| Full text | |
| Author(s): |
Parente, C. B. R.
[1]
;
Mazzocchi, V. L.
[1]
;
Mestnik-Filho, J.
[1]
;
Mascarenhas, Y. P.
[2]
;
Berliner, R.
[3]
Total Authors: 5
|
| Affiliation: | [1] IPEN CNEN SP, BR-05422970 Sao Paulo - Brazil
[2] USP, Inst Fis Sao Carlos, BR-13560940 Sao Carlos, SP - Brazil
[3] Instrumentat Associates, Durham, NC 27709 - USA
Total Affiliations: 3
|
| Document type: | Journal article |
| Source: | NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SP; v. 622, n. 3, p. 678-684, OCT 21 2010. |
| Web of Science Citations: | 3 |
| Abstract | |
A high-resolution powder diffractometer (HRPD) was installed on the IEA-R1 research reactor at IPEN-CNEN/SP, Sao Paulo, SP, Brazil. It is an extensive upgrade of the old IPEN-CNEN/SP multipurpose neutron diffractometer which used a single boron trifluoride (BF(3)) detector and a flat mosaic single crystal copper monochromator. The main modifications introduced were the installation of a position sensitive detector (PSD) and a focusing silicon monochromator. Placed at a distance of 1600 mm from sample, the PSD spans an angular range of 20 degrees of a diffraction pattern. An extensive powder diffraction pattern can be obtained by collecting data in contiguous 20 degrees segments. The double-focusing perfect single crystal silicon monochromator, installed in a take-off angle of 84 degrees, can be positioned to produce 4 different wavelengths, namely 1.111, 1.399, 1.667 and 2.191 angstrom (nominal values). Diffraction patterns, obtained with the instrument, have shown a quite good resolution. Curves full width at half maximum (FWHM) vs. scattering angle (2 theta) have been measured with powdered alumina using three vanadium sample holders 1/8, 1/4 and 3/8 in. in diameter. Such curves give the resolution that can be expected from the instrument in an interval 2 theta from 5 degrees to 130 degrees. In comparison to the former instrument, the new diffractometer has much better resolution and is, per intensity point, ca. 600 times faster in data acquisition. (C) 2010 Elsevier B.V. All rights reserved. (AU) | |