Abstract
Neutron facilities at the ORNL provide a versatile suite of instruments to the neutron scattering community. Neutron-sensitive imaging plates are useful when characterizing neutron beamlines at the SNS and HFIR facilities. We describe a number of characterization, commissioning, and troubleshooting measurements in which we use neutron-sensitive image plates to better understand and improve instrument performance. We have used image plates to characterize neutron beams in many ways: to determine absolute beam size, assess transverse beam distribution, and to measure absolute intensity. During the initial radiation survey of the new US/Japan Cold Triple Axis instrument (CTAX), images of the beam footprint were taken multiple monochromator assembly angles. Images of the CTAX beam footprint showed a secondary beam spot, indicating a misalignment in the monochromator. Measurements at the Fine-Resolution Fermi Chopper Spectrometer (SEQUOIA) instrument for 400, 300, 250 and 120meV provide beam size and relative intensity. We frequently use image plates to verify sample alignment within a neutron beam prior to data acquisition. Finally, we measured the absolute intensity across a very large (20cm by 30cm) mono- chromatic beam with a combination of image plates and a conventional beam monitor on the Fundamental Physics beam line. While there are limitations to the data obtained from image plates, especially on pulsed sources, when combined with other tools, they can provide more depth to beamline analysis and development.
