;+ ; NAME: low_e_spec_eff ; ; PURPOSE: calculate the low energy cross section for ; BATSE spec detectors from materials and geometry ; Only considers the front surface. Validity limited ; to energies less than 14.0 keV ; CALLING SEQUENCE: ; result = low_e_spec_eff( e_in, theta) ; INPUTS: ; e_in - energy in keV ; theta - angle in degrees le 90 degrees ; OPTIONAL INPUTS: ; be_add - more window cross-section in effective beryllium ; thickness ; OUTPUTS: ; photopeak area in cm2 ; OPTIONAL OUTPUTS: ; ; PROCEDURE: ; ; CALLS: ; xsec, other_filters ; COMMON BLOCKS: ; ; RESTRICTIONS: ; ; MODIFICATION HISTORY: ; ras, 2-mar-95 ; ras, 14-dec-95 ;- ; function low_e_spec_eff, e_in, theta, be_add=be_add thetar=theta /!radeg bcrossx = xsec(e_in,4,'pe') + xsec(e_in,4,'si')/2 barea = !pi*3.81^2 acrossx = xsec(e_in,13,'pe') + xsec(e_in,13,'si')/2 scrossx = xsec(e_in,14,'pe') + xsec(e_in,14,'si')/2 annulus = !pi*(6.515^2-3.81^2) *cos( thetar) /exp( ((acrossx*.068 +scrossx*.15)/cos( thetar))<30. ) checkvar, be_add, 0.35 ;thickness to reconcile Tom Skelton's millipore paper attenuation return, (barea*cos( thetar) /exp(bcrossx*(.127+be_add)/cos( thetar)) $ + annulus) * other_filters(e_in,/multi)^(4./cos( thetar)) end