2,679 research outputs found
A complete checklist with new records and geographical distribution of the rove beetles (Coleoptera, Staphylinidae) of Brazil
This paper presents the first comprehensive list of 2,688 species of Staphylinidae (Coleoptera) recorded from Brazil. The list is based on the taxonomic and ecological literature, and new records from some insect collections, and includes locality references for each species. In addition, Brazilian localities and the country-level distribution outside of Brazil are provided for each species. Brazilian localities are organized by state, and include the bibliographic reference and page number where each locality was reported. All localities are geo-referenced, organized by state, and listed in an Appendix.Este trabalho apresenta a primeira lista completa das 2.688 espécies de Staphylinidae (Coleoptera) registradas para o Brasil. A lista inclui todas as localidades citadas para cada espécie e baseia-se na literatura taxonômica e ecológica disponíveis. Cada localidade inclui a referência bibliográfica e o número da página onde foram citadas. Também são apresentados registros inéditos obtidos de algumas coleções de insetos. Além das localidades brasileiras são citados todos os países com ocorrência conhecida para cada espécie. As localidades brasileiras, listadas no Apêndice, estão organizadas por estado e georreferenciadas
Additions to the Staphylinidae (Coleoptera) of the Cayman Islands
In 1947, 20 species of Staphylinidae were reported from the Cayman Islands as a result of an Oxford University expedition there in 1938 which made extensive use of a light trap. The list is here expanded to 62 species based on collections by R. R. Askew, G. E. Ball, E. A. Dilbert, B. K. Dozier, E. J. Gerberg, P. J. Fitzgerald, M. C. Thomas, and R. H. Turnbow since 1970, all of whom also used light traps except for a collection or two by flight intercept trap
Three-dimensional image reconstruction in J-PET using Filtered Back Projection method
We present a method and preliminary results of the image reconstruction in
the Jagiellonian PET tomograph. Using GATE (Geant4 Application for Tomographic
Emission), interactions of the 511 keV photons with a cylindrical detector were
generated. Pairs of such photons, flying back-to-back, originate from e+e-
annihilations inside a 1-mm spherical source. Spatial and temporal coordinates
of hits were smeared using experimental resolutions of the detector. We
incorporated the algorithm of the 3D Filtered Back Projection, implemented in
the STIR and TomoPy software packages, which differ in approximation methods.
Consistent results for the Point Spread Functions of ~5/7,mm and ~9/20, mm were
obtained, using STIR, for transverse and longitudinal directions, respectively,
with no time of flight information included.Comment: Presented at the 2nd Jagiellonian Symposium on Fundamental and
Applied Subatomic Physics, Krak\'ow, Poland, June 4-9, 2017. To be published
in Acta Phys. Pol.
Feasibility studies of the polarization of photons beyond the optical wavelength regime with the J-PET detector
J-PET is a detector optimized for registration of photons from the
electron-positron annihilation via plastic scintillators where photons interact
predominantly via Compton scattering. Registration of both primary and
scattered photons enables to determinate the linear polarization of the primary
photon on the event by event basis with a certain probability. Here we present
quantitative results on the feasibility of such polarization measurements of
photons from the decay of positronium with the J-PET and explore the physical
limitations for the resolution of the polarization determination of 511 keV
photons via Compton scattering. For scattering angles of about 82 deg (where
the best contrast for polarization measurement is theoretically predicted) we
find that the single event resolution for the determination of the polarization
is about 40 deg (predominantly due to properties of the Compton effect).
However, for samples larger than ten thousand events the J-PET is capable of
determining relative average polarization of these photons with the precision
of about few degrees. The obtained results open new perspectives for studies of
various physics phenomena such as quantum entanglement and tests of discrete
symmetries in decays of positronium and extend the energy range of polarization
measurements by five orders of magnitude beyond the optical wavelength regime.Comment: 10 pages, 14 figures, submitted to EPJ
Simulation studies of annihilation-photon's polarisation via Compton scattering with the J-PET tomograph
J-PET is the first positron-emission tomograph (PET) constructed from plastic
scintillators. It was optimized for the detection of photons from
electron-positron annihilation. Such photons, having an energy of 511 keV,
interact with electrons in plastic scintillators predominantly via the Compton
effect. Compton scattering is at most probable at an angle orthogonal to the
electric field vector of the interacting photon. Thus registration of multiple
photon scatterings with J-PET enables to determine the polarization of the
annihilation photons. In this contribution we present estimates on the physical
limitation in the accuracy of the polarization determination of ~keV
photons with the J-PET detector.Comment: Submitted to Hyperfine Interaction
Collins and Sivers asymmetries in muonproduction of pions and kaons off transversely polarised proton
Measurements of the Collins and Sivers asymmetries for charged pions and
charged and neutral kaons produced in semi-inclusive deep-inelastic scattering
of high energy muons off transversely polarised protons are presented. The
results were obtained using all the available COMPASS proton data, which were
taken in the years 2007 and 2010. The Collins asymmetries exhibit in the
valence region a non-zero signal for pions and there are hints of non-zero
signal also for kaons. The Sivers asymmetries are found to be positive for
positive pions and kaons and compatible with zero otherwise.Comment: 15 pages, 13 figures and 1 tabl
Measurement of the charged-pion polarisability
The COMPASS collaboration at CERN has investigated pion Compton scattering,
, at centre-of-mass energy below 3.5 pion
masses. The process is embedded in the reaction
, which is initiated by
190\,GeV pions impinging on a nickel target. The exchange of quasi-real photons
is selected by isolating the sharp Coulomb peak observed at smallest momentum
transfers, \,(GeV/). From a sample of 63\,000 events the
pion electric polarisability is determined to be $\alpha_\pi\ =\ (\,2.0\ \pm\
0.6_{\mbox{\scriptsize stat}}\ \pm\ 0.7_{\mbox{\scriptsize syst}}\,) \times
10^{-4}\,\mbox{fm}^3\alpha_\pi=-\beta_\pi$, which
relates the electric and magnetic dipole polarisabilities. It is the most
precise measurement of this fundamental low-energy parameter of strong
interaction, that has been addressed since long by various methods with
conflicting outcomes. While this result is in tension with previous dedicated
measurements, it is found in agreement with the expectation from chiral
perturbation theory. An additional measurement replacing pions by muons, for
which the cross-section behavior is unambigiously known, was performed for an
independent estimate of the systematic uncertainty.Comment: Published version: 9 pages, 3 figures, 1 tabl
Search for exclusive photoproduction of Z(3900) at COMPASS
A search for the exclusive production of the hadron by
virtual photons has been performed in the channel . The data cover the range from 7 GeV to 19 GeV in the
centre-of-mass energy of the photon-nucleon system. The full set of the COMPASS
data set collected with a muon beam between 2002 and 2011 has been used. An
upper limit for the ratio of has been established at the confidence
level of 90%.Comment: 8 pages, 3 figures, 1 tabl
Spin alignment and violation of the OZI rule in exclusive and production in pp collisions
Exclusive production of the isoscalar vector mesons and is
measured with a 190 GeV proton beam impinging on a liquid hydrogen target.
Cross section ratios are determined in three intervals of the Feynman variable
of the fast proton. A significant violation of the OZI rule is found,
confirming earlier findings. Its kinematic dependence on and on the
invariant mass of the system formed by fast proton
and vector meson is discussed in terms of diffractive
production of resonances in competition with central
production. The measurement of the spin density matrix element of
the vector mesons in different selected reference frames provides another
handle to distinguish the contributions of these two major reaction types.
Again, dependences of the alignment on and on are
found. Most of the observations can be traced back to the existence of several
excited baryon states contributing to production which are absent in
the case of the meson. Removing the low-mass resonant
region, the OZI rule is found to be violated by a factor of eight,
independently of .Comment: 23 pages, 13 figures and 5 table
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