THE CMS ALIGNMENT SYSTEM

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THE CMS ALIGNMENT SYSTEM
Task of the align. system Monitor the position
of the m-chambers and the CT detectors with
respect to each other.

• Alignment scheme

Building blocks 4 subsystems - Internal
tracker align. - Internal muon barrel and
endcap - The link tracker Û muons (3
alignment planes)

• Basic components
• Mechanical structures (rigid, stable)
• Light sources (LED, laser beams)
• Light detectors (DPSD)
• Tilt, proximity and temp. sensors

• System requirements
• Physics requirements
• Position accuracy in rf (referred to the tracker
• detector) for muons up to 2 TeV
• - track reconstruction 500 mm
• - for pt measurement 150(350) mm at
  MB1(MB4)
• 150 mm at ME1 layer
• Operational constraints
• Detector hermeticity
• Large dynamic range (few cm)
• Radiation tolerance and insensitivity to DB
• of the components

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THE CMS ALIGNMENT SYSTEM

• Alignment scheme

3
THE CMS ALIGNMENT SYSTEM

• Alignment scheme

4
MUON ALIGNMENT SYSTEMORGANIZATION AND
PARTICIPANTS

• Internal Barrel Internal Endcap Link system
• CERN (CMT) USA SPAIN
• Hungary (Debrecen) FERMILAB CIEMAT (Madrid)
• Kossuth L. Univ. North-Eastern Univ. IFCA
  (Santander)
• ATOMKI
• Austria (Vienna)
• HEPHY Inst. Fur H. der OAW
• Pakistan (Islamabad)
• Optics Labs.

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Link Tracker - Muons

• Working principle
• Translates Tracker co-ordinates (points, f
  angles) to the linking points in the external
  MABs
• The tracker co-ords are defined by the internal
  tracker alignment at the TK ends (TK alignment
  wheels)
• The MAB linking points serve for Barrel and
  Endcap connection to the Tracker
• Each 1/4 f plane is generated independently. The
  whole system is constrained at the TK volume
• Points (3D co-ords) are measured with laser beams
  semitransparent sensors for the co-ords
  perpendicular to the beams, and by mechanical
  tubes and proximity sensors for the co-ords along
  the beams
• The f angle is measured at each structure (TK
  wheel and MABs) by Laser Level units
• Measures directly ME1/2 chambers (CSCs crossed by
  a secondary link line) and the ME1/1 CSC disk
  (using a ME1/1 transfer platform to bend by 90
  the laser beam)

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Barrel muon alignment

• Working principle
• 36 rigid mechanical structures called
• MABs are holding TV-cameras
• (typically 10 cameras/MAB). These
• cameras are observing LEDs
• mounted on both sides of the barrel
• muon chambers ( 40/chamber) and
• on the so called Z-bars (the reference
• in Z-direction).
• A high level of redundancy is
• achieved by multiple observations
• and loops which make the system
• robust and reliable.
• The barrel system is connected to the
• TK via linking lines.

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Endcap muon alignment

• Connect Endcap CSCs to Tracker
• Tracker co-ordinates (points, f angles) from the
  MAB modules (via link system)
• 6 axial lines (transfer lines) pass through the
  MABs and run outside each CSC station
• Connection between axial lines and SLMs on
  transfer plates.
• Z distance measured by mechanical tubes and
  optical gap sensors
• Radial measurements from transfer plates to CSCs
  by potentiometers
• CSCs alignment design
• 3 laser lines per CSC station (SLM) are linked to
  the axial transfer lines
• SLM measures location of CSCs (on 1/6)
• SLMs are 60 degrees apart, mount on CSCs at same
  point on each chamber
• Precise location of sensors on CSCs using
  internal calibration and photogrammetry
• Precise relationship of strips, alignment pins,
  and sensors on CSCs

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Endcap muon alignment Transfer lines and Z
measurements
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Endcap muon alignment SLMs
ALIGNMENT SCHEMATICS
Transfer Sensor
Transfer Laser
EMU Transfer line


M
M
1
2

SLM Laser
P
1
Transfer Plate
MAB
SLM sensor
LHC Beam
CSC
CSC SLM-line
2-D
P
2

sensor
Transfer Plate
EMU Transfer line
Alignment Schematics. Only one transfer laser is
shown, at the top-left corner, defining the EMU
transfer line. Similarly for the SLM line, only
one laser beam, coming from the top is shown. The
other laser beams coming from the opposite
directions have been omitted for clarity.
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Barrel alignment status

• Mechanics MABs and LED holders
• Minimal system test
• Readout electronics

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MAB Modules (External MABs)

• Barrel cameras
• Link sensors
• 
  Endcap transfer sensors

12
MAB development

• Aluminum prototype used for first tests.
• New prototype under construction (Portugal)
• Glass fiber 1.5 1 m2
• Study deformations at the junctions (data by
  June) Þ define final geometry and materials
• 3D design of the different MAB structures most
  of integration problems (inside the Mu-detector
  and at boundary region) have been identified.

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LED holders in the MB chambers

• - Four forks /chamber
• - Each fork
  instrumented with 10 LED (4/6)
• - LED
  positions within the holder
• 
  
  16 mm (x,y), 60 mm
  (z)
• 
  Total number of
  LED 10000
• 
  - Mounting of
  precalibrated forks and LED driver
  electronics during chamber assembly at the
  production sites.
• -
  Calibration of each chamber at Cern before
  installation in the detector
• 
  Estimated
  calibration precision
• 55-65 mm (x,y) 470 mm (z)

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LED Holder mechanical repeatability

• Deviation wrt to a mean of a series of
  position-reposition tests

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• BARREL alignment stand (CERN ISR I4-hall)
• Layout of the Minimal test of the barrel
  alignment disposition of alignment
• components as for the central muon barrel wheels

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Minimal barrel test results Accurate
reconstruction of LED positions with a floating
calibrated MAB referenced by external system

• s(D5) 18 mm
• s(D4) 38 mm
• s(M5) 11 mm
• s(M4) 25 mm
• s(G5) 20 mm
• s(G4) 52 mm

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Readout electronics
Control room

• Bla bla...

Slow control
Ethernet
MAB
Chamber
Slow control for barrel muon chambers
Board computer
AMPRO Littleboard P5i (PC104 type) 146x203x30 mm3
CAN

• 100/166 MHz Pentium processor
• PC/AT compatible system on a single board
• Up to 128M bytes onboard DRAM
• PC/104 with PCI extension
• Floppy, IDE, EPP, Parallel, 4 Serial ports
• PCI UltraSCSI
• PCI Super VGA LCD/CRT local bus controller
• with GUI accelerator
• High speed Ethernet LAN interface
• Extensive embedded feature set ruggedized
• BIOS, bootable solid state disk,
• watchdog timer, powerfail NMI, locking I/O
• connectors, Advanced Power Management
• Small size 5V only operation, low power
• requirement, extended temperature operation

I2C
Barrel muon chamber slow control unit
Temperature Sensors (4 to 16)
MAB - LEDs (0 to 20)
Z bar - LEDs (0 to 4)
Cameras (16 to 24)
4 LED holders (lt20 LED-s/holder)
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Minimal barrel test results Accurate
reconstruction of LED positions with a floating
calibrated MAB referenced by external system

• s(D5) 18 mm
• s(D4) 38 mm
• s(M5) 11 mm
• s(M4) 25 mm
• s(G5) 20 mm
• s(G4) 52 mm

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Readout electronics
Control room

• Bla bla...

Slow control
Ethernet
MAB
Chamber
Slow control for barrel muon chambers
Board computer
AMPRO Littleboard P5i (PC104 type) 146x203x30 mm3
CAN

• 100/166 MHz Pentium processor
• PC/AT compatible system on a single board
• Up to 128M bytes onboard DRAM
• PC/104 with PCI extension
• Floppy, IDE, EPP, Parallel, 4 Serial ports
• PCI UltraSCSI
• PCI Super VGA LCD/CRT local bus controller
• with GUI accelerator
• High speed Ethernet LAN interface
• Extensive embedded feature set ruggedized
• BIOS, bootable solid state disk,
• watchdog timer, powerfail NMI, locking I/O
• connectors, Advanced Power Management
• Small size 5V only operation, low power
• requirement, extended temperature operation

I2C
Barrel muon chamber slow control unit
Temperature Sensors (4 to 16)
MAB - LEDs (0 to 20)
Z bar - LEDs (0 to 4)
Cameras (16 to 24)
4 LED holders (lt20 LED-s/holder)
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Barrel alignment summary

• Prototypes of components exist
• Mechanical design of LED holders and video
  cameras is ok
• Final MAB design under development
• Neutron irradiation of the opto-electronic
  components up to highest barrel doses (fluences
  2.6 1012 n/cm2) ok
• Magnetic field tests (up to 1T) of cameras, LED,
  and board computer prototype ok
• Readout electronics (prod. version) under
  development
• DAQ Software test version ready
• First test of the system concept ok consistent
  with expectations
• Full simulation of system performance (as for the
  TDR)

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Endcap alignment status

• Mechanical progress
• Sensor developments
• DAQ and software

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Mechanical progress and Sensor technology

• Layout
• Most conflicts resolved
• Required some changes to the disk and cart
  designs
• SLM lines change z position due to RPC chambers
  layout
• Mount positions on CSCs defined Prototype mount
  plates and towers constructed for ME23/2 chamber
• Roughly 50 of transfer plate production drawings
  finished
• Sensor development
• The SLM design requires up to 10 sensors in line
  
• ALMY Semitransparent a-Si sensors (see later)
• DCOPS Digital CCD optical position sensor
• 4 linear CCDs mounted in a window frame
  cross-hair laser beam
• Readout with DSP processor and serial I/O
• Good test results on resolution stability
• Radiation test Test CCDs in 4 MeV proton beam
  (neutron fluences of 1.3 1013 n/cm2 Þ Present
  version of the CCD and readout are acceptable
  (safety factor 3)

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DCOPS sensor board
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DCOPS neutron irradiation
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CCDs neutron irradiation
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DCOPS neutron irradiation

• bbb

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Endcap DAQ and Software

• DAQ system (C in window98 env.) has two
  branches
• DCOPS readout chain
• Line of DCOPS boards read out through serial
  interface
• 1 serial processor / disk
• (Note that the read-out DAQ will be very much the
  same for DCOPS and ALMY)
• HP readout chain
• HP readout unit contains all multiplexers,
  switches and signal conditioning hardware
• 1 HP readout unit /disk
• Two steps offline analysis
• FLAP (First Level Analysis Program, C, OO
  design on UNIX platform )
• Takes raw data from DAQ as input and fits data to
  find centroid in CCD pixel numbers.
• Convers HP DC voltage read out appropiate
  position and temperature units
• SLAP (Second Level Analysis Program)
• Takes FLAP output as input and converts the CCD
  centroid pixel numbers to the real space
  positions using the position calibration
  constants
• .... Design in progress

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Link system status

• Mechanical progress
• Sensor developments (ALMYs and Laser Level)
• DAC system and Software

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Mechanical progress

• Layout
• Mechanical drawings in the endcap/barrel region
  (MAB and ME1/2) ready
• ME1/1 transfer and mounts on ME1/1 CSCs prototype
  drawings exits
• Re-design of the h 3 region in accordance with
  the EE calorimeter support
• TK region in standby ... (position and size of
  passage re-defined for new geometry)
• Complete prototypes for the ISR tests (tests of
  mechanical behaoivor)
• Laser box, Laser Level, distance meas
  (mechanical tube optical and potentiometers),
  periscope -short size, 40 cm-, DPSDs mounts,
  re-positionings platforms
• .

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Sensors develpoment (1)

• ALMY Semitransparent a-Si sensors
• Performance
• Linearity and resolution 5 mm
• Sensor fiducilization 1 mm (2D configuration)
• Radiation hardness
• - g (CIEMAT) up to 10 Mrad ok
• - n (ATOMKI) total fluence 1015 n/cm2 ok
• - p (24 GeV/c PS CERN) total fluence 1013
  n/cm2 sensors still cooling down ...
• Optical properties gt75 transmission
• Serial readout electronics
• New prototypes development
• Stuttgart succeeded to produce test structures
  with dark currents as low as required. They
  proceed now with the fabrication of the first
  set of complete test sensors with final layout
  and bonding pads until beginning of July.
• This effort is carried out -within CMS- by
  Spain. It is done in collaboration with the MPI
  (Munich), institute involved in the alignment
  of the muon chambers of the ATLAS experiment.
• Minnesota produced (by Feb 2000) two complete
  prototypes (with identical geometry as the old
  EGG sensors). Their optical and electrical
  properties have been studied at CIEMAT-Madrid.
• The electrical test was not satisfactory the
  sensors did not show the typical diode curve.
  Instead, they yield IV curves rather symmetric
  with respect to the (0,0) point which correspond
  to two mutually inverted Schottky barriers.
  This behavior was understood given the high
  symmetry of the structure (ITO/intrinsic
  a-Si/ITO) of the prototypes. Two lines of
  actions have been identified for the new
  prototypes to be built.
• The optical test was instead rather
  satisfactory. The measured transmission for both
  devices was over 75 and quite flat over the
  whole working region (wavelength 750-900 nm).
• New prototypes ( 8 units) will be ready by
  summer. We will be testing mainly the electrical
  properties of the junction and charge division
  between strips, given that the optics is already
  properly understood.
• This effort was supported -within CMS- by US
  and Spain until beginning of 2000. It will
  continue mainly by Spanish institutes.

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Semitransparent aSiH sensors (ALMY)

• Thickness aSi 1 mm
• Thickness electrodes 100 nm
• Thickness glass substrate 500
  mm
• Number of electrodes 64 horizontal, 64
  vertical
• Active area 20 mm 20 mm
• Strip pitch 312 mm
• Low Hall mobility Þ B field insensitive
• Amorphous Si Þ Rad. hardness
• Glass substrate Þ Multi-point meas.
  

19 mm dia.
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Sensors develpoment (2)

• Laser Level units
• Consist of
• A laser source a tiltmeter (AGI and AOSI) one
  or two dimensional
• Performance
• Linearity and resolution 10 mrad (independent
  tilt calibration)
• Stability of the assembly lt5 mrad
• Radiation hardness and insesitivity to B to be
  tested
• - From manufacters (AGI) ok up to 10 Mrad g
  doses
• 
  insensitive to uniform fields, and ok up to 80
  gauss/mm

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Tiltmeter (AGI-756) calibration linearity,
resolution and stability
V(mV) 460.35 mV/mrad ?(mrad) - 16.39 mV
After stabilization ? 1.9 ?rad TOTAL 6.7 days
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Laser level calibration and mechanical stability
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DAQ and Control system Software

• DAC configuration
• Level 1 includes sensors and local electronics
  boards(LEB)
• LEB microcontroler with flash program memory and
  data memory CAN controler chip
• The microcontroler is equiped with ADC
  convertors to handle the signal coming from the
  diferent sensors used (temperatutre, DPSD,
  tiltmeters,..), a serial port, timers for signal
  generation and several digital I/O ports to
  control the 2D position sensors.
• It will perform basic treatment of the signals
  (center of gravity, gaussian fits..)
• At the moment each LEB handles up to 4? sensors
  (any type) sitting at lt xx m from the actual
  devices.
• Level 2 comunication via CAN bus between L1 and
  industrial PC
• Each LEB comunicates via CAN bus protocol with
  the PC using a Main Controler Interface (a CAN
  controler board with two ports) placed in the PC
• PC for data storage and processing
• Level 3 comunication via Ethernet between
  align. PC and Detector Control System (DCS)
• Software
• Level 1 LabView (programming graphic platform)
  for data acquisition and control. Fully developed
  for system tests
• Level 2 CMS OO code for optical alignment
  (COCOA). Simulation and reconstruction
  package.(ISR version available)

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Planned activities (Y2000)

• Complete test with Link system, Barrel and Endcap
  alignment (ISR-I4)
• The installation of components and DAQ started
  last week (May 10th)
• 5 weeks for individual calibration of parts
• First common data taking by 20 June.
• The full setup will stay in place up to end of
  the year
• EDR foreseen for October
• Endorse the general scheme
• LED holders for the DT chambers first to go into
  production

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