Fission cross-sections of ^(119)Sn and ^(209)Bi induced by negative pions of two energies 500 and 672 MeV were measured using a CR−39 nuclear track detector.Target-detector stacks were exposed to pion beams at the Bro...Fission cross-sections of ^(119)Sn and ^(209)Bi induced by negative pions of two energies 500 and 672 MeV were measured using a CR−39 nuclear track detector.Target-detector stacks were exposed to pion beams at the Brookhaven National Laboratory(USA).Measurement results are compared with the corresponding calculations using the computer code CEM95.Agreement between measurements and calculations is fairly good for the ^(209)Bi target nuclei whereas it is poor for 119Sn at both investigated energies of 500 and 672 MeV.Fission cross−section results of^( 119)Sn and ^(209)Bi are explained using the equilibrium properties of these nuclides including nuclear electric quadrupole moments which determine the shapes of nuclei.A logarithmic dependence of fission cross−section on Z^(2)/A is observed for the above−mentioned reactions and a critical limit of Z^(2)/A is identified with the value of 30 which divides the curve ofσf versus Z2/A into two regimes,one with weak dependence and the other with strong dependence.展开更多
The potential of the high resolution nuclear track detector (NTD) CR-39 is examined carefully for the measurement of relativistic nuclear projectile fragmentation cross sections and studies of related processes using ...The potential of the high resolution nuclear track detector (NTD) CR-39 is examined carefully for the measurement of relativistic nuclear projectile fragmentation cross sections and studies of related processes using the experience of many years of such measurements. The charge resolution and the charge resolving power of CR-39 detectors for the measurements of 158 A GeV 207Pb projectiles and their fragments are presented. Exposures of target-detector stacks, the chemical etching procedure and the nuclear track measurements are described in detail discussing precautions and possible errors. The procedures discussed are also valid for other NTDs. A comparison with electronic active detectors is also made considering important detection and measurement aspects. An experimental design proposing the co-use of NTDs with in-use active detectors is described.展开更多
Ionizing radiations are widely used to sustain and enhance our quality of life in the areas such as medical diagnosis, therapy, scientific research and industry etc. Ionizing radiations are available from radioactive ...Ionizing radiations are widely used to sustain and enhance our quality of life in the areas such as medical diagnosis, therapy, scientific research and industry etc. Ionizing radiations are available from radioactive sources which are made of radioactive materials. The radioactive materials are produced in either nuclear power or research reactors or nuclear accelerators or extracted from the naturally found radioactive ores. These radioactive sources and radioactive materials need to be transported from their places of production to the places of applications and finally to waste repositories. The radioactive materials are transported in well designed packages having various shapes and sizes. In the field of radioactive transport, it is a mandatory to find the Transport Index (TI) to be mentioned on each package for transportation. This research is focused on the determination of the maximum γ-ray radiation dose at one meter from the surface of cubic and rectangular shaped package or containers. A computer code “Solid Angle for Transport Index” (SAFTI) has been developed using MATLAB to determine the location of maximum value of the radiation dose rate from the surface of a rectangular or square container. This maximum dose rate is used to determine the transport index. Some of the results of the code have been compared with the experimental results. The results of this research are useful not only to determine TI for individual packages but also to find the TI of the vehicles carrying the transport packages.展开更多
文摘Fission cross-sections of ^(119)Sn and ^(209)Bi induced by negative pions of two energies 500 and 672 MeV were measured using a CR−39 nuclear track detector.Target-detector stacks were exposed to pion beams at the Brookhaven National Laboratory(USA).Measurement results are compared with the corresponding calculations using the computer code CEM95.Agreement between measurements and calculations is fairly good for the ^(209)Bi target nuclei whereas it is poor for 119Sn at both investigated energies of 500 and 672 MeV.Fission cross−section results of^( 119)Sn and ^(209)Bi are explained using the equilibrium properties of these nuclides including nuclear electric quadrupole moments which determine the shapes of nuclei.A logarithmic dependence of fission cross−section on Z^(2)/A is observed for the above−mentioned reactions and a critical limit of Z^(2)/A is identified with the value of 30 which divides the curve ofσf versus Z2/A into two regimes,one with weak dependence and the other with strong dependence.
文摘The potential of the high resolution nuclear track detector (NTD) CR-39 is examined carefully for the measurement of relativistic nuclear projectile fragmentation cross sections and studies of related processes using the experience of many years of such measurements. The charge resolution and the charge resolving power of CR-39 detectors for the measurements of 158 A GeV 207Pb projectiles and their fragments are presented. Exposures of target-detector stacks, the chemical etching procedure and the nuclear track measurements are described in detail discussing precautions and possible errors. The procedures discussed are also valid for other NTDs. A comparison with electronic active detectors is also made considering important detection and measurement aspects. An experimental design proposing the co-use of NTDs with in-use active detectors is described.
文摘Ionizing radiations are widely used to sustain and enhance our quality of life in the areas such as medical diagnosis, therapy, scientific research and industry etc. Ionizing radiations are available from radioactive sources which are made of radioactive materials. The radioactive materials are produced in either nuclear power or research reactors or nuclear accelerators or extracted from the naturally found radioactive ores. These radioactive sources and radioactive materials need to be transported from their places of production to the places of applications and finally to waste repositories. The radioactive materials are transported in well designed packages having various shapes and sizes. In the field of radioactive transport, it is a mandatory to find the Transport Index (TI) to be mentioned on each package for transportation. This research is focused on the determination of the maximum γ-ray radiation dose at one meter from the surface of cubic and rectangular shaped package or containers. A computer code “Solid Angle for Transport Index” (SAFTI) has been developed using MATLAB to determine the location of maximum value of the radiation dose rate from the surface of a rectangular or square container. This maximum dose rate is used to determine the transport index. Some of the results of the code have been compared with the experimental results. The results of this research are useful not only to determine TI for individual packages but also to find the TI of the vehicles carrying the transport packages.
