Changeset 15a7577 in sasmodels

Timestamp:

Sep 7, 2018 8:38:31 AM (6 years ago)

Author:

butler

Branches:

master, core_shell_microgels, magnetic_model, ticket-1257-vesicle-product, ticket_1156, ticket_1265_superball, ticket_822_more_unit_tests

Children:

455aaa1

Parents:

917d975

Message:

update hollow_cylinder docs

File:

• sasmodels/models/hollow_cylinder.py (modified) (3 diffs)

sasmodels/models/hollow_cylinder.py

@@ -1 +1 @@
 r"""
+Definition
+----------
+
 This model provides the form factor, $P(q)$, for a monodisperse hollow right
-angle circular cylinder (rigid tube) where the form factor is normalized by the
-volume of the tube (i.e. not by the external volume).
+angle circular cylinder (rigid tube) where the The inside and outside of the
+hollow cylinder are assumed to have the same SLD and the form factor is thus
+normalized by the volume of the tube (i.e. not by the total cylinder volume).
 
 .. math::
@@ -8 +12 @@
     P(q) = \text{scale} \left<F^2\right>/V_\text{shell} + \text{background}
 
-where the averaging $\left<\ldots\right>$ is applied only for the 1D calculation.
+where the averaging $\left<\ldots\right>$ is applied only for the 1D
+calculation. If Intensity is given on an absolute scale, the scale factor here
+is the volume fraction of the shell.  This differs from
+the :ref:`core-shell-cylinder` in that, in that case, scale is the volume
+fraction of the entire cylinder (core+shell). The application might be for a
+bilayer which wraps into a hollow tube and the volume fraction of material is
+all in the shell, whereas the :ref:`core-shell-cylinder` model might be used for
+a cylindrical micelle where the tails in the core have a different SLD than the
+headgroups (in the shell) and the volume fraction of material comes fromm the
+whole cyclinder.  NOTE: the hollow_cylinder represents a tube whereas the
+core_shell_cylinder includes a shell layer covering the ends (end caps) as well.
 
-The inside and outside of the hollow cylinder are assumed have the same SLD.
-
-Definition
-----------
 
 The 1D scattering intensity is calculated in the following way (Guinier, 1955)
@@ -55 +65 @@
 
 * **Author:** NIST IGOR/DANSE **Date:** pre 2010
-* **Last Modified by:** Richard Heenan **Date:** October 06, 2016
-   (reparametrised to use thickness, not outer radius)
-* **Last Reviewed by:** Richard Heenan **Date:** October 06, 2016
+* **Last Modified by:** Paul Butler **Date:** September 06, 2018
+   (corrected VR calculation)
+* **Last Reviewed by:** Paul Butler **Date:** September 06, 2018
 """