No abstract available

[en] Advanced alpha-particle detectors made of heavy elements were investigated as alternatives to silicon surface-barrier detectors for the ''foil-neutralization technique'' of alpha-particle diagnostics in fusion reactors with high neutron backgrounds. From an extensive literature review, it was decided that HgI₂ would make a more suitable detector for alpha-particle diagnostics than other heavy element detectors such as CdTe. Thus, HgI₂ detectors were designed and fabricated. Experimental tests were performed to determine detector characteristics and detector responses to alpha particles. Radiation noise measurements were also performed using the North Carolina State University PULSTAR nuclear reactor for both the HgI₂ detectors and commercial Si(Au) surface barrier detectors. 15 refs., 1 fig

No abstract available

[en] The goals of this three-year study were: (1) design a neutron focusing system for use with the Texas Cold Neutron Source (TCNS) to produce an intense beam of cold neutrons appropriate for prompt gamma activation analysis (PGAA); (2) orchestrate the construction of the focusing system, integrate it into the TCNS neutron guide complex, and measure its performance; and (3) design, setup, and test a cold-neutron PGAA system which utilizes the guided focused cold neutron beam. During the first year of the DOE grant, a new procedure was developed and used to design a focusing converging guide consisting of truncated rectangular cone sections. Detailed calculations were performed using a 3-D Monte Carlo code which the authors wrote to trace neutrons through the curved guide of the TCNS into the proposed converging guide. Using realistic reflectivities for Ni-Ti supermirrors, the authors obtained gains of 3 to 5 for 4 different converging guide geometries. During the second year of the DOE grant, the subject of this final report, Ovonic Synthetic Materials Company was contracted to build a converging neutron guide focusing system to the specifications. Considerable time and effort were spent working with Ovonics on selecting the materials for the converging neutron guide system. The major portion of the research on the design of a cold-neutron PGAA system was also completed during the second year. At the beginning of the third year of the grant, a converging neutron guide focusing system had been ordered, and a cold-neutron PGAA system had been designed. Since DOE did not fund the third year, there was no money to purchase the required equipment for the cold-neutron PGAA system and no money to perform tests of either the converging neutron guide or the cold-neutron PGAA system. The research already accomplished would have little value without testing the systems which had been designed. Thus the project was continued at a pace that could be sustained with internal funding

[en] Simultaneous neutron and gamma-ray measurements were made of the leakage spectra from a ²⁵²Cf spontaneous fission source located at the center of a solid, 9.6-cm thick, spherical shell of niobium. The NE-213 data were unfolded above 1 MeV and compared on an absolute basis to one-dimensional transport calculations; thus, an integral test of Nb cross section data and multi-group processing was made. Several neutron--gamma-ray coupled cross section sets were investigated including the fine group VITAMIN-C library. Calculations based on ENDF/B-III and -IV data were in good agreement with the measured neutron spectrum below 10 MeV, but diverged from the measurement above 10 MeV. ENDF/B-III data were in generally good agreement with the gamma-ray measurement, while ENDF/B-IV gave an overestimation of the leakage. Sensitivity analysis showed that inelastic reactions were the dominant gamma-ray production mechanism for Nb, and that the gamma-ray leakage had much larger cross section sensitivities than the neutron leakage. On the basis of this integral test, it is suggested that a reevaluation of ENDF/B-IV Nb data for inelastic processes above 1 MeV and all processes above 10 MeV be made. 7 figures

[en] The emphasis of the effort has been to fully explore the charge conversion (or neutralization) foil technique so that it can be used with confidence to extract and measure the alpha flux at the edge of TFTR. Two aspects of the technique are being explored. The first is a proof-of-concept experiment which has been designed and fabricated for implementation on PLT; the second are radiation and heat flux simulations of the expected environment of TFTR to estimate their effect on the technique

[en] Funds were received for the first year of a three year DOE Nuclear Engineering Research Grant, ''Study of Neutron Focusing at the Texas Cold Neutron Source'' (FGO2-92ER75711). The purpose of this three year study was to develop a neutron focusing system to be used with the Texas Cold Neutron Source (TCNS) to produce an intense beam of neutrons. A prompt gamma activation analysis (PGAA) facility was also to be designed, setup, and tested under the three year project. During the first year of the DOE grant, a new procedure was developed and used to design a focusing converging guide consisting of truncated rectangular cone sections. Detailed calculations were performed using a 3-D Monte Carlo code which we wrote to trace neutrons through the curved guide of the TCNS into the proposed converging guide. Using realistic reflectivities for Ni-Ti supermirrors, we obtained gains of 3 to 5 for the neutron flux averaged over an area of 1 x 1 cm

[en] The first phase of our research project has as its main goal the development of an image analysis system for Solid State Nuclear Track Detectors (SSNTD) readout. Section I, of this report is an introduction to SSNTDs and image analysis systems for automatic track counting. The development of the image analysis system is described in Section II. The development of our foil holder system is described in Section III. The performance of an image analysis system can only be judged with respect to a particular type of image which is to be analyzed. In order to insure the workability of our image analysis system in analyzing CR-39 SSNTDs, we have made an effort to improve our etching system and our etch procedure. The development of our etching system and our etch procedure is outlined in Section IV. Also included in Section IV are images of protons and alpha particle tracks for our etch procedure. The performance of our image analysis system is reported in Section V for the proton and alpha particle tracks which are reported in Section IV. Also, the performance of the image analysis system is reported for some test images

[en] The purpose of this three year study is to develop a neutron focusing system to be used with the Texas Cold Neutron Source (TCNS) to produce an intense beam of neutrons. A prompt gamma activation analysis (PGAA) facility will also be designed, setup, and tested under this DOE grant. During the first year of the DOE grant, a new procedure was developed and used to design a focusing converging guide consisting of truncated rectangular cone sections. Detailed calculations were performed using a 3-D Monte Carlo code which the authors wrote to trace neutrons through the existing curved guide of the TCNS into the proposed converging guide. Using realistic reflectivities for Ni-Ti supermirrors, they obtained gains of 4 to 5 for the neutron flux averaged over an area of 1 x 1 cm. Two graduate students were supported by the first year of the DOE grant. Both have passed the Nuclear Engineering qualifying examination and have been admitted to candidacy for the doctoral degree at The University of Texas at Austin. Their programs of study and dissertation projects have been approved by the appropriate committees

[en] A method to extract energetic alphas from the edge of a tokamak plasma has been conceived and analyzed, and experiments to test the methods are being fabricated. The analysis addressed the region of alpha phase space sampled, the survivability of the foils required to implement the method, and the overall efficiency of the method. The experimental apparatus being fabricated include a detector head for a proof-of-concept test on PLT and a calibration-test stand as a support experiment for the PLT test and to support possible subsequent experiments on TFTR. A fast pulse height analysis data acquisition system was fabricated and tested and is ready for use in the experiments discussed above