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vertical_seis_approx.m

%% Function to calculate vertical seismic noise (approx)
%% Function vertical_seis_approx = vertical_seis_approx(freq)
function [vertical_seis_approx] = vertical_seis_approx(freq)
 
list_constants;
 
%% Initializations
 
total_wire_length = total_length;      % length of suspension in m
L4 = F_l;                      % fiber length in m; effective value, should change these to CM to CM value
L1 = L_1; % top wire length; effective value, should change these to CM to CM value
L2 = L_2;                       % top mass to UIM wire length; effective value, should change these to CM to CM value
L3 = L_3;                       % UIM to PUM wire length; effective value, should change these to CM to CM value
 
 
m1 = M1; % top mass mass in kg
m2 = M2; % top mass mass in kg
m3 = M3; % top mass mass in kg
m4 = M4;   % top mass mass in kg
g  = constants.g;  % gravitational acceleration in m/s^2
Y3 = constants.Y; % fiber modulus of elastcity; modified by Madeleine Waller with info from Eric Gustafson 8/13/12 (also consistent with 'Temperature dependence of the force sensitivity of silicon cantilevers', which gives 166 GPa at 295 K)                       
fiber_stress = 0.768881e+09; % assumes a fiber area of 0.25 mm^2 with a 143 kg test mass. This area is halfway between Alastair's 0.4 mm^2 and Rana's 0.1 mm^2
freq=frequency;
%freqval=10; % Hz, frequency to evaluate sus longitudinal isolation
aLIGO_isolation_factor = 1.0875e-7; % m/m between the suspension point and test mass along longitudinal axis
 
n=length(freq);
for jj=1:n
zg_approx(jj) = 1./(2*pi*freq(jj)).^8 * 1./(m1*m2*m3*m4) * k1*k2*k3*k4;
seis_ver(jj) = zg_approx(jj);
vertical_seis_approx(jj) = seis_ver(jj);
end
end