a dissertation presented to obtain the degree of doctor of philosophy in physics centro de...
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A dissertation presented to obtain the degree of Doctor of Philosophy in Physics
Centro de InvestigacionesEnergéticas, Medioambientalesy Tecnológicas
Marcos Fernández García
2835 bunches, 1011 particles/bunch, 25 ns Xtime, 20 int/crossing
7 on 7 TeV proton beam collisions
8 straight sections (528 m/section)
2 High L collision pointsCMS & ATLAS2 Lower L
ALICE Pb & LHC B
After LEP the next energy scale to explore lies within the TeV range
One of the 2 general purpose LHC detectors
Design presented first atLHC Workshop (Aachen, 1990)
DESIGN FEATURES1) Very good lepton
(,e) measurement
3) High hermeticity
150 institutions 2000 scientists
International collaboration
2) Robust secondary vertex
Mass value not predicted by theory114 < MSM
H < 236 GeV (95 % C.L.)CMS goal is to scan up to 1 TeV Higss masses
H (MH 150 GeV)Demands 1 GeV and 0 rejection
H W+W- (130 MH 200 GeV)Central distribution of gg scatteringthan bckgd.5 after 5 fb-1
H ZZ* (MH 2mZ)Detection combines CT, Calorimeters, -Chambers
H ZZ (MH > 2 mZ)
510L pb-1 5
pb-1 5 410L
Promising signatures:
SM Higgs
… and yet able to explore other searches beyond the SM as Technicolor signals, new gauge bosons, excited quarks...
CMS will study CP violation, B0
s mixing, rare decays ...
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.
B physics:
SUSY searches:
pT measurement related with bending:
T3.0GeV/cB
Tpm
Radious of curvature can be obtained from the measurement of the sagita after traversing distance d:
sd8
2
Tracking detectors involved: Silicon and Muon spectrometer
New layout after Dec. 1999
Mechanically divided intoTIB: 4 layers, shell mechanicsTOB: 6 layers, rod mechanicsTEC: 9 big, 3 smaller disks, panels
Double sided modules faked using two single sided, (rear tilted 100 mrad)
wire < 250 100 mwire plac = 300 m
chamber = (100 m R150m Z
Layer = cells array Superlayer = 4 layersMuon Chamber = 3 superlayers
CSC= 75 m ME1, 150 m rest
Seven panels, wires doubly woundedin three.
Multiwire proportional chambers.Avalanche developed in a wire induces on cathode an electrostatic charge.
Identification, trigger and muon momentum measurement
Three methods to measure the momentum: CT alone, MS + interaction vertex, CT + MS
MS + interaction vertex CT + MS
Muon chambers rest on return iron yokeExpected cm movement when magnet on/off T changes, humidity
Detectors position changes
Positon need to be monitorised
Maximum misalignmentto avoid degradation on
pT measurement
R = 150-350 m, MB1-MB4
R = 75-200 m, ME1-ME4
R,Z coordinates at the mm level
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
Tasks of TK alignment:
Provide Link with 62 beams of known position and orientation
Independent alignment of Ecs. Monitoring 50% petals, rest using tracks overlap
Relative alignment of ECs
TKAL uses Si-modules as alignment sensors and Tracksto achieve 10 m align. accuracy
placement = 50 m, Si-mod
100 m + Track fits = 10 mTKal
Relative alignment of ECs w.r.t. Inner and Outer Barrel
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
Wires OutsideFiducials
SourcesPrecalibration
60 m R300 m Z
50 m
ExpectedBarrel Alignment
performance
< 150 mR
WithinSector
< 210 mAdyacentSectorsR
(,R,Z) alignment relies on MAB rigidity. Connection to CT via active MABs
Simulation: alignment error CSC resolution ( pT > 100 GeV)
(,R) transfer via Transfer Line
R
Z
3 SLM perpendicular to TLsRest through overlap
R
Z
Z measurement: Proximity sensors R measurement: Cable extensionlinear potentiometer Simulation: CSC= 200 m, rest through overlap
R
Z
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
System performance guaranteed once all sensors in range
System can be switched on/off
Proximity sensors coupled to CF tubes used for (Z,R) measurements. Tubes protect light path
coordinate measured using tiltmeters
Full Simlation with reasonable set of inputs gives R 150 m
(X,Y) 2D
Z Proximity
Tiltmeters
Sensors
2D position sensing detectors: ALMYsTiltmeters for measurementProximity sensorsTemperature sensorsTracker Si-modules
Optomechanical Components
Light sourcesPeriscopesME1/1 Transfer Plate
2D signal integration allows position calculation
Spot position calculation: Gaussian mean or Centroid. Equivalent for true Gaussian beams
Characterization comprises: Linearity studies, Deflection, Ageing2D mapping of relevant magnitudes needed
Signal is integrated by each strip
64 64 crossings act as 64+64 strip photodiodes
CMS and ATLAS alignment systems request 5 m, 5 rad
Easy to integrate solution for multipointalignment problems
Experimental Facilities:
UC ground floor isolation, L-shaped granite bench
dark room, T=0.1 C
MPIMassive granite benchShielded SetupsHigh T stability
Batches of sensors tested
Set I:
Set II:
Set III:
Set IV:
Santander, commercial, 7 sensors
13 sensors
15 sensors, coated
10 sensors, coated, commercial electronics
Laser diodes or HeNe Very Good poinintg stabilityVery stable setups,Shielded meas.: Very Good S/N
Different Systematics from line to line
Platform effect discarded
Different sensors Different patterns
We call it:
INHOMOGENEITY PATTERN
Oscillations on top of linear slope
Different lines Differentpatterns
No correlation between linearity and deflection patterns
We call it:
DEFLECTION PATTERN
Spatial resolution:
residuals Minimum displacement sensor can resolve
x 4.1 my 4.6 m
x 4.0 0.4 my 2.9 0.7 m
Coated sensorsSET III
x 4.4 1.0 my 13.7 7 m
SET IV
SET II
x 7.1 3.0 my 5.8 1.8 m
Coated sensors
CURVED SUBSTRATE
WEDGE
Layer = Interferences
Curved substrate = Slope
Interferentialpatterns
Bulk deflection: n,d
Oscillations: interference
Slope: Substrate curvature
< 175 rad
20
rad
5 rad required
TRANSMITANCE = (21.9 1,1)% @ = 632.5 nm = (57.2 1,6)% @ = 686 nm
2D scan calibration
Matrix xy
New measurement corr current - xyPro
ced
ure
Correction D > 1 m
x 2.2 0.6 rady 2.2 0.7 rad
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 x+e y+ f
1600 precalibrated nodes
12 parameters
Even more valid for coated sensors, were patterns show no oscillations
SET II
x 4.6 1.9 rady 4.8 2.0 rad
Coated sensorsSET III
SET IV
x 4.0 1.6 rady 6.5 1.2 rad
Coated sensors
Nr(till)=N0+N++N-
(e-,h) creation Power (G)
New d.b. inhibited by ner of existing ones
(self limiting)
Nr3(till) = Nr
3(0) + C(At) G2 till
rNGBph ph
G
till
Effects reversibleby annealing
annteindNanntN )0()(ind
Note: Csw independent of incoming photon energy 600,1000 nm
Systematic tests performed on 4 coated sensors
P = 0.9 mW (115 mW/cm2), = 780 nm
Scanned before the test and every 24 hours
PR reduction 2-3% (5 m) for 500 hours
Double CMS or ATLAS operation time
Fit to SW theory performs well
Ageing plus daylight also studied: Effect 5 times faster
SPATIAL UNIFORMITY 2 m
UNCORRECTED Beam deflection 2 rad
Transmittance above 80 %
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
MM(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.
2 = w1 T2 + w2 R
2 +
w3 2n + w4 2
k +
w5 2n + w6 2
k + w7 (6-n)2 + w8(1-n) + w9(1-k2) + w10 k 2
Measured dataMonotonous (n,k)ni ni-1 , ki ki-1 Reasonable index limits
(N,d) calculated via 2 minimizations:
Na-Si:H measured 690,900 nm
Data:
%T vs
Two thickness measurements (@centre,@extreme)
pin a-Si:H layer(JENOPTIK)
Origin of differences is the deposition process
No NITO was measured Data:
Only NITO @ 650, 700, 750, 800 nm%T vs
2 method applied to the 4 tabulated values dITO
(n,k) calculated from TdITO recalculated
dITO = 47.2 nm
No oscillations Thin layer
Itera
tion
Na-Si:H for pin layer on glass (NITO , dITO) thin layer on glass
N values fitted tocontinuous functions
di left free
Startingvalues
(100,1000,100)
%Tand%R
Sensor
Understood
d0= (103,1056,73) nm
dopt= (109,1113,106) nm
T 35 % due to )2,:,1( ITOdHSiadITOdd are possible
Maximum %T compatible with balanced signal requested
Designs tolerance must be calculated
Optimal configuration Tolerance:
Tthreshold > 79% (1,2,3) = ( 12,12,12) nm
Most critical CMS coordinate will be measured using TILMETERS (TmT)
Tiltmeters, clinometers, tiltsensor are equivalent terms
Simulation: TK-MS 20 rad 15 rad
Studied TmT from A.G.I. and A.O.SI.
AGI SCU (ACDC), up to 50 m cable in between, AOSI, “integrated SCU”
Measure angle (w.r.t gravity) of the elements to which they are attached
TmT come calibrated from manufacturer. Prior to utilisationwe 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
v represents the TmT
represents a wedge
( Z , v ) Angle TmT vs gravity. Calculating the complementary
is the misalignment
True angle tilted by TmT
arc sin ( cos sin sin + sin cos )
arc sin ( cos sin sin + sin cos )
Angle tilted by tripodTmT employed to calculatethis angl.e
We always consider the misalignment in the fits.
Is the calculated reliable ?V = V0 + k + k ’
2
= (84.70.6) deg
Approximating in - deg: V = V0+k 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
In a linear calibration is fixed. We can therefore calculate ratios of magnitudes involving .
2'2
2'42
sink
sinkksinksincalc
= moved - calc
AGI sensors suitable for our needs
AOSI sensors are discarded
AGI 1 resolution 3.3 rad
AGI 2 resolution 6.4 rad
AOSI´s resolution 30 rad (order 6 polynomials)
V = V0 + k () + k ’ 2 ()
Calibrated
Unknown
Extra equation needed!
Use 2 sensors undersame
Calibrate each sensor independently
Put them under ANY angle
Calibrate the “dual” device, and calculate 1c - 2
c
Start measuring
Recipe
V1 = V01 + k1 + k1 ’ 2
V2 = V02 + k2 + k2 ’ 2
From equations
From calibration
cos1
21cot1cotsin
sinCurrent misalignment
Former method applied to 2 AGI sensors
1 calculated and utilised to compute moved
Showing platform- moved
Provided misalignment < 4 deg, - < 15 rad
Laser Level (LL) is the junctionof TmT and ALMY+laser systems
TmT reading when TmT g
Angle of laser beam w.r.t.Horizontal when TmT angle is
Values ()=(-750.71.4,-39.3 0.6) rad measured
We detected a combined tilt since:-27 rad
most probably due to mechanics
TmT give local measurements
Measurement of large structures possible combining 2 simultaneous tilt-measuring systems
After 48 hours (4848)=(-723.01.2,-12.3 4.7) rad
15105.0 pbdtL per year at high Luminosity 109 interactions/second
c-Si detectors requested to be operational for 10 years. Same or higher endurance wouldbe desirable for alignment components
Highlights:
Position A1 A2 A3 LB A4 A5,A6Z(cm)R(cm)
Z=121R=22
Z averagedR=35
Z=121R=52
Z=121R=100
Z=666R=460
Z=666r400,700
Hadrons(E100 KeV)
(cm-2)1.6 1014 9 1013 4.7 1013 5 1013 5 109 5 107
Neutrons total(cm-2)
3.5 1013 8.5 1013 1.9 1013 5 1014 5 1011 5 1010
Absorbed dose(kGy)
67 36 19 100 10-3 10-3
10
years
DTs: Machine bckgd. most important at low L
Inner TK: Charged hadron Flux 1/r2, E < 10 GeVOuter TK: bigger n-fluence in last endcap disksECAL: n albedo produced in ECALHCAL: =3, 10 kGy/year, n-fluence 1014 cm-2
-rays and neutron irradiation of 2 ALMY sensorsSchottky + electronics
Bare pin sheetSensors 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 kGyVelocidad de gamma?
n irradiation
Fluence: 1.11015n/cm2 10 years flux = 1.6109 cm-2 s-1
En = 3.7 MeV
Fast n source based on the MGC-20 cyclotron @ ATOMKI (Debrecen, Hungary)
Steps 1.1 1014,1015
Scans utilised HeNe (633 nm), 2 ALMYs (D = 2.58 m)
1616 (1 mm pitch scan)
Halogen lamp + diffuser
DEFXDEFXDEFYDEFY %T%T
1014,1015 n/cm2
irradiation
After 200 Gy MUX SILICONIX DG406 (16:1) malfunctioned.
Resistors and capacitors survived
Sensors illuminated using uniform white light, irradiance 0.16 mW/cm2
After
1015 n/cm2
10% degradation
20% further degradation
15% further degradation
10 kGy photons
1014 n/cm2
Response degradatio
n
%T yet comparable to other samples
Transparent rhomboid prisms and right angle glued together
Attached to TK, splitter and mirror glued to fused silica bar
Link optics
T,R < 0.5 % forsynthetic quartz
rays (1.17 MeV, 1.33 MeV) 60Co3 kGy/hour @ NAYADE (CIEMAT)
BK7-G18 optical grade fused silica (synthetic quartz)
Stable
BK7: turned blackFused silica: turned gray
Irradiated;
RC and ARC increase %R and %T of materials, respectively
Coating performance should remain independently of radiation dose
Triple ARC on BK7-G18Dose: 100 kGy (10 years CMS)Negligible effect
Ag coating on back faceAl coating on front face
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.
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.
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.
Laser Levels are natural extensions of the tiltmeter measurement for extended structures. We have built and studied a prototype that shows the good performance.