TANGRA multidetector systems for investigation of neutron-nuclear reactions at the JINR Frank Laboratory of Neutron Physics

In the framework of TANGRA-project at the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear research in Dubna (Russia), two experimental setups (Fig. 1) have been designed and tested for investigation of 14-MeV neutron-induced nuclear reactions on a number of important for nuclear science and engineering isotopes. As a source of 14-MeV “tagged” neutrons we are using the VNIIA ING-27 steady-state portable neutron generator with embedded in its vacuum tube 64-pixel charge-particle detector. The “Romashka” system is an array of up-to 24 hexagonal NaI(Tl)-crystal scintillation probes, while the “Romasha” array consists of 18 cylindrical BGO-crystal detectors of neutrons and gamma-rays. In addition to these detectors there is a HPGe gamma-ray spectrometer and a number of Stilbene detectors that can be added for high-resolution gamma-ray spectrometry and neutron-gamma detection. The main characteristics of the neutron-induced nuclear reaction products can be investigated by commissioning the detectors in suitable for these experiments’ geometries. Both setups can be used for doing basic and applied scientific research, because they permit simultaneously to measure the energy, angle and multiplicity distributions of gamma-rays and neutrons, produced in the competitive neutron-induced nuclear reactions (n, n’γ), (n,2n), (n, xnγ) and (n, f) in pure or complex substances.

Engineering of a new single-crystal multi-ionic fast and high-light-yield scintillation material (Gd0.5–Y0.5)3Al2Ga3O12:Ce,Mg

A single crystal scintillation material (Gd0.5–Y0.5)3Al2Ga3O12 (GYAGG) doped with Ce and codoped with Mg at a small concentration was grown by the Czochralski technique and studied for its scintillation properties for the first time.

Heuristic Method for Photo-detectors Localization over Continuous Crystal Scintillation Cameras

The construction process of large scintillation cameras with continuous crystals is a complex problem affected by multiple variables, from the physical construction of the scintillation crystal to the dispersion in the sensibility of photomultiplier tubes. The selection of these variables have a strong impact on the final performance of the scintillation camera. A new method to select photomultiplier is presented in this paper, regarding its gain, making use of k-means clustering and genetic algorithms. The proposed algorithm was tested and applied in the construction of six scintillation cameras for the Argentinean positron emission tomogaph prototype (AR-PET), a problem with more than 10+600 possible configurations. The resulting configuration of the scintillation cameras reduced the software-freecalibration FWHM of the camera from 20% to 15% average.

High Resolution Imaging by Means of Backscattered Electrons in the Scanning Electron Microscope

This paper deals with imaging by means of backscattered electrons in the high resolution scanning electron microscopy. Possible backscattered electrons detection systems are outlined and one of the most efficient, the high take of angle single crystal scintillation detector, is described in detail. Its advantages and disadvantages are discussed and the comparison with the secondary electron detection modes is shown. The high resolution micrographs taken by the backscattered electron detector as well as by the secondary electron detectors are displayed.