70 research outputs found
Single electron emission in two-phase xenon with application to the detection of coherent neutrino-nucleus scattering
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
applications 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
ΠΡΠΎΠ±Π΅Π½Π½ΠΎΡΡΠΈ ΡΡΠ½ΠΊΡΠΈΠΎΠ½ΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π²ΡΠΎΠΆΠ΄Π΅Π½Π½ΠΎΠ³ΠΎ ΠΈΠΌΠΌΡΠ½ΠΈΡΠ΅ΡΠ° Ρ Π΄Π΅ΡΠ΅ΠΉ Ρ Ρ ΡΠΎΠ½ΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΊΡΠ°ΠΏΠΈΠ²Π½ΠΈΡΠ΅ΠΉ
Aim. To study the features of the functioning of innate immunity in children with chronic idiopathic urticaria.Materials and methods. The study included 28 children of both sexes aged 6β16 years with chronic idiopathic urticaria (CIU). The median age of the patients was 8 years (p = 0.045). Clinical research methods included an analysis of complaints and anamnestic data, as well as an objective examination of the child (dynamics of urticaria, severity of itching, the presence of angioedema). Immunological techniques included determination of the number of monocytes expressing CD14+CD282+, CD14+CD284+, CD14+CD289+, the number of peripheral blood lymphocytes expressing CD3+CD16+, the levels of immunoglobulin (Ig) E, lactoferrin, interferon (IFN) Ξ³, interleukin (IL)4, and IL-6, and a nitroblue tetrazolium test.Results. In the course of the study, an increase in the expression of Toll-like receptors TLR2 and TLR4 by monocytes, a decrease in the expression of TLR9 by monocytes, a significant rise in lactoferrin levels, a slight decrease in the number of natural killer (NK) cells, a decrease in microbicidal activity and adaptive reserves, a rise in IgE levels, a decrease in IL-4 levels, and an increase in IFNΞ³ and IL-6 were revealed in children with CIU.Conclusion. The immunological changes revealed during the study indicate multidirectional expression of Toll-like receptors, disturbances in the work of the cellular components of innate immunity, and a launch of a proinflammatory cytokine cascade in children with CIU, which can serve as a mainstay for the development of new schemes for personalized therapy of CIU in children.Π¦Π΅Π»Ρ. ΠΠ·ΡΡΠΈΡΡ ΠΎΡΠΎΠ±Π΅Π½Π½ΠΎΡΡΠΈ ΡΡΠ½ΠΊΡΠΈΠΎΠ½ΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π²ΡΠΎΠΆΠ΄Π΅Π½Π½ΠΎΠ³ΠΎ ΠΈΠΌΠΌΡΠ½ΠΈΡΠ΅ΡΠ° Ρ Π΄Π΅ΡΠ΅ΠΉ Ρ Ρ
ΡΠΎΠ½ΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΊΡΠ°ΠΏΠΈΠ²Π½ΠΈΡΠ΅ΠΉ (Π₯Π).ΠΠ°ΡΠ΅ΡΠΈΠ°Π»Ρ ΠΈ ΠΌΠ΅ΡΠΎΠ΄Ρ. Π ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠ΅ Π²ΠΊΠ»ΡΡΠ΅Π½Ρ 28 Π΄Π΅ΡΠ΅ΠΉ ΠΎΠ±ΠΎΠΈΡ
ΠΏΠΎΠ»ΠΎΠ² Π² Π²ΠΎΠ·ΡΠ°ΡΡΠ΅ ΠΎΡ 6 Π΄ΠΎ 16 Π»Π΅Ρ Ρ Ρ
ΡΠΎΠ½ΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΈΠ΄ΠΈΠΎΠΏΠ°ΡΠΈΡΠ΅ΡΠΊΠΎΠΉ (ΡΠΏΠΎΠ½ΡΠ°Π½Π½ΠΎΠΉ) ΠΊΡΠ°ΠΏΠΈΠ²Π½ΠΈΡΠ΅ΠΉ. ΠΠ΅Π΄ΠΈΠ°Π½Π° Π²ΠΎΠ·ΡΠ°ΡΡΠ° β 8 Π»Π΅Ρ (Ρ = 0,045). ΠΠ»ΠΈΠ½ΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΌΠ΅ΡΠΎΠ΄Ρ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ: Π°Π½Π°Π»ΠΈΠ· ΠΆΠ°Π»ΠΎΠ±, Π°Π½Π°ΠΌΠ½Π΅ΡΡΠΈΡΠ΅ΡΠΊΠΈΡ
Π΄Π°Π½Π½ΡΡ
, ΠΎΠ±ΡΠ΅ΠΊΡΠΈΠ²Π½ΡΠΉ ΠΎΡΠΌΠΎΡΡ ΡΠ΅Π±Π΅Π½ΠΊΠ° (Π΄ΠΈΠ½Π°ΠΌΠΈΠΊΠ° ΡΡΡΠΈΠΊΠ°ΡΠΈΠ΅Π², Π²ΡΡΠ°ΠΆΠ΅Π½Π½ΠΎΡΡΠΈ ΠΊΠΎΠΆΠ½ΠΎΠ³ΠΎ Π·ΡΠ΄Π°, Π½Π°Π»ΠΈΡΠΈΠ΅ Π°Π½Π³ΠΈΠΎΠΎΡΠ΅ΠΊΠΎΠ²). ΠΠΌΠΌΡΠ½ΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΌΠ΅ΡΠΎΠ΄Ρ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ: ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΠ΅ ΠΊΠΎΠ»ΠΈΡΠ΅ΡΡΠ²Π° ΠΌΠΎΠ½ΠΎΡΠΈΡΠΎΠ², ΡΠΊΡΠΏΡΠ΅ΡΡΠΈΡΡΡΡΠΈΡ
CD14+CD282+, CD14+CD284+, CD14+CD289+, ΠΊΠΎΠ»ΠΈΡΠ΅ΡΡΠ²Π° Π»ΠΈΠΌΡΠΎΡΠΈΡΠΎΠ² ΠΏΠ΅ΡΠΈΡΠ΅ΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΊΡΠΎΠ²ΠΈ, ΡΠΊΡΠΏΡΠ΅ΡΡΠΈΡΡΡΡΠΈΡ
CD3+CD16+, ΡΠΎΠ΄Π΅ΡΠΆΠ°Π½ΠΈΡ ΠΈΠΌΠΌΡΠ½ΠΎΠ³Π»ΠΎΠ±ΡΠ»ΠΈΠ½Π° E, ΡΡΠΎΠ²Π½Ρ Π»Π°ΠΊΡΠΎΡΠ΅ΡΡΠΈΠ½Π°, ΠΈΠ½ΡΠ΅ΡΡΠ΅ΡΠΎΠ½Π° (IFN) Ξ³, ΠΈΠ½ΡΠ΅ΡΠ»Π΅ΠΉΠΊΠΈΠ½Π° (IL) 4 ΠΈ 6, ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ΠΈΠ΅ ΡΠ΅ΡΡΠ° Ρ Π½ΠΈΡΡΠΎΡΠΈΠ½ΠΈΠΌ ΡΠ΅ΡΡΠ°Π·ΠΎΠ»ΠΈΠ΅ΠΌ.Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ. Π Ρ
ΠΎΠ΄Π΅ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ Ρ Π΄Π΅ΡΠ΅ΠΉ Ρ Π₯Π Π²ΡΡΠ²Π»Π΅Π½ΠΎ ΠΏΠΎΠ²ΡΡΠ΅Π½ΠΈΠ΅ ΡΠΊΡΠΏΡΠ΅ΡΡΠΈΠΈ ΠΌΠΎΠ½ΠΎΡΠΈΡΠ°ΠΌΠΈ Toll-ΡΠ΅ΡΠ΅ΠΏΡΠΎΡΠΎΠ² TLR2 ΠΈ TLR4, ΠΏΠΎΠ΄Π°Π²Π»Π΅Π½ΠΈΠ΅ ΡΠΊΡΠΏΡΠ΅ΡΡΠΈΠΈ ΠΌΠΎΠ½ΠΎΡΠΈΡΠ°ΠΌΠΈ TLR9, Π·Π½Π°ΡΠΈΡΠ΅Π»ΡΠ½ΠΎΠ΅ ΡΠ²Π΅Π»ΠΈΡΠ΅Π½ΠΈΠ΅ ΡΡΠΎΠ²Π½Ρ Π»Π°ΠΊΡΠΎΡΠ΅ΡΡΠΈΠ½Π°, Π½Π΅Π·Π½Π°ΡΠΈΡΠ΅Π»ΡΠ½ΠΎΠ΅ ΡΠΎΠΊΡΠ°ΡΠ΅Π½ΠΈΠ΅ ΠΊΠΎΠ»ΠΈΡΠ΅ΡΡΠ²Π° NK-ΠΊΠ»Π΅ΡΠΎΠΊ, ΡΠ½ΠΈΠΆΠ΅Π½ΠΈΠ΅ ΠΌΠΈΠΊΡΠΎΠ±ΠΈΡΠΈΠ΄Π½ΠΎΠΉ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ ΠΈ Π°Π΄Π°ΠΏΡΠ°ΡΠΈΠΎΠ½Π½ΡΡ
ΡΠ΅Π·Π΅ΡΠ²ΠΎΠ², ΠΏΠΎΠ²ΡΡΠ΅Π½ΠΈΠ΅ ΡΡΠΎΠ²Π½Ρ IgΠ, IFNΞ³ ΠΈ IL-6, ΡΠΌΠ΅Π½ΡΡΠ΅Π½ΠΈΠ΅ ΡΡΠΎΠ²Π½Ρ IL-4.ΠΠ°ΠΊΠ»ΡΡΠ΅Π½ΠΈΠ΅. ΠΡΡΠ²Π»Π΅Π½Π½ΡΠ΅ Π² Ρ
ΠΎΠ΄Π΅ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΠΈΠΌΠΌΡΠ½ΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΈΠ·ΠΌΠ΅Π½Π΅Π½ΠΈΡ ΡΠ²ΠΈΠ΄Π΅ΡΠ΅Π»ΡΡΡΠ²ΡΡΡ ΠΎ ΡΠ°Π·Π½ΠΎΠ½Π°ΠΏΡΠ°Π²Π»Π΅Π½Π½ΠΎΠΉ ΡΠΊΡΠΏΡΠ΅ΡΡΠΈΠΈ Toll-ΡΠ΅ΡΠ΅ΠΏΡΠΎΡΠΎΠ², Π½Π°ΡΡΡΠ΅Π½ΠΈΡΡ
Π² ΡΠ°Π±ΠΎΡΠ΅ ΠΊΠ»Π΅ΡΠΎΡΠ½ΠΎΠ³ΠΎ Π·Π²Π΅Π½Π° Π²ΡΠΎΠΆΠ΄Π΅Π½Π½ΠΎΠ³ΠΎ ΠΈΠΌΠΌΡΠ½ΠΈΡΠ΅ΡΠ°, Π·Π°ΠΏΡΡΠΊΠ΅ ΡΠΈΡΠΎΠΊΠΈΠ½ΠΎΠ²ΠΎΠ³ΠΎ ΠΊΠ°ΡΠΊΠ°Π΄Π° Π²ΠΎΡΠΏΠ°Π»Π΅Π½ΠΈΡ Ρ Π΄Π΅ΡΠ΅ΠΉ Ρ Ρ
ΡΠΎΠ½ΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΈΠ΄ΠΈΠΎΠΏΠ°ΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΊΡΠ°ΠΏΠΈΠ²Π½ΠΈΡΠ΅ΠΉ, ΡΡΠΎ ΠΌΠΎΠΆΠ΅Ρ ΠΏΠΎΡΠ»ΡΠΆΠΈΡΡ ΠΎΡΠ½ΠΎΠ²ΠΎΠΉ Π΄Π»Ρ ΡΠ°Π·ΡΠ°Π±ΠΎΡΠΊΠΈ Π½ΠΎΠ²ΡΡ
ΡΡ
Π΅ΠΌ ΠΏΠ΅ΡΡΠΎΠ½ΠΈΡΠΈΡΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠΉ ΡΠ΅ΡΠ°ΠΏΠΈΠΈ Π₯Π Ρ Π΄Π΅ΡΠ΅ΠΉ
WIMP-nucleon cross-section results from the second science run of ZEPLIN-III
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 1,344 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 4.8E-8 pb near 50 GeV/c^2 WIMP mass
with 90% confidence. Combined with data from the first run, this result
improves to 3.9E-8 pb. The corresponding WIMP-neutron spin-dependent
cross-section limit is 8.0E-3 pb. The ZEPLIN programme reaches thus its
conclusion at Boulby, having deployed and exploited successfully three liquid
xenon experiments of increasing reach
Quenching Factor for Low Energy Nuclear Recoils in a Plastic Scintillator
Plastic scintillators are widely used in industry, medicine and scientific
research, including nuclear and particle physics. Although one of their most
common applications is in neutron detection, experimental data on their
response to low-energy nuclear recoils are scarce. Here, the relative
scintillation efficiency for neutron-induced nuclear recoils in a
polystyrene-based plastic scintillator (UPS-923A) is presented, exploring
recoil energies between 125 keV and 850 keV. Monte Carlo simulations,
incorporating light collection efficiency and energy resolution effects, are
used to generate neutron scattering spectra which are matched to observed
distributions of scintillation signals to parameterise the energy-dependent
quenching factor. At energies above 300 keV the dependence is reasonably
described using the semi-empirical formulation of Birks and a kB factor of
(0.014+/-0.002) g/MeVcm^2 has been determined. Below that energy the measured
quenching factor falls more steeply than predicted by the Birks formalism.Comment: 8 pages, 9 figure
The Inert Doublet Model and Inelastic Dark Matter
The annual modulation observed by DAMA/NaI and DAMA/Libra may be interpreted
in terms of elastic or inelastic scattering of dark matter particles. In this
paper we confront these two scenarios within the framework of a very simple
extension of the Standard Model, the Inert Doublet Model (IDM). In this model
the dark matter candidate is a scalar, the lightest component of an extra Higgs
doublet. We first revisit the case for the elastic scattering of a light scalar
WIMP, M_DM~10 GeV, a scenario which requires that a fraction of events in DAMA
are channelled. Second we consider the possibility of inelastic Dark Matter
(iDM). This option is technically natural in the IDM, in the sense that the
mass splitting between the lightest and next-to-lightest neutral scalars may be
protected by a Peccei-Quinn (PQ) symmetry. We show that candidates with a mass
M_DM between ~535 GeV and ~50 TeV may reproduce the DAMA data and have a cosmic
abundance in agreement with WMAP. This range may be extended to candidates as
light as ~50 GeV if we exploit the possibility that the approximate PQ symmetry
is effectively conserved and that a primordial asymmetry in the dark sector may
survive until freeze-out.Comment: 16 pages, 7 figures. v2: minor changes and discussion on the
embedding in SO(10) added. v3: matches the published version in JCA
Dark Matter Spin-Dependent Limits for WIMP Interactions on 19-F by PICASSO
The PICASSO experiment at SNOLAB reports new results for spin-dependent WIMP
interactions on F using the superheated droplet technique. A new
generation of detectors and new features which enable background discrimination
via the rejection of non-particle induced events are described. First results
are presented for a subset of two detectors with target masses of F of
65 g and 69 g respectively and a total exposure of 13.75 0.48 kgd. No
dark matter signal was found and for WIMP masses around 24 GeV/c new limits
have been obtained on the spin-dependent cross section on F of
= 13.9 pb (90% C.L.) which can be converted into cross section
limits on protons and neutrons of = 0.16 pb and = 2.60 pb
respectively (90% C.L). The obtained limits on protons restrict recent
interpretations of the DAMA/LIBRA annual modulations in terms of spin-dependent
interactions.Comment: Revised version, accepted for publication in Phys. Lett. B, 20 pages,
7 figure
ZE3RA: The ZEPLIN-III Reduction and Analysis package
ZE3RA is the software package responsible for processing the raw data from the ZEPLIN-III dark matter experiment and its reduction into a set of parameters used in all subsequent analyses. The detector is a liquid xenon time projection chamber with scintillation and electroluminescence signals read out by an array of 31 photomultipliers. The dual range 62-channel data stream is optimised for the detection of scintillation pulses down to a single photoelectron and of ionisation signals as small as those produced by single electrons. We discuss in particular several strategies related to data filtering, pulse finding and pulse clustering which are tuned using calibration data to recover the best electron/nuclear recoil discrimination near the detection threshold, where most dark matter elastic scattering signatures are expected. The software was designed assuming only minimal knowledge of the physics underlying the detection principle, allowing an unbiased analysis of the experimental results and easy extension to other detectors with similar requirements. Β©2011 IOP Publishing Ltd and SISSA
Measurement and simulation of the muon-induced neutron yield in lead
A measurement is presented of the neutron production rate in lead by high energy cosmic-ray muons at a depth of 2850 m water equivalent (w.e.) and a mean muon energy of 260 GeV. The measurement exploits the delayed coincidences between muons and the radiative capture of induced neutrons in a highly segmented tonne scale plastic scintillator detector. Detailed Monte Carlo simulations reproduce well the measured capture times and multiplicities and, within the dynamic range of the instrumentation, the spectrum of energy deposits. By comparing measurements with simulations of neutron capture rates a neutron yield in lead of (View the MathML source) Γ10-3 neutrons/muon/(g/cm2) has been obtained. Absolute agreement between simulation and data is of order 25%. Consequences for deep underground rare event searches are discussed
Phenomenology of Light Sneutrino Dark Matter in cMSSM/mSUGRA with Inverse Seesaw
We study the possibility of a light Dark Matter (DM) within a constrained
Minimal Supersymmetric Standard Model (cMSSM) framework augmented by a SM
singlet-pair sector to account for the non-zero neutrino masses by inverse
seesaw mechanism. Working within a 'hybrid' scenario with the MSSM sector fixed
at high scale and the singlet neutrino sector at low scale, we find that,
contrary to the case of the usual cMSSM where the neutralino DM cannot be very
light, we can have a light sneutrino DM with mass below 100 GeV satisfying all
the current experimental constraints from cosmology, collider as well as
low-energy experiments. We also note that the supersymmetric inverse seesaw
mechanism with sneutrino as the lightest supersymmetric partner can have
enhanced same-sign dilepton final states with large missing transverse energy
(mET) coming from the gluino- and squark-pair as well as the squark-gluino
associated productions and their cascade decay through charginos. We present a
collider study for the same-sign dilepton+jets+mET signal in this scenario and
propose some distinctions with the usual cMSSM. We also comment on the
implications of such a light DM scenario on the invisible decay width of an 125
GeV Higgs boson.Comment: 24 pages, 4 figures, 7 tables; matches published versio
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