Changeset 78f02c3 in sasview for src/sas/calculator/media/resolution_calculator_help.rst

Timestamp:

Feb 14, 2015 12:12:40 PM (9 years ago)

Author:

smk78

Branches:

master, ESS_GUI, ESS_GUI_Docs, ESS_GUI_batch_fitting, ESS_GUI_bumps_abstraction, ESS_GUI_iss1116, ESS_GUI_iss879, ESS_GUI_iss959, ESS_GUI_opencl, ESS_GUI_ordering, ESS_GUI_sync_sascalc, costrafo411, magnetic_scatt, release-4.1.1, release-4.1.2, release-4.2.2, release_4.0.1, ticket-1009, ticket-1094-headless, ticket-1242-2d-resolution, ticket-1243, ticket-1249, ticket885, unittest-saveload

Children:

898a8b9

Parents:

3e2ebbb

Message:

Level 1 sphinx-ready commit of remaining help files

File:

• src/sas/calculator/media/resolution_calculator_help.rst (modified) (1 diff)

src/sas/calculator/media/resolution_calculator_help.rst

@@ -1 +1 @@
 ..resolution_calculator_help.rst
 
-Resolution Calculator
-=====================
+.. This is a port of the original SasView html help file to ReSTructured text
+.. by S King, ISIS, during SasView CodeCamp-III in Feb 2015.
 
-Placeholder for resolution calculator help
+Q Resolution Estimator
+======================
+
+Description
+-----------
+
+This tool is to approximately estimate the resolution of Q based on the SAS 
+instrumental parameter values assuming that the detector is flat and vertical 
+to the incident beam direction.
+
+.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
+
+How To
+------
+
+1. Select the source and source type (Monochromatic or TOF). Note that the 
+computational difference between the sources is only the gravitational 
+contribution due to the mass.
+
+2. Change the default values of the instrumental parameters as desired.
+
+3. The input formats of wavelength and its spread (=FWHM/wavelength) depend on 
+the source type.For monochromatic wave, the inputs are just one values as shown 
+with the defaults.For TOF, the min and max values should be separated by "-" 
+to describe the wavelength band range. Optionally, the input of the wavelength 
+(NOT of the wavelength spread) could be extended by adding "; --" where the -- 
+is the number of the bins for the numerical integration. Otherwise, the 
+default value "10" bins will be used. The same number of bins will be used 
+for the corresponding wavelength spread in either cases.
+
+4. For TOF, the default wavelength spectrum is flat. The custom spectrum file 
+(with 2 column text: wavelength(A) vs. intensity) can also be loaded by 
+selecting "Add new" in the combobox.
+
+5. Once set all the input values, click the compute button. Depending on 
+computation loads the calculation time will vary.
+
+6. 1D and 2D dQ will be displayed in the text-box at the bottom of the panel. 
+Two dimensional resolution weight distribution (2D elliptical Gaussian 
+function) will also be displayed in the plot panel even if the Q inputs are 
+outside of the detector limit. The red lines indicate the limits of the 
+detector (if a green lines appear (for TOF), it indicates the limits of the 
+maximum q range for the largest wavelength due to the size of the detector). 
+Note that the effect from the beam block is ignored, so in the small q region 
+near the beam block 
+
+[ie., q<2*pi*(beam block diameter) / (sample to detector distance) / lamda_min] 
+
+the variance is slightly under estimated.
+
+7. The summary can be accessed by clicking the 'light-bulb' icon at the bottom 
+of the SasView main window.
+
+.. image:: resolution_tutor.gif
+
+.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
+
+Theory
+------
+
+The scattering wave transfer vector is by definition
+
+.. image:: q.gif
+
+In the limit of the small angle, the variance of q in the first order 
+approximation is
+
+.. image:: sigma_q.gif
+
+In summary, the geometric and gravitational contributions depending on the 
+shape of each factors can be expressed as shown the table.
+
+.. image:: sigma_table.gif
+
+Finally, we use a Gaussian function to describe the 2D weighting distribution 
+of the uncertainty in q.
+
+.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
+
+References
+----------
+D.F.R. Mildner and J.M. Carpenter, J. Appl. Cryst. 17, 249-256 (1984)
+
+D.F.R. Mildner, J.M. Carpenter and D.L. Worcester, J. Appl. Cryst. 19, 311-319 
+(1986)