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Centro de Investigaciones. Energéticas, Medioambientales. y Tecnológicas. A dissertation presented to obtain the degree of Doctor of Philosophy in Physics. Marcos Fernández García. After LEP the next energy scale to explore lies within the TeV range. 7 on 7 TeV proton beam collisions.
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Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas A dissertation presented to obtain the degree of Doctor of Philosophy in Physics Marcos Fernández García
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
International collaboration 150 institutions 2000 scientists 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
pb-1 5 pb-1 5 SM Higgs B physics: Mass value not predicted by theory 114 < MSMH < 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 W+W- (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 > 2 mZ) … and yet able to explore other searches beyond the SM as Technicolor signals, new gauge bosons, excited quarks...
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
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)
Multiwire proportional chambers. Avalanche developed in a wire induces on cathode an electrostatic charge. Seven panels, wires doubly wounded in three. sCSC= 75 mm ME1, 150 mm rest Identification, trigger and muon momentum measurement Layer = cells array Superlayer = 4 layers Muon Chamber = 3 superlayers swire < 250 100 mm swire plac = 300 mm schamber = (100 mm Rf, 150 mm Z)
Three methods to measure the momentum: CT alone, MS + interaction vertex, CT + MS MS + interaction vertex CT + MS
R = 150-350 m, MB1-MB4 R = 75-200 m, ME1-ME4 R,Z coordinates at the mm level 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
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
placement = 50 m, Si-mod 100 m + Track fits = 10 m TKal 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 62 beams of known position and orientation
Expected Barrel Alignment performance Within Sector < 150 m R Adyacent Sectors <210 m R 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
(,R,Z) alignment relies on MAB rigidity. Connection to CT via active MABs Simulation: alignment error CSC resolution ( pT > 100 GeV) R R Z Z Z R (,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
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 2D (X,Y) Z Proximity Full Simlation with reasonable set of inputs gives R 150 m Tiltmeters
Sensors 2D position sensing detectors: ALMYs Tiltmeters for measurement Proximity sensors Temperature sensors Tracker Si-modules Optomechanical Components Light sources Periscopes ME1/1 Transfer Plate
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 64+64 strip photodiodes Signal is integrated by each strip
Set I: Santander, commercial, 7 sensors Set II: Batches of sensors tested 13 sensors Set III: 15 sensors, coated Set IV: 10 sensors, coated, commercial electronics L-shaped granite bench ground floor isolation, UC dark room, T=0.1 C Experimental Facilities: Massive granite bench Shielded Setups MPI High T stability Laser diodes or HeNe Very Good poinintg stability Very 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 We call it: DEFLECTION PATTERN Oscillations on top of linear slope Different lines Different patterns No correlation between linearity and deflection patterns
Spatial resolution: residuals Minimum displacement sensor can resolve 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
WEDGE Layer = Interferences Curved substrate = Slope CURVED SUBSTRATE
Bulk deflection: n,d Slope: Substrate curvature Oscillations: interference < 175 rad 20 rad Interferential patterns 2D scan calibration Matrix xy Procedure New measurement corr current - xy TRANSMITANCE = (21.9 1,1)% @ = 632.5 nm = (57.2 1,6)% @ = 686 nm Correction D > 1 m 5 rad required
1600 precalibrated nodes 12 parameters SET II x 4.6 1.9 rad y 4.8 2.0 rad SET IV Coated sensors x 4.0 1.6 rad y 6.5 1.2 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 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
G ph till Effects reversible by annealing Nr(till)=N0+N++N- (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
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) for500 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 %
2 = w1 T2 + w2 R2 + w3 2n + w42k + w52n +w6 2k + w7 (6-n)2 + w8(1-n) + w9(1-k2) + w10 k 2 Measured data Monotonous (n,k) ni ni-1 , ki ki-1 Reasonable index limits 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 E1 = M1 M2 M3 … Mq Eb MM(Ni,di) N = n - i k 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:
pin a-Si:H layer (JENOPTIK) Data: Na-Si:H measured 690,900 nm %T vs Two thickness measurements (@centre,@extreme) Origin of differences is the deposition process
No oscillations Thin layer 2 method applied to the 4 tabulated values dITO (n,k) calculated from T dITO recalculated Data: No NITO was measured Only NITO @ 650, 700, 750, 800 nm %T vs Iteration dITO = 47.2 nm
Na-Si:H for pin layer on glass N values fitted to continuous functions (NITO , dITO) thin layer on glass di left free Starting values (100,1000,100) %T and %R Sensor Understood
T 35 % due to are possible Maximum %T compatible with balanced signal requested Designs tolerance must be calculated d0= (103,1056,73) nm dopt= (109,1113,106) nm 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 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 (ACDC), up to 50 m cable in between, AOSI, “integrated SCU”
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
v represents the TmT ( Z , v ) Angle TmT vs gravity. Calculating the complementary represents a wedge is the misalignment Angle tilted by tripod TmT employed to calculate this angl.e True angle tilted by TmT arc sin ( cos sin sin + sin cos )
We always consider the misalignment in the fits. V = V0 + k+ k ’ 2 Is the calculated reliable ? = (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
AGI sensors suitable for our needs In a linear calibration is fixed. We can therefore calculate ratios of magnitudes involving . AOSI sensors are discarded = moved - calc AGI 1 resolution 3.3 rad AGI 2 resolution 6.4 rad AOSI´s resolution 30 rad (order 6 polynomials)
Calibrated Extra equation needed! V = V0 + k () + k ’ 2 () Use 2 sensors under same Unknown Recipe Calibrate each sensor independently Put them under ANY angle Calibrate the “dual” device, and calculate 1c - 2c Start measuring Current misalignment V1 = V01 + k1+ k1 ’ 2 V2 = V02 + k2+ k2 ’ 2 From calibration From equations
Former method applied to 2 AGI sensors 1 calculated and utilised to compute moved Showing platform- moved Provided misalignment < 4 deg, - < 15 rad
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 Laser Level (LL) is the junction of 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
per year at high Luminosity 109 interactions/second c-Si detectors requested to be operational for 10 years. Same or higher endurance would be desirable for alignment components Inner TK: Charged hadron Flux 1/r2, E < 10 GeV Outer TK: bigger n-fluence in last endcap disks ECAL: n albedo produced in ECAL HCAL: =3, 10 kGy/year, n-fluence 1014 cm-2 DTs: Machine bckgd. most important at low L 10 years Highlights:
Schottky + electronics -rays and neutron irradiation of 2 ALMY sensors Bare pin sheet En = 3.7 MeV HeNe (633 nm), 2 ALMYs (D = 2.58 m) 1616 (1 mm pitch scan) 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 @ ATOMKI (Debrecen, Hungary) Fluence: 1.11015n/cm2 10 years flux = 1.6109 cm-2 s-1 Steps 1.1 1014,1015 Scans utilised Halogen lamp + diffuser
irradiation 1014,1015 n/cm2 DEFX %T DEFY
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 10 kGy photons 10% degradation 1014 n/cm2 20% further degradation 1015 n/cm2 15% further degradation Response degradation %T yet comparable to other samples
Link optics Transparent rhomboid prisms and right angle glued together Attached to TK, splitter and mirror glued to fused silica bar Irradiated; BK7-G18 optical grade fused silica (synthetic quartz) BK7: turned black Fused silica: turned gray Stable T,R < 0.5 % for synthetic quartz rays (1.17 MeV, 1.33 MeV) 60Co 3 kGy/hour @ NAYADE (CIEMAT)
Triple ARC on BK7-G18 Dose: 100 kGy (10 years CMS) Negligible effect Ag coating on back face Al coating on front face RC and ARC increase %R and %T of materials, respectively Coating performance should remain independently of radiation dose
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.