Calculate dE/dx for Track ITK from TPC pads

This routine is an ALPHA interface to the ALEPHLIB routine TPDHYP. Note that the user must check the return code IER before trying to use any of the output arguments.

Input arguments:

ITK

ALPHA track number of a charged reconstructed track.

NHYP

Number of hypotheses the user wishes to try. If NHYP=1, then RMASS, Q, RIEXP, and SIGMA may be scalar variables.

RMASS(nhyp)

Array of masses, one for each hypothesis.

Q(nhyp)

Array of charges, one for each hypothesis.

Output arguments:

RI

Measured ionization, normalized such that RI=1 corresponds to minimum ionizing.

XNS

Number of wires on the track (NOT integer!).

TL

Useful length of the track (cm).

RIEXP(nhyp)

Expected ionization for each mass hypothesis, normalized such that RIEXP=1 corresponds to minimum ionizing.

SIGMA(nhyp)

One standard deviation resolution error for each hypothesis. This is the expected dE/dx resolution, given XNS, TL, RIEXP, and the momentum resolution. Note that one can calculate a $\chi^{2}_{}$ with 1 d.o.f. as: $\chi^{2}_{}$ =((RI-RIEXP)/SIGMA)².

IER

Error return code=0: successful return.

• =1: cannot find the track, or ITK is not a charged KRECO track.
• =2: cannot find the measured dE/dx information
• =3: input charged track has no dE/dx information.
• =4: cannot find the necessary database calibration banks, TC1X, TC2X, TP3X and/or TC3X.
• =5: cannot find RUNH or EVEH bank
• =6: cannot find TCSX or TCGX banks