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%% Function to calculate longitudinal seismic noise (approx) %% Function long_seis_approx = long_seis_approx(freq) function [long_seis_approx] = long_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 % Longitudinal Isolation with initial parameters n=length(freq); for j.html">j=1:n xg_approx(j.html">j) = ((g.^4)./((2*pi*freq(j.html">j)).^8))*(1./(L1*L2*L3*L4))*(m1+m2+m3+m4)*(m2+m3+m4)*(m3+m4)./(m1*m2*m3); % approximate longitdudinal ilsolation from TF asymptote, equation 1 in T1300786-v7. long_seis_approx(j.html">j) = xg_approx(j.html">j); end