Direct measurement of cold neutron moderator spectra

✍ Scribed by János Füzi

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 929 KB
• Volume: 586
• Category: Article
• ISSN: 0168-9002
• DOI: 10.1016/j.nima.2007.11.055

✦ Synopsis

The neutron flux distribution with respect to energy/wavelength of the cold source of the Budapest Neutron Centre has been measured using the energy resolved pinhole imaging method. A 2D position sensitive multiwire proportional counter has been used in time of flight regime together with a chopper placed at the position of the pinhole. Gas absorption efficiency and detector dead time corrections have been applied and the accuracy of the results analyzed. Three Maxwell-Boltzmann distributions required for a proper fit to the resulted spectrum yield the multispectral characteristic of the cold source due to incomplete moderation in the finite-sized liquid hydrogen volume. The measurement has been performed during the reconstruction of the out-of-pile guide system of a beamline, offering direct view of the cold source.