, S. Poudel, M. Pyle, H. Qiu, W. Rau, P. Redl, A. Reisetter, A. Roberts, H. E. Rogers, A. E. Robinson, T. Saab, B. Sadoulet, J. Sander, K. Schneck, R. W. Schnee, S. Scorza, K. Senapati, B. Serfass, D. Speller, P. C. F. Di Stefano, M. Stein, J. Street, H. A. Tanaka, D. Toback, R. Underwood, A. N. Villano, B. von Krosigk, B. Welliver, J. S. Wilson, M. J. Wilson, D. H. Wright, S. Yellin, J. J. Yen, B. A. Young, X. Zhang, X. Zhao
The Cryogenic Dark Matter Search (CDMS II) experiment aims to detect dark matter particles that elastically scatter from nuclei in semiconductor detectors. The resulting nuclear-recoil energy depositions are detected by ionization and phonon sensors. Neutrons produce a similar spectrum of low-energy nuclear recoils in such detectors, while most other backgrounds produce electron recoils. The absolute energy scale for nuclear recoils is necessary to interpret results correctly. The energy scale can be determined in CDMS II silicon detectors using neutrons incident from a broad-spectrum $^{252}$Cf source, taking advantage of a prominent resonance in the neutron elastic scattering cross section of silicon at a recoil (neutron) energy near 20 (182) keV. Results indicate that the phonon collection efficiency for nuclear recoils is $4.8^{+0.7}_{-0.9}$% lower than for electron recoils of the same energy. Comparisons of the ionization signals for nuclear recoils to those measured previously by other groups at higher electric fields indicate that the ionization collection efficiency for CDMS II silicon detectors operated at $\sim$4 V/cm is consistent with 100% for nuclear recoils below 20 keV and gradually decreases for larger energies to $\sim$75% at 100 keV. The impact of these measurements on previously published CDMS II silicon results is small.
R. Agnese, A. J. Anderson, T. Aramaki, I. Arnquist, W. Baker, D. Barker, R. Basu Thakur, D. A. Bauer, A. Borgland, M. A. Bowles, P. L. Brink, R. Bunker, B. Cabrera, D. O. Caldwell, R. Calkins, C. Cartaro, D. G. Cerdeño, H. Chagani, Y. Chen, J. Cooley, B. Cornell, P. Cushman, M. Daal, P. C. F. Di Stefano, T. Doughty, L. Esteban, S. Fallows, E. Figueroa-Feliciano, M. Fritts, G. Gerbier, M. Ghaith, G. L. Godfrey, S. R. Golwala, J. Hall, H. R. Harris, T. Hofer, D. Holmgren, Z. Hong, E. Hoppe, L. Hsu, M. E. Huber, V. Iyer, D. Jardin, A. Jastram, M. H. Kelsey, A. Kennedy, A. Kubik, N. A. Kurinsky, A. Leder, B. Loer, E. Lopez Asamar, P. Lukens, R. Mahapatra, V. Mandic, N. Mast, N. Mirabolfathi, R. A. Moffatt, J. D. Morales Mendoza, J. L. Orrell, S. M. Oser, K. Page, W. A. Page, R. Partridge, M. Pepin, A. Phipps, S. Poudel, M. Pyle, H. Qiu, W. Rau, P. Redl, A. Reisetter, A. Roberts, A. E. Robinson, H. E. Rogers, T. Saab, B. Sadoulet, J. Sander, K. Schneck, R. W. Schnee, B. Serfass, D. Speller, M. Stein, J. Street, H. A. Tanaka, D. Toback, R. Underwood, A. N. Villano, B. von Krosigk, B. Welliver, J. S. Wilson, D. H. Wright, S. Yellin, J. J. Yen, B. A. Young, X. Zhang, X. Zhao
SuperCDMS SNOLAB will be a next-generation experiment aimed at directly detecting low-mass (< 10 GeV/c$^2$) particles that may constitute dark matter by using cryogenic detectors of two types (HV and iZIP) and two target materials (germanium and silicon). The experiment is being designed with an initial sensitivity to nuclear recoil cross sections ~ 1 x 10$^{-43}$ cm$^2$ for a dark matter particle mass of 1 GeV/c$^2$, and with capacity to continue exploration to both smaller masses and better sensitivities. The phonon sensitivity of the HV detectors will be sufficient to detect nuclear recoils from sub-GeV dark matter. A detailed calibration of the detector response to low energy recoils will be needed to optimize running conditions of the HV detectors and to interpret their data for dark matter searches. Low-activity shielding, and the depth of SNOLAB, will reduce most backgrounds, but cosmogenically produced $^{3}$H and naturally occurring $^{32}$Si will be present in the detectors at some level. Even if these backgrounds are x10 higher than expected, the science reach of the HV detectors would be over three orders of magnitude beyond current results for a dark matter mass of 1 GeV/c$^2$. The iZIP detectors are relatively insensitive to variations in detector response and backgrounds, and will provide better sensitivity for dark matter particle masses (> 5 GeV/c$^2$). The mix of detector types (HV and iZIP), and targets (germanium and silicon), planned for the experiment, as well as flexibility in how the detectors are operated, will allow us to maximize the low-mass reach, and understand the backgrounds that the experiment will encounter. Upgrades to the experiment, perhaps with a variety of ultra-low-background cryogenic detectors, will extend dark matter sensitivity down to the "neutrino floor", where coherent scatters of solar neutrinos become a limiting background.
R. Agnese, A. J. Anderson, M. Asai, D. Balakishiyeva, R. Basu Thakur, D. A. Bauer, J. Beaty, J. Billard, A. Borgland, M. A. Bowles, D. Brandt, P. L. Brink, R. Bunker, B. Cabrera, D. O. Caldwell, D. G. Cerdeno, H. Chagani, Y. Chen, M. Cherry, J. Cooley, B. Cornell, C. H. Crewdson, P. Cushman, M. Daal, D. DeVaney, P. C. F. Di Stefano, E. Do Couto E Silva, T. Doughty, L. Esteban, S. Fallows, E. Figueroa-Feliciano, G. L. Godfrey, S. R. Golwala, J. Hall, S. Hansen, H. R. Harris, S. A. Hertel, B. A. Hines, T. Hofer, D. Holmgren, L. Hsu, M. E. Huber, A. Jastram, O. Kamaev, B. Kara, M. H. Kelsey, S. Kenany, A. Kennedy, M. Kiveni, K. Koch, A. Leder, B. Loer, E. Lopez Asamar, R. Mahapatra, V. Mandic, C. Martinez, K. A. McCarthy, N. Mirabolfathi, R. A. Moffatt, R. H. Nelson, L. Novak, K. Page, R. Partridge, M. Pepin, A. Phipps, M. Platt, K. Prasad, M. Pyle, H. Qiu, W. Rau, P. Redl, A. Reisetter, R. W. Resch, Y. Ricci, M. Ruschman, T. Saab, B. Sadoulet, J. Sander, R. L. Schmitt, K. Schneck, R. W. Schnee, S. Scorza, D. N. Seitz, B. Serfass, B. Shank, D. Speller, A. Tomada, S. Upadhyayula, A. N. Villano, B. Welliver, D. H. Wright, S. Yellin, J. J. Yen, B. A. Young, J. Zhang
We report a first search for weakly interacting massive particles (WIMPs) using the background rejection capabilities of SuperCDMS. An exposure of 577 kg-days was analyzed for WIMPs with mass < 30 GeV/c2, with the signal region blinded. Eleven events were observed after unblinding. We set an upper limit on the spin-independent WIMP-nucleon cross section of 1.2e-42 cm2 at 8 GeV/c2. This result is in tension with WIMP interpretations of recent experiments and probes new parameter space for WIMP-nucleon scattering for WIMP masses < 6 GeV/c2.
CDMS Collaboration, R. Agnese, Z. Ahmed, A. J. Anderson, S. Arrenberg, D. Balakishiyeva, R. Basu Thakur, D. A. Bauer, A. Borgland, D. Brandt, P. L. Brink, T. Bruch, R. Bunker, B. Cabrera, D. O. Caldwell, D. G. Cerdeno, H. Chagani, J. Cooley, B. Cornell, C. H. Crewdson, P. Cushman, M. Daal, F. Dejongh, P. C. F. Di Stefano, E. do Couto e Silva, T. Doughty, L. Esteban, S. Fallows, E. Figueroa-Feliciano, J. Filippini, J. Fox, M. Fritts, G. L. Godfrey, S. R. Golwala, J. Hall, R. H. Harris, S. A. Hertel, T. Hofer, D. Holmgren, L. Hsu, M. E. Huber, A. Jastram, O. Kamaev, B. Kara, M. H. Kelsey, A. Kennedy, P. Kim, M. Kiveni, K. Koch, M. Kos, S. W. Leman, E. Lopez-Asamar, R. Mahapatra, V. Mandic, C. Martinez, K. A. McCarthy, N. Mirabolfathi, R. A. Moffatt, D. C. Moore, P. Nadeau, R. H. Nelson, K. Page, R. Partridge, M. Pepin, A. Phipps, K. Prasad, M. Pyle, H. Qiu, W. Rau, P. Redl, A. Reisetter, Y. Ricci, T. Saab, B. Sadoulet, J. Sander, K. Schneck, R. W. Schnee, S. Scorza, B. Serfass, B. Shank, D. Speller, K. M. Sundqvist, A. N. Villano, B. Welliver, D. H. Wright, S. Yellin, J. J. Yen, J. Yoo, B. A. Young, J. Zhan
Apr 12, 2013·astro-ph.CO·PDF We report results of a search for Weakly Interacting Massive Particles (WIMPs) with the Si detectors of the CDMS II experiment. This report describes a blind analysis of the first data taken with CDMS II's full complement of detectors in 2006-2007; results from this exposure using the Ge detectors have already been presented. We observed no candidate WIMP-scattering events in an exposure of 55.9 kg-days before analysis cuts, with an expected background of ~1.1 events. The exposure of this analysis is equivalent to 10.3 kg-days over a recoil energy range of 7-100 keV for an ideal Si detector and a WIMP mass of 10 GeV/c2. These data set an upper limit of 1.7x10-41 cm2 on the WIMP-nucleon spin-independent cross section of a 10 GeV/c2 WIMP. These data exclude parameter space for spin-independent WIMP-nucleon elastic scattering that is relevant to recent searches for low-mass WIMPs.
SuperCDMS Collaboration, R. Agnese, A. J. Anderson, D. Balakishiyeva, R. Basu Thakur, D. A. Bauer, J. Billard, A. Borgland, M. A. Bowles, D. Brandt, P. L. Brink, R. Bunker, B. Cabrera, D. O. Caldwell, D. G. Cerdeno, H. Chagani, Y. Chen, J. Cooley, B. Cornell, C. H. Crewdson, P. Cushman, M. Daal, P. C. F. Di Stefano, T. Doughty, L. Esteban, S. Fallows, E. Figueroa-Feliciano, M. Fritts, G. L. Godfrey, S. R. Golwala, M. Graham, J. Hall, H. R. Harris, S. A. Hertel, T. Hofer, D. Holmgren, L. Hsu, M. E. Huber, A. Jastram, O. Kamaev, B. Kara, M. H. Kelsey, A. Kennedy, M. Kiveni, K. Koch, A. Leder, B. Loer, E. Lopez Asamar, R. Mahapatra, V. Mandic, C. Martinez, K. A. McCarthy, N. Mirabolfathi, R. A. Moffatt, D. C. Moore, R. H. Nelson, S. M. Oser, K. Page, W. A. Page, R. Partridge, M. Pepin, A. Phipps, K. Prasad, M. Pyle, H. Qiu, W. Rau, P. Redl, A. Reisetter, Y. Ricci, H. E. Rogers, T. Saab, B. Sadoulet, J. Sander, K. Schneck, R. W. Schnee, S. Scorza, B. Serfass, B. Shank, D. Speller, S. Upadhyayula, A. N. Villano, B. Welliver, D. H. Wright, S. Yellin, J. J. Yen, B. A. Young, J. Zhang
We report on the results of a search for a Weakly Interacting Massive Particle (WIMP) signal in low-energy data of the Cryogenic Dark Matter Search (CDMS~II) experiment using a maximum likelihood analysis. A background model is constructed using GEANT4 to simulate the surface-event background from $^{210}$Pb decay-chain events, while using independent calibration data to model the gamma background. Fitting this background model to the data results in no statistically significant WIMP component. In addition, we perform fits using an analytic ad hoc background model proposed by Collar and Fields, who claimed to find a large excess of signal-like events in our data. We confirm the strong preference for a signal hypothesis in their analysis under these assumptions, but excesses are observed in both single- and multiple-scatter events, which implies the signal is not caused by WIMPs, but rather reflects the inadequacy of their background model.
R. Agnese, A. J. Anderson, M. Asai, D. Balakishiyeva, D. Barker, R. Basu Thakur, D. A. Bauer, J. Billard, A. Borgland, M. A. Bowles, D. Brandt, P. L. Brink, R. Bunker, B. Cabrera, D. O. Caldwell, R. Calkins, D. G. Cerdeño, H. Chagani, Y. Chen, J. Cooley, B. Cornell, C. H. Crewdson, P. Cushman, M. Daal, P. C. F. Di Stefano, T. Doughty, L. Esteban, S. Fallows, E. Figueroa-Feliciano, G. L. Godfrey, S. R. Golwala, J. Hall, H. R. Harris, S. A. Hertel, T. Hofer, D. Holmgren, L. Hsu, M. E. Huber, D. Jardin, A. Jastram, O. Kamaev, B. Kara, M. H. Kelsey, A. Kennedy, M. Kiveni, K. Koch, A. Leder, B. Loer, E. Lopez Asamar, P. Lukens, R. Mahapatra, V. Mandic, K. A. McCarthy, N. Mirabolfathi, R. A. Moffatt, S. M. Oser, K. Page, W. A. Page, R. Partridge, M. Pepin, A. Phipps, K. Prasad, M. Pyle, H. Qiu, W. Rau, P. Redl, A. Reisetter, Y. Ricci, H. E. Rogers, T. Saab, B. Sadoulet, J. Sander, K. Schneck, R. W. Schnee, S. Scorza, B. Serfass, B. Shank, D. Speller, D. Toback, S. Upadhyayula, A. N. Villano, B. Welliver, J. S. Wilson, D. H. Wright, X. Yang, S. Yellin, J. J. Yen, B. A. Young, J. Zhang
CDMS II data from the 5-tower runs at the Soudan Underground Laboratory were reprocessed with an improved charge-pulse fitting algorithm. Two new analysis techniques to reject surface-event backgrounds were applied to the 612 kg days germanium-detector WIMP-search exposure. An extended analysis was also completed by decreasing the 10 keV analysis threshold to $\sim$5 keV, to increase sensitivity near a WIMP mass of 8 GeV/$c^2$. After unblinding, there were zero candidate events above a deposited energy of 10 keV and 6 events in the lower-threshold analysis. This yielded minimum WIMP-nucleon spin-independent scattering cross-section limits of $1.8 \times 10^{-44}$ and $1.18 \times 10 ^{-41}$ cm$^2$ at 90\% confidence for 60 and 8.6 GeV/$c^2$ WIMPs, respectively. This improves the previous CDMS II result by a factor of 2.4 (2.7) for 60 (8.6) GeV/$c^2$ WIMPs.
K. Schneck, B. Cabrera, D. G. Cerdeno, V. Mandic, H. E. Rogers, R. Agnese, A. J. Anderson, M. Asai, D. Balakishiyeva, D. Barker, R. Basu Thakur, D. A. Bauer, J. Billard, A. Borgland, D. Brandt, P. L. Brink, R. Bunker, D. O. Caldwell, R. Calkins, H. Chagani, Y. Chen, J. Cooley, B. Cornell, C. H. Crewdson, P. Cushman, M. Daal, P. C. F. Di Stefano, T. Doughty, L. Esteban, S. Fallows, E. Figueroa-Feliciano, G. L. Godfrey, S. R. Golwala, J. Hall, H. R. Harris, T. Hofer, D. Holmgren, L. Hsu, M. E. Huber, D. M. Jardin, A. Jastram, O. Kamaev, B. Kara, M. H. Kelsey, A. Kennedy, A. Leder, B. Loer, E. Lopez Asamar, P. Lukens, R. Mahapatra, K. A. McCarthy, N. Mirabolfathi, R. A. Moffatt, J. D. Morales Mendoza, S. M. Oser, K. Page, W. A. Page, R. Partridge, M. Pepin, A. Phipps, K. Prasad, M. Pyle, H. Qiu, W. Rau, P. Redl, A. Reisetter, Y. Ricci, A. Roberts, T. Saab, B. Sadoulet, J. Sander, R. W. Schnee, S. Scorza, B. Serfass, B. Shank, D. Speller, D. Toback, S. Upadhyayula, A. N. Villano, B. Welliver, J. S. Wilson, D. H. Wright, X. Yang, S. Yellin, J. J. Yen, B. A. Young, J. Zhang
Mar 11, 2015·astro-ph.CO·PDF We examine the consequences of the effective field theory (EFT) of dark matter-nucleon scattering for current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. We demonstrate that spectral differences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. We also discuss the implications of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.
R. Agnese, A. J. Anderson, M. Asai, D. Balakishiyeva, R. Basu Thakur, D. A. Bauer, J. Billard, A. Borgland, M. A. Bowles, D. Brandt, P. L. Brink, R. Bunker, B. Cabrera, D. O. Caldwell, D. G. Cerdeno, H. Chagani, J. Cooley, B. Cornell, C. H. Crewdson, P. Cushman, M. Daal, P. C. F. Di Stefano, T. Doughty, L. Esteban, S. Fallows, E. Figueroa-Feliciano, G. L. Godfrey, S. R. Golwala, J. Hall, H. R. Harris, S. A. Hertel, T. Hofer, D. Holmgren, L. Hsu, M. E. Huber, A. Jastram, O. Kamaev, B. Kara, M. H. Kelsey, A. Kennedy, M. Kiveni, K. Koch, B. Loer, E. Lopez Asamar, R. Mahapatra, V. Mandic, C. Martinez, K. A. McCarthy, N. Mirabolfathi, R. A. Moffatt, D. C. Moore, P. Nadeau, R. H. Nelson, K. Page, R. Partridge, M. Pepin, A. Phipps, K. Prasad, M. Pyle, H. Qiu, W. Rau, P. Redl, A. Reisetter, Y. Ricci, T. Saab, B. Sadoulet, J. Sander, K. Schneck, R. W. Schnee, S. Scorza, B. Serfass, B. Shank, D. Speller, A. N. Villano, B. Welliver, D. H. Wright, S. Yellin, J. J. Yen, B. A. Young, J. Zhang
SuperCDMS is an experiment designed to directly detect Weakly Interacting Massive Particles (WIMPs), a favored candidate for dark matter ubiquitous in the Universe. In this paper, we present WIMP-search results using a calorimetric technique we call CDMSlite, which relies on voltage- assisted Luke-Neganov amplification of the ionization energy deposited by particle interactions. The data were collected with a single 0.6 kg germanium detector running for 10 live days at the Soudan Underground Laboratory. A low energy threshold of 170 eVee (electron equivalent) was obtained, which allows us to constrain new WIMP-nucleon spin-independent parameter space for WIMP masses below 6 GeV/c2.
D. Brandt, R. Agnese, P. Redl, K. Schneck, M. Asai, M. Kelsey, D. Faiez, E. Bagli, B. Cabrera, R. Partridge, T. Saab, B. Sadoulet
A phonon and charge transport simulation based on the Geant4 Monte Carlo toolkit is presented. The transport code is capable of propagating acoustic phonons, electrons and holes in cryogenic crystals. Anisotropic phonon propagation, oblique carrier propagation and phonon emission by accelerated carriers are all taken into account. The simulation successfully reproduces theoretical predictions and experimental observations such as phonon caustics, heat pulse propagation times and mean carrier drift velocities. Implementation of the transport code using the Geant4 toolkit ensures availability to the wider scientific community.
CDMS Collaboration, R. Agnese, Z. Ahmed, A. J. Anderson, S. Arrenberg, D. Balakishiyeva, R. Basu Thakur, D. A. Bauer, J. Billard, A. Borgland, D. Brandt, P. L. Brink, T. Bruch, R. Bunker, B. Cabrera, D. O. Caldwell, D. G. Cerdeno, H. Chagani, J. Cooley, B. Cornell, C. H. Crewdson, P. Cushman, M. Daal, F. Dejongh, E. Do Couto E Silva, T. Doughty, L. Esteban, S. Fallows, E. Figueroa-Feliciano, J. Filippini, J. Fox, M. Fritts, G. L. Godfrey, S. R. Golwala, J. Hall, R. H. Harris, S. A. Hertel, T. Hofer, D. Holmgren, L. Hsu, M. E. Huber, A. Jastram, O. Kamaev, B. Kara, M. H. Kelsey, A. Kennedy, P. Kim, M. Kiveni, K. Koch, M. Kos, S. W. Leman, B. Loer, E. Lopez Asamar, R. Mahapatra, V. Mandic, C. Martinez, K. A. McCarthy, N. Mirabolfathi, R. A. Moffatt, D. C. Moore, P. Nadeau, R. H. Nelson, K. Page, R. Partridge, M. Pepin, A. Phipps, K. Prasad, M. Pyle, H. Qiu, W. Rau, P. Redl, A. Reisetter, Y. Ricci, T. Saab, B. Sadoulet, J. Sander, K. Schneck, R. W. Schnee, S. Scorza, B. Serfass, B. Shank, D. Speller, K. M. Sundqvist, A. N. Villano, B. Welliver, D. H. Wright, S. Yellin, J. J. Yen, J. Yoo, B. A. Young, J. Zhang
We report results of a search for Weakly Interacting Massive Particles (WIMPS) with the silicon detectors of the CDMS II experiment. This blind analysis of 140.2 kg-days of data taken between July 2007 and September 2008 revealed three WIMP-candidate events with a surface-event background estimate of 0.41^{+0.20}_{-0.08}(stat.)^{+0.28}_{-0.24}(syst.). Other known backgrounds from neutrons and 206Pb are limited to < 0.13 and <0.08 events at the 90% confidence level, respectively. The exposure of this analysis is equivalent to 23.4 kg-days for a recoil energy range of 7-100 keV for a WIMP of mass 10 GeV/c2. The probability that the known backgrounds would produce three or more events in the signal region is 5.4%. A profile likelihood ratio test of the three events that includes the measured recoil energies gives a 0.19% probability for the known-background-only hypothesis when tested against the alternative WIMP+background hypothesis. The highest likelihood occurs for a WIMP mass of 8.6 GeV/c2 and WIMP-nucleon cross section of 1.9e-41 cm2.