Thermal neutron induced (n,p) and (n,alpha) reactions on 37Ar

The 37Ar(n_th,alpha)34S and 37Ar(n_th,p)37Cl reactions were studied at the high flux reactor of the ILL in Grenoble. For the 37Ar(n_th,alpha_0) and 37Ar(n_th,p) reaction cross sections, values of (1070+/-80)b and (37+/-4)b, respectively, were obtained. Both values are about a factor 2 smaller than results of older measurements. The observed suppression of the 37(n_th,alpha_1) transition could be verified from theoretical considerations. Finally, evidence was found for the two-step 37Ar(n_th,gamma-alpha) process.Comment: 11 pages, 5 figures, accepted for publication in Nuclear Physics

Subjectively interpreted shape dimensions as privileged and orthogonal axes in mental shape space

The shape of an object is fundamental in object recognition but it is still an open issue to what extent shape differences are perceived analytically (i.e., by the dimensional structure of the shapes) or holistically (i.e., by the overall similarity of the shapes). The dimensional structure of a stimulus is available in a primary stage of processing for separable dimensions, although it can also be derived cognitively from a perceived stimulus consisting of integral dimensions. Contrary to most experimental paradigms, the present study asked participants explicitly to analyze shapes according to two dimensions. The dimensions of interest were aspect ratio and medial axis curvature, and a new procedure was used to measure the participants' interpretation of both dimensions (Part I, Experiment 1). The subjectively interpreted shape dimensions showed specific characteristics supporting the conclusion that they also constitute perceptual dimensions with objective behavioral characteristics (Part II): (1) the dimensions did not correlate in overall similarity measures (Experiment 2), (2) they were more separable in a speeded categorization task (Experiment 3), and (3) they were invariant across different complex 2-D shapes (Experiment 4). The implications of these findings for shape-based object processing are discussed

The 41Ca(n,α)38Ar cross section up to 100 keV neutron energy

The 41Ca(n,alpha)38Ar reaction cross section has been studied with resonance neutrons at the GELINA neutron facility of the Institute for Reference Materials and Measurements in Geel (Belgium) from a few eV up to 100 keV. A Frisch-gridded ionization chamber with methane as detector gas was installed at a 30 meter long flight path. About 20 resonances have been identified. From the cross section data obtained, the Maxwellian averaged cross section (MACS) as a function of stellar temperature has been calculated by numerical integration

245Cm fission cross section measurement in the thermal energy region

A new cross section measurement for the ^245Cm(n,f) reaction in the thermal energy region has been performed at the GELINA neutron facility of the Institute for Reference Materials and Measurements (IRMM) in Geel, Belgium. The energy of the neutrons is determined applying the time of flight method using a flight path length of about 9 m. In the present work, the incident neutron energy covers 10 meV up to a few eV. A 98.48% enriched ^245Cm sample was mounted back-to-back with a ^10B sample in the centre of a vacuum chamber together with two surface barrier detectors positioned outside the neutron beam. One detector measured the ^10B(n,a)^7Li reaction products for the neutron flux determination, while the second one registered the ^245Cm(n,f) fragments. In this way, the neutron flux can be determined simultaneously with the fission fragments. A control measurement has been performed replacing the ^245Cm sample with a ^235U sample in order to check that the well-known ^235U(n,f) cross section can be reproduced. Our measurement yielded a ^245Cm(nth,f) cross section of 2131±43±173 b and a Westcott factor gf=0.939±0.019

How to identify an argument type? On the hermeneutics of persuasive discourse

This paper proposes a theory of interpreting argument types as an integral part of a systematic and comprehensive ‘hermeneutics of persuasive discourse’. It first explains how such a hermeneutics can be developed based on pragmatic insights about the use of language for persuasive purposes expressed in the philosophy of argument. Then, after having provided an overview of the main hermeneutical stages involved in interpreting persuasive discourse, the paper focuses on the stage of argument type identification. It formulates a ‘hermeneutics of argument type’ in terms of the Periodic Table of Arguments (PTA), an argument categorization framework systematizing existing accounts of arguments in the broad sense of the term (topoi, loci, argument schemes, fallacies, means of persuasion). For each of the three parameters within this framework, ‘argument form’, ‘argument substance’, and ‘argument lever’, the paper describes how to determine their value by analyzing several examples of natural arguments.</p

Experimental determination of the 17O(n_th,alpha)14C reaction cross section

The 17O(n_th,alpha)14C reaction cross section was determined at the high flux reactor of the ILL in Grenoble relative to the known 14N(n_th,p)14C cross section. The 17O(n_th,alpha)14C measurements were performed with several highly enriched oxygen gas samples and the flux calibration was done with 14N_2 from the air. This resulted in a precise value of (244+/-7)mb for the 17O(n_th,alpha)14C cross section.Comment: 4 pages, 3 figures, to be published in proceedings of Nuclei in the Cosmos V (1998