Using the currently-defined (2013-05-22) Stv TPC hit errors in eval, for the inner TPC:

    row.yErr	 = 0.004782729; // Intrinsic resolution, padrow or Y direction		;
    row.zErr	 = 0.01044907; // Intrinsic resolution, z direction			;
    row.thkDet	 =     1.3225; // detector thickness , not fitted			;
    row.yyDiff	 = 0.00415362; // Diffusion in XY direction				;
    row.zzDiff	 = 2.078202e-05; // Diffusion in Z direction  				;
    row.yFact	 =  0.5432957; // Error factor in Y-direction 			;
    row.zFact	 =   0.535692; // Error factor in Z-direction 			;
    row.zAB2	 = 5.0293e-06; // Constant member in Z direction (a*b)**2		;

...and outer:

    row.yErr	 = 0.002699037; // Intrinsic resolution, padrow or Y direction		;
    row.zErr	 = 0.006222453; // Intrinsic resolution, z direction			;
    row.thkDet	 =     3.8025; // detector thickness , not fitted			;
    row.yyDiff	 = 0.001743757; // Diffusion in XY direction				;
    row.zzDiff	 = 1.000247e-08; // Diffusion in Z direction  				;
    row.yFact	 =  0.4319568; // Error factor in Y-direction 			;
    row.zFact	 =  0.4098761; // Error factor in Z-direction 			;
    row.zAB2	 = 5.0293e-06; // Constant member in Z direction (a*b)**2		;

...and the parameterization provided by Victor:

<Y*Y> = (tan(Psi)**2* thkDet/12 + yyDiff*dZ/cos(Psi)**2) *yFact*yFact*|cos(Lam)*cos(Psi)| +YErr;
<Z*Z> =((tan(Lam)**2*(thkDet/12 + yyDiff*dZ) + zAB2/180)/cos(Psi)**2 +zzDiff*dZ)*zFact*zFact*|cos(Lam)*cos(Psi)| +ZErr;
<Y*Z> =tan(Psi)*tan(Lam)/cos(Psi)*(DD + yyDiff*dZ)*yFact*zFact;
dZ = |Z-210|

...ignoring the cross term <Y*Z> for now, and using Lam=0 when looking at Δhit_Rφ = sqrt(<Y*Y>), and using Psi=0 when looking at Δhit_Z = sqrt(<Z*Z>):

ΔhitRφ = sqrt{[tan(Psi)**2 * thkDet/12 + yyDiff*|Z-210|/cos(Psi)**2]*yFact*yFact*|cos(Psi)| + YErr}
ΔhitZ = sqrt{[tan(Lam)**2 * (thkDet/12 + yyDiff*|Z-210|) + zAB2/180 + zzDiff*dZ]*zFact*zFact*|cos(Lam)| + ZErr}

...I get the following plots:



I have placed the macro for creating these plots in CVS at: offline/users/genevb/hitErrorsStv.C

Further discussion of these plots is here.

-Gene