From eafa51b5f86df853c282f2b857fe0b12010d97c3 Mon Sep 17 00:00:00 2001
From: Jens Wiechula <Jens.Wiechula@cern.ch>
Date: Wed, 8 Jan 2014 23:40:42 +0100
Subject: [PATCH] don't use multiplicity correction for MC (Benjamin)

---
 STEER/STEERBase/AliPIDResponse.cxx | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/STEER/STEERBase/AliPIDResponse.cxx b/STEER/STEERBase/AliPIDResponse.cxx
index 81274ba2346..3b0422d9a86 100644
--- a/STEER/STEERBase/AliPIDResponse.cxx
+++ b/STEER/STEERBase/AliPIDResponse.cxx
@@ -1309,15 +1309,19 @@ void AliPIDResponse::SetTPCParametrisation()
   // PbPb 2010, period 10h.pass2
   //TODO Needs further development const Bool_t is10hpass2 = period.Contains("LHC10H") && recopass == 2;
   
+  
+  // In case of MC without(!) tune on data activated for the TPC, don't use the multiplicity correction for the moment
+  Bool_t isMCandNotTPCtuneOnData = fIsMC && !(fTuneMConData && ((fTuneMConDataMask & kDetTPC) == kDetTPC));
+  
   // If correction is available, but disabled (highly NOT recommended!), print warning
-  if (!fUseTPCMultiplicityCorrection && !isPP) {
+  if (!fUseTPCMultiplicityCorrection && !isPP && !isMCandNotTPCtuneOnData) {
     //TODO: Needs further development if (is10hpass2 || isPPb2013LowLuminosity) {
     if (isPPb2013LowLuminosity) {
       AliWarning("Mulitplicity correction disabled, but correction parameters for this period exist. It is highly recommended to use enable the correction. Otherwise the splines might be off!");
     }
   }
   
-  if (fUseTPCMultiplicityCorrection && !isPP) {
+  if (fUseTPCMultiplicityCorrection && !isPP && !isMCandNotTPCtuneOnData) {
     AliInfo("Multiplicity correction enabled!");
     
     //TODO After testing, load parameters from outside       
@@ -1407,8 +1411,16 @@ void AliPIDResponse::SetTPCParametrisation()
     // directly and use it for calculations - which should still give valid results, even if
     // the multiplicity correction is explicitely enabled in such expert calls.
     
+    TString reasonForDisabling = "requested by user";
+    if (fUseTPCMultiplicityCorrection) {
+      if (isPP)
+        reasonForDisabling = "pp collisions";
+      else
+        reasonForDisabling = "MC w/o tune on data";
+    }
+    
     AliInfo(Form("Multiplicity correction %sdisabled (%s)!", fUseTPCMultiplicityCorrection ? "automatically " : "",
-                 fUseTPCMultiplicityCorrection ? "pp collisions" : "requested by user"));
+                 reasonForDisabling.Data()));
     
     fUseTPCMultiplicityCorrection = kFALSE;
     fTPCResponse.ResetMultiplicityCorrectionFunctions();
-- 
2.43.0