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Nuclear Cross Section and Neutron Time of Flight
RPI's Linear Accelerator (LINAC) is used in this experiment, which is conducted to calculate the cross section as a function of energy for each of the samples analyzed. The time of flight of neutrons involved will also be calculated.
The experiment uses several pieces of advanced equipment. Chief among all of the high tech things involved in this lab is the RPI LINAC, which is one of the best scientific devices of its kind. Not long ago it was declared a Nuclear Historic Landmark by the American Nuclear Society, in honor of the many accomplishments of the facility in its more than 40 years of service to the scientific community. Samples are brought into LINAC via a "rabbit system", a tube system(pictured below) developed here at RPI which remotely delivers samples into the LINAC or exposure and activation. A computer controls the LINAC and another is used for data capture and analysis of gamma emission from the sample.
The first experiment in this lab involves the detrmination of nuclear cross sections of the samples. A sample is inserted at the end of the LINAC via the rabbit system, and then irradiated with the electron beam of the LINAC, as pictured below. The total nuclear cross section is found by summing all of the interaction cross sections from neutron capture, neutron scattering, and other processes. These cross sections are measured by a counter measuring the numbe rof neutrons that make it through the sample. A calibration run with no sample is done, and then different samples are analyzed..
The second experiment in this lab is done to find the time of flight for neutrons. Using the detected energy levels of the neutrons, along with the subsequent velocity that can be calculated, the time of flight can be derived. Statistical accuracy is ensured by repeated trials. Knowledge of a material's nuclear cross section properties is very crucial to using any material that will be exposed to nuclear processes and neutron emission. Materials should not be used that will be reactiove with the processes going on that they are supposed to help or shield, as seen in various industry incidents in both research and commercial |
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NEEP Lab Course Instructor:
Yaron Danon, vist Dr.
Danon's web site |
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