3,083 research outputs found
Search for a bound Kâ pp system
Data from the K â absorption reaction on 6,7 Li, 9 Be, 13 C and 16 O have recently been collected by FINUDA at the DA Ί NE Ï -factory (Laboratori Nazionali di Frascati-INFN), following an earlier lower statitics run on 12 C and some other targets. FINUDA is a high acceptance magnetic spectrometer which performed a wide range of studies by detecting the charged particles and neutrons exiting the targets after the absorption event. In this paper it is discussed about the study of the A( K â , Î p) reaction in the context of the search for deeply bound - nuclear states. The observation of a bump in the Î p invariant mass distribution is discussed in terms of a possible signature of a deeply bound K â pp kaonic cluster as well as of more conventional physics. An overview of the experimental situation in this field will be given
Support to triage and public risk perception considering long-term response to a Cs-137 radiological dispersive device scenario
A radiological dispersive device (RDD) spreads radioactive material, complicates the treatment of physical injuries, raises cancer risk, and induces disproportionate fear. Simulating such an event enables more effective and efficient utilization of the triage and treatment resources of staff, facilities, and space. Fast simulation can give detail on events in progress or future events. The resources for triage and treatment of contaminated trauma victims can differ for pure exposure individuals, while discouraging the âworried wellâ from presenting in the crisis phase by media announcement would relieve pressure on hospital facilities. The proposed methodology integrates capabilities from different platforms in a convergent way composed of three phases: (a) scenario simulation, (b) data generation, and (c) risk assessment for triage focused on follow-up epidemiological assessment. Simulations typically indicate that most of the affected population does not require immediate medical assistance. Medical triage for the few severely injured and the radiological triage to diminish the contamination with radioactivity will always be the priority. For this study, however, higher priorities should be given to individuals from radiological âwarmâ and âhotâ zones as required by risk criteria. The proposed methodology could thus help to (a) filter and reduce the number of individuals to be attended, (b) optimize the prioritization of medical care, (c) reduce or prepare for future costs, (d) effectively locate the operational triage site to avoid possible contamination on the main facility, and (e) provide the scientific data needed to develop an adequate approach to risk and its proper communication
The pi -> pi pi process in nuclei and the restoration of chiral symmetry
The results of an extensive campaign of measurements of the pi -> pi pi
process in the nucleon and nuclei at intermediate energies are presented. The
measurements were motivated by the study of strong pi pi correlations in
nuclei. The analysis relies on the composite ratio C_{pi pi}^A, which accounts
for the clear effect of the nuclear medium on the (pi pi) system. The
comparison of the C_{pi pi}^A distributions for the (pi pi)_{I=J=0} and (pi
pi)_{I=0,J=2} systems to the model predictions indicates that the C_{pi pi}^A
behavior in proximity of the 2m_pi threshold is explainable through the partial
restoration of chiral symmetry in nuclei.Comment: accepted for publication in Nucl. Phys.
The interaction in nuclear matter from a study of the reactions
The pion-production reactions were studied on
, , , and nuclei at an incident pion energy
of =283 MeV. Pions were detected in coincidence using the CHAOS
spectrometer. The experimental results are reduced to differential cross
sections and compared to both theoretical predictions and the reaction phase
space. The composite ratio between the
invariant masses on nuclei and on the nucleon is also presented. Near the
threshold pion pairs couple to when produced in
the reaction channel. There is a marked near-threshold
enhancement of which is consistent with theoretical
predictions addressing the partial restoration of chiral symmetry in nuclear
matter. Furthermore, the behaviour of is well
described when the restoration of chiral symmetry is combined with standard
P-wave renormalization of pions in nuclear matter. On the other hand, nuclear
matter only weakly influences , which displays a flat
behaviour throughout the energy range regardless of .Comment: 30 pages, 16 figures, PS format, accepted for publication in Nucl.
Phys
Photoproduction of charm near threshold
Charm and bottom production near threshold is sensitive to the multi-quark,
gluonic, and hidden-color correlations of hadronic and nuclear wavefunctions in
QCD since all of the target's constituents must act coherently within the small
interaction volume of the heavy quark production subprocess. Although such
multi-parton subprocess cross sections are suppressed by powers of ,
they have less phase-space suppression and can dominate the contributions of
the leading-twist single-gluon subprocesses in the threshold regime. The small
rates for open and hidden charm photoproduction at threshold call for a
dedicated facility.Comment: 5 pages 5 figures Changes: 1- Added refs 24,25; 2- Added two
sentences, top of column 2 of page 3, on the definition of x, its range and
the domain of validity of the mode
Industrial Ceramics: From Waste to New Resources for Eco-Sustainable Building Materials
Today, the need to dispose of a huge amount of ceramic industrial waste represents an important problem for production plants. Contextually, it is increasingly difficult to retrieve new mineral resources for the realization of building materials. Reusing ceramic industrial waste as precursors for building blocks/binders, exploiting their aluminosilicate composition for an alkaline activation process, could solve the problem. This chemical process facilitates the consolidation of new binders/blocks without thermal treatments and with less CO2 emissions if compared with traditional cements/ceramics. The alkali-activated materials (AAMs) are today thought as the materials of the future, eco-sustainable and technically advanced. In this study, six different kind of industrial ceramic waste are compared in their chemical and mineralogical composition, together with their thermal behaviour, reactivity in an alkaline environment and surface area characteristics, with the aim of converting them from waste into new resources. Preliminary tests of AAM synthesis by using 80%â100% of ceramic waste as a precursor show promising results. Workability, porosity and mechanical strengths in particular are measured, showing as, notwithstanding the presence of carbonate components, consolidated materials are obtained, with similar results. The main factors which affect the characteristics of the synthetized AAMs are the precursorsâ granulometry, curing temperature and the proportions of the activating solutions
Functional heartburn has more in common with functional dyspepsia than with non-erosive reflux disease
INTRODUCTION: Functional dyspepsia and non-erosive reflux disease (NERD) are prevalent gastrointestinal conditions with accumulating evidence regarding an overlap between the two. Still, patients with NERD represent a very heterogeneous group and limited data on dyspeptic symptoms in various subgroups of NERD are available. AIM: To evaluate the prevalence of dyspeptic symptoms in patients with NERD subclassified by using 24 h impedance-pH monitoring (MII-pH). METHODS: Patients with typical reflux symptoms and normal endoscopy underwent impedance-pH monitoring off proton pump inhibitor treatment. Oesophageal acid exposure time (AET), type of acid and non-acid reflux episodes, and symptom association probability (SAP) were calculated. A validated dyspepsia questionnaire was used to quantify dyspeptic symptoms prior to reflux monitoring. RESULTS: Of 200 patients with NERD (105 female; median age, 48 years), 81 (41%) had an abnormal oesophageal AET (NERD pH-POS), 65 (32%) had normal oesophageal AET and positive SAP for acid and/or non-acid reflux (hypersensitive oesophagus), and 54 (27%) had normal oesophageal AET and negative SAP (functional heartburn). Patients with functional heartburn had more frequent (p<0.01) postprandial fullness, bloating, early satiety and nausea compared to patients with NERD pH-POS and hypersensitive oesophagus. CONCLUSION: The increased prevalence of dyspeptic symptoms in patients with functional heartburn reinforces the concept that functional gastrointestinal disorders extend beyond the boundaries suggested by the anatomical location of symptoms. This should be regarded as a further argument to test patients with symptoms of gastro-oesophageal reflux disease in order to separate patients with functional heartburn from patients with NERD in whom symptoms are associated with gastro-oesophageal reflux
General properties of the pion production reaction in nuclear matter
The pion production reaction on was
studied at incident pion energies of = 240, 260, 280, 300, and
320 MeV. The experiment was performed using the pion-channel at TRIUMF,
and multiparticle events, () and
(), were detected with the CHAOS spectrometer. Results
are reported in the form of both differential and total cross sections, and are
compared to theoretical predictions and the reaction phase space. The present
investigation of the T-dependence of the
reaction complements earlier examinations of the A-dependence of the reaction,
which was measured using , , , , , and
targets at 280 MeV. Some general properties of the
pion-induced pion production reaction in nuclear matter will be presented,
based on the combined results of the two studies.Comment: 23 pages, Latex, accepted for publication in Nucl. Phys.
- âŠ