Sin t

1
ATLAS ACTIVITIES _at_ VALENCIA
SemiConductor Tracker
J. E. García, S. González, J. Bernabéu, J. V.
Civera, M. J. Costa, J. Fuster, C. García, F.
González, C. Lacasta, G. Llosá, S. Martí, F.
Martínez, P. Modesto, A. Oyanguren, R. Rodriguez,
E. Ros, J. Salt, F. J. Sánchez, L. Sospedra ,V.
Strachko, M. Vos.
Physics and detector simulation S. González, E.
Ros, M. Vos
The Inner Detector is a sub-detector of the ATLAS
experiment. It will provide a very precise
tracking and vertex determination. The
Semiconductor Tracker is a part of the tracking
system based upon silicon microstrip detector
technology. The SCT will be composed by one
barrel and two forward structures. Four different
types of modules are employed in the SCT (one in
the barrel and three in the forward regions).

• The flavour tagging performance of the ATLAS
  detector is determined using GEANT simulations of
  the full detector. GRID test bed computing power
  is used for simulation and reconstruction.

Metrology System

• The discovery potential of the ATLAS detector for
  the lightest MSSM Higgs bosons is studied.
  Tagging of the associated b-jets is crucial to
  reduce the background. For A/h masses between 100
  and 120 GeV and tan(? ) gt 15 the muonic decay
  channel would be observable even with a
  relatively low luminosity.

Si Detector Characterization
A total of 880 silicon wafers have been fully
characterized. This is equivalent to 3.2 m2 of
microstrip silicon detectors. For each wafer the
leakage current and
Significance after 3 years _at_low luminosity
An automatic measurement system has been
developed in order to verify the correct assembly
of SCT modules. The device uses a combination of
two cameras with high magnification optics and a
laser interferometer provide accurate measures
of the position with a precision of 0.3 ?m.
depletion voltage have been measured and compared
with the SCT specifications. More exhaustive
tests are perfomed on a subset of detectors.
TILE CALORIMETER
Forward outer module
Assembly System
Bonding
All the components need to be assembled together
with high precision, being the alignment
tolerances of few microns.
Quality Assurance
F.Camarena, J.M.Castelo,V.Castillo, C.Cuenca,
F.Fassi, A.Ferrer, E.Fullana, E.Higón,
B.Salvachúa
A full assembled module must pass several
quality assurance (QA) tests. The aim of the QA
procedures is to ensure that each SCT forward
module fulfills all required specifications
An assembly system has been built in Valencia in
order to achieve the mechanical precisions.
PHOTOMULTIPLIERSTETBENCH
SUBMODULES CONSTRUCTION
Read Out Driver (ROD)
Through a wire-bonding technique, each strip on
the detector is ultrasonically stitched to its
corresponding amplifier on a readout chip with an
aluminum wire of 17-24 ?m of diameter.

• Infrared thermal imaging can reveal hidden
  systematic problems like bonding failures or
  hybrid hot points.

• The module performance is tested under realistic
  conditions using the CERN and KEK beam
  facilities.

• The behaviour of the chips in Gain and Noise is
  one of the most important results of the
  electrical characterization.

High PT Top Mass Measurement in Single Lepton
Jets Channel Using a Large Calorimeter Cluster
F. Fassi, I. Efthymiopoulos, V. Castillo, E. Higón
Top mass (mt) is a fundamental Standard Model
(SM) input parameter. It is present in the
radiative corrections which connet several other
SM parameters. An accurate knowledge of the top
mass can put constraints on the Higgs mass. The
large production rate at LHC allows the
possibility to use special sub-sample of the tt
events. Such a sub-sample is the high Pt (gt200
GeV) top sample.
Due to the high PT, the three jets (jjb) from
hadronic top decay are very close in space. To
exploit this particular topology, mt is directly
reconstructed from the calorimeter towers (?????
0.1?0.1) around the top quark direction.
Expected strong dependence of mt with the cluster
size because of the Underlying Event (UE)
contribution. After UE subtraction inv. mass
independent of cone size, but lower value
lt159.1?0.11 GeVgt. To re-scale mt to top mass,
The two jets from W decay in inclusive top sample
have been used. The resulting re-scaled top mass
is lt175.86?0.12 GeVgt.