Changes between Version 31 and Version 32 of WorkBook/PileUp

Timestamp:

Dec 21, 2013, 3:27:51 PM (11 years ago)

Author:

Michele Selvaggi

Comment:

ach

WorkBook/PileUp

@@ -28 +28 @@
 * {{{ZVertexSpread}}}:
 
-Pile-up events randomly populate the z-axis. The position of each pile-up event is generated from a gaussian distribution with a standard deviation ZVertexSpread.
+Pile-up and hard scattering events are randomly distributed in time and z position according to some parametrization specified by the user (in meters and second units). It can be either continuous or binned:
 
-* {{{ZVertexResolution}}}
+{{{
+set VertexDistributionFormula {exp(-(t^2/(2*(0.05/2.99792458E8*exp(-(z^2/(2*(0.05)^2))))^2)))}
+}}}
 
-For |z|< ZVertexResolution the hard interaction vertex cannot be distinguished from pile-up vertices. For such pile-up events both charged and neutrals are then merged in the event (no charged particle subtraction).
-For |z|> ZVertexResolution the hard interaction vertex can be distinguished from pile-up vertices. For such pile-up events only neutrals are merged in the event (total charged particle subtraction), which assumes perfect vertex resolution and efficiency.
+{{{
+set VertexDistributionFormula { (abs(t) <= 1.0e-09) * (abs(z) <= 0.15) * (1.00) + \
+                                                 (abs(t) >  1.0e-09) * (abs(z) <= 0.15) * (0.00) + \
+                                                 (abs(t) <= 1.0e-09) * (abs(z) > 0.15)  * (0.00) + \
+                                                 (abs(t) >  1.0e-09) * (abs(z) > 0.15)  * (0.00)}
+
+}}}
+ 
+
+=== Time propagation and measurement ===
+
+The time particle candidate of each particle candidate is then propagated up to the calorimeters. 
+For calorimeter towers and jets, which are composite objects, the final time is simply the average time weighted by sqrt(E) of each individual component.
+
+By default the time information is now stored in each output collection object. However, in order to account for the an actual timing measurement,
+the module !TimeSmearing should be called. This module simply smears the final time according to some resolution specificed by the user, controlled by the parameter
+
+{{{
+set TimeResolution 1.0e-10
+}}}
+
+A simple example of time propagation for muons is provided in the card {{{examples/delphes_card_CMS_PileUp_Timing.tcl }}}
 
 === Pile-up contamination ===
 
-For estimating pile-up contribution we use the well known fastjet area method, see for instance [http://arxiv.org/abs/0802.1188 arXiv:0802.1188], [http://arxiv.org/abs/0707.1378 arXiv:0707.1378].
+For estimating neutral pile-up contribution we use the well known fastjet area method, see for instance [http://arxiv.org/abs/0802.1188 arXiv:0802.1188], [http://arxiv.org/abs/0707.1378 arXiv:0707.1378].
 
 First, the user must specify whether to calculate the area while clustering the jets within the {{{FastJetFinder}}} module. Several methods for the area calculation can be specified (active area, passive area, Voronoi …) via the parameter {{{AreaAlgorithm}}}. By default this parameter is set to 0 (no area calculation):
@@ -63 +85 @@
 
 
-=== Pile-up subtraction ===
+=== Charged Pile-up subtraction ===
+
+The charged pile-up subtraction is done via the !TrackPileUpSubtractor module. 
+It simply removes from the specified input collections tracks that are distant enough from the primary vertex.
+The distance is controlled by the parameter !ZVertexResolution:
+
+* {{{ZVertexResolution}}}
+
+For |z|< ZVertexResolution the hard interaction vertex cannot be distinguished from pile-up vertices.
+For |z|> ZVertexResolution the hard interaction vertex can be distinguished from pile-up vertices.
+
+
+{{{
+
+module TrackPileUpSubtractor TrackPileUpSubtractor {
+
+  add InputArray Calorimeter/eflowTracks eflowTracks
+  add InputArray ElectronEnergySmearing/electrons electrons
+  add InputArray MuonMomentumSmearing/muons muons
+
+  set ZVertexResolution 0.0001
+}
+
+}}}
+
+=== Neutral Pile-up subtraction ===
 
 Since charged particles have already been subtracted to some extent, pile-up contamination only affects the jet energy resolution and the lepton/photon isolation.
@@ -79 +126 @@
 set RhoInputArray rho
 }}}
+
+
+
+