Measurement parameters

The m e a s u r e m e n t parameters indicate what is measured by the layer, and with what precision. For the tracking detectors, the possible parameters are: SIG_RPHI, SIG_Z, SIG_PHI, SIG_TH, SIG_X, SIG_Y, ANG_EXP and CODE. CODE can take the values 0, 1, 2, or 10. The interpretation is:

0: No measurement at all.
1: Measurement of coordinates.
2: Measurement of coordinates and angles (Barrel detectors only).
10: The layer is a calorimeter. No track parameter measurement, entry only concerns the material.

ANG_EXP is the angular exponent in sigma on measurement : Normally, it is assumed that the point-precision is independent of the angle of incidence of the particle ( $\alpha$ ). For some types of detectors (notably, silicon detectors), this is not so. By giving a number in this field, the point resolution will be calculated as :

$\begin{displaymath} \sigma = \sigma_{perp}/( \cos \alpha )^{ANG\_EXP} \end{displaymath}$

were $\sigma_{perp}$ is the point-resolution given in the input file, assumed to be the value for perpendicular incidence (ie $\alpha$ =0).

The other parameters give the standard deviations in the different direction in centimeters or degrees. SIG_X and SIG_Y is for forward detectors, the rest for barrel ones. If a particular parameter is absent, SGV assumes that the layer makes no measurement of the coresponding quantaty.

For calorimeters, the possible measurement parameters are:

ROOT_E_COEFF, CONST_TERM, EFFI, THRES: Showering particle response
MIP_AVE_SIGN, MIP_SIGN_WIDTH, MIP_EFF, MIP_TRESH: Minimum ionising particle response, in equivalent GeV.
TYPE: The type of the calorimeter : 1 (Electromagnetic), 2 (Hadronic), or 3 (Both).
SHOWER_POS_MEAS: How the shower axis is measured : 0 (measured), 1 (module centre, modules in ( $\phi$ ,z) for barrel ( $\phi$ ,R) for forward), 2 (module centre, modules in ( $\phi$ , $\theta$ ) for barrel (x, y) for forward).
SIG_TH, SIG_PHI: Shower axis resolution in degrees, relevant for SHOWER_POS_MEAS=0.
SIG_RPHI, SIG_Z (barrel) SIG_X and SIG_Y (forward): Shower start-point resolution. Ditto.
NCELL1, NCELL2: Number of modules in the two directions, relevant for SHOWER_POS_MEAS $\neq$ 0.
PHI_FST_CELL: If SHOWER_POS_MEAS $\neq$ 0, and one of the variables that the modules are divided in is $\phi$ , this parameter gives the $\phi$ of the low-edge of the first module that is entirely at positive $\phi$ . Give $\phi$ in degrees.

The energy resolution of the calorimeter is calculated by:

$\begin{displaymath} \sigma_{E} = \sqrt{ {\rm ROOT\_E\_COEFF}^{2}/E^{2} + {\rm CONST\_TERM}^{2} } \end{displaymath}$

(hence, the unit is GeV). EFFI is the efficiency (in %), and THRES is the threshold (in GeV).

For taggers, the same parameters as for calorimeters should be used, except than SHOWER_POS_MEAS is not allowed to be 0.

Also for scintilators, the same parameters as for calorimeters should be used, except than SHOWER_POS_MEAS is not allowed to be 0, the TYPE will automatically be set to 4 (all particles treated as mip's), and hence the only the Minimum ionising particle response is used in the simulation.