The increased availability of advanced synchrotron radiation sources is resulting in a resurgence of activity in the field of x-ray and extreme ultraviolet imaging systems. However, scattering effects caused by residual optical fabrication errors frequently dominate geometrical design errors in the degradation of image quality at these very short wavelengths. Traditional optical design and analysis techniques (geometrical ray tracing) are therefore inadequate for predicting the performance of high-resolution synchrotron beam-line optics. A surface-scattering theory must be implemented to model the image degradation effects of residual surface irregularities over the entire range of relevant spatial frequencies. This includes small-angle scattering effects caused by mid-spatial-frequency surface errors that fall between the traditional figure and finish specifications. Performance predictions are presented parametrically to provide insight into the optical fabrication tolerances necessary to meet the requireme nts of a specific application.
In interactions of 800-GeV protons with emulsion nuclei, the multiplicity and rapidity distributions of charged secondary particles are studied. The existence of strong short-range correlations among the secondary particles is found. Evidence of independent emission of low-multiplicity clusters is presented.One of the most attractive features to study at high energies is the mechanism of multiparticle production. Although several models have been proposed to explain this phenomenon, one of the most widely accepted is the cluster model.' The reason for its general acceptance has been the observation of correlations among the secondary particles in hadron-hadron and hadron-nucleus interactions at high energies. Several features of this ~u b j e c t ,~~~u c h as the determination of cluster size, the strength of correlation, dependence of cluster size upon other parameters such as inelasticity, multiplicity, etc., have been investigated. It would be interesting to investigate the phenomenon of cluster production at the highest available machine energy, which is double the energy that was available earlier for fixed-target experiments.We present below the first experimental results on 800-GeV proton-nucleus interactions. The existence of strong short-range correlations among the secondary particles has been observed. The data suggest production of twoparticle clusters which seems to be the predominant mode of multiparticle production in the interactions.A stack consisting of 40 G 5 emulsion pellicles of dimensions 1 0~ 8 x 0.06 cm was exposed to a proton beam of energy 800 GeV at Fermilab. The beam flux was 8.7X lo4 particles/cm2 and the distribution of the primary energy was <0.05%. The emulsion plates were carefully area scanned for inelastic events. All of the interactions were scanned twice by each observer and the average scanning efficiency was found to be -96%.Scanning was done at a distance of 1 cm from the leading edge of the emulsion. In order to select the events due to the primary protons, the following criteria were followed. (a) The primary of each interaction was followed up to the entry point in emulsion and there should be no interaction due to a secondary track. (b) The primary particle should make an angle < 2 " with the mean beam direction.Events lying up to 25 p m from the surface or glass side of the emulsion pellicle were not considered. Taking the above criteria into account, a total of 1005 events were obtained. Following the usual emulsion terminology,* the secondary particles having B(v/c) 2 0.7 and /3 < 0.7 were designated as shower and heavy tracks, respectively. The total number of shower tracks obtained here is -17000.The multiplicity of shower and heavy tracks is designated by n, and n h , respectively. The value of nh has been used to designate4 the type of target nucleus in emulsion.Events with nh =O,1 mostly belong to H target nuclei or effectively with a single target nucleon, while events with 2 i nh 5 5 belong to the light (CNO) nuclei category and those with nh 2 9 belong unambi...
When a large aperture is synthesized with an array of smaller subapertures for high-resolution imaging applications, it is important not only to arrange the subapertures to achieve minimal spatial frequency redundancy but also to choose the size of the subapertures (i.e., the dilution ratio) necessary to achieve the best possible image quality. Spurious or ghost images often occur even for nonredundant dilute subaperture arrays. We show that array configurations producing a uniform modulation transfer function will not exhibit these undesirable ghost images. A prescription that is unique and original (to the best of our knowledge) is then presented for constructing both one-dimensional and two-dimensional configurations of dilute subaperture arrays that results in a uniform spatial frequency response with an arbitrarily high spatial resolution for reciprocal path-imaging applications.
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