-
R. Agnese,
A. J. Anderson,
D. Balakishiyeva,
R. Basu Thakur, D. A. Bauer,
A. Borgland,
D. Brandt,
P. L. Brink,
R. Bunker,
B. Cabrera, [......],
B. Shank,
D. Speller,
A. Tomada,
A. N. Villano,
B. Welliver,
D. H. Wright,
S. Yellin,
J. J. Yen,
B. A. Young,
J. Zhang
[show abstract]
[hide abstract]
ABSTRACT: SuperCDMS, a direct search for WIMPs, is currently operating a 9-kg array of
cryogenic germanium (Ge) detectors in the Soudan Underground Laboratory. These
detectors, known as iZIPs, use ionization and phonon sensors placed
symmetrically on both sides of a Ge crystal to measure both charge and athermal
phonons from each particle interaction. The information from each event
provides excellent discrimination between electron recoils and nuclear recoils,
as well as discrimination between events on the detector surface and those in
the interior. To demonstrate the surface electron rejection capabilities, two
$^{210}$Pb sources were installed facing detectors, producing $\sim$130 beta
decays/hr. In $\sim$800 live hours, no events leaked into the WIMP signal
region in the recoil energy range 8--115 keVr, providing an upper limit to the
surface event leakage fraction of $1.7 \times 10^{-5}$ at 90% C.L. This
rejection factor demonstrates that surface electrons would produce $< 0.6$
event background in the 0.3 ton-year exposure for the proposed 200-kg iZIP
array in SuperCDMS SNOLAB.
05/2013;
-
CDMS Collaboration,
R. Agnese,
Z. Ahmed,
A. J. Anderson,
S. Arrenberg,
D. Balakishiyeva,
R. Basu Thakur, D. A. Bauer,
J. Billard,
A. Borgland, [......],
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
[show abstract]
[hide abstract]
ABSTRACT: We report results of a search for Weakly Interacting Massive Particles
(WIMPs) with the silicon detectors of the CDMS II experiment. A blind analysis
of 140.2 kg-days of data revealed three WIMP-candidate events with an expected
total background of 0.7 events. 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/c^2 and WIMP-nucleon cross section
of 1.9x10^-41 cm^2.
04/2013;
-
R Agnese,
Z Ahmed,
A J Anderson,
S Arrenberg,
D Balakishiyeva,
R Basu Thakur, D A Bauer,
L Hsu,
M E Huber,
A Jastram, [......],
M Pyle,
H Qiu,
W Rau,
P Redl,
A Reisetter,
Y Ricci,
T Saab,
B Sadoulet,
J Sander,
K Schneck
[show abstract]
[hide abstract]
ABSTRACT: 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. These data set an upper limit of 1.7 × 10 −41 cm 2 on the WIMP-nucleon spin-independent cross section of a 10 GeV/c 2 WIMP; this limit improves to 8.3 × 10 −42 cm 2 in combination with previous Si data from this installation. These data exclude parameter space for spin-independent WIMP-nucleon elastic scattering that is relevant to recent searches for low-mass WIMPs.
04/2013; 8(10).
-
CDMS Collaboration,
R. Agnese,
Z. Ahmed,
A. J. Anderson,
S. Arrenberg,
D. Balakishiyeva,
R. Basu Thakur, D. A. Bauer,
A. Borgland,
D. Brandt, [......],
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
[show abstract]
[hide abstract]
ABSTRACT: 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. 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; this limit improves to 8.3x10-42 cm2 in combination with previous Si data
from this installation. These data exclude parameter space for spin-independent
WIMP-nucleon elastic scattering that is relevant to recent searches for
low-mass WIMPs.
04/2013;
-
CDMS Collaboration,
Z. Ahmed,
D. S. Akerib,
A. J. Anderson,
S. Arrenberg,
C. N. Bailey,
D. Balakishiyeva,
L. Baudis, D. A. Bauer,
P. L. Brink, [......],
D. Speller,
K. M. Sundqvist,
M. Tarka,
R. B. Thakur,
A. N. Villano,
B. Welliver,
S. Yellin,
J. Yoo,
B. A. Young,
J. Zhang
[show abstract]
[hide abstract]
ABSTRACT: We report limits on annual modulation of the low-energy event rate from the
Cryogenic Dark Matter Search (CDMS II) experiment at the Soudan Underground
Laboratory. Such a modulation could be produced by interactions from Weakly
Interacting Massive Particles (WIMPs) with masses ~10 GeV/c^2. We find no
evidence for annual modulation in the event rate of veto-anticoincident
single-detector interactions consistent with nuclear recoils, and constrain the
magnitude of any modulation to <0.06 event [keVnr kg day]^-1 in the 5-11.9
keVnr energy range at the 99% confidence level. These results disfavor an
explanation for the reported modulation in the 1.2-3.2 keVee energy range in
CoGeNT in terms of nuclear recoils resulting from elastic scattering of WIMPs
at >98% confidence. For events consistent with electron recoils, no significant
modulation is observed for either single- or multiple-detector interactions in
the 3.0-7.4 keVee range.
03/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: Amplifying the phonon signal in a semiconductor dark matter detector can be
accomplished by operating at high voltage bias and converting the electrostatic
potential energy into Luke-Neganov phonons. This amplification method has been
validated at up to |E|=40V/cm without producing leakage in CDMSII Ge detectors,
allowing sensitivity to a benchmark WIMP with mass = 8GeV and cross section
1.8e-42cm^2 assuming flat electronic recoil backgrounds near threshold.
Furthermore, for the first time we show that differences in Luke-Neganov gain
for nuclear and electronic recoils can be used to discriminate statistically
between low-energy background and a hypothetical WIMP signal by operating at
two distinct voltage biases. Specifically, 99% of events have p-value<1e-8 for
a simulated 20kg-day experiment with a benchmark WIMP signal with mass =8GeV
and cross section =3.3e-41cm^2.
01/2012;
-
Z Ahmed,
D S Akerib,
S Arrenberg,
C N Bailey,
D Balakishiyeva,
L Baudis, D A Bauer,
P L Brink,
T Bruch,
R Bunker, [......],
M Kiveni,
M Kos,
S W Leman,
S Liu,
R Mahapatra,
V Mandic,
K A Mccarthy,
N Mirabolfathi,
D Moore,
H Nelson
[show abstract]
[hide abstract]
ABSTRACT: Results are presented from a reanalysis of the entire five-tower data set acquired with the Cryo-genic Dark Matter Search (CDMS II) experiment at the Soudan Underground Laboratory, with an exposure of 969 kg-days. The analysis window was extended to a recoil energy of 150 keV, and an improved surface-event background-rejection cut was defined to increase the sensitivity of the experiment to the inelastic dark matter (iDM) model. Three dark matter candidates were found between 25 keV and 150 keV. The probability to observe three or more background events in this energy range is 11%. Because of the occurrence of these events the constraints on the iDM param-eter space are slightly less stringent than those from our previous analysis, which used an energy window of 10–100 keV.
07/2011; 18(11):14-15.
-
Z Ahmed,
D S Akerib,
S Arrenberg,
C N Bailey,
D Balakishiyeva,
L Baudis, D A Bauer,
P L Brink,
T Bruch,
R Bunker, [......],
M Kiveni,
M Kos,
S W Leman,
S Liu,
R Mahapatra,
V Mandic,
K A Mccarthy,
N Mirabolfathi,
D Moore,
H Nelson
[show abstract]
[hide abstract]
ABSTRACT: Results are presented from a reanalysis of the entire five-tower data set acquired with the Cryo-genic Dark Matter Search (CDMS II) experiment at the Soudan Underground Laboratory, with an exposure of 969 kg-days. The analysis window was extended to a recoil energy of 150 keV, and an improved surface-event background-rejection cut was defined to increase the sensitivity of the experiment to the inelastic dark matter (iDM) model. Three dark matter candidates were found between 25 keV and 150 keV. The probability to observe three or more background events in this energy range is 11%. Because of the occurrence of these events the constraints on the iDM param-eter space are slightly less stringent than those from our previous analysis, which used an energy window of 10–100 keV.
07/2011; 18(11):14-15.
-
CDMS,
EDELWEISS Collaborations: Z. Ahmed,
D. S. Akerib,
E. Armengaud,
S. Arrenberg,
C. Augier,
C. N. Bailey,
D. Balakishiyeva,
L. Baudis, D. A. Bauer, [......],
A. S. Torrento-Coello,
L. Vagneron,
M-A. Verdier,
R. J. Walker,
P. Wikus,
E. Yakushev,
S Yellin,
J Yoo,
B. A. Young,
J Zhang
[show abstract]
[hide abstract]
ABSTRACT: The CDMS and EDELWEISS collaborations have combined the results of their
direct searches for dark matter using cryogenic germanium detectors. The total
data set represents 614 kg.d equivalent exposure. A straightforward method of
combination was chosen for its simplicity before data were exchanged between
experiments. The results are interpreted in terms of limits on spin-independent
WIMP-nucleon cross-section. For a WIMP mass of 90 GeV/c^2, where this analysis
is most sensitive, a cross-section of 3.3 x 10^{-44} cm^2 is excluded at 90%
CL. At higher WIMP masses, the combination improves the individual limits, by a
factor 1.6 above 700 GeV/c^2. Alternative methods of combining the data provide
stronger constraints for some ranges of WIMP masses and weaker constraints for
others.
Physical Review D 05/2011; 84:011102. · 4.56 Impact Factor
-
Z Ahmed,
D S Akerib,
S Arrenberg,
C N Bailey,
D Balakishiyeva,
L Baudis, D A Bauer,
P L Brink,
T Bruch,
R Bunker, [......],
R W Schnee,
D N Seitz,
B Serfass,
K M Sundqvist,
M Tarka,
P Wikus,
S Yellin,
J Yoo,
B A Young,
J Zhang
[show abstract]
[hide abstract]
ABSTRACT: We report results from a reanalysis of data from the Cryogenic Dark Matter Search (CDMS II) experiment at the Soudan Underground Laboratory. Data taken between October 2006 and September 2008 using eight germanium detectors are reanalyzed with a lowered, 2 keV recoil-energy threshold, to give increased sensitivity to interactions from weakly interacting massive particles (WIMPs) with masses below ∼10 GeV/c(2). This analysis provides stronger constraints than previous CDMS II results for WIMP masses below 9 GeV/c(2) and excludes parameter space associated with possible low-mass WIMP signals from the DAMA/LIBRA and CoGeNT experiments.
Physical Review Letters 04/2011; 106(13):131302. · 7.37 Impact Factor
-
CDMS Collaboration,
Z. Ahmed,
D. S. Akerib,
S. Arrenberg,
C. N. Bailey,
D. Balakishiyeva,
L. Baudis, D. A. Bauer,
P. L. Brink,
T. Bruch, [......],
R. W. Schnee,
D. N. Seitz,
B Serfass,
K. M. Sundqvist,
M. Tarka,
P. Wikus,
S Yellin,
J Yoo,
B. A. Young,
J Zhang
[show abstract]
[hide abstract]
ABSTRACT: Results are presented from a reanalysis of the entire five-tower data set
acquired with the Cryogenic Dark Matter Search (CDMS II) experiment at the
Soudan Underground Laboratory, with an exposure of 969 kg-days. The analysis
window was extended to a recoil energy of 150 keV, and an improved
surface-event background-rejection cut was defined to increase the sensitivity
of the experiment to the inelastic dark matter (iDM) model. Three dark matter
candidates were found between 25 keV and 150 keV. The probability to observe
three or more background events in this energy range is 11%. Because of the
occurrence of these events the constraints on the iDM parameter space are
slightly less stringent than those from our previous analysis, which used an
energy window of 10-100 keV.
12/2010;
-
CDMS Collaboration,
D. S. Akerib,
M J Attisha,
L. Baudis, D. A. Bauer,
A. I. Bolozdynya,
P. L. Brink,
R. Bunker,
B. Cabrera,
D O Caldwell, [......],
B Sadoulet,
J. Sander,
C Savage,
R. W. Schnee,
D. N. Seitz,
T. A. Shutt,
G Wang,
S Yellin,
J Yoo,
B. A. Young
[show abstract]
[hide abstract]
ABSTRACT: Data taken during the final shallow-site run of the first tower of the
Cryogenic Dark Matter Search (CDMS II) detectors have been reanalyzed with
improved sensitivity to small energy depositions. Four ~224 g germanium and two
~105 g silicon detectors were operated at the Stanford Underground Facility
(SUF) between December 2001 and June 2002, yielding 118 live days of raw
exposure. Three of the germanium and both silicon detectors were analyzed with
a new low-threshold technique, making it possible to lower the germanium and
silicon analysis thresholds down to the actual trigger thresholds of ~1 keV and
~2 keV, respectively. Limits on the spin-independent cross section for weakly
interacting massive particles (WIMPs) to elastically scatter from nuclei based
on these data exclude interesting parameter space for WIMPs with masses below 9
GeV/c^2. Under standard halo assumptions, these data partially exclude
parameter space favored by interpretations of the DAMA/LIBRA and CoGeNT
experiments' data as WIMP signals, and exclude new parameter space for WIMP
masses between 3 GeV/c^2 and 4 GeV/c^2.
10/2010;
-
Z Ahmed,
D S Akerib,
S Arrenberg,
C N Bailey,
D Balakishiyeva,
L Baudis, D A Bauer,
P L Brink,
T Bruch,
R Bunker, [......],
R W Schnee,
D N Seitz,
B Serfass,
K M Sundqvist,
M Tarka,
P Wikus,
S Yellin,
J Yoo,
B A Young,
J Zhang
[show abstract]
[hide abstract]
ABSTRACT: Astrophysical observations indicate that dark matter constitutes most of the mass in our universe, but its nature remains unknown. Over the past decade, the Cryogenic Dark Matter Search (CDMS II) experiment has provided world-leading sensitivity for the direct detection of weakly interacting massive particle (WIMP) dark matter. The final exposure of our low-temperature germanium particle detectors at the Soudan Underground Laboratory yielded two candidate events, with an expected background of 0.9 +/- 0.2 events. This is not statistically significant evidence for a WIMP signal. The combined CDMS II data place the strongest constraints on the WIMP-nucleon spin-independent scattering cross section for a wide range of WIMP masses and exclude new parameter space in inelastic dark matter models.
Science 02/2010; 327(5973):1619-21. · 31.20 Impact Factor
-
P. L. Brink,
Z. Ahmed,
D. S. Akerib,
C. N. Bailey,
D. Balakishiyeva, D. A. Bauer,
J. Beaty,
R. Bunker,
B. Cabrera,
D. O. Caldwell, [......],
R. W. Schnee,
D. N. Seitz,
B. Serfass,
K. M. Sundqvist,
A. Tomada,
G. Wang,
P. Wikus,
S. Yellin,
J. Yoo,
B. A. Young
[show abstract]
[hide abstract]
ABSTRACT: The CDMS collaboration utilizes Ge detectors for their Weakly Interacting Massive Particle (WIMP) search at the Soudan mine, Minnesota. The final data run of CDMS II is complete and a detector upgrade for SuperCDMS has commenced. A SuperTower of five 1‐inch thick Ge crystals has been installed and undergoing commissioning. Its surface‐event rejection capability should allow SuperCDMS to continue to run background free for the next proposed phases: 15 kg Ge deployment at Soudan, and up to 150 kg Ge deployment at SNOLAB. Recent detector advances to allow a 1 tonne Ge experiment are also discussed.
AIP Conference Proceedings. 12/2009; 1182(1):260-263.
-
N. Mirabolfathi,
Z. Ahmed,
D. S. Akerib,
S. Arrenberg,
C. N. Bailey,
D. Balakishiyeva,
L. Baudis, D. A Bauer,
J. Beaty,
P. L. Brink, [......],
B. Sadoulet,
J. Sanders,
R. W. Schnee,
D. N. Seitz,
B. Serfass,
K. M. Sundqvist,
G. Wang,
S. Yellin,
J. Yoo,
B. A. Young
[show abstract]
[hide abstract]
ABSTRACT: The Cryogenic Dark Matter Search experiment (CDMS) is using Phonon+Ionization detectors to search for Dark Matter in the form of Weakly Interactive Massive Particles (WIMPs). We report on new results from the operation of CDMS five “towers” at Soudan underground laboratory. With new and more massive detectors, SuperCDMS project has been started since March 2009. We report on the current status of SuperCDMS and its perspective.
AIP Conference Proceedings. 12/2009; 1185(1):623-626.
-
P. L. Brink,
Z. Ahmed,
D. S. Akerib,
C. N. Bailey,
D. Balakishiyeva, D. A. Bauer,
J. Beaty,
R. Bunker,
B. Cabrera,
D. O. Caldwell, [......],
R. W. Schnee,
D. N. Seitz,
B. Serfass,
K. M. Sundqvist,
A. Tomada,
G. Wang,
P. Wikus,
S. Yellin,
J. Yoo,
B. A. Young
[show abstract]
[hide abstract]
ABSTRACT: For its dark matter search the SuperCDMS collaboration has developed new
Ge detectors using the same athermal phonon sensors and ionization
measurement technology of CDMS II but with larger mass, superior sensor
performance and increased fabrication efficiency. The improvements in
fabrication are described, a comparison of CDMS II and SuperCDMS
detector production yield is reported, and future scalability addressed.
11/2009; 1185:655-658.
-
Z Ahmed,
D S Akerib,
S Arrenberg,
C N Bailey,
D Balakishiyeva,
L Baudis, D A Bauer,
J Beaty,
P L Brink,
T Bruch, [......],
J Sander,
R W Schnee,
D N Seitz,
B Serfass,
K M Sundqvist,
M Tarka,
G Wang,
S Yellin,
J Yoo,
B A Young
[show abstract]
[hide abstract]
ABSTRACT: We report on the first axion search results from the Cryogenic Dark Matter Search (CDMS) experiment at the Soudan Underground Laboratory. An energy threshold of 2 keV for electron-recoil events allows a search for possible solar axion conversion into photons or local galactic axion conversion into electrons in the germanium crystal detectors. The solar axion search sets an upper limit on the Primakov coupling g(agammagamma) of 2.4x10(-9) GeV-1 at the 95% confidence level for an axion mass less than 0.1 keV/c2. This limit benefits from the first precise measurement of the absolute crystal plane orientations in this type of experiment. The galactic axion search analysis sets a world-leading experimental upper limit on the axioelectric coupling g(aee) of 1.4x10(-12) at the 90% confidence level for an axion mass of 2.5 keV/c2.
Physical Review Letters 10/2009; 103(14):141802. · 7.37 Impact Factor
-
Z. Ahmed,
D. S. Akerib,
S. Arrenberg,
C. N. Bailey,
D. Balakishiyeva,
L. Baudis, D. A. Bauer,
J Beaty,
P. L. Brink,
T. Bruch, [......],
J. Sander,
R. W. Schnee,
D. N. Seitz,
B Serfass,
K. M. Sundqvist,
G Wang,
S Yellin,
J Yoo,
B. A. Young,
The CDMS Collaboration
[show abstract]
[hide abstract]
ABSTRACT: We report on the analysis of the low-energy electron-recoil spectrum from the CDMS II experiment using data with an exposure of 443.2 kg-days. The analysis provides details on the observed counting rate and possible background sources in the energy range of 2 - 8.5 keV. We find no significant excess in the counting rate above background, and compare this observation to the recent DAMA results. In the framework of a conversion of a dark matter particle into electromagnetic energy, our 90% confidence level upper limit of 0.246 events/kg/day at 3.15 keV is lower than the total rate above background observed by DAMA by 8.9$\sigma$. In absence of any specific particle physics model to provide the scaling in cross section between NaI and Ge, we assume a Z^2 scaling. With this assumption the observed rate in DAMA differs from the upper limit in CDMS by 6.8$\sigma$. Under the conservative assumption that the modulation amplitude is 6% of the total rate we obtain upper limits on the modulation amplitude a factor of ~2 less than observed by DAMA, constraining some possible interpretations of this modulation. Comment: 4 pages, 3 figures
07/2009;
-
P L Brink,
Z Ahmed,
D S Akerib,
C N Bailey, D A Bauer,
J Beaty,
R Bunker,
S Burke,
B Cabrera,
D O Caldwell, [......],
R W Schnee,
D N Seitz,
B Serfass,
A Sirois,
K M Sundqvist,
A Tomada,
G Wang,
S Yellin,
J Yoo,
B A Young
[show abstract]
[hide abstract]
ABSTRACT: Weakly Interacting Massive Particles (WIMPs) are a strong candidate for the Cold Dark Matter of the Universe. CDMS-II is a direct-search WIMP search experiment, operating at 50 mK and housed at the Soudan mine, Minnesota. The 250 gram Ge detectors utilize athermal phonon sensors where tungsten transition edge sensors are operated in negative electrothermal feedback. The search at Soudan is ongoing with an expected final reach of CDMS-II by the end of 2008 of a WIMP-nucleon cross-section sensitivity of 2.1 x10-44 cm2, at a WIMP mass of 60 GeV/c2. To proceed further, we have proposed the SuperCDMS program.
Journal of Physics Conference Series 03/2009; 150(1):012006.
-
Z Ahmed,
D S Akerib,
S Arrenberg,
M J Attisha,
C N Bailey,
L Baudis, D A Bauer,
J Beaty,
P L Brink,
T Bruch, [......],
D N Seitz,
B Serfass,
A Sirois,
K M Sundqvist,
M Tarka,
A Tomada,
G Wang,
S Yellin,
J Yoo,
B A Young
[show abstract]
[hide abstract]
ABSTRACT: We report results from the Cryogenic Dark Matter Search at the Soudan Underground Laboratory (CDMS II) featuring the full complement of 30 detectors. A blind analysis of data taken between October 2006 and July 2007 sets an upper limit on the weakly interacting massive particle (WIMP) nucleon spin-independent cross section of 6.6x10;{-44} cm;{2} (4.6x10;{-44} cm;{2} when combined with previous CDMS II data) at the 90% confidence level for a WIMP mass of 60 GeV/c;{2}. This achieves the best sensitivity for dark matter WIMPs with masses above 44 GeV/c;{2}, and significantly restricts the parameter space for some favored supersymmetric models.
Physical Review Letters 02/2009; 102(1):011301. · 7.37 Impact Factor
