A
bstract
Heavy Neutral Leptons (HNLs) are hypothetical particles predicted by many extensions of the Standard Model. These particles can, among other things, explain the origin of neutrino masses, ...generate the observed matter-antimatter asymmetry in the Universe and provide a dark matter candidate.
The SHiP experiment will be able to search for HNLs produced in decays of heavy mesons and travelling distances ranging between
O
(50 m) and tens of kilometers before decaying. We present the sensitivity of the SHiP experiment to a number of HNL’s benchmark models and provide a way to calculate the SHiP’s sensitivity to HNLs for arbitrary patterns of flavour mixings. The corresponding tools and data files are also made publicly available.
Electrocaloric effect (ECE) as well as field induced pyroelectric and piezoelectric effects were investigated in relaxor ceramics 0.84 PbMg
1/3
Nb
2/3
O
3
–0.14 PbTiO
3
–0.02 SrTiO
3
. Dielectric and ...elastic properties of the solid solution were also studied. To improve the accuracy and reliability of the results obtained, the electrocaloric temperature change δ
T
was measured both by the well-known quasi-adiabatic technique with a contact temperature sensor and by the radiometric mid Infrared technique developed by the authors. The contribution of the secondary pyroelectric effect to the total pyroelectric and ECE was studied in detail. The effect of the induced piezoelectricity on the range of the temperature stability of pyroelectric and electrocaloric responses was shown. The resulting combination of material parameters at reasonable operating temperatures and electric fields, including both the possibility of increasing
δT
and the existence of its temperature-independent range from 10 to 80 °C, predestines the solid solution as a promising electrocaloric material.
The structure of isocyanide-phosphine complexes of palladium(II) dihalides PdX
2
(CNR)(PPh
3
) (X = Cl, Br, I; R =
t-
Bu, Xyl, and Mes) in CDCl
3
solutions and in solid phase, and also their ...resistance to
cis/trans
isomerization and ligands disproportionation were studied. The isocyanide-phosphine complexes of palladium(II) chloride, bromide, and iodide in crystals take the
cis
configuration. In solution isocyanide-phosphine complexes of palladium(II) chloride and bromide exist predominantly in the
cis
configuration. They are resistant to ligand disproportionation and can be prepared by mixing equivalent amounts of the corresponding bisisocyanide and bisphosphine complexes. In contrast, mixed-ligand isocyanide-phosphine complexes of palladium iodide in solution rapidly form mixtures of
cis
and
trans
isomers, and also of bisisocyanide and bisphosphine complexes.
A
bstract
A comprehensive set of azimuthal single-spin and double-spin asymmetries in semi-inclusive leptoproduction of pions, charged kaons, protons, and antiprotons from transversely polarized ...protons is presented. These asymmetries include the previously published HERMES results on Collins and Sivers asymmetries, the analysis of which has been extended to include protons and antiprotons and also to an extraction in a three-dimensional kinematic binning and enlarged phase space. They are complemented by corresponding results for the remaining four single-spin and four double-spin asymmetries allowed in the one-photon-exchange approximation of the semi-inclusive deep-inelastic scattering process for target-polarization orientation perpendicular to the direction of the incoming lepton beam. Among those results, significant non-vanishing cos (
ϕ−ϕ
S
) modulations provide evidence for a sizable worm-gear (II) distribution,
g
1
T
q
x
p
T
2
. Most of the other modulations are found to be consistent with zero with the notable exception of large sin (
ϕ
S
) modulations for charged pions and
K
+
.
Vulvar varicosity is a relatively common venous disorder in women with varicose veins of the pelvis and lower extremities and in pregnant women, but there is little information in the medical ...literature concerning its diagnosis and management. The aim of this study was to describe our experience with 101 women with vulvar varicosities who were examined and treated at our center during 2000-2014.
Patients were divided into two groups: group 1 with 61 women with varicose veins of the pelvis and enlarged vulvar veins, and group 2 with 40 pregnant women (11-38 weeks of pregnancy) with vulvar varicosities.
In most cases, vulvar varicosities were able to be diagnosed at clinical examination. In both groups, duplex ultrasound of the veins of the pelvis and lower extremities was used to confirm the presence of varicose veins, identify any retrograde flow, accurately determine vein diameter, and to reveal any anatomical feature of the intrapelvic veins. Treatment approaches varied significantly between the two groups from purely conservative measures during pregnancy to surgical procedures on the ovarian and vulvar veins in group 1. The venoactive agent, micronized purified flavonoid fraction, was effective at reducing the symptoms of vulvar varicosities in both groups.
A tailored approach to the diagnosis and treatment of vulvar varicosities can significantly improve the quality of care of women with this disorder.
A series of gold(I) monoisocyanide AuCl(CNC
6
H
4
-4-X) (X = Cl (
IIa
), Br (
IIb
), I (
IIc
) and bis
-
isocyanide Au(CNC
6
H
4
-4-X)
2
(PF
6
) (X = Cl (
IIIa
), Br (
IIIb
), I (
IIIc
) complexes ...were prepared by the reaction of AuCl(Tht) (Tht = tetrahydrothiophene) with the specified isocyanide. The molecular structure of
IIa
–
IIc
was established by X-ray diffraction (CCDC no. 2253450 (
IIa
), 2253447 (
IIb
), 2253448 (
IIc
)). The crystals of
IIb
and
IIc
are isostructural; they were found to have several types of intermolecular interactions, particularly, C–X⋯Cl–Au halogen bonds, π-hole (C
CNR
)···
(Au) interactions, and Au⋯Au aurophilic contacts, which form together a two-layer 2D supramolecular polymer. The crystals of
IIb
,
IIc
and
IIIa
,
IIIb
exhibit phosphorescence at room temperature; compounds
IIa
and
IIIc
do not possess luminescent properties; and mechanical grinding of
IIa
‒
IIc
and
IIIa
‒
IIIc
powders does not change the photophysical properties.
Dark photons are hypothetical massive vector particles that could mix with ordinary photons. The simplest theoretical model is fully characterised by only two parameters: the mass of the dark photon ...m
γ
D
and its mixing parameter with the photon,
ε
. The sensitivity of the SHiP detector is reviewed for dark photons in the mass range between 0.002 and 10 GeV. Different production mechanisms are simulated, with the dark photons decaying to pairs of visible fermions, including both leptons and quarks. Exclusion contours are presented and compared with those of past experiments. The SHiP detector is expected to have a unique sensitivity for m
γ
D
ranging between 0.8 and 3.3
-
0.5
+
0.2
GeV, and
ε
2
ranging between
10
-
11
and
10
-
17
.
The Search for Hidden Particles (SHiP) Collaboration has proposed a general-purpose experimental facility operating in beam-dump mode at the CERN SPS accelerator to search for light, feebly ...interacting particles. In the baseline configuration, the SHiP experiment incorporates two complementary detectors. The upstream detector is designed for recoil signatures of light dark matter (LDM) scattering and for neutrino physics, in particular with tau neutrinos. It consists of a spectrometer magnet housing a layered detector system with high-density LDM/neutrino target plates, emulsion-film technology and electronic high-precision tracking. The total detector target mass amounts to about eight tonnes. The downstream detector system aims at measuring visible decays of feebly interacting particles to both fully reconstructed final states and to partially reconstructed final states with neutrinos, in a nearly background-free environment. The detector consists of a 50
m
long decay volume under vacuum followed by a spectrometer and particle identification system with a rectangular acceptance of 5 m in width and 10 m in height. Using the high-intensity beam of 400
GeV
protons, the experiment aims at profiting from the
4
×
10
19
protons per year that are currently unexploited at the SPS, over a period of 5–10 years. This allows probing dark photons, dark scalars and pseudo-scalars, and heavy neutral leptons with GeV-scale masses in the direct searches at sensitivities that largely exceed those of existing and projected experiments. The sensitivity to light dark matter through scattering reaches well below the dark matter relic density limits in the range from a few
MeV
/
c
2
up to 100 MeV-scale masses, and it will be possible to study tau neutrino interactions with unprecedented statistics. This paper describes the SHiP experiment baseline setup and the detector systems, together with performance results from prototypes in test beams, as it was prepared for the 2020 Update of the European Strategy for Particle Physics. The expected detector performance from simulation is summarised at the end.
Atomic-force microscopy methods were used to study specimens of cathodes of multiwire proportional chambers subjected to a long-term exposure to a β-source
90
Sr in the course of laboratory longevity ...tests. The changes in the surface morphology of the copper foil at the detector cathode that have occurred as a result of action of an electron beam have been described. The quantitative estimate and analysis of the evolution of radiation defects depending on the irradiation dose are presented. The similarity of the radiation-induced defects in the laboratory prototypes and in the full-scale proportional chambers after their use for 10 years at the Large Hadron Collider is demonstrated.
PDF
