3,459 research outputs found
Production of Sigma{\pm}pi?pK+ in p+p reactions at 3.5 GeV beam energy
We study the production of Sigma^+-pi^+-pK^+ particle quartets in p+p
reactions at 3.5 GeV kinetic beam energy. The data were taken with the HADES
experiment at GSI. This report evaluates the contribution of resonances like
Lambda(1405$, Sigma(1385)^0, Lambda(1520), Delta(1232), N^* and K^*0 to the
Sigma^+- pi^-+ p K+ final state. The resulting simulation model is compared to
the experimental data in several angular distributions and it shows itself as
suitable to evaluate the acceptance corrections properly.Comment: 15 pages, 5 figure
In-Medium Effects on K0 Mesons in Relativistic Heavy-Ion Collisions
We present the transverse momentum spectra and rapidity distributions of
and K in Ar+KCl reactions at a beam kinetic energy of 1.756 A
GeV measured with the spectrometer HADES. The reconstructed K sample is
characterized by good event statistics for a wide range in momentum and
rapidity. We compare the experimental and K distributions to
predictions by the IQMD model. The model calculations show that K at low
tranverse momenta constitute a particularly well suited tool to investigate the
kaon in-medium potential. Our K data suggest a strong repulsive in-medium
K potential of about 40 MeV strength.Comment: 10 pages, 10 figures, accepted by Phys. Rev.
An upper limit on hypertriton production in collisions of Ar(1.76 AGeV)+KCl
A high-statistic data sample of Ar(1.76 AGeV)+KCl events recorded with HADES
is used to search for a hypertriton signal. An upper production limit per
centrality-triggered event of x on the level is
derived. Comparing this value with the number of successfully reconstructed
hyperons allows to determine an upper limit on the ratio
, which is confronted with statistical and
coalescence-type model calculations
Anterior T-Wave Inversion in Young White Athletes and Nonathletes: Prevalance and Significance
BACKGROUND: Anterior T-wave inversion (ATWI) on electrocardiography (ECG) in young white adults raises the possibility of cardiomyopathy, specifically arrhythmogenic right ventricular cardiomyopathy (ARVC). Whereas the 2010 European consensus recommendations for ECG interpretation in young athletes state that ATWI beyond lead V1 warrants further investigation, the prevalence and significance of ATWI have never been reported in a large population of asymptomatic whites. OBJECTIVES: This study investigated the prevalence and significance of ATWI in a large cohort of young, white adults including athletes. METHODS: Individuals 16 to 35 years of age (n = 14,646), including 4,720 females (32%) and 2,958 athletes (20%), were evaluated by using a health questionnaire, physical examination, and 12-lead ECG. ATWI was defined as T-wave inversion in ≥2 contiguous anterior leads (V1 to V4). RESULTS: ATWI was detected in 338 individuals (2.3%) and was more common in women than in men (4.3% vs. 1.4%, respectively; p < 0.0001) and more common among athletes than in nonathletes (3.5% vs. 2.0%, respectively; p < 0.0001). T-wave inversion was predominantly confined to leads V1 to V2 (77%). Only 1.2% of women and 0.2% of men exhibited ATWI beyond V2. No one with ATWI fulfilled diagnostic criteria for ARVC after further evaluation. During a mean follow-up of 23.1 ± 12.2 months none of the individuals with ATWI experienced an adverse event. CONCLUSIONS: ATWI confined to leads V1 to V2 is a normal variant or physiological phenomenon in asymptomatic white individuals without a relevant family history. ATWI beyond V2 is rare, particularly in men, and may warrant investigation
Searching for the Nuclear Liquid-Gas Phase Transition in Au + Au Collisions at 35 MeV/nucleon
Within the framework of Classical Molecular Dynamics, we study the collision
Au + Au at an incident energy of 35 MeV/nucleon. It is found that the system
shows a critical behaviour at peripheral impact parameters, revealed through
the analysis of conditional moments of charge distributions, Campi Scatter
Plot, and the occurrence of large fluctuations in the region of the Campi plot
where this critical behaviour is expected. When applying the experimental
filters of the MULTICS-MINIBALL apparatus, it is found that criticality signals
can be hidden due to the inefficiency of the experimental apparatus. The
signals are then recovered by identifying semi-peripheral and peripheral
collisions looking to the velocity distribution of the largest fragment, then
by selecting the most complete events.Comment: RevTex file, 21 pages + 19 figures available upon request from
[email protected]
Teleology and Realism in Leibniz's Philosophy of Science
This paper argues for an interpretation of Leibniz’s claim that physics requires both mechanical and teleological principles as a view regarding the interpretation of physical theories. Granting that Leibniz’s fundamental ontology remains non-physical, or mentalistic, it argues that teleological principles nevertheless ground a realist commitment about mechanical descriptions of phenomena. The empirical results of the new sciences, according to Leibniz, have genuine truth conditions: there is a fact of the matter about the regularities observed in experience. Taking this stance, however, requires bringing non-empirical reasons to bear upon mechanical causal claims. This paper first evaluates extant interpretations of Leibniz’s thesis that there are two realms in physics as describing parallel, self-sufficient sets of laws. It then examines Leibniz’s use of teleological principles to interpret scientific results in the context of his interventions in debates in seventeenth-century kinematic theory, and in the teaching of Copernicanism. Leibniz’s use of the principle of continuity and the principle of simplicity, for instance, reveal an underlying commitment to the truth-aptness, or approximate truth-aptness, of the new natural sciences. The paper concludes with a brief remark on the relation between metaphysics, theology, and physics in Leibniz
The 33S(n,α)30Si cross section measurement at n-TOF-EAR2 (CERN) : From 0.01 eV to the resonance region
The 33S(n,α)30Si cross section measurement, using 10B(n,α) as reference, at the n-TOF Experimental Area 2 (EAR2) facility at CERN is presented. Data from 0.01 eV to 100 keV are provided and, for the first time, the cross section is measured in the range from 0.01 eV to 10 keV. These data may be used for a future evaluation of the cross section because present evaluations exhibit large discrepancies. The 33S(n,α)30Si reaction is of interest in medical physics because of its possible use as a cooperative target to boron in Neutron Capture Therapy (NCT)
Inclusive dielectron production in proton-proton collisions at 2.2 GeV beam energy
Data on inclusive dielectron production are presented for the reaction p+p at
2.2 GeV measured with the High Acceptance DiElectron Spectrometer (HADES). Our
results supplement data obtained earlier in this bombarding energy regime by
DLS and HADES. The comparison with the 2.09 GeV DLS data is discussed. The
reconstructed e+e- distributions are confronted with simulated pair cocktails,
revealing an excess yield at invariant masses around 0.5 GeV/c2. Inclusive
cross sections of neutral pion and eta production are obtained
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