@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
@prefix ns0: <http://gcmd.gsfc.nasa.gov/kms#> .

<https://gcmd.earthdata.nasa.gov/kms/concept/d49b2313-2fb1-464c-a2f8-5ff5799344a7>
  skos:prefLabel "X-Ray/Gamma Ray Detectors"@en ;
  a skos:Concept ;
  skos:narrower <https://gcmd.earthdata.nasa.gov/kms/concept/f54aafd2-925e-4653-b897-c6ae4e094c69> .

<https://gcmd.earthdata.nasa.gov/kms/concept/f54aafd2-925e-4653-b897-c6ae4e094c69>
  ns0:altLabel [ ] ;
  skos:definition """An x-ray powder diffractometer is primarily used for the
identification of phases in powder form. An x-ray beam of known
wavelength is focused on a powdered sample and x-ray
diffraction peaks are measured using a germanium detector; the
d-spacing of the observed diffraction peaks is calculated using
Bragg's Law [n*lamda = 2dsin(theta)]. The Scintag Pad V
automated powder diffractometer uses a Cu x-ray tube with
variable filters, a four-sample changer, and a low-noise, high
efficiency, liquid-nitrogen cooled germanium detector. The
goniometer is automated and software packages are run from a PC
running Windows NT 4. A number of Scintag software packages are
available for routine powder diffraction data acquisition,
background correction and peak identification. Unknowns can be
matched to JCPDS cards in an on-line database. Other software
is available for quantitative analysis of powder mixtures, unit
cell refinement, Rietveld analysis, and GSAS structural
analysis. Samples sho uld be prepared as powders with a grain
size of 10 um (approximately), and typically about 100
milligrams of sample is required.

Additional information available at
"http://www.gps.caltech.edu/facilities/analytical/xrd.html"

[Summary provided by Caltech]"""@en ;
  skos:prefLabel "XRPD"@en ;
  skos:inScheme <https://gcmd.earthdata.nasa.gov/kms/concepts/concept_scheme/instruments> ;
  skos:broader <https://gcmd.earthdata.nasa.gov/kms/concept/d49b2313-2fb1-464c-a2f8-5ff5799344a7> ;
  a skos:Concept .