High precision photon flux determination for photon tagging experiments Teymurazyan, A.; Ahmidouch, A.; Ambrozewicz, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2014, Letnik:
767, Številka:
C
Journal Article
Recenzirano
The Jefferson Laboratory PrimEx Collaboration has developed and implemented a method to control the tagged photon flux in photoproduction experiments at the 1% level over the photon energy range from ...4.9 to 5.5GeV. This method has been successfully implemented in a high precision measurement of the neutral pion lifetime. Here, we outline the experimental equipment and the analysis techniques used to accomplish this. These include the use of a total absorption counter for absolute flux calibration, a pair spectrometer for online relative flux monitoring, and a new method for post-bremsstrahlung electron counting.
Two neutron correlations in photo-fission Dale, D. S; Kosinov, O; Forest, T ...
International journal of modern physics. Conference series,
2016, Letnik:
44
Journal Article
Recenzirano
Odprti dostop
A large body of experimental work has established the strong kinematical correlation between fission fragments and fission neutrons. Here, we report on the progress of investigations of the potential ...for strong two neutron correlations arising from the nearly back-to-back nature of the two fission fragments that emit these neutrons in the photo-fission process. In initial measurements, a pulsed electron linear accelerator was used to generate bremsstrahlung photons that impinged upon an actinide target, and the energy and opening angle distributions of coincident neutrons were measured using a large acceptance neutron detector array. A planned comprehensive set of measurements of two neutron correlations in the photo-fission of actinides is expected to shed light on several fundamental aspects of the fission process including the multiplicity distributions associated with the light and heavy fission fragments, the nuclear temperatures of the fission fragments, and the mass distribution of the fission fragments as a function of energy released. In addition to these measurements providing important nuclear data, the unique kinematics of fission and the resulting two neutron correlations have the potential to be the basis for a new tool to detect fissionable materials. A key technical challenge of this program arises from the need to perform coincidence measurements with a low duty factor, pulsed electron accelerator. This has motivated the construction of a large acceptance neutron detector array, and the development of data analysis techniques to directly measure uncorrelated two neutron backgrounds.
The cross section of atomic electron Compton scattering γ+e→γ′+e′ was measured in the 4.400–5.475 GeV photon beam energy region by the PrimEx collaboration at Jefferson Lab with an accuracy of 2.6% ...and less. The results are consistent with theoretical predictions that include next-to-leading order radiative corrections. The measurements provide the first high precision test of this elementary QED process at beam energies greater than 0.1 GeV.
In this work, physical and chemical properties of CdTe low-dimensional crystallites obtained by grinding or colloidal synthesis have been investigated. In particular, we have analyzed the ...photoluminescent characteristics of CdTe nanocrystals stabilized by thioglycolic acid, synthesized by using deionized water and water solutions of ethylene glycol and glycerin of different concentrations as dispersion medium. It has been shown that the stability of colloidal solutions of CdTe nanocrystals depends on the nature of dispersion medium and the stabilizer concentration.
The physicochemical properties of low-dimensional structures based on cadmium telluride obtained by the colloidal synthesis method are investigated. It is established that the change in the ratio of ...the Cd2+: Te2– concentrations in the reaction medium significantly influences the properties of the colloidal synthesis of CdTe NCs. It is shown that the ratio of 8: 1 is the optimal ratio of the concentrations of Cd2 +: Te2– to obtain NCs of CdTe. It is shown that the use of a vinyl acetate-acrylate copolymer as a matrix material for the transfer of NCs CdTe from colloidal solutions allows obtaining non-toxic Nanoheterogeneous film structures, characterized by satisfactory optical properties. The main photoluminescent characteristics of the materials under study are analyzed.
The cross section of atomic electron Compton scattering \(\gamma + e \rightarrow \gamma^\prime + e^\prime \) was measured in the 4.40--5.475 GeV photon beam energy region by the {\em PrimEx} ...collaboration at Jefferson Lab with an accuracy of 2\% and less. The results are consistent with theoretical predictions that include next-to-leading order radiative corrections. The measurements provide the first high precision test of this elementary QED process at beam energies greater than 0.1 GeV.
A series of CsCa1−xEuxBr3 (0≤x≤0.08) single crystals has been grown using the Bridgman–Stockbarger technique and their luminescent and scintillation properties have been studied. The ...radioluminescence spectra of CsCaBr3:Eu2+(with 0.5, 1.0, 3.0, 5.0 and 8.0mol% of Eu2+) materials include a narrow band with the maximum which position is shifted from 442 to 447nm with the increase of Eu2+ concentration in the growth melt. The maximal light yield achieves 28,000ph/MeV at CsCa0.92Eu0.08Br3 with energy resolution of 9.3% at 662keV.
► A new CsCa1−xEuxBr3 (0≤x≤0.08) scintillation material has been studied. ► The crystals were grown using the Bridgman–Stockbarger technique. ► All the crystals had excellent transparency. ► The maximal light yield is 28,000ph/MeV with energy resolution of 9.3% at 662keV. ► The main decay time constant for CsCa0.92Eu0.08Br3 is 6.097±0.002μs.
The paper considers the essence, advantages, and problems of a new and popular approach to the dissemination of scientific data, which were formulated in
1
under the name of the FAIR (findability, ...accessibility, interoperability, reusability) principles. The main goal of FAIR is to improve the information infrastructure to ensure the reusability of research data through personal or automated queries, as well as to create conditions for the discoverability, accessibility, compatibility, and processing of the required data by interested consumers. Active support of this area in the field of information technology involves assistance in working with data in relation to one of the acute problems of modern science—the exponential growth in the volume of received and replicated data, moreover, in a variety of possible formats.
—The European experience in creating a large-scale infrastructure that provides material modeling tasks during the development of new technologies is considered. The infrastructure combines ...information and computing resources and numerous services that allow one to apply a new business model in the field of high technology. The leading role in the organization of such an infrastructure is played by a system of ontologies for standardization of the conceptual apparatus appearing in the documents, models and software used. The main ideas in the implementation of modeling are systematized through the European Materials Modeling Ontology (EMMO), which is capable of expanding and covering new objects and research methods. The unique standards that underlie ontologies and cover almost all types of material objects, from atoms up to building materials, are described.
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