Results 1 - 10 of 7023
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[en] A method is suggested for determination of the thickness of nuclear photoemulsions applied in luminous- and electron-microscopy autoradiography. The method is based on measuring both the speed of sample withdrawal out of the emulsion melt and the thickness of the emulsion layer applied. The emulsion layer is obtained by the slide submergence technique. Using the least square fit the curve was obtained for the dependence of the emulsion applied layer thickness on the speed of sample withdrawal out of the emulsion melt. The proportionality coefficient, k, has been defined, to characterize the emulsion properties. Thus, basing on the emulsion thickness required for the autoradiography system and knowing the k value, it is possible to determine the sample withdrawal speed corresponding to the given thickness. Every type of emulsion has its own k-value which also depends on the batch of the nuclear emulsion used
[en] The target unit of the OPERA detector, the so called brick, is made of lead plates acting as the neutrino target interleaved with nuclear emulsion films acting as trackers with micrometric accuracy. In this paper we report the nuclear emulsion analysis chain, from the confirmation of the electronic detector trigger for the brick tagging to the neutrino interaction vertex location and reconstruction.
[en] Nuclear emulsions for OPERA and WIMPs detection are characterized in the overview of photographic emulsions with respect to the grain size dependence of their sensitivities. The emulsions are classified into three groups. The grains in Class I, which are larger than 0.5 μm in diameter, are highly sensitive owing to their large light absorbance, and used for color films. The grains in Class II, which are 0.1 ∼ 0.5 μm in diameter and include those for OPERA films, are principally defect-free and therefore afford efficient latent image formation. The grains in Class III, which are smaller than 0.1 eV and expected to be available for WIMPs detection, are still poorly understood and interesting to study from the viewpoints of the formation and characterization of quantum-sized grains. Discussions are also made on the mechanism of the reset function brought about by the 'refresh' treatment for OPERA films and its applicability to those for WIMPs detection.
[en] The interactions of 29 MeV He3 particles with 32S, 19F and 12C, irradiated in the Nuffield cyclotron (Birmingham University) have been studied using the nuclear emulsion technique. The first excitation levels of 12C and 32S have been obtained and the pick-up reaction 12C(3He, 4He) 11C has been studied and used to calculate its Q-values and the first levels of 1C. (Author) 24 refs
[en] Nuclear emulsion, a tracking detector with sub-micron position resolution, has played a successful role in the field of particle physics and the analysis speed has been substantially improved by the development of automated scanning systems. This paper describes a newly developed automated scanning system and its application to the analysis of nuclear fragments emitted almost isotropically in nuclear evaporation. This system is able to recognize tracks of nuclear fragments up to |tan θ| < 3.0 (where θ is the track angle with respect to the perpendicular to the emulsion film), while existing systems have an angular acceptance limited to |tan θ| < 0.6. The automatic scanning for such a large angle track in nuclear emulsion is the first trial. Furthermore the track recognition algorithm is performed by a powerful Graphics Processing Unit (GPU) for the first time. This GPU has a sufficient computing power to process large area scanning data with a wide angular acceptance and enough flexibility to allow the tuning of the recognition algorithm. This new system will in particular be applied in the framework of the OPERA experiment: the background in the sample of τ decay candidates due to hadronic interactions will be reduced by a better detection of the emitted nuclear fragments.
[en] A methodological study of various technical aspects of photographic emulsions is presented. This study enables the emulsion method to be used in certain physical problems, and can be summarized under the following headings. 1) Variation of different ionization indices with the degree of development. A measure of the degree of development is introduced. This measure called the α -mark, is based on the average width of tracks due to α-particles. Using the α-mack the influence of several factors such as the duration, temperature and concentration of the developing liquid are investigated. A comparative study of the sensitivity of llford C2 and K2 emulsions is given. (Author) 9 refs
[en] We report on the development of an automated scanning system for nuclear emulsions aiming at very precise spatial and angular measurements. An accuracy of 0.06μm in position was achieved with the emulsion films used for the measurement. An accuracy of 0.4mrad was achieved for tracks penetrating orthogonally the emulsion films while an accuracy of 1mrad was obtained for tracks inclined by about 300mrad with respect to the perpendicular direction. This result shows unprecedented position and angular resolutions achieved by automated measurements
[en] The main mechanisms which govern the development process are described and some practical considerations on the specific case of ionographic emulsions, mostly used in corpuscular physics and in autoradiography are proposed. The introduction of the activation procedure, based on the concept of the stable sub-latent image, in the development of photographic recording systems are shortly described in terms of efficiency, noise reduction and increase in resolution
[en] The dependence of the thickness of the developed layer of the nuclear photoemulsion BR-2M on the environmental humidity is investigated. It is found that the BRT-2M emulsion layer thickness is varied. The developed emulsion is almost pure gelatin whose the refractive index is varied from 1.540 up to 1.515 under changing the humidity from 44% up to 84%