Calculate dE/dx for Track ITK from TPC wires

This routine is an ALPHA interface to the ALEPHLIB routine TIDHYP. Note that the user must check the return code IER before trying to use any of the output arguments - not all charged tracks have dE/dx information!

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

The measured truncated mean ionization, normalized such that RI=1 corresponds to minimum ionizing.

NS

Number of useful wire samples on the track.

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 NS, 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 (bank TEXS).
• =3: input KRECO charged track has no dE/dx information.
• =4: cannot find the necessary database calibration banks, TC1X, TC2X, and/or TC3X.
• =5: cannot find RUNH or EVEH bank
• =6: there is no valid dE/dx calibration for this run