Currently, there are three spectrometer experiments available through the MIT Nuclear Reactor iLab. Each of these experiments utilizes a 4" beamport which provides a continuous beam of low-energy neutrons that is controlled using a mechanical chopper.
1) Maxwell Boltzmann Distribution This lab measures the Maxwell Boltzmann Distribution of thermal neutrons from the MIT Reactor. The objective of this experiment is to correlate the temperature of the reactor with the availability of thermal neutrons for measurement, and then to compare the results with the Maxwell Boltzmann distribution that is predicted. Students are asked to perform measurements at two points in the beam guide tube using neutron detectors, multi-channel analyzers, and oscilloscopes. Students plot the data they gather and attempt to calculate thermal neutron velocity and flux density.
2) Bragg Diffraction and the DeBroglie Wavelength This lab demonstrates the Bragg Diffraction and the DeBroglie Wavelength. The objective of this experiment is to demonstrate neutron diffraction using a crystal monochromater. Students are asked to measure the Bragg-diffracted beam that is created by altering the neutron beam path with a copper crystal. They perform several measurements at various angles of incidence, and are asked to plot their data to demonstrate the DeBroglie relation.
3) Neutron Beam Absorption This lab demonstrates half thickness or shielding effectiveness in a neutron beam. The objective of this experiment is to demonstrate thermal neutron behavior in the presence of various absorption materials. Students are asked to calculate neutron flux and neutron density using the data gathered from the neutron detectors. Then, the students are asked to position standard pieces of lead, boron, cadmium, and aluminum prior to the neutron detectors in the beam guide tube. They perform another round of measurements. Based on the data collected, students are asked to calculate the half-thickness (or shielding effectiveness) of various materials.
Demonstration Video
| Topics/Standards it Teaches: | Nuclear theory, Particle wave theory, Absorption |
| Correlating High School Course: | AP Physics B (particularly the Neutron Beam experiment), AP Chemistry |
| Interaction Mode: | Synchronous |
The iLab Network is supported in part by the National Science Foundation under grant OCI-0753324. However, any opinions, findings, conclusions, and/or recommendations are those of the investigators and do not necessarily reflect the views of the Foundation.