نتایج جستجو برای: neutrons
تعداد نتایج: 20708 فیلتر نتایج به سال:
If you want to see an object, you have to illuminate it. If you want to discern details of an object, you will have to illuminate it with "light" of a wavelength equal to or smaller than the distance between the object details you are interested in. For most solids (or condensed media), such details of interest to physicists (for example, lattice sites, liquids, colloids, plastics, polymer and ...
A measurement of the production of ultracold neutrons from velocity-selected cold neutrons on gaseous and solid deuterium targets is reported. The expected energy dependence for two-particle collisions with well defined neutron and Maxwell-Boltzmann distributed molecular velocities is found for the gas target. The solid target data agree in shape with the phonon density-of-states curve and prov...
Using simulations to understand backgrounds from muon-induced neutrons is important in designing next-generation low-background underground experiments. Validation of relevant physics within the Geant4 simulation package has been completed by comparing to data from two recent experiments. Verification focused on the production and propagation of neutrons at energies important to underground exp...
A method of measuring the close to threshold meson production in neutronneutron collisions is described where the momenta of the colliding neutrons can be determined with the accuracy obtainable for the proton-proton reaction. The technique is based on the double quasi-free nn → nnX reaction, where deuterons are used as a source of neutrons. PACS: 13.60.Le, 13.75.-ni, 13.75.Cs Typeset using REVTEX
It is shown that fusion of neutrons and protons to He nuclei occurs in γ−ray burst outflows in a process similar to big-bang nucleosynthesis in the early Universe. Only the surviving free neutrons can then decouple kinematically from the charged fluid so that the multi-GeV neutrino signal predicted from inelastic nuclear n−p collisions is significantly reduced. It is also argued that a sizeable...
Neutron scattering is a powerful and direct means for investigating the vibrational, magnetic, and structural properties of materials. In this paper, I will present a brief introduction to neutron scattering. I will discuss why neutrons are important, how and where you get neutrons, and types of neutron scattering. This paper is meant as brief introduction into an interesting field of science t...
This report describes the design and development of a plastic scintillating high energy neutron detector to be implemented as a micro-class satellite payload. The primary function of this detector is to identify and characterize the energy distribution of solar accelerated neutrons resulting from massive solar events. Accelerated neutrons will be identified by a pulse counting system using the ...
In solids random motions of atoms may take place in connection with disorder; for instance diffusion of interstitials in solid solutions or orientation fluctuations in molecular solids. Experimentally these motions are observed mostly by resonance and relaxation techni ques, by optical spectroscopy and, recently, by neutron spectroscopy. In comparison to the other me thods neutron spectroscop...
Results are presented from the exposure of a CMS performance prototype MSGC to a fast neutron beam having an average energy of 20 MeV and an intensity of 7 106 neutrons/mm2/s. A fluence equivalent to 3 years of LHC operation has been accumulated without damages to the detector. The stability of the MSGC operation in a heavily ionising particle flux is reported and the estimation of their produc...
The strongly spin-dependent absorption of neutrons in nuclear spin-polarized (3)He opens up the possibility of polarizing neutrons from reactors and spallation sources over the full kinematical range of cold, thermal and hot neutrons. This paper gives a report on the neutron spin filter (NSF) development program at Mainz. The polarization technique is based on direct optical pumping of metastab...
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