missing factor in res gas damping

gwinc/noise/residualgas.py

@@ -85,7 +85,7 @@ def residual_gas_damping(f, ifo, species, sustf, squeezed_film):
     # infinite volume viscous damping coefficient for a cylinder
     # table 1 of https://doi.org/10.1016/j.physleta.2010.06.041
     beta_inf = pi * radius**2 * pressure/thermal_vel
-    beta_inf *= (1 + thickness/(2*radius) + pi/4)
+    beta_inf *= sqrt(8/pi) * (1 + thickness/(2*radius) + pi/4)
 
     force_noise = 4 * kT * beta_inf