----+ Testbeam 2015 Analysis page

Description of the data

Beamline

Runs

The list of runs can be found in the ATLAS Tile Run Information Database. To get the list of runs that have been taken during this testbeam, request tb='Oct-2015' and type='Phys' (list of physics runs). The database gives you the following information for each run :

run	run number from 510008 to 510853
energy	beam energy : 50, 150, 180 GeV
beam	type of beam : mu, e, pi for muons, electrons, pions respectively
events	number of events in the run. We usually consider only runs with more than 5000 events.
module	='M0' for module 0, 'EB' for extended barrel
eta	Value of pseudo-rapidity at which the beam enters in the module. It is filled only for projective runs
theta	Incidence of the beam with respect to the front face of TileCal : 20°, 90°, -90°
cell	For runs at theta=20°, this is the name of the cell in which the beam is entering A1 to A10 in module 0, A12 to D4 in Extended Barrel. For runs at theta=90°, this is the tile row number from 1 to 11.
z	For runs at theta=90°, it is the encoded position of the table with respect to the beam. z=18070744 is the edge of tile 11, z=18081250 is the edge of tile 1.

A list of runs for physics analysis is available here.

You have also the possibility to generate your own list of runs accessing the TileCal Info database from lxplus. Ex :

 /usr/bin/mysql -h pcata007.cern.ch tile -e 'select run, events, beam, energy, module,theta,cell,eta,z from runinfo where tb="Oct-2015" and events>2000’ 

Testbeam ntuple

The ntuples can be found at : root://eosatlas//eos/atlas/atlascerngroupdisk/det-tile/testbeam/2015/tiletb_ run number .root

Ntuple variables

Beamline scintillators

Variable name	Description	Suggested cut
S1cou	signal in S1 scintillator, in adc	1000<S1<2500 adc
S2cou	signal in S2 scintillator, in adc	500<S2<1500 adc
S3cou	signal in S3 scintillator, in adc

Cherenkov counters

Cherenkov counters 1 and 2 provide a useful information for particle identification. They can be used at low energy (50 GeV) where the gas pressure in are such that electrons and muons give a cherenkov signal, while protons and kaons give a pedestal.

WARNING : check the distribution of the signal in the cherenkov counters before applying a cut : the values might change after run 510374.

Cher1	signal in the first Cherenkov counter (in adc)	Cher1<300 : pedestal, Cher1>300 : signal
Cher2	signal in the second Cherenkov counter (in adc)	Cher2<350 : pedestal, Cher2>350 : signal

Beam chambers

Beam chambers 1 and 2 give the coordinate at which a particle passed. X and Y are the horizontal and vertical axis respectively (X=0;Y=0 approximately corresponds to the geometric centre of the beam spot).

Variable name	Description
btdc1[8]	Time (in adc) between the gate and the arrival of the first hit in the BCs. [0-3] : BC1 left,right,up,down; [4-7] : BC2 left,right,up,down
Xcha1	X position in BC1 (in mm)
Ycha1	Y position in BC1 (in mm)
Xcha2	X position in BC2 (in mm)
Ycha2	Y position in BC2 (in mm)
Ximp	Extrapolated X-position of the beam at the level of the TileCal table.
Yimp	Extrapolated Y-position of the beam at the level of the TileCal table.

Suggested cut
Limit the extension of the beam to a spot of radius R : sqrt(Ximp*Ximp + Yimp*Yimp)<R
Remove particles that are not parallel to the beam axis : Xcha1-Xcha2<Cut, Ycha1-Ycha2<Cut

In addition, you might want to check and reject events with multi hits in the beam chambers. The distributions of btdc1[0]+btdc1[1], btdc1[2]+btdc1[3] (BC1) and btdc1[4]+btdc1[5], btdc1[6]+btdc1[7] (BC2) should show a narrow peak at a given value. Events far away from this peak correspond to multi-hits in the chamber and should be rejected.

TileCal variables

WARNING : the index from 0 to 47 corresponds to the pmt number -1 : see TileCal mapping.

Variable name for module 0 (M0) and Extended Barrel (EB)	Description
EoptC01[48], EoptE02[48]	Energy in femto Coulomb (fC) reconstructed by optimal filter.
ToptC01[48], ToptE02[48]	Timing in ns reconstructed by optimal filter.
GainC01[48], GainE02[48]	0=low gain, 1=high gain.
SampleC01[48][7], SampleE02[48][7]	Signal in adc for the 7 timing samples, for each pmt.
PedoptC01[48], PedoptE02[48]	Pedestal (in adc) obtained by optimal filter.
Chi2optC01[48], Chi2optE02[48]	Chi2 of the fit.

Analysis

90° muons in each Tile row

180 GeV muon runs have been taken at +/-90°, in each of the 11 tile rows of Module 0 and Extended barrel. The goal of the 90° muon analysis is to compute the energy loss in the scintillators (dE/dx) for each TileCal cell. The dE/dx is measured in each cell, by dividing the response to muons in the cell by the number of scintillators in the corresponding tile row. Ideally (ie if the cells response have been inter-calibrated by Cs scan), dE/dx should be the same in each cell. If not, an inter-calibration factor has to be applied.

Persons in charge of the analysis : Tamar Zakareishvili (for Module 0) Shannon Towey (for Extended Barrel)

Help : analysis from previous test-beams ATL-TILECAL-2004-007

90° muons, z-scan in Extended Barrel

Persons in charge of the analysis : Lasha Pantskhava

Comparison between 90° muons and projective muons

Persons in charge of the analysis :

20° electrons

ATL-TILECAL-2004-013, ATL-TILECAL-PUB-2005-005