1,721,482 research outputs found
Measurement of Υ production in pp collisions at √s = 2.76 TeV
No full textThe production of Υ(1S), Υ(2S) and Υ(3S) mesons decaying into the dimuon final state is studied with the LHCb detector using a data sample corresponding to an integrated luminosity of 3.3pb-1 collected in proton-proton collisions at a centre-of-mass energy of √s = 2.76 TeV. The differential production cross-sections times dimuon branching fractions are measured as functions of the Υ transverse momentum and rapidity, over the ranges pT < 15 GeV/c and 2.0 < y < 4.5. The total cross-sections in this kinematic region, assuming unpolarised production, are measured to be (Formula presented.) where the first uncertainty is statistical and the second systematic. © 2014 CERN for the benefit of the LHCb collaboration
Measurement of ψ(2S) polarisation in pp collisions at √s = 7 TeV
No full textThe polarisation of prompt ψ(2S) mesons is measured by performing an angular analysis of ψ(2S) → μ+μ- decays using proton-proton collision data, corresponding to an integrated luminosity of 1.0 fb-1, collected by the LHCb detector at a centre-of-mass energy of 7 TeV. The polarisation is measured in bins of transverse momentum pT and rapidity y in the kinematic region 3.5 < pT < 15 GeV/c and 2.0 < y < 4.5, and is compared to theoretical models. No significant polarisation is observed. © 2014 CERN for the benefit of the LHCb collaboration
ORANGE: A high sensitivity particle tracker based on optically read out GEM
No full textGEM-based detectors had a noticeable development
in last years and have successfully been employed in different
fields from High Energy Physics to imaging applications. Light
production associated to the electron multiplication allows to
perform an optical readout of these devices. The big progress
achieved in CMOS-based photo-sensors makes possible to develop
a high sensitivity, high granularity and low noise readout. In this
paper we present the results obtained by reading out the light
produced by a triple-GEM structure by means o
f a 4 mega-pixel
CMOS sensor having a noise level less than two photons per
pixel. The choice of a CF
4
rich gas mixture (He/CF
4
60/40) and a
detailed optimization of the electric fields allowed to reach a light-
yield high enough to obtain very visible signals from minimum
ionizing particles. In a test performed with 450 MeV electron
beam, about 700 photons per millimeter were collected and a
space resolution of about 75μm was obtained.
Moreover, the device showed to be very sensitive to the density
of energy deposit: a relative uncertainty of 35% was found in
the measurement of the dE/dx
MONDO: A neutron tracker for particle therapy secondary emission fluxes measurements
No full textCancer treatment is performed, in Particle Therapy, using accelerated charged particles whose high
irradiation precision and conformity allows the tumor destruction while sparing the surrounding healthy
tissues. Dose release monitoring devices using photons and charged particles produced by the beam
interaction with the patient body have already been proposed, but no attempt based on the detection of
the abundant secondary radiation neutron component has been made yet. The reduced attenuation
length of neutrons yields a secondary particle sample that is larger in number when compared to
photons and charged particles. Furthermore, neutrons allow for a backtracking of the emission point that
is not affected by multiple scattering. Since neutrons can release a significant dose far away from the
tumor region, a precise measurement of their flux, production energy and angle distributions is eagerly
needed in order to improve the Treatment Planning Systems (TPS) software, so to predict not only the
normal tissue toxicity in the target region but also the risk of late complications in the whole body. All
the aforementioned issues underline the importance for an experimental effort devoted to the precise
characterization of the neutron production gaining experimental access both to the emission point and
production energy. The technical challenges posed by a neutron detector aiming for a high detection
efficiency and good backtracking precision will be addressed within the MONDO (MOnitor for Neutron
Dose in hadrOntherapy) project. The MONDO's main goal is to develop a tracking detector targeting fast
and ultrafast secondary neutrons. The tracker is composed by a scintillating fiber matrix ð4 4 8 cm3Þ.
The full reconstruction of protons, produced in elastic interactions, will be used to measure energy and
direction of the impinging neutron. The neutron tracker will measure the neutron production yields, as a
function of production angle and energy, using different therapeutic beams at CNAO in Pavia (protons,
12C ions and possibly 4He and 16O ions)
The Upstream Detectors of the FIRST Experiment at GSI
No full textFIRST (Fragmentation of Ions Relevant for Space and Therapy) is an experiment devoted to a precise measurement of ion fragmen- tation for space radiation protection and hadron therapy applications. A first run dedicated to the fragmentation of fully stripped 12C ions on a thin graphite target has been already performed during August 2011 at GSI. The experiment is composed of already existing detectors complemented by a newly designed interaction region, including the so - called Upstream Detectors: a Start Counter and a Beam Monitor. The Start Counter is used to trigger the beam and to give a precise time reference for time of flight measurements, while the Beam Monitor is needed to track ions before their interaction in the target. In this paper we present their description and the results of the tests performed on different beams to validate their performances before the installation at GSI
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