Post on 20-Mar-2016
description
HEP Tel Aviv University
LuminosityMeasurement using
BHABHA events
Ronen Ingbir
MDI
SLAC
Lumical - A Future Linear Collider detector
Tel Aviv University HEP experimental Group
ΔE~0.31√E
)(54~)( rade
RL
Cracow
Strip design
Lumical - A Future Linear Collider detector
Pad design
0.34 cm Tungsten
0.31 cm Silicon
Cell Size1.3cm*2cm>1.3cm*6cm<~1 Radiation
length~1 Radius Moliere
HEP Tel Aviv University
15 cylinders * 24 sectors * 30 rings = 10800 cells
RL
8 cm
28 cm
6.10 m
Lumical - A Future Linear Collider detector
HEP Tel Aviv University
Reconstruction Algorithm
)]}ln([,0max{T
ii E
EconstW
i
ii
EEX
X
i
ii
WWX
X
Events Num.
)(radgenrec
)(radgenrec
)(radgen
We explored two reconstruction algorithms:
The log. weight fun. was designed to reduce steps in a granulated detector :
1. Selection of significant cells.
2. Log. smoothing.
Log. weight.
E weight.
Lumical - A Future Linear Collider detector
T.C Awes et al. Nucl. Inst. Meth. A311 (1992) 130.
HEP Tel Aviv University
Logarithmic Constant
Constant value
Constant value
)]}ln([,0max{T
ii E
EconstW
After selecting:
We explored a more systematic approach.
The first step is finding the best constant to use under two criteria:
1. Best resolution.
2. Minimum bias.
400 GeV
))(_( radmean genrec
))(( rad
Lumical - A Future Linear Collider detector
HEP Tel Aviv University
Energy dependent constant
)]}ln()([,0max{T
ibeami E
EEconstW
The goal is to find a global weight function.
Is the the log. weight constant really a constant ?
Constant value
Lumical - A Future Linear Collider detector
HEP Tel Aviv University
Shower reconstruction
Num
. of C
ells
Num
. of S
ecto
rs
Num
. of C
ylin
d ers
Ene
rgy
port
ion
(%)
En>90%
)(rad )(rad
)(rad)(rad
What happens when we select the best log. weight constant ?
Shower size
Log. Weight Selection
Most of the information is in the selected cells.
Lumical - A Future Linear Collider detector
HEP Tel Aviv UniversityLumical - A Future Linear Collider detector
Magnetic field
HEP Tel Aviv University
Background studiesBHWIDE + CIRCE
Lumical - A Future Linear Collider detector
HEP Tel Aviv University
33 mrad
Geometric acceptance
Energy Resolution )( GeV
)(rad
Out
In
)(rad
Eout-EinEout+EinP=
3 cylinders
2 cylinders
1 cylinders
Lumical - A Future Linear Collider detector
HEP Tel Aviv University
Left-Right balance RLSimulation distribution
Distribution after acceptance and energy balance selection
Right side detector signal
Lef
t sid
e de
tect
or si
gnal Right signal - Left signal
)(21 rad
(deg)21
Lumical - A Future Linear Collider detector
HEP Tel Aviv University
Energy resolution
Ntuple No cuts
With cuts
Pure electrons
31% 29%
Bhabha
42% 24%
Bhabha + Beamstrahlung
45% 24%
Bhabha + Beamstrahlung + Beam spread (0.05%)
46% 25%
Bhabha + Beamstrahlung +Beam spread (0.5%)
49% 29%
Lumical - A Future Linear Collider detector
HEP Tel Aviv University
Angular resolution
Lumical - A Future Linear Collider detector
HEP Tel Aviv UniversityLumical - A Future Linear Collider detector
‘Pure’ electrons simulation Bhabha+Beam+BS(5e-4)
)(radgenrec
Bias study
44 103.1107.5
HEP Tel Aviv UniversityLumical - A Future Linear Collider detector
Real life algorithm
Working with both sides of the detector and looking at the difference between the reconstructed properties:
(In real life we don’t have generated properties)
2new
Dense0.156e-3Regular0.137e-3
Dense, 35%
Regular, 27%
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35
Ang
ular
reso
lutio
n(ra
d)E
nerg
y re
solu
tion
(GeV
)^0.
5
RegularDense
HEP Tel Aviv UniversityLumical - A Future Linear Collider detector
0.34 cm Tungsten
0.31 cm Silicon
0.55 cm Tungsten
0.1 cm Silicon
Dense design
HEP Tel Aviv UniversityLumical - A Future Linear Collider detector
30 radiation length detector47 radiation length detector
Z (cm)
Detector Signal
0.8cm
1.1cm
Moliere radius & Radiation length
HEP Tel Aviv UniversityLumical - A Future Linear Collider detector
)(rad
Energy Resolution )( GeV
)(rad
Events
New geometric acceptance
HEP Tel Aviv UniversityLumical - A Future Linear Collider detector
Optimization
HEP Tel Aviv UniversityLumical - A Future Linear Collider detector
Margins in between cells
Energy resolution Polar resolution
HEP Tel Aviv UniversityLumical - A Future Linear Collider detector
Our basic detector is designed with
30 rings * 24 sectors * 15 cylinders = 10,800 channels
Do we use these channels in the most effective way?
Maximum peak shower design
30 rings 15 cylinders
20 cylinders
10 cylinders
24 sectors * 15 rings * (10 cylinders + 20 cylinders) = 10,800 channels
4 rings 15 rings 11 rings
10 cylinders
HEP Tel Aviv UniversityLumical - A Future Linear Collider detector
Maximum peak shower design
Basic Design
Angular resolution improvement
without changing the number of
channels
Other properties remain the same
))(_( radmean genrec
))(( rad
Constant value
Constant value
Polar reconstruction
0.11e-3 rad0.13e-3 rad
HEP Tel Aviv UniversityLumical - A Future Linear Collider detector
High Statistics MC
)),(( N
NLL
)(rad)(rad
min
*2
LL
BHWIDE + fast detector simulation
HEP Tel Aviv UniversityLumical - A Future Linear Collider detector
‘Real physics’ MC + digitization + elec. noise + New max peak design + Margins
Final optimization
Pure electron MC Detector
propertiesEvents
selection‘Real
physics’ MCBhabha + Beamstrahlung
+ Beamspread
R&D status & future steps
))(,,),(( EENN
LL High statistics MC
410 N
N
Luminosity with a crossing angle
Luminosity with polarised beams (Gideon Alexander)
HEP Tel Aviv UniversityLumical - A Future Linear Collider detector
THE END