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M. Antonello, P. Azzi, S. Braibant, E. Fontanesi,
S. Lo Meo, L. Pezzotti, M. Selvaggi
13th June 2019 - Bologna
IDEA Collaboration Meeting
Fast and full simulationof the IDEA detector
Outline2
Geant4
A standalone full simulation
Delphes
A parametricfast simulation
Plan to provide a complete geometry of the IDEA detector in Geant4
Status of the IDEA detector implementation
and possible future improvements
Outline2
Geant4
A standalone full simulation
Delphes
A parametricfast simulation
Status of the IDEA detector implementationand possible future improvements
Choice of a standalone Geant4 simulation of the IDEA detector for
performance and local reconstruction studies
to optimize baseline geometry
Outline2
Geant4
A standalone full simulation
Delphes
A parametricfast simulation
Status of the IDEA detector implementationand possible future improvements
Plan to provide a standalone Geant4 simulation of the IDEA detector
PHYSICS BENCHMARK STUDIES with the IDEA baseline detector design
PERFORMANCE STUDIES
Delphes fast simulation3
Fast simulation of detector concept
Particle trajectory is followed in the detector.It only needs general volumes foracceptances, a resolution drivensegmentation, resolution and responsefunctions as obtained from full simulation orrelated to desired/studied performances.
A parametric simulation
It takes into account subdetector types(described as cylinders) with their extension,segmentation and resolution:• a tracker in a solenoidal magnetic field,• a calorimeter with its electromagnetic
and hadronic sections,• a muon system. Schematic view of the baseline DELPHES detector
IDEA description in DelphesB field and tracker
4• B field description
(Particle Propagator module)
- Half length of the magnetic field coverage: 2.5 m- Radius of the magnetic field coverage: 2.25 m- Homogeneous magnetic field: 2 T
• Tracker description(TrackingEfficiency, MomentumSmearing module)
The response of tracking detectors has beenparametrized in the same way for electrons,muons and charged hadrons:=> unique efficiency formula (dependent on E and η);=> total pT resolution formula.
|η| ≥ 3.0 0.00%
E ≥ 500 MeV in |η| ≤ 3.0 99.7%
300 ≤ E ≤ 500 MeV in |η| ≤ 3.0 65%
E ≤ 300 MeV in |η| ≤ 3.0 6%
σpT / pT = √[(7.e-5*pT ) 2 + 0.00062]
Idea to include in Delphes the full covariancematrix for tracking parameters smearingprovided by a specific fast simulation [*].
[*] F. Bedeschi @ Oxford: https://indico.cern.ch/event/783429/contributions/3376675/attachments/1829951/2996531/Oxford_April2019_V1.pdf
➢ Tracking parameter covariance matrix calculationincluding multiple scattering effects
➢ Covariance matrix grid stored for fast calculation Several parametrizations usable in same program
➢ Track parameter smearing according to appropriate covariance matrix Validated with full simulation
Potential implementation in DELPHES➢ Usable to provide to Delphes fast simulation a realistic full covariance matrix to
parametrize track resolution
ROOT based classes:➢ Simple tracking geometry implementation with
txt files: Easy to implement a modified geometry
and change detector performances
Fast tracking simulation5
[*] F. Bedeschi @ Oxford: https://indico.cern.ch/event/783429/contributions/3376675/attachments/1829951/2996531/Oxford_April2019_V1.pdf
cos(ϑ)
Mat
eria
l
Thanks to F. Bedeschi
Examplesee ZH (H µµ)ee ZH (Z µµ)• Higgs from Z recoil• Full recoil study (IDEA)
Fast tracking simulation6
[*] F. Bedeschi @ Oxford: https://indico.cern.ch/event/783429/contributions/3376675/attachments/1829951/2996531/Oxford_April2019_V1.pdf
L = 5 ab-1
Higgs recoil mass (GeV) Mass (GeV)
Even
ts/1
.0 G
eV
Higgs mass (GeV)
Even
ts/1
.0 G
eV
Even
ts/1
.0 G
eV 0.136% beam spread
0.136% beam spread
Thanks to F. Bedeschi
7• Dual-Readout (DR) calorimeter description
(DualReadout Calorimeter module)
Implementation of a monolithic calorimeter in a dedicated IDEA card:➢ single segmentation
=> Need to define an appropriate granularity➢ different energy resolution for electromagnetic and hadronic showers
E
%1310−
E
%30
IDEA description in DelphesDual-Readout calorimeter
Never implementedand never studiedin a fast simulation
before
IDEA DR calorimeter in Delphes8
E
%1310−
E
%30
e± barrel
Cell size: 6 cm x 6 cm
Validation plots
Energy resolution forreconstructed objects(both had and emparticles) consideringtwo different regionsof pseudorapidity (η)with particle gun eventsγ barrel
endcap
π± barrel
n barrel
endcap
IDEA DR calorimeter in Delphes9
• The geometry is given in Delphes as asegmentation of the calorimeter cylinderin cells (η-φ directions).
• Since each tower reconstructed in thecalorimeter corresponds to a single cell inDelphes work flow, the granularity has tobe defined accordingly to the physicsdimensions of showers.
➢ No clustering➢ No longitudinal segmentation➢ Need to take into account the possible
overlap between particles
Cell size: 30 cm x 30 cm
• Modified Energy Flow in Delphes: hadronic resolution (pessimisticscenario) in case of an electromagneticand hadronic deposit in the same cell
➢ New branch availablein Delphes (by Michele):branch DualReadout
GOAL: Check the effect in Delphes given by changing DR calorimeter granularity
Different cell sizeConfigurations have
been implemented and studied for variousphysics processes
Etower= E1 + E2
E1 E2
Jet energy resolution10
Cell size: 30 cm x 30 cmCell size: 6 cm x 6 cm
Cell size: 6 cm x 6 cm Cell size: 30 cm x 30 cmCell size: 10 mm x 10 mm
ENDCAP
Cell size: 10 mm x 10 mm
BARREL
σ(E
)/E
(%)
σ(E
)/E
(%)
σ(E
)/E
(%)
σ(E
)/E
(%)
σ(E
)/E
(%)
σ(E
)/E
(%)
The jet energy resolution is not particularly affected by the variation of the cell size
Jet angular resolution11
The angular resolution is not so much dependenton the cell size. It decreases in the same way withthe increase of the cell size for PF and Calo jets.
PF jet Calo jet
σ(θ) = θGEN - θRECO
σ(θ) [rad] 2 mm x 2mm 3 cm x 3 cm 30 cm x 30 cm 40 cm x 40 cm 60 cm x 60 cm 80 cm x 80 cm
PF jet 0.01 0.01 0.02 0.02 0.03 0.04
Calo jet 0.03 0.03 0.04 0.05 0.07 0.1
ZH(ττ+jets)12
The number of towers with both an electromagnetic and hadronicdeposit increases when increasing granularity.
Dijet mass resolution is not significantly affected by the different cellsize, while the τ jet invariant mass gets worse.
Need to invastigate this case: τ studies, considering especially π0 decay into two photons
ZH(ττ+jets): ρ invariant mass13
e+ e- Z H
τ+τ-
τ decay forced to ρ π± π0 ντ
Jets (u, d s) Invariant mass of ρ resonance searching for acharged pion and distinguishing two categories:
➢ Presence of two reconstructed pion inthe cone around π±
➢ Presence of one reconstructed pion inthe cone around π±
Cell size: 10 mm x 10 mm Cell size: 6 cm x 6 cmCell size: 30 cm x 30 cmCell size: 40 cm x 40 cmCell size: 60 cm x 60 cmCell size: 80 cm x 80 cm
# reco photons per event
The number of reconstructedphotons per event decreases withthe increasing size of thecalorimeter cells.
➢ If more photons arrive in the samecell, we reconstruct only one ofthem with an energy correspondingto all of them.
14
Considering a cell size of6 cm x 6 cm or greater,the peak in the π± + 2γis considerably reduced.
ZH(ττ+jets): ρ invariant mass
15
The mass resolution on thediphoton invariant massgets worse changing the cellsize from 10 mm x 10 mm to30 cm x 30 cm effectof the implemented EFlow
ZH(ττ+jets): ρ invariant mass
16
The category π± + 1γshow the effect of theworsen energy resolutionon the photons increasingthe cell size of the DRcalorimeter.
ZH(ττ+jets): ρ invariant mass
17
Combination of both π± + 2γ and π± + 1γ categories
π± + 2γ π± + 1γ π± + 0γ
2 mm x 2 mm 51% 35% 14%
10 mm x 10 mm 51% 35% 14%
3 cm x 3 cm 51% 35% 14%
6 cm x 6 cm 43% 43% 14%
16 cm x 16 cm 6% 47% 47%
22 cm x 22 cm 2% 32% 66%
30 cm x 30 cm 0.4% 19.3% 80.3%
The best choice seems to be a cell size not greater than 6 cm x 6 cm to be able to reconstructin a good way overlapping photons => we need some investigation using DR full simulation
Selected event for each category (%)
ZH(ττ+jets): ρ invariant mass
Tracker
(G. Tassielli)
Preshower
(E. Fontanesi)
Magnet
(L. Pezzotti)
Calorimeter
(L. Pezzotti, M. Antonello)
Standalone Geant4 simulation18
Uniqueframework
(S. Lo Meo)
Drift chamber
+
Silicon wrapper
Two μ-RWELL layers in BARREL
+ ENDCAP
MagnetFull projective geometry
(BARREL + ENDCAP)
Standalone Geant4 simulation18
Uniqueframework
To be tested
[*] See Massimiliano’s talk for details!
[*] More info in my talk later
• A general framework to include standalone geometry of each IDEA sub-detector is ready.This MC provides:➢ the chance to choose a specific physics list (specifying the desired cuts);➢ the possibility to include easily another geometry described in a separate file.cc and file.hh;➢ the creation of a basic rootfile (each sub-detector have to specify its sensitive volume in a
dedicated section).For now it contains only the basic geometry of the preshower detector.
• We imported this new framework in Lorenzo’s github in order to have an easy way toshare the code.
Standalone Geant4 simulation19
Conclusions and plans20
DELPHES - FAST SIMULATION
The implementation is based on the output of dedicated Geant4 simulation of the IDEAtracker and DR calorimeter
Delphes is flexible enough to provide a fast simulation of the IDEA detector Significant improvements can be provided by the inclusion of the full covariance matrix
to provide tracks smearing, the development of new algorithms oriented to e+e- physics(adeguate clustering for jets), …
GEANT4 – STANDALONE FULL SIMULATION
Combined performances of the IDEA sub-detectors have to be investigated with acomplete full simulation
We are almost ready to try to merge all the IDEA sub-detector in an unique geometry Best solution to have a quick development of the IDEA baseline geometry and then
facilitate the import of the detector description in FCC/CEPC framework
Additional slides
THANK YOU!
IDEA baseline detector
z[m]
r[m]
BARREL until 45° (|η| = 0.88)
ENDCAP
• A magnetic field of 2 T with
- Solenoid length: 5 m- Solenoid inner radius: 2.1 m- Solenoid outer radius: 2.4 m
• A Tracker composed of
- a drift chamber and a drift chamberservice area (DCH);
- silicon pixels and a silicon strips doublestereo layer;
- a μ-RWELL double layer as preshower.Angular coverage up to 100 mrad (η = 3.0)
• A Dual-Readout calorimeterAngular coverage up to 100 mrad (η = 3.0)
• A muon system composed of three
μ-RWELL stations (each of them has abidimensional view)
IDEA tracker – Geant4
• ROOT based classes:➢ Simulation of the tracking system geometry➢ Validation using tracker full simulation in Geant4➢ Easy to implement a modified geometry➢ Easy to change detector performances
Fast tracking simulation
[*] F. Bedeschi @ Oxford: https://indico.cern.ch/event/783429/contributions/3376675/attachments/1829951/2996531/Oxford_April2019_V1.pdf
Track fit χ2 linearized in the fit parameters:
Parameter resolution depends only on S and derivatives:
d/d* = predicted/measured distance of track from wire or pixel
p = track parametersS = covariance of all measurements:
resolution & MSMS → worse resolution and non
diagonal correlation terms
cos(ϑ)
Mat
eria
l
Fast tracking simulation
[*] F. Bedeschi @ Oxford: https://indico.cern.ch/event/783429/contributions/3376675/attachments/1829951/2996531/Oxford_April2019_V1.pdf
DR full simulation
[*] Massimiliano’s talk here in Bologna
Electron 40 GeV
DR full simulation
[*] Massimiliano’s talk here in Bologna
Photons 40 GeV
DR full simulation
[*] Massimiliano’s talk here in Bologna
Pions 40 GeV
ZH(ττ+jets): ρ studiesG
enle
veld
istr
ibu
tio
ns
Gen GenReco
ZH(ττ+jets): ρ studies
π± + 2γ π± + 1γ π± + 0γ # π± matched to τ daughter
2 mm x 2 mm 20309 13757 5508 39574
10 mm x 10 mm 20330 13727 5544 39601
3 cm x 3 cm 20111 13958 5517 39586
6 cm x 6 cm 16889 17131 5575 39595
16 cm x 16 cm 2247 18743 18618 39608
22 cm x 22 cm 616 12745 12745 39594
30 cm x 30 cm 133 7657 31811 39601
40 cm x 40 cm 20 4343 35210 39573
60 cm x 60 cm 5 2547 37017 39569
80 cm x 80 cm 0 1354 38224 39578
Summary of selected event for each category
ZH(eebb)
No significant discrepancies on electron/muon resolution mass:signal leptons are very well isolated,
so changing the granularity does not affect the peak reconstruction
Z mass Higgs recoil mass
Dilepton invariant mass
Comparison with other detectors
Dilepton invariant mass
ZH (10k events)
As we develop the IDEA detector description in Delphes, we try to compare the IDEAperformance with other detector implemented in Delphes and fully validated
➢ waiting for a full simulation of the IDEA detector
Z mass Higgs recoil mass
Dijet invariant mass
ZH(10K events)
As we develop the IDEA detector description in Delphes, we try to compare the IDEAperformance with other detector implemented in Delphes and fully validated
➢ waiting for a full simulation of the IDEA detector
Z(10K events)
Comparison with other detectors
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