6,815 research outputs found
The simultaneous long- and short-lived neutral kaon beams for experiment NA48
Simultaneous, nearly-collinear beams of long- and short-lived neutral kaons are an essential feature of the precision CP-violation experiment NA48 *) at the SPS. The present report describes the design and performance of these beams in relation to the requirements of the experiment
The simultaneous and nearly-collinear beams for experiment NA48
A system of simultaneous and nearly-collinear beams of long- and short-lived neutral kaons has been installed and extensively studied. These beams form an integral part of the NA48 experiment at the CERN SPS, which aims to study direct CP-violation. The beam splitting is achieved by a novel application of a bent silicon crystal. The principles and design of these beams, as well as their performance are described
Pseudorapidity Distribution of Charged Particles in PbarP Collisions at root(s)= 630GeV
Using a silicon vertex detector, we measure the charged particle
pseudorapidity distribution over the range 1.5 to 5.5 using data collected from
PbarP collisions at root s = 630 GeV. With a data sample of 3 million events,
we deduce a result with an overall normalization uncertainty of 5%, and typical
bin to bin errors of a few percent. We compare our result to the measurement of
UA5, and the distribution generated by the Lund Monte Carlo with default
settings. This is only the second measurement at this level of precision, and
only the second measurement for pseudorapidity greater than 3.Comment: 9 pages, 5 figures, LaTeX format. For ps file see
http://hep1.physics.wayne.edu/harr/harr.html Submitted to Physics Letters
Age- and sex-related variations in platelet count in Italy: a proposal of reference ranges based on 40987 subjects' data
BACKGROUND AND OBJECTIVES: Although several studies demonstrated that platelet count is higher in women, decreases with age, and is influenced by genetic background, most clinical laboratories still use the reference interval 150-400×10(9) platelets/L for all subjects. The present study was to identify age- and sex-specific reference intervals for platelet count. METHODS: We analysed electronic records of subjects enrolled in three population-based studies that investigated inhabitants of seven Italian areas including six geographic isolates. After exclusion of patients with malignancies, liver diseases, or inherited thrombocytopenias, which could affect platelet count, reference intervals were estimated from 40,987 subjects with the non parametric method computing the 2.5° and 97.5° percentiles. RESULTS: Platelet count was similar in men and women until the age of 14, but subsequently women had steadily more platelets than men. The number of platelets decreases quickly in childhood, stabilizes in adulthood, and further decreases in oldness. The final result of this phenomenon is that platelet count in old age was reduced by 35% in men and by 25% in women compared with early infancy. Based on these findings, we estimated reference intervals for platelet count ×10(9)/L in children (176-452), adult men (141-362), adult women (156-405), old men (122-350) and, old women (140-379). Moreover, we calculated an extended reference interval that takes into account the differences in platelet count observed in different geographic areas. CONCLUSIONS: The age-, sex-, and origin-related variability of platelet count is very wide, and the patient-adapted reference intervals we propose change the thresholds for diagnosing both thrombocytopenia and thrombocytosis in Italy
Effects of sports experience on children's gross motor coordination level
Background: Gross motor coordination (GMC) development could be
influenced by age, gender, weight status, geographical area, living setting,
home environment, socio-economic status, sports practice.
Purpose: To verify whether practicing sports and practicing different sports
could influence children’s GMC level.
Methods: A total of 295 children aged 8–11 years were involved in the study and
divided into 5 groups in relation to the sport they practiced: gymnastics group
(n = 67; 51F, 16M), cycling group (n = 64; 15F, 49M), athletics group (n = 47;
22F, 25M), swimming group (n = 35; 20F, 15M), control group (n = 82; 42F,
40M). The four subtests of the Körperkoordinations Test für Kinder (KTK)
assessed children’s GMC level. The scores from each of the four subtests were
summed into the KTK total raw score (RS) and then converted into a gender and age-specific motor quotient (MQ).
Results: Children practicing sports showed significantly higher RS and MQ score
than children of control group (203.14 ± 38.55 vs. 163.63 ± 43.50 and 98.56 ±
15.79 vs. 83.01 ± 16.71, respectively; p < 0.001). Children practicing gymnastics
had a significantly higher RS and MQ than children of cycling, swimming, and
control groups (p < 0.05), children of control group had a significantly lower RS
and MQ than children of all other groups (p < 0.05). Children practicing
gymnastics performed better walking backwards subtest than all other children’s
groups (p < 0.001). Children of control group performed worse jumping sideways
subtest than children of gymnastics, athletics and swimming groups (p < 0.01).
Children practicing gymnastics performed better moving sideways subtest than
children of athletics, cycling and control groups (p < 0.01); children of control
group performed worse than children of all other groups (p < 0.01). Children of
control group performed worse hopping for height subtest than children of
gymnastics, athletics and cycling groups (p < 0.05); children practicing gymnastics
performed better than children of swimming and control groups (p < 0.05).
Conclusions: The performance model and therefore the specialized training that
each sport discipline required, could justified the differences in children’s GMC
level among sports groups. Thus, coaches should plan individualized
interventions and choose activity contents to support children’s GMC development
The Influence of Radiation Damage on the Deflection of High-Energy Beams in Bent Silicon Crystals
Experimental results obtained for deflection of 450 GeV/c protons channeling along the {111} planes in a bent, strongly irradiated silicon crystal are presented. A comparison between the deflection efficiencies in irradiated areas and non-irradiated areas in the crystal shows that irradiation by 2.4 · 1020 protons/cm2 leads to a reduction of around 30 % in deflection efficiency. As a consequence, beam-splitting and extraction from an accelerator by means of a bent crystal are feasible solutions at high energies even for intense beams and during long periods
Double-Spin Asymmetry of J/psi Production in Polarized pp Collisions at HERA-
We calculated the color-octet contribution to the double spin asymmetry of
hadroproduction with nonzero transverse momenta at fixed target
energies GeV. It is shown that the color-octet contribution
is dominant in the asymmetries. The expected asymmetries and statistical errors
in a future option of HERA with longitudinally polarized protons at HERA- should allow one to distinguish between different parametrizations for the
polarized gluon distribution in the proton.Comment: 14 pages with 6 figures (epsfig), LaTeX; Some figures are changed and
misprint is correcte
Systematics of Heavy Quark Production at HERA
We discuss heavy quark and quarkonium production in various kinematic regions
at the HERA ep collider. In contrast to fixed target experiments, collider
kinematics allows the possibility of detailed measurements of particle
production in the proton fragmentation region. One thus can study parton
correlations in the proton Fock states materialized by the virtual photon
probe. We discuss various configurations of inelastic electron-proton
scattering, including peripheral, diffractive, and deep inelastic processes. In
particular, we show that intrinsic heavy quark Fock states can be identified by
the observation of quarkonium production at large and a low mean
transverse momentum which is insensitive to the virtuality of the photon.Comment: 17 pages, postscript. To obtain a copy of this paper send e-mail to
[email protected]
Record deflection efficiencies measured for high energy protons in a bent germanium crystal
New experimental results on the deflection of high energy protons in a bent germanium crystal are presented. At 450 GeV/c, the 50 mm long crystal gave record deflection efficiencies up to 60% for small angles (1 mrad), while at angles as large as 12 mrad, the efficiency is about 25 times larger than for a silicon crystal of the same size. The experimental results are in good agreement with a model for channeling and deflection developed by Ellison and give - together with a similar comparison for a 200 GeV/c beam - confidence in extrapolations to higher energies (e.g. to LHC), other crystal materials or different deflection angles
First observation of the deflection of a 33 TeV Pb ion beam in a bent silicon crystal
For the first time, the deflection of an ultra-relativistic, fully stripped Pb82+ ion beam in a bent silicon crystal has been observed. The ions were provided by the CERN-SPS in the H4 beam at a momentum of 400 GeV/c per unit of charge. A 60 mm long silicon crystal, bent over 50 mm to give a 4 mrad deflection angle, was used in this experiment. The measured Pb ion deflection efficiency is comparable to the one obtained with protons at an equivalent ratio of momentum per charge, and is found to be about 15\% for a beam with a divergence of 35 microradians (FWHM). The interaction rate observed in a background counter is found to drop when the crystal is well aligned with the beam. This corroborates further the channeling model, which predicts that channeled ions are steered away from regions of high electron densities as well as the nuclei in the crystal
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