Beam Scintillation Counters Offline Software

Complete:

Introduction

This page documents Beam Scintillation Counters offline software. The description of the BSC system can be found at the CMS Beam Conditions and Radiation Monitoring System wiki page.

The usage of BSC fr trigger purposes is described BSC Trigger.

Offline software components

BSC simulation

Implementation of the BSC in the CMSSW simulation. Currently under test and only in my private area.
Currently only BSC1 tiles are implemented on the Forward Shield 01 (on the inner face of HF front) surfaces.
It is then located at the foreseen 10.91 m from the interaction point
The numbering is that of the Z+ side, the Z- side is the mirror image around Y.

Setting up with CMSSW_1_6_7

scramv1 p CMSSW CMSSW_1_6_7
 cd CMSSW_1_6_7/src
 eval `scramv1 runtime -sh`
project CMSSW
addpkg SimG4Core/Application 
addpkg Geometry/ForwardCommonData 
cvs co Geometry/ForwardCommonData/data/brm*
cvs co -r V01-01-05 SimG4Core/Geometry
cvs co -r V04-01-03 DetectorDescription/Parser
cp /afs/cern.ch/user/m/muriel/scratch0/CMSSW_1_6_7/src/SimG4Core/Application/data/g4SimHits.cfi SimG4Core/Application/data/.
cp /afs/cern.ch/user/m/muriel/scratch0/CMSSW_1_6_7/src/SimG4Core/Application/data/SimG4Object.cfi SimG4Core/Application/data/.
cp /afs/cern.ch/user/m/muriel/scratch0/CMSSW_1_6_7/src/SimG4Core/Application/plugins/OscarProducer.cc SimG4Core/Application/plugins/.
cp -r /afs/cern.ch/user/m/muriel/scratch0/CMSSW_1_6_7/src/SimG4CMS .
scramv1 b

Running it

In the copied SimG4CMS/Forward/test/ you can run runBSC.cfg for beam halo.
It calls the module HaloFltr which will select events that cross a disk in which the BSC tiles are contained at least on one side of the detector, in order not to waste time simulating halo particles not crossing the interesting area. Many will still not cross any tile.

Analysing it

A basic analyzer is available in the copied SimG4CMS/BSCAnalysis that runs on the output root file of runBSC.cfg

Some Results

These results use only simHits, no digitization is performed such that scintillator noise is not taken into account.

Beam Halo particles simulated with 0BX.

Beam Halo Hits in the BSC's on the Z+ side . The beam halo seems not to be centered (more on the outer part of the LHC ring).


If we take simple coincidence within +- 3ns of the TOF for a muon to reach the BSC on the other Z side we get 27% of the event being a useable track for TEC alignment.
(This will get worse with 3BX and scintillator noise)...

Coincidences between paddle numbers for 1371 Muon tracks (out of about 484k generated events) for the numbering see paddle numbering scheme in the IGUANA picture above:

Random coincidences between paddle numbers within +-3ns of the muon TOF:

Number of Paddles Hit for Muons and Random coincidence tracks within the +-3ns of the muon TOF:

Requesting one and only one hit on each side during +-[33.4,39.4]ns intervals and at TOF of +-3ns of the muon arrival time gives a S/N of 4.6 and keeps 94% of the original muon tracks (not counting scintillator noise).

TEC coverage of triggered tracks

The graphs below show (left) the TEC module rings hit as a function of the wheel nb (from Z- wheel 9 to 1, Z+ wheel 1 to 9, to have a sense of Z ordering ), as well as the coincident rings on either Z side of the detector (right):

Position of the modules hit in TEC- Wheel1 by halo muon tracks triggering with the scheme above : all 7 rings get tracks going through.

Minimum Bias events

QCD and diffractive events corresponding to the standard minbias samples have been simulated through the detector BSC included.
Out of 77000 events, 71463 pass the genfilter requiring at least one track to point through a disk located at the Z position of each BSC.
The detector occupancy from minbias events on Z+ side and hit arrival times:

The number of BSC paddles hit on each side is shown on the graph below as well as the paddle coincidences (at 37.3 ns ):

Responsible: Gaelle Boudoul

Reviewer/Editor and Date (copy from screen)	Comments
MurielVanderDonckt - 05 Oct 2007	created wiki page
Last reviewed by: VasileGhete - 30 Jan 2009	moved to SWGuide
Responsible: MurielVanderDonckt