Sin ttulo de diapositiva

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A dissertation presented to obtain the degree of
Doctor of Philosophy in Physics
Marcos Fernández García
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After LEP the next energy scale to explore lies
within the TeV range
7 on 7 TeV proton beam collisions
8 straight sections (528 m/section)
2 High L collision points CMS ATLAS 2 Lower
L ALICE Pb LHC B
2835 bunches, 1011 particles/bunch, 25 ns Xtime,
20 int/crossing
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One of the 2 general purpose LHC detectors
Design presented first at LHC Workshop (Aachen,
1990)
DESIGN FEATURES
1) Very good lepton (?,e) measurement
2) Robust secondary vertex
3) High hermeticity
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SM Higgs
B physics
? Mass value not predicted by theory 114 lt MSMH lt
236 GeV (95 C.L.) CMS goal is to scan up to 1
TeV Higss masses
? CMS will study CP violation, B0s mixing, rare
decays ...
SUSY searches
? Promising signatures
SM known to be incomplete (mH divergence, no
unification of forces) SUSY solves these
problems. In the MSSM the Higgs sector extends to
5 particles. Again, most important signatures
are leptons and b-quarks.
H ? ?? (MH ? 150 GeV) Demands ????1 GeV and ?0
rejection H ? WW- (130 ? MH ? 200 GeV) Central
distribution of gg scattering than bckgd. 5?
after 5 fb-1 H ? ZZ (MH ? 2mZ) Detection
combines CT, Calorimeters, ?-Chambers H ? ZZ
(MH gt 2 mZ)
and yet able to explore other searches beyond
the SM as Technicolor signals, new gauge bosons,
excited quarks...
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pT measurement related with bending
Radious of curvature ? can be obtained from the
measurement of the sagita after traversing
distance d
Tracking detectors involved Silicon and Muon
spectrometer
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? New layout after Dec. 1999
? Mechanically divided into TIB 4 layers, shell
mechanics TOB 6 layers, rod mechanics TEC 9
big, 3 smaller disks, panels
? Double sided modules faked using two single
sided, (rear tilted 100 mrad)
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? Identification, trigger and muon momentum
measurement
Layer cells array Superlayer 4
layers Muon Chamber 3 superlayers
swire lt 250 ? 100 mm swire plac 300 mm
schamber (100 mm Rf, 150 mm Z)
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Three methods to measure the momentum CT alone,
MS interaction vertex, CT MS
MS interaction vertex
CT MS
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Muon chambers rest on return iron yoke Expected
cm movement when magnet on/off T changes,
humidity
Detectors position changes ? Positon need to be
monitorised
Maximum misalignment to avoid degradation on pT
measurement
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? CMS alignment is organised in TK alignment,
Muon system alignment and Link system
Alignmenttasks ? Internal TK alignment ?
Internal Muon Barrel alignment ? Internal Endcap
alignment ? Link system to relate TK and Muon
Spectrometer
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Tasks of TK alignment
? TKAL uses Si-modules as alignment sensors and
Tracks to achieve 10 ?m align. accuracy
? Independent alignment of Ecs. Monitoring 50
petals, rest using tracks overlap
? Relative alignment of ECs
? Relative alignment of ECs w.r.t. Inner and
Outer Barrel
? Provide Link with 6?2 beams of known position
and orientation
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? Measures position of chambers w.r.t each other
? MS monitoring wrt network 36 MABs. 6 RZ active
planes, 6 passive planes
? Connections by light sources in frames
Precalibration
Outside Fiducials
Sources
Wires
60 ?m R? 300 ?m Z
50 ?m
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? (?,R) transfer via Transfer Line
? 3 SLM perpendicular to TLs Rest through ?
overlap
? Z measurement Proximity sensors ? R
measurement Cable extension linear
potentiometer ? Simulation ?CSC 200 ?m, rest
through ? overlap
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? Transports CT coordinate system to Muon Chambers
? Six 1/4? planes every 60 degrees ? reference
of each barrel sector to CT
? Layout accommodates to detector geometry
? 2 laser sources generate 3 beams each
? Light Beams seen by 2D sensors
? Periscopes embed beam within TK
? ? coordinate measured using tiltmeters
? Proximity sensors coupled to CF tubes used for
(Z,R) measurements. Tubes protect light path
? System performance guaranteed once all sensors
in range
? System can be switched on/off
(X,Y)
2D
Z
Proximity
? Full Simlation with reasonable set of inputs
gives ?R?? 150 ?m
?
Tiltmeters
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? 2D signal integration allows position
calculation
? CMS and ATLAS alignment systems request 5 ?m,
5 ?rad
? Easy to integrate solution for
multipoint alignment problems
? Spot position calculation Gaussian mean or
Centroid. Equivalent for true Gaussian beams
? Characterization comprises Linearity
studies, Deflection, Ageing 2D mapping of
relevant magnitudes needed
? 64 ? 64 crossings act as 6464 strip photodiodes
? Signal is integrated by each strip
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Laser diodes or HeNe Very Good poinintg
stability Very stable setups, Shielded meas.
Very Good S/N
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Oscillations on top of linear slope
Different lines ? Different patterns
No correlation between linearity and deflection
patterns
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?x ? 4.1 ?m ?y ? 4.6 ?m
SET II
?x ? 7.1 ? 3.0 ?m ?y ? 5.8 ? 1.8 ?m
Coated sensors SET III
?x ? 4.0 ? 0.4 ?m ?y ? 2.9 ? 0.7 ?m
Coated sensors
SET IV
?x ? 4.4 ? 1.0 ?m ?y ? 13.7 ? 7 ?m
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WEDGE
Layer Interferences
Curved substrate Slope
CURVED SUBSTRATE
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Correction D gt 1 m
5 ?rad required
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? Alternative correction method Provided
amplitude of oscillations is small, a quadratic
fit of the deflection distribution is a good
correction method.
? a x2 b y2 c xy d xe y f
? Even more valid for coated sensors, were
patterns show no oscillations
Coated sensors SET III
?x ? 2.2 ? 0.6 ?rad ?y ? 2.2 ? 0.7 ?rad
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Nr(till)N0NN-
(e-,h) creation ? Power (G)
New d.b. inhibited by ner of existing ones (self
limiting)
Nr3(till) Nr3(0) C(At) G2 till
Note Csw independent of incoming photon energy
???600,1000? nm
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Ageing plus daylight also studied Effect 5 times
faster
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SPATIAL UNIFORMITY ? 2 ?m
UNCORRECTED Beam deflection ? 2 ?rad
Transmittance above 80
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Twofold Simulation Aim i) Provide an
explanation for the observed sensor systematics
ii) Being able to define repeatable
configurations ensuring maximum T for balanced
sensor response.
Hypothesis Interferences rule sensor operation ?
Calculation of T ?R? curves
N n - i k
E1 M1 M2 M3 Mq Eb
M?M(Ni,di)
? Non-infinite substrate must be included in
simulation
? (N,d) difficult to be measured. T and R are
easily measured
We have developed a calculation method which
provides knowledge of (N,d) of a multilayer, once
T and/or R are measured.
? (N,d) calculated via ?2 minimizations
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Data
Na-SiH measured ? ? ?690,900 ? nm
T vs ?
Two thickness measurements (_at_centre,_at_extreme)
Origin of differences is the deposition process
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Data
No NITO was measured
Only NITO _at_ 650, 700, 750, 800 nm
T vs ?
Iteration
dITO 47.2 nm
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T and R
Sensor Understood
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Optimal configuration Tolerance
Tthreshold gt 79 ? (?1,?2,?3) ( 12,12,12) nm
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Most critical CMS coordinate ? will be measured
using TILMETERS (TmT)
Tiltmeters, clinometers, tiltsensor are
equivalent terms
Measure angle (w.r.t gravity) of the elements to
which they are attached
Simulation ?TK-MS ? 20 ?rad ??? ? 15 ?rad
Studied TmT from A.G.I. and A.O.SI.
AGI SCU (AC?DC), up to 50 m cable in between,
AOSI, integrated SCU
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? TmT come calibrated from manufacturer. Prior
to utilisation we re-calibrated them. We WANT
LINEAR and PRECALIBRATED sensors.
? Calibration Find relationship between angle
moved in plane XZ and output voltage
? TmT 1D sensors, 3D objects
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?
? ? Angle tilted by tripod TmT employed to
calculate this angl.e
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? ? True angle tilted by TmT
?? ? ? ? ? ? arc sin ( cos ? ? sin ? ? sin ?
sin ? ? cos ? )
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? Approximating ? in ???-???????? deg V V0k
sin ? ? k sin2 ? ?2
Not possible to calculate k and ? in single
fit (k,?) from fit will always be correlated
? Proper calibration of the sensor demands
misalignment to be known
AGI controls ?calibration to 1 deg ? k AGI can
be trusted
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Laser Level (LL) is the junction of TmT and
ALMYlaser systems
? ? TmT reading when TmT ? g
? ? Angle of laser beam w.r.t. Horizontal when
TmT angle is ?
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Values (???)(-750.7?1.4,-39.3 ? 0.6) ?rad
measured
We detected a combined tilt since ??????-27 ?rad
most probably due to mechanics
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10 years
Highlights
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Sensors not powered during tests
Measuring optical properties after each
iteration. Also response to white light recorded
for Schottky
? irradiation Steps of 100 Gy, 10, 15, 20
kGy Velocidad de gamma?
n irradiation
? Fast n source based on the MGC-20 cyclotron
_at_ ATOMKI (Debrecen, Hungary)
? Fluence 1.1?1015n/cm2 ? 10 years flux
1.6?109 cm-2 s-1
? Steps 1.1 ? 1014,1015
Scans utilised
Halogen lamp diffuser
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DEFX
T
DEFY
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After 200 Gy MUX SILICONIX DG406 (161)
malfunctioned.
Resistors and capacitors survived
Sensors illuminated using uniform white light,
irradiance 0.16 mW/cm2
After
10 degradation
10 kGy photons
20 further degradation
1014 n/cm2
1015 n/cm2
15 further degradation
Response degradation
T yet comparable to other samples
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? ? rays (1.17 MeV, 1.33 MeV) 60Co 3 kGy/hour _at_
NAYADE (CIEMAT)

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? RC and ARC increase R and T of materials,
respectively
? Coating performance should remain independently
of radiation dose
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? We have introduced the LHC machine and the CMS
experiment as the collider machine and particle
physics experiment of a new generation
? To fulfil physic goals, stringent performance
in lepton measurements are needed. For muons,
this demands a knowledge of the detector
positions comparable to detectors intrinsic
resolution. This can be achieved by the hardware
alignment system described.
? Alignment tools are laser beams, position
detectors (that give true spatial information of
the beam coordinates), tiltmeters (to measure
orientation), distance-meters and temperature
probes. All components should cope with radiation
environment and space constraints.
? ALMYs are an innovative solution for alignment
strategies. They are transparent allowing a
multipoint alignment easy to implement.
? Our tests of ALMY sensors have shown that
their spatial resolution is better than5 ?m,
which matches alignment requirements.
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? We have studied and understood the effects
associated with the detection and transmission of
the light through the sensors, and have developed
a method to correct these effects. The systematic
contributions observed in the traversing beam
were factorised. The oscillations were due to
interferences in the multilayer structure, while
the non-constancy of the deflection angle was due
to the curvature of the substrate. New sensor
designs have overcome this problem by using
highly parallel glass substrates.
? A simulation of the T and R of the ALMY
multilayer allowed to identify interferences as
the physical process which rules the functioning
of the sensor. In order to get this conclusion we
had to develop a method to obtain information of
the multilayer stack from T and R curves. This
modelisation also allowed us to optimise the
sensor design parameters to match our needs.
? As another key element of the alignment system,
tiltmeters were tested in depth. We developed a
geometrical characterisation of the tiltmeter
measurement process. We have stablished the
variables that should be taken into account to
obtain maximum performance of the sensors. We
have identified sensors with adequate performance
that can be implemented in the system.
? Laser Levels are natural extensions of the
tiltmeter measurement for extended structures.
We have built and studied a prototype that shows
the good performance.
? Alignment components have been irradiated.
Radiation hard optical materials (BK7-G18,
synthetic qurtz) have been identified. The
radiation endurance of ALMY sensors for 10 years
of CMS operation has been demonstrated.
? With these studied components we have made a
real scale test of the Link system were we have
been able to obtain the expected performance of
the system.