► DRIFT is only one of a handful of directional dark matter detectors. ► A method of rejecting Radon Progeny Recoils, DRIFT’s main background, is discussed. ► Additionally DRIFT-IId was found to run ...stably with a mixture of CS2 and CF4. ► DRIFT’s sensitivity is orders of magnitude better than other directional detectors.
Data are presented from the DRIFT-IId detector operated in the Boulby Underground Science Facility in England. A 0.8m3 fiducial volume, containing partial pressures of 30Torr CS2 and 10Torr CF4, was exposed for a duration of 47.4 live-time days with sufficient passive shielding to provide a neutron free environment within the detector. The nuclear recoil events seen are consistent with a remaining low-level background from the decay of radon daughters attached to the central cathode of the detector. However, charge from such events must drift across the entire width of the detector, and thus display large diffusion upon reaching the readout planes of the device. Exploiting this feature, it is shown to be possible to reject energy depositions from these Radon Progeny Recoil events while still retaining sensitivity to fiducial-volume nuclear recoil events. The response of the detector is then interpreted, using the F nuclei content of the gas, in terms of sensitivity to proton spin-dependent WIMP–nucleon interactions, displaying a minimum in sensitivity cross section at 1.8pb for a WIMP mass of 100GeV/c2. This sensitivity was achieved without compromising the direction sensitivity of DRIFT.
In Study 1, children were reinterviewed about an event they had taken part in 2 years earlier when they were 6 years old (
M.-E. Pipe & J. C. Wilson, 1994
). In Study 2, children were reinterviewed ...about an event in which they had participated 1 year earlier when they were 6 or 9 years of age (
S. Gee & M.-E. Pipe, 1995
). Interviews were conducted with or without cue items and distractors, as in the original studies. The amount of information reported in free recall decreased over the 1- or 2-year delays, and for 6-year-olds, there was also a small decrease in accuracy of free recall. Reinstating specific cue items in Study 2 maintained recall when attention was drawn to them, but prompting children led to a decrease in accuracy. Whereas information repeated across interviews was highly accurate, information reported for the first time at the long delays was not.
The luminescence and scintillation properties of ZnS–Ag/6LiF where studied in the 7–295K temperature range to evaluate the suitability of the scintillator for neutron detection at very low ...temperature (<1K). It is shown that decrease of temperature has little effect upon principal luminescence and scintillation characteristics of ZnS–Ag: the changes of emission intensity are small for photoexcitation and negligible for excitation with α-particles. The recombination kinetics of the scintillation decay exhibits modest shortening of the fast decay time constant, from 4.52 to 3.35μs with cooling to 10K. It is concluded that ZnS–Ag/6LiF is a promising scintillator for cryogenic application.
► Luminescence and scintillations of ZnS–Ag/6LiF neutron scintillator are studied over 7–295K. ► Interpretation of excitation spectra is offered. ► Scintillation properties exhibit little changes with cooling. ► ZnS–Ag/6LiF can be used as neutron scintillation detector at cryogenic temperatures.
Children's memories for an experienced and a never-experienced medical procedure were examined. Three- to 13-year-olds were questioned about a voiding cystourethrogram fluoroscopy (VCUG) they endured ...between 2 and 6 years of age. Children 4 years or older at VCUG were more accurate than children younger than 4 at VCUG. Longer delays were associated with providing fewer units of correct information but not with more inaccuracies. Parental avoidant attachment style was related to increased errors in children's VCUG memory. Children were more likely to assent to the false medical procedure when it was alluded to briefly than when described in detail, and false assents were related to fewer “do-not-know” responses about the VCUG. Results have implications for childhood amnesia, stress and memory, individual differences, and eyewitness testimony.
Returning to the Scene Priestley, Gina; Roberts, Susan; Pipe, Margaret-Ellen
Developmental psychology,
07/1999, Letnik:
35, Številka:
4
Journal Article
Recenzirano
Two studies examined the efficacy of context reinstatement as a reminder in enhancing 5- to 7-year-old children's recall. In Experiment 1, children who had been interviewed shortly after an event ...were reinterviewed 6 months later. Children exposed to a context reminder 24 hr before the 6-month interview and children interviewed in the event context did not differ but reported significantly more information in a verbal interview than children receiving a standard interview. A control group experienced the reminder but not the event and established that the effects of the reminder were not due to new learning. There was no effect of the reminder on accuracy and no effect in reenactment. In Experiment 2, children were interviewed for the first time after 6 months, and effects of the reminder were found for both verbal recall and reenactment. Nonverbal reminders may effectively enhance the amount of information children report without decreasing accuracy.
Children between 7 and 8 years old took part in a staged event at school and 1 week later were assessed using a short form of the Wechsler Intelligence scale for children (third edition) and measures ...of metamemory, narrative ability, and socioeconomic status. Two weeks following the event, children either received narrative elaboration training (NET;
K.J. Saywitz & L. Snyder, 1996
) and were prompted with the four NET cue cards at interview; received verbal prompts corresponding to the cue card categories, but without prior training; or were presented with the cards at interview without prior training. Children given verbal labels as prompts recalled as much information as children who received NET training and cue cards. Measures of intelligence were predictive of amount recalled for cards-only children but not for the other 2 groups, indicating that differences in recall between low- and high-IQ groups were attenuated when recall was supported by NET training or verbal prompting.
Groundwater can influence the geomagnetic field measured underground in at least two key ways. The water levels in rock will determine its electrical conductivity, and thus change the magnitude of ...the telluric currents induced in the rock by changing magnetic fields generated in the ionosphere. This can be studied by using multiple magnetometers at different underground locations. Secondly the flow of water through rock will generate a small magnetic signal, of unknown magnitude, through the electrokinetic effect. SQUID magnetometry has the potential to allow passive studies of groundwater changes in complex systems such as karst. We have monitored geomagnetic signals using two SQUID magnetometers at the LSBB underground laboratory, and set an initial limit on the magnitude of the electrokinetic signal. We now plan to carry out a longer term measurement using three SQUID systems as well as fluxgate sensors to track changes in the gradient of the magnetic field across the underground complex.
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