Update of the sld calculator documentation. Fixes #2689.

src/sas/qtgui/Calculators/media/sld_calculator_help.rst

@@ -19,7 +19,7 @@ This SLD calculator utilizes the periodictable python package\ :sup:`1`, which i
 User Inputs
 ----------------------------
 **Molecular Formula** (required)
-    This field defines the material for which you are calculating the SLD. For more guidance on how to enter molecules, biomolecules, and more complex mixtures scroll down to "Specifying Materials or Mixtures in the Molecular Formula Field" section.
+    This field defines the material for which you are calculating the SLD. The section "Specifying Materials or Mixtures in the Molecular Formula Field" offers further guidance on how to enter molecules, biomolecules, and more complex mixtures.
 
 **Mass Density** |g/cm^3| (required)
     This field defines the density of the material for which you are calculating the SLD of your material. Density uncertainty is likely the largest source of error in the SLD calculator.
@@ -32,25 +32,33 @@ User Inputs
 
 Calculator Output
 ----------------------------
-Neutron SLD
-(|Ang^-2|)
+**Neutron SLD** (|Ang^-2|)
 
-X-ray SLD
-(|Ang^-2|)
+   A measure of the neutron scattering power of the material. A required input for most scattering models using in neutron scattering experiments.
 
-Neutron Incoherent Cross-section (cm\ :sup:`-1`)
+**X-ray SLD** (|Ang^-2|)
 
-Neutron Absorption Cross-Section (cm\ :sup:`-1`)
+    A measure of the x-ray scattering power of the material.  A required input for most scattering models using in x-ray scattering experiments.
 
-Neutron 1/e length (cm)
+**Neutron Incoherent Cross-section** (cm\ :sup:`-1`)
+
+    A measure of the probability that the neutron will scatter incoherently.
+
+**Neutron Absorption Cross-Section** (cm\ :sup:`-1`)
+
+    A measure of the probability that a neutron will be absorbed by the material.
+
+**Neutron 1/e length** (cm)
+
+    The sample thickness required to reduce the transmission to 36.8% (1/e).
 
 Specifying Materials or Mixtures in the Molecular Formula Field
 ----------------------------
-**Molecular formulas** can be entered intuitively with atoms being represented by their atomic symbol. For example, let us consider calcium carbonate (CaCO\ :sub:`3`):
+**Molecular formulas** can be entered intuitively with atoms being represented by their atomic symbol. For example, calcium carbonate (CaCO\ :sub:`3`):
 
     CaCO3
 
-**Multipart species** can be constructed by as a single molecular formula, or by separating the components with a + or a space. For example let us consider the hexahydrate of calcium carbonate, ikaite, (CaCO\ :sub:`3` |cdot| 6(H\ :sub:`2`\O)) which can be denoted as:
+**Multipart species** can be constructed by as a single molecular formula, or by separating the components with a + or a space. For example, consider the hexahydrate of calcium carbonate, ikaite, (CaCO\ :sub:`3` |cdot| 6(H\ :sub:`2`\O)) which can be denoted as:
 
     CaCO3(H2O)6
 
@@ -68,23 +76,23 @@ Specifying Materials or Mixtures in the Molecular Formula Field
 
     3H2O+7D2O
 
-For isotopic substitution you must also adjust the density for your mixture.
+*For isotopic substitution you must also adjust the density for your mixture.* There is a density calculator in SASview that may be useful.
 
 **Mass Fraction** can be entered with each component of the mixture written as XX%wt "component" and each component separated with //. The mass fraction of the last component does not need to be specified as the sum of the fractions must add to 100. For example:
 
     50%wt Co // Ti
 
     1%wtNaCl // 50%wtD2O // H2O
 
-**Volume Fraction** can be entered in the same way by substituting %vol for %wt.
+**Volume Fraction** can be entered in the same way by substituting *%vol* for *%wt* (note: vol% and wt% will are syntax errors).
 
     50%vol H2O // D2O
 
 These can be combined for more complicated solutions. For example, if you have a 10wt% sodium chloride in water solution and you dilute 20 mL of this solution to 100 mL with D2O this can be represented as:
 
     20%vol (10%wt NaCl // H2O) // D2O
 
-for even more complicated solutions parenthesis can be nested, and number of atoms can be integer or decimal (eg (HO0.5)2 is equivalent to H2O).
+For even more complicated solutions parenthesis can be nested, and number of atoms can be integer or decimal (eg (HO0.5)2 is equivalent to H2O).
 
 **Solution Composition with Mass and Volume** can be specified in units of mass and volume:
 
@@ -104,24 +112,29 @@ for even more complicated solutions parenthesis can be nested, and number of ato
 DNA, Peptides, RNA can be described using the FASTA format.\ :sup:`2, 3` When using this format density will be estimated automatically and the SLD will be calculated for the biomolecule with all exchangeable hydrogens as H.
 Use the following codes:
 
-"aa" - amino acid sequences
- A=Alanine, R=Arginine, L= Leucine
+    "aa" - amino acid sequences
+    A=Alanine, R=Arginine, L= Leucine
 
-"dna" - DNA sequences
- A = adenosine, C = cytidine, G = guanine, T = thymidine
+    "dna" - DNA sequences
+    A = adenosine, C = cytidine, G = guanine, T = thymidine
 
-"rna" - RNA sequences
- U = uridine
+    "rna" - RNA sequences
+    U = uridine
 
 For example, the amino acid sequence for {beta}-casein can be written as:
 
-    aa:RELEELNVPGEIVESLSSSEESITRINKKIEKFQSEEQQQTEDELQDKIHPFAQTQSLVYPFPGPIPNSLPQNIPPLTQTPVVVPPFLQPEVMGVSKVKEAMAPKHKEMPFPKYPVEPFTESQSLTLTDVENLHLPLPLLQSWMHQPHQPLPPTVMFPPQSVLSLSQSKVLPVPQKAVPYPQRDMPIQAFLLYQEPVLGPVRGPFPIIV
+    aa: RELEELNVPGEIVESLSSSEESITRINKKIEKFQSEEQQQTEDELQDKIHPFA
+        QTQSLVYPFPGPIPNSLPQNIPPLTQTPVVVPPFLQPEVMGVSKVKEAMAPKH
+        KEMPFPKYPVEPFTESQSLTLTDVENLHLPLPLLQSWMHQPHQPLPPTVMFPP
+        QSVLSLSQSKVLPVPQKAVPYPQRDMPIQAFLLYQEPVLGPVRGPFPIIV
 
 **References:**
 
 [1] Kienzle, P. A. (2008-2019). Extensible periodic table (v1.5.2). Computer Software. https://periodictable.readthedocs.io. [calculator source, web service source]
+
 [2] Pearson WR, Lipman DJ (April 1988). "Improved tools for biological sequence comparison". Proceedings of the National Academy of Sciences of the United States of America. 85 (8): 2444–8. doi:10.1073/pnas.85.8.2444.
-[3] https://zhanggroup.org/FASTA/  (helpful explanation)
+
+[3] https://zhanggroup.org/FASTA/  (helpful explanation of FASTA syntax)
 
 .. note::  This help document was last changed by Katie Weigandt, 01Jan2024