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.