i worked on the detector so i want other to have good understanding on GEM so i uploaded it

1. Presented to: Dr. Muhammad Shoaib Bloach
Presented By: Quratulain Zahoor
Roll No:F21BPHYS301096
Semester: Mphill 1st
EXPERIMENTAL HIGH ENERGY PHYSICS
GROUP
Institute of Physics
The Islamia University of Bahawalpur
Gaseous Electron Multiplier & its
Simulation

2. Table of Contents
 History
 Introduction
 Working Principle of GEM
 Construction Of GEM
 Working Of GEM
 Operational Parameters
 Background of GEM simulation
 Purpose of GEM Simulation
 Stages of simulation
 Components of detector simulation
 GEANT4
 Garfield++
 Simulation of GEM using gas Composition
 Stages of GEM Simulation
 1st stage
 2nd stage
 Role of GEM in CERN
 GEM in CMS upgrade

3. Research Poster Of GEM

4. History
 Gaseous Electron Multiplier(GEM) is a well
known MPGD technology developed by F. Sauli
at CERN in 1997
 Micro pettran gaseous detector (MPGD)
combines the basic gas amplification principle
with the micro structured printed circuit to
provide detector with excellent spatial and time
resolution ,high rate capability ,low material
budget and high radiation tolerance
 GEM has played a pivotal rule in tracking devices
in the field of particle physics experiment for the
last 50 years.

5. Introduction
 GEM is a type of gaseous ionizing detector used
in nuclear and particle physics and radiation
detection GEM is a proven amplification for the
position detection of neutron in gas detector
ionizing radiation such as charged particles X ray,
photon and GEM is proposed as one of the
upgrade in moun detection system of CMS
experiment.

6. Gaseous Electron Multiplier

7. Principle of GEM
 Consisting of the anode of thin parallel anode
wire, on application of suitable voltage the device
collect and amplify by electron multiplication The
tiny ionization cluster released by ionizing
radiations permitting detection by electronic
means.

8. Construction
 GEM is constructed with 50-70 micrometer
kapton foil copper clad on both sides A
photolithography and acid etching process makes
30-50 micrometer diameter holes through both
copper layers A second etching process extend
these holes all the way to kapton The small holes
can be made very regular and dimensionally
stable
 The holes are hexagonal and due to etching bi
canonical in shape holes have inner diameter of
about 55 micrometer.

9. GEM Geometries

10. Operational Parameters of
GEM
 Electric Field
 Top metal
 Bottom metal
 Pitch
 outer diameter
 Inner diameter
 Primary charges
 Secondary charges
 Gain
 Optical transparency
 Gas mixture

11. Components of GEM

12. Working
 All gaseous detectors collect the electrons
released by ionizing radiation guiding them
toward the region of large magnetic field the
electron released by ionizing and thus creating
the electron avalanche which is able to produce
current or charges , the collected electrons from
avalanche are guided toward readout
 GEM Create a large magnetic field in a thin
polymer sheet the avalanche occur in holes The
resulted electrons are ejected from the sheet and
separate system is used to collect these electron
and guide them towards readout
 For operation a voltage of 150-400V is applied
across two

13. Continue
 copper layers making large electric field in holes
under the presence of appropriate gases
 A single electron entering the hole can create the
avalanche of 100-1000 electrons .Many
experiment using double or triple GEM stakes to
achieve the gain of one million or more. GEM
based detector require several independent
setting.
 A Drift voltage to guide the electron from the
ionization point of GEM
 An Amplification and transfer voltage is to guide
the electron from the GEM to exit the readout
plane

14. Readout
 A GEM chamber can be readout by simple
constructive strip laid across the flat plane
constructive strip laid across the flat plane
lithography technique on ordinary circuit board.
The readout strip re not involved in amplification
so they can be made of any shape and size.

15. Background of GEM
Simulation
 GEM simulation was done because the CERN gas
team (EP-DS-FS) have define several strategies to
reduce the green house coming from particle detector
 Different setup has been implemented to study the
both gas system and gas detector performance .In
this contest Monte carlo carlo simulation of detector
with different gas mixture composition was useful
 The gas tem has developed different R & D programs
One of these was studying the performance of GEM
in the gas recirculation system and under high
irradiation at CERN gamma irradiation
 Monto carlo simulation of the detector is used to
estimate the performance

16. Purpose of GEM Simulation
Following were the reasons for GEM
simulation
 1: The future of large Hadron collider set
important challenge for all the detector system
and also concerning to the moun system one of
the changes to reduce the gas emission and
operational cost while maintaining the high
performance level
 2: Simulation was design to compare the actual
or experimental data and computed or simulated
data .
 3: Simulation can be done using different
parameter to batter its performance.

17. Stages and types of simulation
 Stages of performing simulation are
1-Event generators and detector simulation
2-Scale from full detail to fast simulation
3-Simulation of energy deposition or signal generation
4-Assessment of radiation effects
5-Key tools: Event generators, detector Monte Carlo,
radiation transport
6-Detector Monte Carlo: Geant, Fluka, Geant4
7-Radiation related MC: Fluka, Mars, Mcnp/Mcnpx
8-Signal generation: Garfield++

18. Components of Detector
Simulation
 The components of computer simulation are
described below:
1-Geometry description and navigation
2-External fields
3-Electromagnetic physics models
4-Hadronic physics models
5-Low-energy neutron interactions
6-Accuracy of simulation
7-Fast simulation
8-Signal generation
9-Biasing, production thresholds

19. Geometry and Tracking
(GEANT4)
 Geant4 is a toolkit for simulating the passage of
particles through matter.
 It includes a complete range of functionality
including
 tracking,
 geometry,
 physics models and hits.
 The physics processes offered cover a
comprehensive range, including electromagnetic,
hadronic and optical processes, a large set of
long-lived particles, materials and elements, over
a wide energy range starting, in some cases,
from 250eV and extending in others to the TeV
energy range

20. Garfield++
 Garfield++ is a toolkit for the detailed simulation
of particle detectors based on ionization
measurement in gases and semiconductors.
 The main area of application is currently in micro
pattern gaseous detectors.
 Garfield++ shares functionality with the Garfield
program. The main differences are the more up-
to-date treatment of electron transport, the
possibility to simulate silicon sensors, and the
user interface, which is based on ROOT
 Garfield++, is a subversion of Geant4.

21. Simulation Of GEM Detector By
using Gas Mixture Ar/Co2
 In this Project we have simulation of GEM using
gas mixture of Argon and Carbon dioxide in 70:30
concentration
 Photon of source 55Fe is used
 Different characteristics of the system, such as
photon sensitivity of the gas gap, can be
calculated using a Monte Carlo simulation, but
are much harder to measure in a real experiment.
 We can study different properties of the GEM
detector and their dependency on a change in
gas mixture composition.

22. Stages of Simulation In GEM
detector
 Simulation is divided by 2 stages:
1ST STAGE
 Primary ionization of a gas by initial photons and
further creation and development of an avalanche.
 The first stage uses a physical toolkit Geant4 mainly
because of its flexibility and a wide range of
supported physical processes.
 Stages are separated from each other, so initial
particles can be easily changed. For example, a 55Fe
source, used in this project, can be replaced by a
beam of high energy muon, and Geant 4 is able to
handle a simulation of ionization with different
processes.

23. Continue ..
 Tracking function of the application is implemented via
Tracking Action of Geant4. Custom action launches
when a new particle is created inside of the gas gap.
 The initial properties of the particle are stored in the
ROOT Tree. The action saves x, y, z coordinates of
the particle, 3 projections of its momentum, energy,
time, id of the parent particle and PDG code.
 A PDG code is used to distinguish electrons from
other particles.
 Geant4 is able to simulate a passage of particle in the
electromagnetic field.
 Electrical field does not change a trajectory of
photons and the characteristics of electrons are saved
before they can be affected by the electromagnetic
field.

24. Properties of the electrons were analyzed to
cross-check the chosen Geant4 physical model.
Photon sensitivity of the gas gap can be easily
measured as a ratio between produced primary
ionization electrons and the number photons
reaching the gap (not absorbed by the window
layers). The dependency of the sensitivity on gap
thickness follows an exponential law

25. Garfield++
2ND STAGE
 The second stage is responsible for a passage of
electron avalanche through a matter of the
detector.
 In this case, a Garfield++ toolkit is suitable
due to the detailed simulation of low energy
electromagnetic interaction and influence of gas
properties.
 Data transfer between two stages (and therefore
two different applications) is organized using root
files
 They can be easily analyzed to compare real

26. Continue
 The Garfield++ application simulates the
remaining part of a GEM detector, not covered by
Geant4, GEM foils and readout.
 Garfield++ toolkit is mainly chosen due to the
detailed simulation of interactions of charged
particles with gas.
 Necessary libraries (Heed, Magboltz model etc)
are already integrated into the software. Fractions
of mixture components can be changed easily
and mixture properties are linked (as Penning
transfer, drift velocity). Pressure and temperature
can also be separately set. The characteristics of
the initial electron are taken from the ROOT file
from Geant4 application.

27. Continue
 This electron interacts with the gas and creates
an avalanche. All secondary electrons are tracked
and their properties are stored in the output
ROOT file.
 For each secondary particle id of the initial
electron, end-point coordinates, time and energy
are saved.
 A fraction of avalanche electrons reaches the
readout plane; their number represents the gain
of the detector.

28. Avalanche Process in GEM

29. Role of GEM at CERN
 1-Gas electron multiplier (GEM) detectors
represent a new muon system in CMS, in order to
complement the existing systems in the endcaps.
 2-The forward region is the part of CMS most
affected by large radiation doses and high event
rates, and we foresee these parameters to be
again enhanced during phase 2 of the LHC.
 3-The GEM chambers will provide additional
redundancy and measurement points, allowing a
better muon track identification and also wider
coverage in the very forward region.

30. Installation of First GEM at
CERN

31. Continue
 4-The CMS GEM detectors are made of three
layers, each of which is a 50 micron thick copper
claded polyimide foil.
 5-These chambers are filled with an Ar/CO2 gas
mixture, where the primary ionization due to
incident muons will occur. the primary ionization
due to incident muons will occur.
 6-The CMS GEM detectors will be the first 1-2
m^2 sized chambers of this kind, compared with
previous GEM detectors.

32. GEM at CMS upgrade
 A first batch of 144 chambers will be installed
during 2019-2020 in the first disk of both
endcaps.
 Multiple quality and performance tests have
already been performed, as well as first
measurements with cosmic ray muons. Others
chambers will follow before phase 2 of the LHC,
and will be installed during 2024-2026.

33. GEM in CMS Upgrade
 GEMs will also play a major role in the upcoming
CMS upgrade. This upgrade will involve the
installation of large-area GEM detectors, called
GE1/1, in a certain region of the forward muon
endscap.
 The existing endscap system only uses cathode
strip chambers in this specific region, which are
unable to handle the large inundations of muons
that are expected after the large inundations of
muons that are expected after the upgrade. But
this can be solved with GEM.

34. Applications of GEM
 GEM has application in different fields
 High Energy Physics
 Medical Physics
 Radiation therapy dosimeter
 Astronomy or Astrophysics
 Material analysis
 system for radiation detection and monitoring