2,270 research outputs found
A proton-recoil track imaging system for fast neutrons: the RIPTIDE detector
Fast neutron detection is often based on the neutron-proton elastic
scattering reaction: the ionization caused by recoil protons in a hydrogenous
material constitutes the basic information for the design and development of a
class of neutron detectors. Although experimental techniques have continuously
improved, proton-recoil track imaging remains still at the frontier of
n-detection systems, due to the high photon sensitivity required. Several
state-of-the-art approaches for neutron tracking by using n-p single and double
scattering - referred to as Recoil Proton Track Imaging (RPTI) - can be found
in the literature. So far, they have showed limits in terms of detection
efficiency, complexity, cost, and implementation. In order to address some of
these deficiencies, we have proposed RIPTIDE a novel recoil-proton track
imaging detector in which the light output produced by a fast scintillator is
used to perform a complete reconstruction in space and time of the interaction
events. The proposed idea is viable thanks to the dramatic advances in low
noise and single photon counting achieved in the last decade by new scientific
CMOS cameras as well as pixel sensors, like Timepix or MIMOSIS. In this
contribution, we report the advances on the RIPTIDE concept: Geant4 Monte Carlo
simulations, light collection tests as well as state-of-the-art approach to
image readout, processing and fast analysis.Comment: proceeding of the 23rd International Workshop on Radiation Imaging
Detectors, IWoRID 2022, 26-30 June 2022, Riva del Garda (TN), Ital
FOOT: FragmentatiOn Of Target Experiment
The main goal of the FOOT (FragmentatiOn Of Target) experiment is the measurement of the differential cross sections as a function of energy and direction of the produced fragments in the nuclear interaction between a ion beam (proton, helium, carbon, ...) and different targets (proton, carbon, oxygen, ...). Depending on the beam energy, the purpose of the measurements is twofold: in the [150-400] MeV/u range, the data will be used to evaluate the side effects of the nuclear fragmentation in the hadrontherapy treatment, while in the [700-1000] MeV/u range it will be used to optimize the shielding of spaceships for long term space missions. The experiment has been funded by the INFN since September 2017 and it is currently in the construction phase. An overview of the detector, of the results obtained in several beam tests and of the expected performances will be presented
Analysis of charmonium production at fixed-target experiments in the NRQCD approach
We present an analysis of the existing data on charmonium hadro-production
based on non-relativistic QCD (NRQCD) calculations at the next-to-leading order
(NLO). All the data on J/psi and psi' production in fixed-target experiments
and on pp collisions at low energy are included. We find that the amount of
color octet contribution needed to describe the data is about 1/10 of that
found at the Tevatron
Measurements of the reaction of antiproton annihilation at rest at three hydrogen target densities
The proton-antiproton annihilation at rest into the final state
was measured for three different target densities: liquid hydrogen, gaseous
hydrogen at NTP and at a low pressure of 5 mbar. The yield of this reaction in
the liquid hydrogen target is smaller than in the low-pressure gas target. The
branching ratios of the channel were calculated on the basis of
simultaneous analysis of the three data samples. The branching ratio for
annihilation into from the protonium state turns out to be
about ten times smaller as compared to the one from the state.Comment: 10 pages, 3 Postscript figures. Accepted by Physics Letters
Present knowledge of the Cabibbo-Kobayashi-Maskawa matrix
A complete review of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements and
of the experimental methods for their determination is presented. A critical
analysis of the relevant experimental results, and in particular of the most
recent ones, allows to improve the accuracies of all the matrix elements. A
chi-square minimization with the three-family unitarity constraint on the CKM
matrix is performed to test the current interpretation of the CP violating
phenomena inside the Standard Model. A complete and unambiguous solution
satisfying all the imposed constraints is found. As a by-product of the fit,
the precision on the values of the matrix elements is further increased and it
is possible to obtain estimates for the important CP violation observables , and . Finally, an independent estimation of the
CKM elements based on a Bayesian approach is performed. This complementary
method constitutes a check of the results obtained, providing also the
probability functions of the CKM elements and of the related quantities.Comment: 81 pages, 1 file (with 15 figures); v2: misprints corrected on pages
32 & 3
New data on OZI rule violation in bar{p}p annihilation at rest
The results of a measurement of the ratio R = Y(phi pi+ pi-) / Y(omega pi+
pi-) for antiproton annihilation at rest in a gaseous and in a liquid hydrogen
target are presented. It was found that the value of this ratio increases with
the decreasing of the dipion mass, which demonstrates the difference in the phi
and omega production mechanisms. An indication on the momentum transfer
dependence of the apparent OZI rule violation for phi production from the 3S1
initial state was found.Comment: 11 pages, 3 PostScript figures, submitted to Physics Letter
Open and Hidden Charm Production in 920 GeV Proton-Nucleus Collisions
The HERA-B collaboration has studied the production of charmonium and open
charm states in collisions of 920 GeV protons with wire targets of different
materials. The acceptance of the HERA-B spectrometer covers negative values of
xF up to xF=-0.3 and a broad range in transverse momentum from 0.0 to 4.8
GeV/c. The studies presented in this paper include J/psi differential
distributions and the suppression of J/psi production in nuclear media.
Furthermore, production cross sections and cross section ratios for open charm
mesons are discussed.Comment: 5 pages, 9 figures, to be published in the proceedings of the 6th
International Conference on Hyperons, Charm & Beauty Hadrons (BEACH04),
Chicago, IL, June 27 - July 3, 200
Search for the Flavor-Changing Neutral Current Decay with the HERA-B Detector
We report on a search for the flavor-changing neutral current decay using events recorded with a dimuon trigger in
interactions of 920 GeV protons with nuclei by the HERA-B experiment. We find
no evidence for such decays and set a 90% confidence level upper limit on the
branching fraction .Comment: 17 pages, 4 figures (of which 1 double), paper to be submitted to
Physics Letters
Inclusive Production Cross Sections from 920 GeV Fixed Target Proton-Nucleus Collisions
Inclusive differential cross sections and
for the production of \kzeros, \lambdazero, and
\antilambda particles are measured at HERA in proton-induced reactions on C,
Al, Ti, and W targets. The incident beam energy is 920 GeV, corresponding to
GeV in the proton-nucleon system. The ratios of differential
cross sections \rklpa and \rllpa are measured to be and , respectively, for \xf . No significant dependence upon the
target material is observed. Within errors, the slopes of the transverse
momentum distributions also show no significant
dependence upon the target material. The dependence of the extrapolated total
cross sections on the atomic mass of the target material is
discussed, and the deduced cross sections per nucleon are
compared with results obtained at other energies.Comment: 17 pages, 7 figures, 5 table
Measurement of the J/Psi Production Cross Section in 920 GeV/c Fixed-Target Proton-Nucleus Interactions
The mid-rapidity (dsigma_(pN)/dy at y=0) and total sigma_(pN) production
cross sections of J/Psi mesons are measured in proton-nucleus interactions.
Data collected by the HERA-B experiment in interactions of 920 GeV/c protons
with carbon, titanium and tungsten targets are used for this analysis. The
J/Psi mesons are reconstructed by their decay into lepton pairs. The total
production cross section obtained is sigma_(pN)(J/Psi) = 663 +- 74 +- 46
nb/nucleon. In addition, our result is compared with previous measurements
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