PCPA-based Energy Flow

This algorithm is described in the report ALEPH 92-055 (PHYSIC 92-048).

The PCPA-based energy flow uses neutral objects derived from the PCPA bank in addition to selected charged tracks. The logical function XFRIQF(ITK) may be used to test whether a track has been included for the PCPA energy-flow analysis. The PCPA neutral objects are stored in the NET section by default. (Filling of the NEOB section may be disabled by including the card NOPC in the ALPHA card file.) These objects can be accessed with DO loops (KFNET, KLNET, KNNET - see 7.1.1) or with the particle name `NEOB' using the functions KPDIR and KFOLLO (described in 7.4).

To use the event topology routines described in Chapter 10 with PCPA-based energy flow ( i.e., selected charged tracks plus PCPA neutral objects), use option 'PC' with subroutine QJOPTR (see 10.1):

      CALL QJOPTR('PC',' ').

To use only NEOB objects:

      CALL QJOPTR('NO','NEOB').

The following statement functions may be used to access additional information on NEOB objects:

XPCQ (I)

.TRUE. if PCQA data are available for ``track'' I

KPCQNA (I)

NAture of neutral object (see Sec. 11.3)

• 1 Isolated gamma
• 2 Gamma from multi-gamma neutral cluster
• 3 Gamma from identified $\pi^{0}_{}$
• 4 Gamma from electron bremsstrahlung
• 5 Gamma from electromagnetic charged cluster
• 10 Unresolved gamma-gamma
• 12 Residual electromagnetic energy from neutral cluster
• 13 Residual electromagnetic energy from charged cluster
• 17 Neutral hadron
• 18 Residual hadronic energy from neutral cal object
• 19 Residual hadronic energy from charged cal object with no HCAL component
• 20 Residual hadronic energy from charged cal object with HCAL component
• 21 contribution from an ECAL cluster for which EBNEUT was in error
• 22 contribution from an LCAL object

Example:

The following code calculates the total energy energy of an event and finds the sphericity using PCPA-based energy flow.

C---    First add up neutral energy
    E = 0.
    DO 10 I = KFNET, KLNET
    E=E+QE(I)
10  CONTINUE
C---    Add energies of selected tracks
    DO 20 I = KFCHT, KLCHT
    IF(XFRIQF(I)) E = E + QE(I)
20  CONTINUE
C---    Find sphericity
    CALL QJOPTR('PC', ' ')
    CALL QJSPHE(SPHE, 'SPHE', KRECO)