Installation and Commissioning of the LHCb Outer Tracking System:
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		The LHCb Outer Tracker Collaboration


Abstract:
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The straw tube technology is used for the Outer Tracking System of 
the LHCb experiment. A special straw tube material made of a layer
of Kapton XC and a layer of an Kapton XC/Aluminium laminate has been
developed by the LHCb OT collaboration to meet the needs of the 
experiment. They have a diameter of 5mm and a length of 2.5m. The 
system consists in total of 53760 straw tubes arranged in 5m long and
34cm wide detector modules. Each detector module houses in total 256
straw tubes. In test beam experiments using the final readout electronics
it has been demonstrated that the chosen technology fulfills the stringent 
requirements in terms of spatial resolution, efficiency and charge 
collection time. 
In july 2005 the installation of the detectors in the experiment begun. 
This talk highlights the performance of the detector modules and the
experiences gained so far during installation, alignment and commissioning
of the outer tracking system. 


Summary:
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LHCb is a dedicated experiment to exploit CP violation and rare decays in 
the B meson system. The spectrometer covers an opening angle of 300mrad x 
250mrad. Its design goals are an excellent vertex resolution, a very good
mass resolution and particle identification to reconstruct B-mesons and a 
fast trigger these particles. 
The LHCb tracking system is divided into the inner part made of silicon detectors
and the outer part constructed in the straw tube technology. The tracking
stations cover an area of 6m x 5m in planar geometry. The design of the outer
tracking system (OT) is modular, i.e. it is build from detector modules of 
5m length and 0.34m width. A detector module houses 256 straw tubes of 5mm
diameter and 2.5m length arranged in two layerers. The tracking system is
divided in three tracking stations, each station is made of four detector layers
arranged in the X/U/V/X geometry. 
The choice of the straw tubes has been driven by the need for a technology
that combines a good spatial resolution of better than 200µm, fast charge
collection time and high efficiency with the requirement for a light and 
radiation hard structure. A research effort has been launched between 2000
and 2003 to optimize this technology and to design the layout of the LHCb
tracking system. It results in a straw tube material of a layer of Kapton XC
and a layer of an Kapton XC/Aluminium laminate. 
A dedicated frontend electronics has been developed to benefit from the full 
potential of the detectors used on one hand and fulfilling the specifications
imposed by the LHCb readout architecture on the other hand. Its main components
are the 
1. HV board. It distributes the HV to the anode wires and decouples the HV from the
   the input of the preamplifier. 
2. ASDBLR chip as preamplifier and discrimator. The ASDBLR chip has originally
   been developed for the Atlas experiment. 
3. OTIS chip, a 16 channel TDC chip working at a readout rate of 40MHz with a time
   resolution better than 1ns. This chip has been developed by the LHCb OT collaboration.
4. GOL chip (Gigabit Optical Link) used to convert the output of the OTIS into
   a optical signals.  The GOL chip has been developed at CERN. 
In 2005 ít has been demonstrated in test beam experiment that the LHCb detector 
modules operated with the final frontend electronics fulfill the specifications
for the OT.
In total 300(???)  detector modules have been produced between 2004 and 2005 in 
three production centres in Amsterdam, Heidelberg and Warsaw. 
The detector installation begun in April 2006. After installation of the support 
structure the detector installation started in july 2006. In november 2006 half of the
detectors have been installed. Much effort has been spent to guarantee that the high 
quality of the detectors demonstrated during their production is maintained during 
transport and installation. For this, measurements of gas tightness, dark currents and 
with radioactives sources are performed. A careful detector adjustment procedure is 
followed after the installation to ease the final alignment procedure performed during 
data taking. Commissioning of the detector has begun by performing system tests 
including the final frontend electronics and readout chain and detector services. 
In this talk the design of the LHCb outer tracking system and its performance is described. 
Main emphasis is placed to describe the experiences gained during detector installation, 
adjustment and commissioning.