A
bstract
The production of
J/ψ
mesons in proton-proton collisions at a centre-of-mass energy of
s
=
13
TeV is studied with the LHCb detector. Cross-section measurements are performed as a function ...of the transverse momentum
p
T
and the rapidity
y
of the
J/ψ
meson in the region
p
T
<
14 GeV/
c
and 2
.
0
< y <
4
.
5, for both prompt
J/ψ
mesons and
J/ψ
mesons from
b
-hadron decays. The production cross-sections integrated over the kinematic coverage are 15
.
30 ± 0
.
03 ± 0
.
86 μb for prompt
J/ψ
and 2
.
34 ± 0
.
01 ± 0
.
13 μb for
J/ψ
from
b
-hadron decays, assuming zero polarization of the
J/
ψ meson. The first uncertainties are statistical and the second systematic. The cross-section reported for
J/ψ
mesons from
b
-hadron decays is used to extrapolate to a total
b
b
¯
cross-section. The ratios of the cross-sections with respect to
s
=
8
TeV are also determined.
The CP asymmetry in the mixing of B0s and B¯0s mesons is measured in proton-proton collision data corresponding to an integrated luminosity of 3.0 fb-1, recorded by the LHCb experiment at ...center-of-mass energies of 7 and 8 TeV. Semileptonic B0s and B¯0s decays are studied in the inclusive mode D∓sμ±ν(–)μX with the D∓s mesons reconstructed in the K+K–π∓ final state. Correcting the observed charge asymmetry for detection and background effects, the CP asymmetry is found to be assl = (0.39 ± 0.26 ± 0.20)%, where the first uncertainty is statistical and the second systematic. This is the most precise measurement of assl to date. It is consistent with the prediction from the standard model and will constrain new models of particle physics.
The fluorescence detector of the Pierre Auger Observatory Abreu, P.; Aguirre, C.; Argirò, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2010, Letnik:
620, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays. It combines a surface array to measure secondary particles at ground level together with a fluorescence detector ...to measure the development of air showers in the atmosphere above the array. The fluorescence detector comprises 24 large telescopes specialized for measuring the nitrogen fluorescence caused by charged particles of cosmic ray air showers. In this paper we describe the components of the fluorescence detector including its optical system, the design of the camera, the electronics, and the systems for relative and absolute calibration. We also discuss the operation and the monitoring of the detector. Finally, we evaluate the detector performance and precision of shower reconstructions.
► Correlation of ultra high energy cosmic rays with nearby extragalactic matter. ► Evidence of anisotropy in ultra high energy arrival directions. ► Autocorrelation of arrival directions shows modest ...excess over broad range of small angular scales. ► The largest observed excess occurs in the region around the radiogalaxy Cen A.
Data collected by the Pierre Auger Observatory through 31 August 2007 showed evidence for anisotropy in the arrival directions of cosmic rays above the Greisen–Zatsepin–Kuz’min energy threshold, 6
×
10
19
eV. The anisotropy was measured by the fraction of arrival directions that are less than 3.1° from the position of an active galactic nucleus within 75
Mpc (using the Véron-Cetty and Véron 12th catalog). An updated measurement of this fraction is reported here using the arrival directions of cosmic rays recorded above the same energy threshold through 31 December 2009. The number of arrival directions has increased from 27 to 69, allowing a more precise measurement. The correlating fraction is
38
-
6
+
7
%
, compared with 21% expected for isotropic cosmic rays. This is down from the early estimate of
69
-
13
+
11
%
. The enlarged set of arrival directions is examined also in relation to other populations of nearby extragalactic objects: galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in hard X-rays by the Swift Burst Alert Telescope. A celestial region around the position of the radiogalaxy Cen A has the largest excess of arrival directions relative to isotropic expectations. The 2-point autocorrelation function is shown for the enlarged set of arrival directions and compared to the isotropic expectation.
The second phase of the T2K experiment is expected to start data taking in autumn 2022. An upgrade of the Near Detector (ND280) is under development and includes the construction of two new Time ...Projection Chambers called High-Angle TPC (HA-TPC). The two endplates of these TPCs will be paved with eight Micromegas type charge readout modules. The Micromegas detector charge amplification structure uses a resistive anode to spread the charges over several pads to improve the space point resolution. This innovative technique is combined with the bulk-Micromegas technology to compose the “Encapsulated Resistive Anode Micromegas” detector. A prototype has been designed, built and exposed to an electron beam at the DESY II test beam facility.
The data have been used to characterize the charge spreading and to produce its map. Spatial resolution better than 600 μm and energy resolution better than 9% are obtained for all incident angles. These performances fulfil the requirements for the upgrade of the ND280 TPC.
Charm meson oscillations are observed in a time-dependent analysis of the ratio of D0→K+π−π+π− to D0→K−π+π−π+ decay rates, using data corresponding to an integrated luminosity of 3.0 fb−1 recorded ...by the LHCb experiment. The measurements presented are sensitive to the phase-space averaged ratio of doubly Cabibbo-suppressed to Cabibbo-favored amplitudes rK3πD and the product of the coherence factor RK3πD and a charm mixing parameter y′K3π. The constraints measured are rK3πD=(5.67±0.12)×10−2, which is the most precise determination to date, and RK3πDy′K3π=(0.3±1.8)×10−3, which provides useful input for determinations of the CP-violating phase γ in B±→DK±, D→K∓π±π∓π± decays. The analysis also gives the most precise measurement of the D0→K+π−π+π− branching fraction, and the first observation of D0-¯D0 oscillations in this decay mode, with a significance of 8.2 standard deviations.
A
bstract
The production of
ψ
(2
S
) mesons is studied in dimuon final states using proton-lead (
p
Pb) collision data collected by the LHCb detector. The data sample corresponds to an integrated ...luminosity of 1
.
6 nb
−1
. The nucleon-nucleon centre-of-mass energy of the
p
Pb collisions is
s
N
N
=
5
TeV. The measurement is performed using
ψ
(2
S
) mesons with transverse momentum less than 14 GeV/
c
and rapidity
y
in the ranges 1
.
5
< y <
4
.
0 and −5
.
0
< y <
−2
.
5 in the nucleon-nucleon centre-of-mass system. The forward-backward production ratio and the nuclear modification factor are determined for
ψ
(2
S
) mesons. Using the production cross-section results of
ψ
(2
S
) and
J/ψ
mesons from
b
-hadron decays, the
b
b
¯
cross-section in
p
Pb collisions at
s
N
N
=
5
TeV is obtained.
L’haemolacria est un syndrome hémorragique rare caractérisé par l’écoulement de larmes de sang. Les étiologies de cette pathologie sont variées, les plus fréquentes sont l’inflammation, l’infection ...ou encore des lacérations. D’autres causes plus rares sont également connues pour entraîner cette manifestation clinique.
Nous rapportons le cas d’un garçon de 14 ans ayant consulté pour une haemolacria. Dans les antécédents familiaux, une maladie de Willebrand était diagnostiquée chez sa mère et sa sœur. Si le patient n’était pas porteur de la maladie de Willebrand, un dosage de vitamine C confirmait un scorbut consécutif à une malnutrition. Ce déficit vitaminique était retenu comme étiologie de son syndrome hémorragique ; la carence vitaminique C pouvant être à l’origine d’autres manifestations hémorragiques telles que des ecchymoses.
L’haemolacria est une manifestation clinique rare dont le diagnostic étiologique peut être difficile à appréhender. Il est important d’envisager l’ensemble des causes potentiellement impliquées.
Hemolacria is a rare hemorrhagic syndrome characterized by bloody tears. The most common etiologies are inflammation, infection or laceration. However, other rarer diseases may also cause this clinical manifestation.
We describe the case of a 14-year-old male patient hospitalized for hemolacria. A history of von Willebrand disease was present in his family, diagnosed in his mother and sister, but absent in our patient. A vitamin C dosage was obtained in our patient and revealed scurvy consecutive to malnutrition. After having excluded other bleeding symptoms like bruises we retained vitamin C deficiency as the etiology of the hemorrhagic syndrome.
Bloody tears are a rare clinical manifestation and the etiology may be difficult to determine. Bloody tears are a rare clinical manifestation of hemorrhagic syndrome. To determine the underlying etiology, screening should consider all possible causes including the rarest.
ABSTRACT We present the results of an analysis of the large angular scale distribution of the arrival directions of cosmic rays with energy above 4 EeV detected at the Pierre Auger Observatory ...including for the first time events with zenith angle between 60° and 80°. We perform two Rayleigh analyses, one in the right ascension and one in the azimuth angle distributions, that are sensitive to modulations in right ascension and declination, respectively. The largest departure from isotropy appears in the EeV energy bin, with an amplitude for the first harmonic in right ascension , that has a chance probability , reinforcing the hint previously reported with vertical events alone.
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