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| author | Thomas White <taw@physics.org> | 2009-11-27 15:18:55 +0100 |
|---|---|---|
| committer | Thomas White <taw@physics.org> | 2009-11-27 15:18:55 +0100 |
| commit | 3a6f08ad10aa901d3c75165c3c2e47361c719847 (patch) | |
| tree | 78f7a1c6a1c794f169bb6ca2bf73e4d53856f68d | |
| parent | 7fb6226e91449278537f4bf71a8ccd35cda02e02 (diff) | |
Slightly better water calculation
| -rw-r--r-- | src/diffraction.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/src/diffraction.c b/src/diffraction.c index 80232210..11f82397 100644 --- a/src/diffraction.c +++ b/src/diffraction.c @@ -94,14 +94,22 @@ double water_intensity(struct threevec q, double en, { double complex fH, fO; double s, modq; + double width; double complex ifac; /* Interatomic distances in water molecule */ const double rOH = 0.09584e-9; const double rHH = 0.1515e-9; - /* Volume of water column */ - const double water_v = M_PI*pow(water_r, 2.0) * 2.0 * beam_r; + /* Volume of water column, approximated as: + * (2water_r) * (2beam_r) * smallest(2beam_r, 2water_r) + * neglecting the curvature of the faces of the volume */ + if ( beam_r > water_r ) { + width = 2.0 * water_r; + } else { + width = 2.0 * beam_r; + } + const double water_v = 2.0*beam_r * 2.0*water_r * width; /* Number of water molecules */ const double n_water = water_v * WATER_DENSITY |