How to run NTCAFIX on the QCD NTUPLES

Author: Bob Hirosky
Last Update: JUL, 24 1998

NTCAFIX seems to have been promoted from a tool used in the CAFIX 5.1
derivation.  This document gives a brief introduction to it's use.

    I have written a simple example kumac and fortran file to demonstrate
how to run CAFIX corrections on the QCD global ntuples.  This note
describes the necessary steps to get NTCAFIX working for your
studies.  This is not intended to be a piafserver tutorial, for more piaf
server info consult the D0WEB pages under COMPUTING.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
A word on paw versions: 
	I have personally tested this code on the official version of
	pawx11 on the alpha and fnald0 clusters and also on the current
	version of pawX11 available on the SGI/d0ch clusters


When you run paw on a VMS node you should get this message:

******************************************************
*                                                    *
*            W E L C O M E    to   P A W             *
*                                                    *
*       Version 2.06/20       3 March 1995           *
*                                                    *
*  Stage command modified for D0 at FNAL 1-Nov-95    *
*                                                    *
******************************************************

IF YOU DON'T GET THIS VERSION YOU MAY HAVE PROBLEMS RUNNING THE CODE
ON THE CHALLENGE.


on Unix nodes:

 ******************************************************
 *                                                    *
 *            W E L C O M E    to   P A W             *
 *                                                    *
 *       Version 2.08/14      21 January 1997         *
 *                                                    *
 ******************************************************


+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++


    NTCAFIX provides nearly full CAFIX functionality for the uncorrected
mpf ntuples used in the escale analysis.   It provided an excellent testing
ground for develpement of CAFIX5.1 and may also be used to recorrect
jets in the qcd global ntuple to the 5.1 level.

Advantages include:

    running CAFIX on the mpf ntuples in a few minutes!
    running CAFIX on the qcd_global ntups in < 1 hour!

   all standard library code + the newest cafix corrections are implimented


    It is completely RCP driven using CAFIX.RCP and QCD_JET_CORRECTION.RCP

Limitations are as follows:

MET is only corrected for changes to jets.  This isn't a problem for
the escale analysis, or qcd jets analyses, but any electron or photon + MET
analysis should stick w/ standard cafix.  A possible work around would be to
uncorrect your jets and use the uncorrected jet vectors to remove the jet
corrections from PNUT4 MET, then use this modified PNUT4 in your call to
ntcafix.
The only flags in CAFIX_RCP used by NTCAFIX are:

DO_JET_CORRECTION
    DO_ZSP_CORRECTION
    DO_UND_CORRECTION
    DO_CONE_CORRECTION

DO_MET_CORRECTION
    USE_JET_CORRECTION


In CAFIX 5.1 EM clusters may be removed from jets and corrected separately
from the rest of the jet.  JNEP banks are generally not available in the 
ntuples, so this option is efectively always off.  These jets are corrected 
like any other jet - therefore they are typically overcorrected relative to 
CAFIX w/ the remove option turned on.  Otherwise the functionality is the same.
For jets analysis this distinction is unimportant.

**********************************************************************
The following example shows you how to run ntcafix on the qcd_global ntups:
1) setup of your area on D0CHA:

    this requires that you point to the cafix51 libraries I
    have made on the challenge:

cd ~
ln -sf /new.proj1/qcd_group/service/piaf.setup_nodeb piaf.setup

also link to the global qcd_ntuples:

cd ~/piaf
ln -sf /new.proj1/qcd_group/allcones1b/ allcones1b


2) copy my example files to your paw area:

    on the alpha:

PRJ$ROOT349:[ECAL_3.CAFIX_51_1.NTCAFIX]CAF51_EZ_EXAMPLE.F

                                           CAF51_EZ_EXAMPLE.KUMAC
                                           ERRMSG_SETUP.RCP
PRJ$ROOT349:[ECAL_3.CAFIX_51_1]CAFIX.RCP
                             QCD_JET_CORRECTION.RCP
(note: use MC_QCD_JET_CORRECTION.RCP or QCD_JET_CORRECTION51_630.RCP, if you
want to use these data instead of the global qcd data in the example)

3) USAGE: exec CAF51_EZ_EXAMPLE

    you'll get a number of histograms both w/ caf50 and caf51 corrections


                          * Some words on the code *

CAF51_EZ_example.f is well docmented, so it should be self explanitory

NT_CAFIX_EVINI: must be called for each event to setup the correction
                this feeds event info to NTCAFIX


FAKE_JBANK: is called for each jet algorithm you want to correct
            this passes the uncorrected jet arrays to NTCAFIX

NT_CAFIX: input original METX,Y
          corrected METX,Y are returned (if MET correction is on in cafix.rcp,
          otherwise they are unchanged)
          and all jet algorithms selected via FAKE_JBANK are corrected

GET_COR_JETS: used to access corrected jet information

GET_JET_QUANS: used to get detailed error and correction factor for each jet


!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

One word of caution: NTCAFIX may not work forever.  The current piaf server
	uses an old version of the SGI loader which predates the current
	software release.  Due to technical features of memory management in
	the new loader it may not be possible to continue creating the 
	necessary ZEBRA structures to support RCP file input, if a future
	SGI system release breaks the loader we are now using.  But so far, so
	good...