Component Manual for the Neutron Ray-Tracing Package McStas, version 3.8.6

14.89  The SANS_Liposomes_Abs McStas Component

Solid dilute monodisperse spheres sample with transmitted beam for Small Angle Neutron Scattering.

Identification

Description

Sample for Small Angle Neutron Scattering. Modified from the Any Sample model. Normalization of scattering is done in INITIALIZE. Some elements of Sans_spheres have been re-used

Some remarks: Scattering function should be a defined the same way in INITIALIZE and TRACE sections There exist maybe better library functions for the integral.

Transmitted paths set to 50% of all paths to be optimised for SESANS. In this simulation method paths are well distributed among transmission and scattering (equally in Q-space).

Sample components leave the units of flux for the probability of the individual paths. That is more consitent than the Sans_spheres routine. Furthermore one can simulate the transmitted beam. This allows to determine the needed size of the beam stop. Absorption is included to these sample-components.

Example: SANS_Spheres_Abs(R=100, Phi=1e-3, Delta_rho=0.6, sigma_a = 50, qmax=0.03, xwidth=0.01, yheight=0.01, zthick=0.001)

Input parameters

Parameters in boldface are required; the others are optional.

Name

Unit

Description

Default

R

Å

Radius of scattering hard spheres

100

dR

0.0

Phi

1

Particle volume fraction

1e-3

Delta_rho

fm/Å\(^{3}\)

Excess scattering length density

0.6

sigma_a

m\(^{-1}\)

Absorption cross section density at 2200 m/s

0.50

qmax

Å\(^{-1}\)

Maximum scattering vector (typically 10/R to observe the 3rd ring)

0.03

xwidth

m

horiz. dimension of sample, as a width

0.01

yheight

m

vert.. dimension of sample, as a height

0.01

zthick

m

thickness of sample

0.001

dbilayer

35

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