A new copper(
ii
) complex (
I
) was obtained by the reaction of a sterically crowded 2,4-di-(
tert
-butyl)-9-chloro-benzo5,61,4oxazine2,3-
b
phenoxazine bridging ligand with Cu(
ii
) ...hexafluoroacetylacetonate. Compound
I
is a quasi-one-dimensional complex in which the Cu(hfac)
2
moieties are co-crystallized with the triphenodioxazine molecules through only weak Cu N short intermolecular interactions (the Cu N distances are 2.732 and 2.752 Å). The magnetic AC susceptibility data show that in spite of the absence of zero-field splitting in the Cu(
ii
) ion with
S
= 1/2, the compound demonstrates a slow magnetic relaxation behaviour at a weak applied magnetic field (
H
DC
= 500 Oe). The EPR spectra and DC magnetic measurements show the strong axial anisotropy of the g-tensor. The temperature dependence of the relaxation time is well described by the combination of one-phonon direct and two-phonon Raman processes.
A new copper(
ii
) complex (
I
) was obtained by the reaction of a sterically crowded 2,4-di-(
tert
-butyl)-9-chloro-benzo5,61,4oxazine2,3-
b
phenoxazine bridging ligand with Cu(
ii
) hexafluoroacetylacetonate.
We studied the application of statistical reconstruction algorithms, namely maximum likelihood and least squares methods, to the problem of event reconstruction in a dual phase liquid xenon detector. ...An iterative method was developed for in-situ reconstruction of the PMT light response functions from calibration data taken with an uncollimated γ -ray source. Using the techniques described, the performance of the ZEPLIN-III dark matter detector was studied for 122 keV γ-rays. For the inner part of the detector ( R <; 100 mm) , spatial resolutions of 13 mm and 1.6 mm FWHM were measured in the horizontal plane for primary and secondary scintillation, respectively. An energy resolution of 8.1% FWHM was achieved at that energy. The possibility of using this technique for improving performance and reducing cost of scintillation cameras for medical applications is currently under study.
The study was first carried out on stimulus-specific adaptation of neurons in the primary and anterior fields of the awake house mice auditory cortex to sound sequences of four 100-ms tonal signals, ...with a frequency of tones corresponding to the neuronal characteristic frequency, and also with the inter-tone interval constant for one sequence and varying from 0 to 2000 ms in different sequences. The analysis of the data obtained showed the adaptation effect in the responses of all studied primary auditory cortex neurons, which was observed as the absence or significant decrease in activity evoked by the components of a series of tones following the 1st, at inter-stimulus intervals of 0–500 ms. A quantitative assessment of the adaptation effects as a function of inter-stimulus intervals within the tonal sequence, performed over a whole population of studied neurons, showed that the individual time scales of adaptation of neurons varied significantly, which may be crucial for the formation of optimal time windows for the processing of grouping and separation of sound events, which are important both for perception of animal vocalizations and human speech.
We report experimental upper limits on WIMP-nucleon elastic scattering cross sections from the second science run of ZEPLIN-III at the Boulby Underground Laboratory. A raw fiducial exposure of 1344 ...kg⋅days was accrued over 319 days of continuous operation between June 2010 and May 2011. A total of eight events was observed in the signal acceptance region in the nuclear recoil energy range 7–29 keV, which is compatible with background expectations. This allows the exclusion of the scalar cross-section above 4.8×10−8 pb near 50 GeV/c2 WIMP mass with 90% confidence. Combined with data from the first run, this result improves to 3.9×10−8 pb. The corresponding WIMP-neutron spin-dependent cross-section limit is 8.0×10−3 pb. The ZEPLIN programme reaches thus its conclusion at Boulby, having deployed and exploited successfully three liquid xenon experiments of increasing reach.
A comparative assessment of the reproductive qualities of beef-cows of the Hereford and Kazakh white-headed breeds is given, depending on the Body Condition Scoring. In the scientific and economic ...experiment in three farms on 3 groups of cows of two breeds, the influence of Body Condition Scoring on the reproductive qualities of cows was studied. It was found that cows with a Body Condition Scoring of 6 points have a significantly shorter service period (by 10-13 days) and the interval between calving (by 6-9 days), with an increase in the duration of pregnancy by 2-4 days, compared with cows with a score of 3 points. The calf crop per 100 cows, in groups with 6 Body Condition Scoring points, was higher than in groups with 3 Body Condition Scoring points by 9.2, 8.3 and 5.1%.
We study experimentally and theoretically the effects of high-frequency strain pulse trains on the charge transport in a weakly coupled semiconductor superlattice. In a frequency range of the order ...of 100 GHz such excitation may be considered as single harmonic hypersonic excitation. While travelling along the axis of the SL, the hypersonic acoustic wavepacket affects the electron tunnelling, and thus governs the electrical current through the device. We reveal how the change of current depends on the parameters of the hypersonic excitation and on the bias applied to the superlattice. We have found that the changes in the transport properties of the superlattices caused by the acoustic excitation can be largely explained using the current-voltage relation of the unperturbed system. Our experimental measurements show multiple peaks in the dependence of the transferred charge on the repetition rate of the strain pulses in the train. We demonstrate that these resonances can be understood in terms of the spectrum of the applied acoustic perturbation after taking into account the multiple reflections in the metal film serving as a generator of hypersonic excitation. Our findings suggest an application of the semiconductor superlattice as a hypersonic-electrical transducer, which can be used in various microwave devices.
Scintillation and ionisation yields for nuclear recoils in liquid xenon above 10 keVnr (nuclear recoil energy) are deduced from data acquired using broadband Am–Be neutron sources. The nuclear recoil ...data from several exposures to two sources were compared to detailed simulations. Energy-dependent scintillation and ionisation yields giving acceptable fits to the data were derived. Efficiency and resolution effects are treated using a light collection Monte Carlo, measured photomultiplier response profiles and hardware trigger studies. A gradual fall in scintillation yield below ∼40 keVnr is found, together with a rising ionisation yield; both are in agreement with the latest independent measurements. The analysis method is applied to the most recent ZEPLIN-III data, acquired with a significantly upgraded detector and a precision-calibrated Am–Be source, as well as to the earlier data from the first run in 2008. A new method for deriving the recoil scintillation yield, which includes sub-threshold S1 events, is also presented which confirms the main analysis.
A
bstract
We present an experimental study of single electron emission in ZEPLIN-III, a two-phase xenon experiment built to search for dark matter WIMPs, and discuss appli-cations enabled by the ...excellent signal-to-noise ratio achieved in detecting this signature. Firstly, we demonstrate a practical method for precise measurement of the free electron lifetime in liquid xenon during normal operation of these detectors. Then, using a realistic detector response model and backgrounds, we assess the feasibility of deploying such an instrument for measuring coherent neutrino-nucleus elastic scattering using the ionisation channel in the few-electron regime. We conclude that it should be possible to measure this elusive neutrino signature above an ionisation threshold of ~3 electrons both at a stopped pion source and at a nuclear reactor. Detectable signal rates are larger in the reactor case, but the triggered measurement and harder recoil energy spectrum afforded by the accelerator source enable lower overall background and fiducialisation of the active volume.
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