The MINOS CollaborationArgonne -Athens -Caltech -Chicago -Dubna -Fermilab -Harvard IHEP-Beijing -Indiana -ITEP-Moscow -Lebedev Livermore VCL-London Minnesota -Oxford -Pittsburgh -Protvino -Rutherford -Stanford -SussexTexas A&M -Texas-Austin -Tufts -Western Washington - Executive summaryThe MINOS (Main Injector Neutrino Oscillation Search) experiment is designed to search for neutrino oscillations with a sensitivity significantly greater than has been achieved to date. The phenomenon of neutrino oscillations, whose existence has not been proven convincingly so far, allows neutrinos of one "flavor" (type) to slowly transform themselves into another flavor, and then back again to the original flavor, as they propagate through space or matter.The MINOS experiment is optimized to explore the region of neutrino oscillation "para meter space" (values of the !:l.m 2 and sin 2 29 parameters) suggested by previous investigations of atmospheric neutrinos: the Kamiokande, 1MB, Super-Kamiokande and Soudan 2 experi ments. The study of oscillations in this region with a neutrino beam from the Main Injector requires measurements of the beam after a very long flight path. This in turn requires an intense neutrino beam and a massive detector in order to have an adequate event rate at a great distance from the source.We propose to enhance significantly the physics capabilities of the MINOS experiment by the addition of a Hybrid Emulsion Detector at Soudan, capable of unambigous identification of the neutrino flavor. Recent developments in emulsion experiments make such a detector possible, although significant technological challenges must be overcome. We propose to initiate an R&D effort to identify major potential problems and to develop practical solutions to them.In addition to this primary motivation for this R&D work, we note that the strong and growing interest in studies of neutrino oscillations using neutrino beams from future muon storage rings provides another potential application. These beams will offer significantly higher intensities, albeit of mixed 1I1J-and lie, beams. In order to take full advantage of these beams for neutrino oscillation studies it will be necessary that the detector be capable of determination of the flavor of the final state lepton, and the lepton's charge in a significant fraction of the interactions. At present, an emulsion detector in an external magnetic field appears best suited to offer such capabilities. The R&D effort discussed here will be an important step towards a design of such a future detector. This document is organized as follows:• Chapter 1 summarizes the physics motivation for the proposed emulsion detector,• Chapter 2 briefly reviews the status of the emulsion technology and its aplication to particle physics experiments,• Chapter 3 discusses design considerations for an emulsion detector,• Chapter 4 describes some of the details of a possible detector as well as results from the work up to date,• Chapter 5 outlines the proposed R&D program and summarizes the resources req...
Passive and active detection techniques have been employed in order to measure neutron fluence rates and corresponding exposure rates around medical electron accelerators operating at energies well above the neutron binding energies of the structural materials. In these conditions from the treatment head, in the direct photon flux and from the shielded region, a fast neutron flux emerges which is partly absorbed and partly scattered by the walls, eventually establishing a nearly uniform thermal and epithermal flux in the room. Both direct and scattered flux contribute to the dose to the patient. A smaller neutron dose rate can also be found outside the treatment room, where the therapy staff works. Passive detectors, of moderation type, have been employed in the treatment room and 3He active detectors in the external zones. For the treatment room the activation data were compared with results of Monte Carlo simulation of the neutron transport in the room. Technical features of the two measures are briefly presented and results obtained around three different types of accelerators are reported. At the higher beam energies, i.e., 25 MV, a neutron dose of 0.36 Sv was estimated in the treatment field in addition to a therapeutic x-ray dose of 50 Gy. At lower energies or out of the treatment field the neutron dose drops significantly. In the external zones the dose rates everywhere are below the recommended limits and normally very low, the highest values being recorded in positions very close to the access door of the treatment room.
The photoneutron dose equivalent in a linac radiotherapy room and its entrance maze was investigated by means of Monte Carlo simulations under different conditions. Particularly, the effect of neutron absorbers and moderator layers placed on the maze walls was considered. The contribution of prompt gamma rays emitted in absorption reactions of thermal neutrons was also taken into account. The simulation results are compared with some experimental measurements in the therapy room and in the maze.
In this paper, the impact of the Si nanocrystals technological fluctuations on the programming window dispersion of multi nanocrystals memory is thoroughly investigated. Techno-logical dispersions of different nanocrystals populations, directly measured by high-resolution transmission electron microscopy, are used as starting points for the modeling of the device charac-teristics. Numerical Monte Carlo simulations as well as an original compact modeling, based on the compound distributions (CD) statistics, are here presented. Exact analytical results (CD model), approximated analytical results (CD+Central Limit Theorem model) and numerical results (numerical convolution) are deeply discussed. Finally, the good agreement between our simulations and experimental data of ultrascaled nanocrystal devices, made by conventional UV lithography or by e-beam lithography, definitively confirms the validity of our theoretical approach.
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