Changeset bc9a0e1 in sasview


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Timestamp:
Feb 19, 2015 6:27:22 AM (10 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:
a97c51e, 98f6916, 66f21cd
Parents:
60e1a73
Message:

Proof read.

File:
1 edited

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  • src/sas/perspectives/calculator/media/resolution_calculator_help.rst

    rec392464 rbc9a0e1  
    33.. This is a port of the original SasView html help file to ReSTructured text 
    44.. by S King, ISIS, during SasView CodeCamp-III in Feb 2015. 
     5 
     6.. |pi| unicode:: U+03C0 
     7.. |lambda| unicode:: U+03BB 
     8.. |Ang| unicode:: U+212B 
    59 
    610Q Resolution Estimator 
     
    1014----------- 
    1115 
    12 This tool is to approximately estimate the resolution of Q based on the SAS  
    13 instrumental parameter values assuming that the detector is flat and vertical  
    14 to the incident beam direction. 
     16This tool is approximately estimates the resolution of Q from SAS instrumental  
     17parameter values assuming that the detector is flat and normal to the  
     18incident beam. 
    1519 
    1620.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ 
     
    1923------ 
    2024 
    21 1. Select the source and source type (Monochromatic or TOF). Note that the  
    22 computational difference between the sources is only the gravitational  
    23 contribution due to the mass. 
     251) Select *SAS Resolution Esimator* from the *Tool* menu on the SasView toolbar. 
    2426 
    25 2. Change the default values of the instrumental parameters as desired. 
     272) Select the source (Neutron or Photon) and source type (Monochromatic or TOF). 
    2628 
    27 3. The input formats of wavelength and its spread (=FWHM/wavelength) depend on  
    28 the source type.For monochromatic wave, the inputs are just one values as shown  
    29 with the defaults.For TOF, the min and max values should be separated by "-"  
    30 to describe the wavelength band range. Optionally, the input of the wavelength  
    31 (NOT of the wavelength spread) could be extended by adding "; --" where the --  
    32 is the number of the bins for the numerical integration. Otherwise, the  
    33 default value "10" bins will be used. The same number of bins will be used  
    34 for the corresponding wavelength spread in either cases. 
     29   *NOTE! The computational difference between the sources is only the  
     30   gravitational contribution due to the mass of the particles.* 
    3531 
    36 4. For TOF, the default wavelength spectrum is flat. The custom spectrum file  
    37 (with 2 column text: wavelength(A) vs. intensity) can also be loaded by  
    38 selecting "Add new" in the combobox. 
     323) Change the default values of the instrumental parameters as required. Be  
     33   careful to note that distances are specified in cm! 
    3934 
    40 5. Once set all the input values, click the compute button. Depending on  
    41 computation loads the calculation time will vary. 
     354) Enter values for the source wavelength(s) and its spread (= FWHM / wavelength). 
     36    
     37   For monochromatic sources, the inputs are just one value. For TOF sources,  
     38   the minimum and maximum values should be separated by a '-' to specify a  
     39   range. 
     40    
     41   Optionally, the wavelength (BUT NOT of the wavelength spread) can be extended  
     42   by adding '; nn' where the 'nn' specifies the number of the bins for the  
     43   numerical integration. The default value is nn = 10. The same number of bins  
     44   will be used for the corresponding wavelength spread. 
    4245 
    43 6. 1D and 2D dQ will be displayed in the text-box at the bottom of the panel.  
    44 Two dimensional resolution weight distribution (2D elliptical Gaussian  
    45 function) will also be displayed in the plot panel even if the Q inputs are  
    46 outside of the detector limit. The red lines indicate the limits of the  
    47 detector (if a green lines appear (for TOF), it indicates the limits of the  
    48 maximum q range for the largest wavelength due to the size of the detector).  
    49 Note that the effect from the beam block is ignored, so in the small q region  
    50 near the beam block  
     465) For TOF, the default wavelength spectrum is flat. A custom spectral  
     47   distribution file (2-column text: wavelength (|Ang|\) vs Intensity) can also  
     48   be loaded by selecting *Add new* in the combo box. 
    5149 
    52 [ie., q<2*pi*(beam block diameter) / (sample to detector distance) / lamda_min]  
     506) When ready, click the *Compute* button. Depending on the computation the  
     51   calculation time will vary. 
    5352 
    54 the variance is slightly under estimated. 
     537) 1D and 2D dQ values will be displayed at the bottom of the panel, and a 2D  
     54   resolution weight distribution (a 2D elliptical Gaussian function) will also  
     55   be displayed in the plot panel even if the Q inputs are outside of the  
     56   detector limit (the red lines indicate the limits of the detector). 
     57    
     58   TOF only: green lines indicate the limits of the maximum Q range accessible  
     59   for the longest wavelength due to the size of the detector. 
     60     
     61   Note that the effect from the beam block/stop is ignored, so in the small Q  
     62   region near the beam block/stop  
    5563 
    56 7. The summary can be accessed by clicking the 'light-bulb' icon at the bottom  
    57 of the SasView main window. 
     64   [ie., Q < 2*|pi|\*(beam block diameter) / (sample-to-detector distance) / |lambda|\_min]  
     65 
     66   the variance is slightly under estimated. 
     67 
     688) A summary of the calculation is written to the SasView *Console* at the  
     69   bottom of the main SasView window. 
    5870 
    5971.. image:: resolution_tutor.gif 
     
    6880.. image:: q.gif 
    6981 
    70 In the limit of the small angle, the variance of q in the first order  
    71 approximation is 
     82In the small-angle limit, the variance of Q is to a first-order  
     83approximation 
    7284 
    7385.. image:: sigma_q.gif 
    7486 
    75 In summary, the geometric and gravitational contributions depending on the  
    76 shape of each factors can be expressed as shown the table. 
     87The geometric and gravitational contributions can then be summarised as 
    7788 
    7889.. image:: sigma_table.gif 
    7990 
    80 Finally, we use a Gaussian function to describe the 2D weighting distribution  
    81 of the uncertainty in q. 
     91Finally, a Gaussian function is used to describe the 2D weighting distribution  
     92of the uncertainty in Q. 
    8293 
    8394.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ 
     
    8596References 
    8697---------- 
    87 D.F.R. Mildner and J.M. Carpenter, J. Appl. Cryst. 17, 249-256 (1984) 
    8898 
    89 D.F.R. Mildner, J.M. Carpenter and D.L. Worcester, J. Appl. Cryst. 19, 311-319  
    90 (1986) 
     99D.F.R. Mildner and J.M. Carpenter  
     100*J. Appl. Cryst.* 17 (1984) 249-256 
     101 
     102D.F.R. Mildner, J.M. Carpenter and D.L. Worcester  
     103*J. Appl. Cryst.* 19 (1986) 311-319 
     104 
     105.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ 
     106 
     107.. note::  This help document was last changed by Steve King, 19Feb2015 
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