[u/mrichter/AliRoot.git] / ISAJET / doc / tape.doc

\newpage
\section{File Reading\label{TAPE}}

      The FORTRAN instruction
\begin{verbatim}
      CALL RDTAPE(IDEV,IFL)
\end{verbatim}
will read a beginning record, an end record or an event (which can be
more than one record). IDEV is the tape number and
\begin{verbatim}
      IFL=0  for a good read,
      IFL=-1 for an end of file.
\end{verbatim}
The information is restored to the common blocks described above. The
type of record is contained in
\begin{verbatim}
#include "rectp.inc"
\end{verbatim}
\begin{tabular}{lcl}
IRECTP            &=& 100 for an event record\\
IRECTP            &=& 200 for a beginning record\\
IRECTP            &=& 300 for an end record\\
IREC              &=& no. of physical records in event record, 0 
                      otherwise\\
\end{tabular}

      The parton momenta from the primary hard scattering are
contained in /PJETS/. The parton momenta generated by the QCD cascade
are contained in /JETSET/. The hadron momenta both from the QCD jets
and from the beam jets are contained in /PARTCL/. The final hadron
momenta and the associated pointers should be used to calculate the
jet momenta, since they are changed both by the QCD cascade and by
hadronization. Particles with IDCAY=0 are stable, while the others are
resonances.

      The weight per event needed to produce a weighted histogram in
millibarn units is SIGF/NEVENT. The integrated cross section SIGF is
calculated by Monte Carlo integration during the run for the given
kinematic limits and JETTYPE, WTYPE, and WMODE selections. Any of three
methods can be used to find the value of SIGF:

      (1) The current value, which is written out with each event, can
be used. To prevent enormous fluctuations at the beginning of a run,
NSIGMA extra primary parton events are generated first. The default
value, NSIGMA = 20, gives negligible overhead but may not be large
enough for good accuracy.

      (2) The value SIGF calculated with the full statistics of the run
can be obtained by reading through the tape until an end record
(IRECTP=300) is found. After SIGF is saved with a different name, the
first event record for the run can be found by backspacing the tape
NRECS times.

      (3) Unweighted histograms can be made for the run and the weight
added after the end record is found. An implementation of this using
special features of HBOOK is contained in ISAPLT.

      The functions AMASS(IDENT), CHARGE(IDENT), and LABEL(IDENT) are
available to determine the mass, charge, and character label in A8
format. Subroutine FLAVOR returns the quark content of any hadron and
may be useful to convert IDENT codes to other schemes. CALL PRTEVT(0)
prints an event.
Commit	Line	Data
0795afa3	1	\newpage
	2	\section{File Reading\label{TAPE}}
	3
	4	The FORTRAN instruction
	5	\begin{verbatim}
	6	CALL RDTAPE(IDEV,IFL)
	7	\end{verbatim}
	8	will read a beginning record, an end record or an event (which can be
	9	more than one record). IDEV is the tape number and
	10	\begin{verbatim}
	11	IFL=0 for a good read,
	12	IFL=-1 for an end of file.
	13	\end{verbatim}
	14	The information is restored to the common blocks described above. The
	15	type of record is contained in
	16	\begin{verbatim}
	17	#include "rectp.inc"
	18	\end{verbatim}
	19	\begin{tabular}{lcl}
	20	IRECTP &=& 100 for an event record\\
	21	IRECTP &=& 200 for a beginning record\\
	22	IRECTP &=& 300 for an end record\\
	23	IREC &=& no. of physical records in event record, 0
	24	otherwise\\
	25	\end{tabular}
	26
	27	The parton momenta from the primary hard scattering are
	28	contained in /PJETS/. The parton momenta generated by the QCD cascade
	29	are contained in /JETSET/. The hadron momenta both from the QCD jets
	30	and from the beam jets are contained in /PARTCL/. The final hadron
	31	momenta and the associated pointers should be used to calculate the
	32	jet momenta, since they are changed both by the QCD cascade and by
	33	hadronization. Particles with IDCAY=0 are stable, while the others are
	34	resonances.
	35
	36	The weight per event needed to produce a weighted histogram in
	37	millibarn units is SIGF/NEVENT. The integrated cross section SIGF is
	38	calculated by Monte Carlo integration during the run for the given
	39	kinematic limits and JETTYPE, WTYPE, and WMODE selections. Any of three
	40	methods can be used to find the value of SIGF:
	41
	42	(1) The current value, which is written out with each event, can
	43	be used. To prevent enormous fluctuations at the beginning of a run,
	44	NSIGMA extra primary parton events are generated first. The default
	45	value, NSIGMA = 20, gives negligible overhead but may not be large
	46	enough for good accuracy.
	47
	48	(2) The value SIGF calculated with the full statistics of the run
	49	can be obtained by reading through the tape until an end record
	50	(IRECTP=300) is found. After SIGF is saved with a different name, the
	51	first event record for the run can be found by backspacing the tape
	52	NRECS times.
	53
	54	(3) Unweighted histograms can be made for the run and the weight
	55	added after the end record is found. An implementation of this using
	56	special features of HBOOK is contained in ISAPLT.
	57
	58	The functions AMASS(IDENT), CHARGE(IDENT), and LABEL(IDENT) are
	59	available to determine the mass, charge, and character label in A8
	60	format. Subroutine FLAVOR returns the quark content of any hadron and
	61	may be useful to convert IDENT codes to other schemes. CALL PRTEVT(0)
	62	prints an event.