Dear all:
We're in the midst of Rietveld refinements of neutron TOF data acquired at LANSCE NPDF. The NPDF gives very high backgrounds in low d- values (TOF time), which drop quickly with d-value. After many iterations, the fit between the data and model looks very reasonable, including the background. The model is very close to what has been reported before and it makes sense. However, the Chi^2 doesn't come down close to one. We refined using the Le Bail method, and got a very similar result, including the Chi^2 value (about 20). We feel comfortable with our model, but a high Chi^2 is bothering. Reading the literature, high Chi^2 can occur where data are collected to very high precision. We think this might be our case, but how can we prove so? Any comments and suggestions are appreciated. Best, Juske ********************************************************* Juske Horita Chemical Sciences Division, Oak Ridge National Laboratory P.O.Box 2008, MS 6110 Oak Ridge, TN 37831-6110 (865) 576-2750; Fax (865) 574-4961 For express-mail: Juske Horita Chemical Sciences Division, Oak Ridge National Laboratory Bethel Valley Rd, 4500S, S214 Oak Ridge, TN 37830 ********************************************************************
