Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 11 de 11
Filter
2.
Phys Rev Lett ; 121(5): 051301, 2018 Aug 03.
Article in English | MEDLINE | ID: mdl-30118251

ABSTRACT

We present the first limits on inelastic electron-scattering dark matter and dark photon absorption using a prototype SuperCDMS detector having a charge resolution of 0.1 electron-hole pairs (CDMS HVeV, a 0.93 g CDMS high-voltage device). These electron-recoil limits significantly improve experimental constraints on dark matter particles with masses as low as 1 MeV/c^{2}. We demonstrate a sensitivity to dark photons competitive with other leading approaches but using substantially less exposure (0.49 g d). These results demonstrate the scientific potential of phonon-mediated semiconductor detectors that are sensitive to single electronic excitations.

3.
Phys Rev Lett ; 120(6): 061802, 2018 Feb 09.
Article in English | MEDLINE | ID: mdl-29481237

ABSTRACT

We report the result of a blinded search for weakly interacting massive particles (WIMPs) using the majority of the SuperCDMS Soudan data set. With an exposure of 1690 kg d, 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 1.4×10^{-44} (1.0×10^{-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}.

4.
Phys Rev Lett ; 116(7): 071301, 2016 Feb 19.
Article in English | MEDLINE | ID: mdl-26943526

ABSTRACT

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 day, 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}.

5.
Phys Rev Lett ; 114(11): 111302, 2015 Mar 20.
Article in English | MEDLINE | ID: mdl-25839256

ABSTRACT

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 finds no candidates, thereby excluding new parameter space for particles with electric charges between e/6 and e/200.

6.
Phys Rev Lett ; 112(4): 041302, 2014 Jan 31.
Article in English | MEDLINE | ID: mdl-24580434

ABSTRACT

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 Letter, 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 ten 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.

7.
Phys Rev Lett ; 112(24): 241302, 2014 Jun 20.
Article in English | MEDLINE | ID: mdl-24996080

ABSTRACT

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/c(2), 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 1.2×10(-42) cm(2) at 8 GeV/c(2). 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/c(2).

8.
Phys Rev Lett ; 111(25): 251301, 2013 Dec 20.
Article in English | MEDLINE | ID: mdl-24483735

ABSTRACT

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 day of data taken between July 2007 and September 2008 revealed three WIMP-candidate events with a surface-event background estimate of 0.41(-0.08)(+0.20)(stat)(-0.24)(+0.28)(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 day 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 1.9×10(-41) cm2.

9.
J Intellect Disabil Res ; 54(9): 843-59, 2010 Sep.
Article in English | MEDLINE | ID: mdl-20712698

ABSTRACT

BACKGROUND: Onsite standard care and remote telecare supports were provided to adults with intellectual disabilities living in integrated community settings and evaluated in terms of effectiveness as consumers completed a series of novel household activities. METHODS: Using an alternating treatment design with baseline and follow-up conditions in this single-case study, investigators compared the prompting effectiveness provided by onsite standard care staff and a remote telecare provider. RESULTS: While both types of supports resulted in consumers completing tasks, results indicated consumers achieved slightly more independence when prompted by the telecare support provider. Additionally, telecare supports resulted in greater duration for task completion per consumer. CONCLUSIONS: Although consumers completed tasks with greater independence using telecare supports, caution should be used when interpreting results due to the small number of participants. The potential for this technology certainly exists in supporting consumers in their own homes thus, suggestions for future investigations are provided.


Subject(s)
Activities of Daily Living , Home Care Services/organization & administration , Intellectual Disability/therapy , Telemedicine/organization & administration , Adult , Consumer Behavior , Female , Housing , Humans , Internet/organization & administration , Male , Middle Aged , Program Evaluation , Residence Characteristics , Social Support
10.
Med Sci Sports Exerc ; 30(9): 1399-407, 1998 Sep.
Article in English | MEDLINE | ID: mdl-9741608

ABSTRACT

UNLABELLED: Previously, this laboratory has demonstrated that exhaustive aerobic exercise performance is not subject to significant chronobiological variation between 0800 and 2000 h, but certain physiological responses to maximal aerobic effort do fluctuate significantly within that time frame. PURPOSE: The purpose of the present investigation was to determine whether muscle performance, and selected physiological responses to resistance exercise, was significantly influenced by time of day effects. METHODS: Ten healthy, but untrained, men (21.1+/-0.6 yr, mean +/- SE) volunteered to participate in the study. In a balanced and randomized study design, each subject performed resistance exercise protocols on an isokinetic dynamometer with maximal effort at 0800 h, 1200 h, 1600 h, and 2000 h. Selected physiological and hormonal data were recorded before and immediately following the exercise stimulus. RESULTS: The data demonstrated significant chronobiological oscillation in peak torque, average power, maximal work in a single repetition, and total work per set. Interestingly, this oscillation was manifested only at the fastest velocities of limb movement utilized. Pre- and postexercise rectal temperature exhibited significant time of day fluctuation, as did postexercise blood pressure. Plasma levels of testosterone and cortisol also displayed significant biorhythmicity under both pre- and postexercise conditions. However, exercise-induced responses (pre- to postexercise differences) of those steroid hormones did not exhibit significant biorythmic variation. Although plasma concentrations of both testosterone and cortisol were highest at 0800 h, testosterone to cortisol ratios were greatest at 2000 h. CONCLUSIONS: In summary, these data suggest that maximal muscle performance does vary within the segment of the day when exercise typically occurs (0800-2000 h) but that this variation is specific to speed of movement.


Subject(s)
Circadian Rhythm/physiology , Exercise/physiology , Muscle, Skeletal/physiology , Adult , Blood Pressure/physiology , Body Temperature/physiology , Energy Metabolism/physiology , Heart Rate/physiology , Humans , Hydrocortisone/blood , Lactates/blood , Male , Muscle Fatigue/physiology , Testosterone/blood , Torque
11.
J Prosthet Dent ; 77(1): 83-5, 1997 Jan.
Article in English | MEDLINE | ID: mdl-9029470

ABSTRACT

A restoration that the patient reports as "high" is a common problem for the restorative dentist. Check bite, dual bite, or closed mouth impressions address this problem effectively by eliminating the opposing arch impression and articulating the opposing cast accurately. In this article a procedure that combines irreversible hydrocolloid and reversible hydrocolloid results in a rapid, clean, and effective solution.


Subject(s)
Dental Impression Materials/chemistry , Dental Impression Technique , Models, Dental , Alginates , Colloids , Humans , Jaw Relation Record/methods , Reproducibility of Results
SELECTION OF CITATIONS
SEARCH DETAIL