A year of ATLAS preparation. Steve Snow New Year 2006 The resolution of tracks reconstructed in ATLAS ID should be: Good enough for some physics from the.

A year of ATLAS preparation.Steve Snow New Year 2006

The resolution of tracks reconstructed in ATLAS ID should be:

• Good enough for some physics from the first collisions

• Rapidly improved by using track-based alignment tools

• Eventually good enough that track systematic errors do not dominate the measurement mW to ~15 MeV

• Inner detector magnetic field map fit.

• SCT detector alignment.

• NMR probe preparation.• Write/edit endcap module paper

• SCT status paper at PSD7.

• Organise seminars

• SuperNEMO tracker.• CALICE thermal simulation.

What I did last year

My ATLAS aims

Field map objectives• A useful test of the Standard Model would be measurement of W mass with uncertainty of

25 MeV per lepton type per experiment.• W mass derived from the position of the falling edge of the transverse mass distribution.• Momentum scale will be dominant uncertainty in W mass measurement:

– Need to keep uncertainty in momentum down to ~15 MeV.• Measure isolated muon tracks with pT ~ 40 GeV over large range of η:

– Uncertainty in energy loss negligible.– Concentrate on alignment and B-field.

• Momentum accuracy depends on ∫ r(rmax - r)Bzdr :– Field at intermediate radii, as measured by the sagitta, is most important.

• Typical sagitta will be ~1 mm and target accuracy would be 0.02%, implying a systematic error on sagitta of 0.02 μm:

– Technically impossible!– Will need to use Z mass, which is nearby and very well known.

• In reality, the limit on silicon alignment, even with infinite statistics and ideal algorithms, will be ~1 μm.

• We target an accuracy of 0.05% on sagitta to ensure that B-field measurement is not the limiting factor on momentum accuracy.

This and following slides copied from Paul Miyagawa's talk at the 2nd ATLAS magnetic field workshop

Field shape.

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Z (m)

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Z component

R component

Bending power

The field is very non-uniform at the ends of the coil; the Z component drops off and the R component rises sharply at z=2.65 m. Also plotted is the bending power per unit of radial travel for straight tracks coming from the origin.

Mapper Survey Requirements• At first workshop, survey requirements of

mapper machine relative to Inner Detector were reported as ~1 mm and ~0.2 mrad.

• Reinvestigated these requirements.• 1 mm survey error in x (or y) significant for

high η tracks.• 1 mm survey error in z significant for

endcap tracks.• 0.1 mrad rotation around x (or y) axis

significant for high η tracks.• Conclusions remain unchanged. -8

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Pseudorapidity

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Effect of 1 mm displacement in X direction

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Effect of 1 mm displacement in Z direction

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Effect of 0.1 mrad rotation around the X axis

Field Mapping Simulation

• Field model sampled on a grid of 90 z-positions × 8 -angles (defined by encoder values of machine).

• 4 calibration points (2 near centre, 2 near one end) visited after every 25 measurements.

• Used current design of machine to determine positions of 48 Hall + 1 NMR probes.

• At each map point, wrote the following data to file:

– Time stamp– Solenoid current– z and encoder values– Field modulus measured by 5 NMR

probes (1 moving + 4 fixed)– 3 field components measured by 48

Hall probes

Simulated ErrorsSix cumulative levels of error added to simulated data:

1. No errors.

2. Random errors in each measurement of:• Solenoid current, 1 A• NMR B-field modulus, 0.1 G• Each component of Hall probe B-field, 3 G

3. Drifts by random walk process in each measurement of:• Solenoid current, 1 A• Each component of Hall probe B-field, 0.1 G

4. Random calibration scale and alignment errors, which are constant for each run:• Each component of Hall probe B-field, 0.05% scale• Rotation about 3 axes of each Hall probe triplet, 1 mrad

5. Symmetry axis of field model displaced and rotated relative to the mapper machine axis. These misalignments are assumed to be measured perfectly by the surveyors.

6. Each Hall probe triplet has a systematic rotation of 1 mrad about the axis which mixes the Br and Bz components.

Correction for Current Drift• Average B-field of 4 NMR probes used

to calculate “actual” solenoid current.• Scale all measurements to a reference

current (7600 A).• Effect of drift in current removed• Calibration capable of coping with any

sort of drift.

Correction for Hall Probe Drift

• Mapping machine regularly returns to fixed calibration positions– Near coil centre to calibrate Bz

– Near coil end for Br

– No special calibration point for B

• Each channel is calibrated to a reference time (beginning of run)

• Offsets from calibration points used to determine offsets for measurements between calibrations

Fit Quality with Expected Performance

• Expected mapper performance corresponds to error level 5.

• Both fits accurate within target level of 5×10-4.

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Geometrical fit. Error level 5

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Fourier-Bessel fit. Error level 5

Probe normalisation and alignment correctionsHall probe triplets are accurately perpendicular to each other, but their mounting on mapper can have ~1 mrad errors.

Hall probe calibration will probably be good to 0.1% but we can improve it by taking normalisation from the NMR probe at Z=R=0.

We get best results by calculating PNA corrections with a variant of the Fourier-Bessel fit and using the corrected values in the geometrical fit :

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Before probe normalisation and alignment correctionsAfter probe normalisation and alignment corrections

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Ten runs with different random errors

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Before probe normalisation and alignment correctionsAfter probe normalisation and alignment corrections

Field fitting conclusions• With no simulated errors, both fits have excellent technical

accuracy.• With realistic simulated errors, both fits give results within

target of 5×10-4.• Fourier-Bessel fit more sensitive to random measurement

errors:– Due to more free parameters.– F-B fit designed for any solenoid-like field, whereas geometrical

fit is specifically for the ATLAS solenoid.• Probe normalisation & alignment correction from F-B fit

helps significantly.• Require survey of mapper machine relative to Inner

Detector to be accurate to ~1 mm.

Initial SCT AlignmentI have been promoting the idea making an initial SCT alignment based on conventional surveys. This is a backup / alternative to the Oxford plan for an X-ray survey combined with FSI monitoring. The accuracy of the SCT endcap as built, and as surveyed is now becoming clear

Intrinsic resolution of SCT detector; 22 m (just under pitch/12).

Detector positions in module; build 4 m , survey 1 m (Joe's talk).

Location holes in module; build 10 m , survey 3 m.

Module mounting pins on disc; build 100 m , survey 10 m.

Discs in support cylinder; build 200 m , survey 100 m.

Hole to pin clearance; <10 m .

Stability of mounting pins on disc; 20 - 50 m . (temperature, moisture,bending )

X-ray survey now cancelled

Modified copy of slide from last year

7 microns random + 50 microns systematic (proportional to distance)

SCT endcap alignment from surveysModule internal alignment

Relative positions of the four detectors and two mounting holes.

Corrections of ~5 m known to ~1 m.

Pin alignment

Relative positions of the module mounting pins on discs.

Corrections of ~100 um known to ~10 um.

Disc alignment

Relative positions of the 9 discs in each endcap

Corrections of ~200 um known to ~100 um.

Module production database

Completed July 05

Understand and correct for small (1-2 um) systematic differences between surveys done at different sites.

Joe Foster. In progress.

Corrected final module data.

Joe Foster. Expected Jan 06

Tables associating module serial number with position mounted on disc.

Joe Foster. Endcap C complete. Endcap A expected December 05.

Tables of pin position offsets from nominal in each disc.

Collecting data from surveys done at Liverpool (Peter Sutcliffe) and NIKHEF (Patrick Werneke).

Steve Snow. Endcap C complete, endcap A discs 9,8,7,6,5,4 done.

Detector/module offsets from nominal in each disc.

Steve Snow, Joe Foster. Expected March 06.

Survey reports of disc alignment in each endcap.

First few reports available from endcap C.

Surveys should be repeated when the endcaps reach CERN.

Steve Snow. In progress.

combine Detector/module offsets from nominal in each endcap.

Steve Snow, Joe Foster. Expected May 06.

Learn how to load data into, and use data from, the conditions database. Upload this ? or this ? data

Paul Miyagawa. Expected July 06.

Disc surveysSurvey of module mounting pins on all endcap C (UK) discs is complete.

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Overlap statistics

Actual phi overlap between neighbouring modules will always be within 120 microns of the design value, and typically within 50 microns.

Strip pitch is 80 microns, design overlap is 5,8,18 strips. (I,M,O rings)

There will always be a small but useful overlap between modules to use for alignment with tracks.

NMR system

• Purpose and description of the NMR

• Overview of system

• Parts of the system

• Software for: Noise testsSignal tests

• Installation and Commissioning

• Configuration during field mapping

Steve Snow

26/10/05

Technical support in Manchester: Julian Freestone, Mike Perry

CERN contact: Pippa Wells

Overview

Aim is to measure the magnetic field strength in the Inner Detector.

NMR requires a very uniform field (<250 ppm/cm) so we must place the probes at z=0. Extrapolation to other parts of the Inner Detector relies increasingly on the field map as one moves towards the end-caps.

NMR is intrinsically accurate; it it works at all we get a result accurate within a few x 10 ppm.

Based on a system supplied by Metrolab, with modifications to improve radiation hardness of the probe and cables.

Operating at/beyond the limits of some specifications:• expected field gradient is 310 ppm/cm• probe-amp cable length is 15m, Metrolab standard is 7m• amp-readout cable length is 125m, standard is up to 100m

Metrolab say their specifications are conservative and this should be no problem.

NMR system

Standard Metrolab system with the addition of Pico 2-channel digitiser and PC to monitor noise, pickup, signal size, etc.

Grounded only at ID ground point.

Readout using LabVIEW on PC. Interface to DCS not yet defined.

Parts of the system

Probe

Probe in clamp on

cryostat wall

Amplifier

Readout

Cables

All of the hardware is ready. Some software still being developed.

Noise TestsIn lab, pickup depends strongly on layout of cables ; as soon as cables are laid in Atlas we want to measure noise and check it is not excessive.

Maybe an opportunity to immediately re-route or bundle cables more tightly together. Final test is the ability to lock onto the NMR resonance - not possible until much later, when solenoid is turned on.

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Frequency (MHz)

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Noise test results in good conditions:r.m.s. ~ 20 mV, peaks < 100 mVmains pickup < random noise

The only thing likely to prevent the NMR system from working is noise pickup.

NoiseTest.VI - automates all the NMR tests we can do in absence of field.

Signal TestsWhen the Teslameter is locked on the NMR resonance, as well as reading out the field value we monitor peak height, peak asymmetry and noise (between peaks).

SignalTest.VI

Mapping time scale

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Jul '06May '06 Jun '06 Jun '07

ID A connection and testing

Aug '06 Sep '06

Chains

Endcap Cal. A services connection, test & commissioning

Muon Barrel A

Side A closed

Endcap Cal. C services

Fiel

d m

appi

ng

Endcap Cal. C testing & commissioning

VA

Barrel Calorimeter services, 1st fix on truck

Big Wheels C (TGC1)

JNEndcap Calorimeter C Services

1st fix

Barrel Toroid Coils 7-8

Muon brackets & rails

Platf. Remov.

ID services through Muons

Endcap cryo lines.

Barrel Calo services

Barrel Cryo lines

Barrel Toroid servicesBT testing &

commissioningPlatforms removal

Big Wheels C (MDT+TGC2+TGC3)Endcap Toroid C

Endcap Toroid C cooldown & testing

Small Wheel C

JN

Endcap Toroid AEndcap Toroid A

cooldown & testing

JT?

ID Barrel connection and testing IDC connection and

testing

Small Wheel A

JF

HS arches preparation JF Side A

LAr

JT

Big Wheel A, (TGC1)

Big Wheels A (MDT+TGC2+TGC3)

Muon Barrel C

JD

JD

Sole

noid

Endcap Calo A

Barrel Calo testing and commissioning

LAr

BMS

HS arches

May '07

Full

mag

net t

est?

Feb '07 Mar '07Oct '06 Jan '07Dec '06

VT

Glo

bal C

omm

issi

onin

g

VTVA

Apr '07

glob

al te

sts,

pum

p do

wn

& b

ake

out

VJ

Pixel connection and testing

Oct '05

Services 1st fix

Aug '05 Mar '06

Chi

mne

y

Muon services

Che

ck ra

ils ID services along Barrel

Cable chains

Nov '06Apr '06Dec '05 Jan '06 Feb '06Jul '05 Sep '05 Nov '05

JF

VJ

Side CJF

EO, side C

Barrel

EO, side A

Global Commissioning

Full magnet test

Latest ATLAS schedule shows mapping in April/May.

We will prepare for that date but I would be surprised if it does not slip by 2 or 3 months.

Looking forward

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80%90%

100%

2006 2007

Field map

NMR

Survey alignment

Track alignment

SuperNEMO

My changing priorities in the next year.

Seminars11/01/0618/01/06 Experiment Brian Fulton (York) COBRA25/01/06 Theory01/02/06 Schuster08/02/06 Experiment Yoshi Uchida (Imperial) KamLAND15/02/06 Experiment Tara Shears LHCb22/02/06 Theory01/03/06 Schuster08/03/06 Experiment Amanda Cooper-Sarkar15/03/06 Theory22/03/06 Experiment Chris Booth MICE29/03/06 Experiment Alfons Weber MINOS30/03/06 Experiment Emily Nurse CDF05/04/06 Schuster

Not yet fixed:

Martin Erdmann - Auger, Dino Jaroszynski - plasma acceleration.