667 research outputs found
Characteristics of alpha projectile fragments emission in interaction of nuclei with emulsion
The properties of the relativistic alpha fragments produced in interactions
of 84^Kr at around 1 A GeV in nuclear emulsion are investigated. The
experimental results are compared with the similar results obtained from
various projectiles with emulsion interactions at different energies. The
total, partial nuclear cross-sections and production rates of alpha
fragmentation channels in relativistic nucleus-nucleus collisions and their
dependence on the mass number and initial energy of the incident projectile
nucleus are investigated. The yields of multiple alpha fragments emitted from
the interactions of projectile nuclei with the nuclei of light, medium and
heavy target groups of emulsion-detector are discussed and they indicate that
the projectile-breakup mechanism seems to be free from the target mass number.
It is found that the multiplicity distributions of alpha fragments are well
described by the Koba-Nielsen-Olesen (KNO) scaling presentation. The mean
multiplicities of the freshly produced newly created charged secondary
particles, normally known as shower and secondary particles associated with
target in the events where the emission of alpha fragments were accompanied by
heavy projectile fragments having Z value larger than 4 seem to be constant as
the alpha fragments multiplicity increases, and exhibit a behavior independent
of the alpha fragments multiplicity.Comment: 33 pages, 8 figures and 3 tables (in press
Supersymmetric Gauge Theories with an Affine Quantum Moduli Space
All supersymmetric gauge theories based on simple groups which have an affine
quantum moduli space, i.e. one generated by gauge invariants with no relations,
W=0, and anomaly matching at the origin, are classified. It is shown that the
only theories with no gauge invariants (and moduli space equal to a single
point) are the two known examples, SU(5) with 5-bar + 10 and SO(10) with a
spinor. The index of the matter representation must be at least as big as the
index of the adjoint in theories which have a non-trivial relation among the
gauge invariants.Comment: Incorrect proof that theories with constraints must have mu >=
mu(adj) replaced by a correct one (6 pages, uses revtex, amssymb, array
Environmental pollutants in blood donors: The multicentre Norwegian donor study
Objectives - The aim of this study was to measure blood concentrations of environmental pollutants in Norwegian donors and evaluate the risk of pollutant exposure through blood transfusions.
Background - Transfused blood may be a potential source of exposure to heavy metals and organic pollutants and presents a risk to vulnerable patient groups such as premature infants.
Methods/Materials - Donors were randomly recruited from three Norwegian blood banks: in Bergen, Tromsø and Kirkenes. Selected heavy metals were measured in whole blood using inductively coupled plasma mass spectrometry (ICP‐MS), and perfluoroalkyl substances (PFAS) were measured in serum by ultrahigh‐pressure liquid chromatography coupled with a triple‐quadrupole mass spectrometer (UHPLC‐MS/MS).
Results - Almost 18% of blood donors had lead concentrations over the limit suggested for transfusions in premature infants (0.09 μmol/L). About 11% of all donors had mercury concentrations over the suggested limit of 23.7 nmol/L. Cadmium was higher than the limit, 16 nmol/L, in 4% of donors. Perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) concentrations were over the suggested limit of 0.91 ng/mL in 68% and 100% of the donors, respectively. PFAS concentrations and heavy metal concentrations increased with donor's age.
Conclusion - A considerable percentage of donors had lead, PFOS and PFOA concentrations over the suggested limits. In addition, at each study site, there were donors with high mercury and cadmium concentrations. Selecting young donors for transfusions or measurements of pollutants in donor blood may be a feasible approach to avoid exposure through blood transfusions to vulnerable groups of patients such as premature infants
Two-particle rapidity correlations between relativistic particles in central collisions of 197 Au nuclei in emulsion at 11.6 A GeV/c
Enabling comparison of UrQMD with Geant4 hadronic models
Geant4 has an abundant set of physics models that handle the diverse
interaction of particles with matter across a wide energy range. However, there
are also many well established reaction codes currently used in the same fields
where Geant4 is applied. One such code is the Ultra-relativistic Quantum
Molecular Dynamics (UrQMD) model. In order to take advantage of the UrQMD code,
we create a tool to enable comparisons among UrQMD and Geant4 hadronic models.
This tool allows a user to process the output file of UrQMD through Geant4
toolkit, while at the same time, can choose among different Geant4 hadronic
model generators. As an example, the UrQMD model is compared with the HARP-CDP
experimental data and with the Binary and FRITIOF generators, in the framework
of Geant4. It is shown that the UrQMD model can better reproduce charged pion
production for p+Cu and Pb interactions at 3, 8 and 15 GeV/c, and is a good
candidate for Geant4 hadronic models.Comment: 17 pages, 5 Figure
Momentum Correlations of Charmed Pairs Produced in Interactions at 230 GeV/c
We study the production characteristics of 557 pairs of charmed hadrons
produced in \ interactions at 230~GeV/c using a momentum estimator
for charmed hadrons with missing decay products. We find, the mean value of the
transverse momentum squared of the charmed pairs is GeV/c, the mean rapidity difference is , and the mean effective mass is GeV/c. Comparing these results with the next-to-leading order QCD
predictions we find an agreement for the \yd\ and \mef, whilst the measured
mean value of \pts\ is significantly larger than the predicted value.Comment: 10 pages, LaTeX, 4 (pages) postscript figure
Dissociation of relativistic C nuclei in nuclear track emulsion
Dissociation of 1.2 A GeV C nuclei in nuclear track emulsionis is
studied.
It is shown that most precise angular measurements provided by this technique
play a crucial role in the restoration of the excitation spectrum of the
2+2p system. Strong contribution of the cascade process
CBBe identified.Comment: 5 pages, 3 figures, conference: The 21st European Conference on
Few-Body Problems in Physics, Salamanca, Spain, 29th August - 3rd September,
201
Применение белого люпина в качестве компонента комбикормов для ценных видов рыб
Применение белого люпина как компонента для производства комбикормов применяемых при выращивании ценных видов рыб позволяет увеличить эффективность усвояемости белка, повысит плавучесть и водостойкость гранул комбикорма применяемого в индустриальной аквакультуре
ON THE INTRINSIC CHARM COMPONENT OF THE NUCLEON
Using a meson cloud model we calculate the squared charm radius
of the nucleon . The ratio between this squared radius and the ordinary baryon
squared radius is identified with the probability of ``seeing'' the intrinsic
charm component of the nucleon. Our estimate is compatible with those used to
successfully describe the charm production phenomenology.Comment: 9 pages, 2 figures not included, avaiable from the author
Alignment in Gamma-Hadron Families of Cosmic Rays
Alignment of main fluxes of energy in a target plane is found in families of
cosmic ray particles detected in deep lead X-ray chambers. The fraction of
events with alignment is unexpectedly large for families with high energy and
large number of hadrons. This can be considered as evidence for the existence
of coplanar scattering of secondary particles in interaction of particles with
superhigh energy, eV. Data analysis suggests that production of
most aligned groups occurs low above the chamber and is characterized by a
coplanar scattering and quasiscaling spectrum of secondaries in the
fragmentation region. The most elaborated hypothesis for explanation of
alignment is related to the quark-gluon string rupture. However, the problem of
theoretical interpretation of our results still remains open.Comment: 15 pages, 2 tables, 6 figures (not included), Stanford University
preprint SU-ITP-94-2
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