Carrier in Research Work and current activities
The nature of my research work was started on detector physics and its readout
hardware, as well as physics analysis in Standard Model, seven years before.
The timeline on which this proposal is based covers five years working experience
in CMS-RPC and CMS-SM (Top quark physics).
The focus of my M.Phil dissertation was, to take part in the R&D for Endcap
Resistive Plate Chambers (RPCs) and to study the gas gaps using
phenolic/melamine Bakelite plates required for the Compact Muon Solenoid
detector. For that purpose, gas gaps with different gap widths and various off-set
areas were selected to study the high voltage versus current behavior. Later on
resistivity of local and Italian Bakelite sheets measurement was performed and
dependence on temperature, humidity to attained CMS required value was studied.
The construction of small prototype Double gap RPC and the signal detection
technique was also studied first time in our institution (NCP)
The Pakistani group is responsible for assembling and commissioning of the RPCs
for CMS, which is a very important sub-detector of the muon system of CMS for
Level-1 trigger, due to having excellent time resolution, high rate capability and
good efficiency. For this purpose several prototypes were made from 1999-2003
and they were tested at European Centre for Nuclear Research (CERN) using X5
beam from SPS accelerator.
A large scale production of 432 Endcap RPCs is in the process of being assembled
and tested. In order to meet the RPC quality control criteria, we have established
a cosmic ray test facility (hodoscopes) in our institution, which is fully equipped
with Data Acquisition (DAQ) system, trigger and readout electronics. I have
participated in cosmic tests of RPCs both at CERN and at National Centre for
Physics (NCP). Pre-existing DAQ offline analysis program was made compatible
according to our test setup.
In more detail I remained actively involved in the prototyping of RPCs. I
assembled two full-scale Endcap RPC prototypes, RPC/PK-p2 (2002) and
RPC/PK-p3 (2003). Both prototypes were based on the principles of the gaseous
detectors. I took part in the test beam activity and the RPC/PK-p3 was tested
successfully at CERN using the 200 GeV beam of muons from SPS accelerator.
The data analysis of the both above mentioned tests was carried out with different
FORTRAN based PAW macros and now C++ based DAQ programs. DAQ is also
connected with Front end, readout and trigger electronics as well.
I am also working on the physics topics related to the physics of Large Hadron
Collider (LHC) under construction at European Organization for Nuclear
research (CERN), Geneva, Switzerland.
Talking about my main physics field of study is the production of top anti-top
quark pairs at LHC through gluon fusion, which has the dominant cross-section
over all other production mechanisms. Since LHC would be a top factory, so it
will allow us to measure more precisely the mass of the top quark in lepton plus
jets channel, which a key parameter is to bound the Higgs mass.
Basic Idea of top physics study at LHC:
More than one top mass estimator is required in any experiment one of them is the
high Pt top analysis. In which highly boosted top quarks decay back-back making
two hemispheres inside the two parts of the detector.
High Pt tops have decay angles very close to the top flight direction and therefore
the mass of the calorimetric (ECAL+HCAL) objects (clusters, cells, seeds) in a
large cone around top direction is correlated with the real top mass. When the top
has a higher boost, one expect the opening angle between W boson and b quark
from top decay to be much smaller,
so for that purpose the jet cone is reconstructed with a very narrow cone size
equal to 0.2-0.3. One could calculate the mass of the objects which are in a larger
cone around top quark direction. For this reason top quark needs to have a larger
(>200 GeV) Hence one need to make an event selection in such a way, which is
selecting those events with a high Signal/Background ratio. This phenomenon will
be sensitive to the energy deposited by the underlying event, pileup and
calorimeter noise.
In addition, to accomplish the Full and Fast CMS detector simulation based study,
I learnt the computing techniques and different relevant CERN simulation
packages like PYTHIA/JETSET, OSCAR, ORCA, CMSSW, while for analysis
ROOT and PAW were used.
I submitted my PhD thesis on June 2007.
Currently I am working in CLIC CTF3 experiment as a post doc fellow in the
beam dynamics group at CERN. My aim is to estimate the halo and tail
backgrounds in the CLIC main beam delivery system using the tracking
algorithms.
It would be my pleasure to join your institution to enhance my intellectual abilities
and research capabilities. I am anxiously waiting to test my analysis program on
the real data from LHC.
IJAZ AHMED
National Centre for Physics, Quaid-iAzam University Islamabad, Pakistan