ψ′ production is studied in Pb–Pb collisions at 158 GeV/c per nucleon incident momentum. Absolute cross-sections are measured and production rates are investigated as a function of the centrality of ...the collision. The results are compared with those obtained for lighter colliding systems and also for the J/ψ meson produced under identical conditions.
In a carbon ion treatment the nuclear fragmentation of both target and beam projectiles impacts on the dose released on the tumor and on the surrounding healthy tissues. Carbon ion fragmentation ...occurring inside the patient body has to be studied in order to take into account this contribution. These data are also important for the development of the range monitoring techniques with charged particles. The production of charged fragments generated by carbon ion beams of 115-353 MeV/u kinetic energy impinging on carbon, oxygen, and hydrogen targets has been measured at the CNAO particle therapy center (Pavia, Italy). The use of thin targets of graphite (C), PMMA (C 2 O 5 H 8 ) and polyvinyl-toluene plastic scintillator (PS), <inline-formula> <tex-math notation="LaTeX">{\text{C}}_{b}{\text{H}}_{a} </tex-math></inline-formula> allowed to measure fragments production cross sections, exploiting a time-of-flight (ToF) technique. PS detectors have been used to perform the ToF measurements, while LYSO crystals have been used for the deposited energy measurement and to perform particle identification. Cross sections have been measured at 90° and 60° with respect to the beam direction. The measured proton, deuteron, and triton differential production cross sections on C, O, and H, obtained exploiting the target subtraction strategy, are presented here as a function of the fragment kinetic energy.
A multi-step setup for heavy-flavor studies in high-energy nucleus-nucleus (AA) collisions - addressing within a comprehensive framework the initial QQ production, the propagation in the hot medium ...until decoupling and the final hadronization and decays - is presented. The propagation of the heavy quarks in the medium is described in a framework provided by the relativistic Langevin equation and the corresponding numerical results are compared to experimental data from RHIC and the LHC. In particular, outcomes for the nuclear modification factor R sub(AA) and for the elliptic flow nu sub(2) of D/B mesons, heavy-flavor electrons and non-prompt J/psi's are displayed.
Detection of atmospheric muons with ALICE detectors Alessandro, B.; Cortes Maldonado, I.; Cuautle, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
The calibration, alignment and commissioning of most of the ALICE (A Large Ion Collider Experiment at the CERN LHC) detectors have required a large amount of cosmic events during 2008. In particular ...two types of cosmic triggers have been implemented to record the atmospheric muons passing through ALICE. The first trigger, called ACORDE trigger, is performed by 60 scintillators located on the top of three sides of the large L3 magnet surrounding the central detectors, and selects atmospheric muons. The Silicon Pixel Detector (SPD) installed on the first two layers of the Inner Tracking System (ITS) gives the second trigger, called SPD trigger. This trigger selects mainly events with a single atmospheric muon crossing the SPD. Some particular events, in which the atmospheric muon interacts with the iron of the L3 magnet and creates a shower of particles crossing the SPD, are also selected. In this work the reconstruction of events with these two triggers will be presented. In particular, the performance of the ACORDE detector will be discussed by the analysis of multi-muon events. Some physical distributions are also shown.
The
J
/
ψ
azimuthal distribution relative to the reaction plane has been measured by the NA50 experiment in Pb-Pb collisions at 158 GeV/nucleon. Various physical mechanisms related to charmonium ...dissociation in the medium created in the heavy ion collision are expected to introduce an anisotropy in the azimuthal distribution of the observed
J
/
ψ
mesons at SPS energies. Hence, the measurement of
J
/
ψ
elliptic anisotropy, quantified by the Fourier coefficient
v
2
of the
J
/
ψ
azimuthal distribution relative to the reaction plane, is an important tool to constrain theoretical models aimed at explaining the anomalous
J
/
ψ
suppression observed in Pb-Pb collisions. We present the measured
J
/
ψ
yields in different bins of azimuthal angle relative to the reaction plane, as well as the resulting values of the Fourier coefficient
v
2
as a function of the collision centrality and of the
J
/
ψ
transverse momentum. The reaction plane has been estimated from the azimuthal distribution of the neutral transverse energy detected in an electromagnetic calorimeter. The analysis has been performed on a data sample of about 100 000 events, distributed in five centrality or
p
T
sub-samples. The extracted
v
2
values are significantly larger than zero for non-central collisions and are seen to increase with
p
T
.
The MACRO detector has as one of its main goals the search, over a large range of velocities, of superheavy magnetic monopoles well below the astrophysical bounds. It employs three different ...techniques (limited streamer tubes, liquid scintillators and nuclear track detectors) to gain redundancy and complementarity. A null search from data taken in the period 1989–1995 using single subdetectors will be reported.
Dual-energy mammographic imaging experimental tests have been performed using a compact dichromatic imaging system based on a conventional x-ray tube, a mosaic crystal, and a 384-strip silicon ...detector equipped with full-custom electronics with single photon counting capability. For simulating mammal tissue, a three-component phantom, made of Plexiglass, polyethylene, and water, has been used. Images have been collected with three different pairs of x-ray energies:
16
–
32
keV
,
18
–
36
keV
, and
20
–
40
keV
. A Monte Carlo simulation of the experiment has also been carried out using the MCNP-4C transport code. The Alvarez-Macovski algorithm has been applied both to experimental and simulated data to remove the contrast between two of the phantom materials so as to enhance the visibility of the third one.
FOOT (FragmentatiOn Of Target) is an applied nuclear physics experiment conceived to conduct high-precision cross section measurements of nuclear fragmentation processes relevant for particle therapy ...and radiation protection in space. These measurements are important to estimate the physical and biological effects of nuclear fragments, which are produced when energetic particle beams penetrate human tissue.
A component of the FOOT experiment is the ΔE-TOF system. It is designed to measure energy loss and time-of-flight of nuclear fragments produced in particle collisions in thin targets in order to extract their charge and velocity. The ΔE-TOF system is composed of a start counter, providing the start time for the time-of-flight, and a 40 × 40 cm2 wall of thin plastic scintillator bars, providing the arrival time and energy loss of the fragments passing through the detector. Particle charge discrimination can be achieved by correlating the energy loss in the scintillator bars with the measured time-of-flight.
Recently, we have built a full-size ΔE-TOF detector. In this work, we describe the energy and time-of-flight calibration procedure and assess the performance of this system. We use data acquired during beam tests at CNAO with proton and 12C beams and at GSI with 16O beams in the energy range relevant for particle therapy, i.e., from 60 to 400 MeV/u. For heavy fragments (C and O), we obtain energy and time resolutions ranging from 4.0 to 5.2% and from 54 to 76 ps, respectively. The procedure is also applied to a fragmentation measurement of a 400 MeV/u 16O beam on a 5 mm carbon target, showing that the system is able to discriminate the charges of impinging fragments.
The calibration and performance of the Silicon Drift Detector of the ALICE experiment during the 2008 cosmic ray run will be presented. In particular the procedures to monitor the running parameters ...(baselines, noise, drift speed) are detailed. Other relevant parameters (SOP delay, time-zero, charge calibration) were also determined.
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