cantilevers, conditions databases and gauge couplings

Cantilevers, Conditions Databases and Gauge Couplings

1. Hardware ATLAS SCT End-Cap Assembly and Integration

2. Software ATLAS SCT Offline Software and the Conditions Database

3. Physics W production: Quartic Gauge Couplings and the Radiation Zero

Paul BellManchester HEP Christmas Group Meeting

January 2006

Activities to Date

2001

2002

2003

2004

2005

Anomalousquartic gauge

couplings at OPAL in the final

state

ATLAS study of W

production:quartic gauge

couplings and radiation

zero

System test of the ATLAS

barrel SCT

SCT offline software,

conditions database

issues

QA testing of the ATLAS

SCT end-cap modules

ATLAS SCT EC assembly & integration

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1. ATLAS SCT End-Cap: Assembly and Integration

1. ATLAS SCT EC Assembly and Integration

Introduction: ATLAS and the SCT

Construction• Four concentric barrels and two end-caps each of nine disks• Tiled with 4088 Si micro-strip modules: 988 per end-cap

Physics Role• Gives four space point measurements per charged particle track• Vital role in momentum, vertex and impact parameter measurements inside psuedorapidity range of || < 2.5

Performance• Gives transverse momentum resolution of dpT/pT = 0.3 for pT = 500 GeV• Binary readout: each module has two silicon planes with 768 channels per side readout by 12 FE chips



EC Assembly: Liverpool and Nikhef


EC AssemblyModules-to-disk and disk-to-cylinder taking place at macro-assembly sites:

- Nikhef (EC-A) and Liverpool (EC-C)- ECs shipped to CERN as complete cylinders of 9 disks from these sites

Nikhef Status- module-to-disk completed for 7of 9 disks- 6 finished disks have been tested- disk-to-cylinder completed for disks 7, 8, 9

Liverpool Status- module-to-disk completed for all disks- all disks inserted to cylinder and aligned- power tapes ("LMTs') defining the schedule- disk testing inside cylinder still to be done

Expect shipment to CERN mid-Feb for EC-C and after mid-March for A


EC Assembly

1. Reception testing

- verify no damage occured in transport, focus on thorough checks of cooling circuits

Approximately 3.5 weeks (till early March)

2. Final assembly (addition of thermal enclosures)- transfer to cantilever beam used for integration, assemble thermal enclosure, G+S

Approximately 6.5 weeks* (end April)

3. Testing inside thermal enclosure- re-check cooling circuits, test noise peformance of modules now in final environment

Approximately 3 weeks (mid May)

4. Integration with TRT- roll TRT over the SCT cylinder to complete ID EC

Approximately 5 weeks (mid June)

5. Combined testing

- move to test area, cable up, perform tests (6 weeks), uncable, prepare for pit

Approximately 10 weeks (start Sept.)

⇒ Ready for pit start September 2006 (end-cap A will follow by about 1 month)

* Following final engineering review on 14th December, this now looks insufficient


EC-C Programme at CERN


Final Assembly Stage• EC arrives semi-complete

• Note the TPP frame for reception tests and eventual combined tests

• Must be transferred to cantilever stand for addition of thermal enclosure

• TRT eventually rolls over the EC held on the beam


The EC Area in SR1, CERN

Reception, assembly and integration take place inside the EC area of SR1



Reception, assembly and integration take place inside the EC area of SR1

Current status

• First cantilever stand is installed

• Extra floor strenthening has been added

• Stand has been load tested

• DAQ experts continue to develop DAQ code using the barrel sector

• Didier and Jo commission the test setups cooling and electronics (see Jo's talk)

Space in EC area is limited so we hope to expand into the barrel area once the SCTbarrel is integrated to the TRTA second cantilver stand will be installed: work on the two end-caps will be in parallel



Once cylinder is inside its thermal enclosure

but before integration with TRT, 3 weeks

allowed for testing:

• test functionallity of TE

(internal humidity, function of

external heaters...)

• test noise performance of modules

in close to final environment

Must be planned for now as we need to make

sure necessary temporary cooling connections

are added during assembly of thermal enclosure.


Testing After Final Assembly

• Rails are installed on the floor and aligned parallel to SCT EC cylinder

• ID trolley with TRT inside is installed on rails

(Radial clearance is 5mm so may use wires passing through inner diameter to align)

• Trolley passes over SCT...


Integration Stage


Integration Stage• Rails are installed on the floor and aligned

parallel to SCT EC cylinder

• ID trolley with TRT inside is installed on rails


• Trolley passes over SCT...


Integration Stage• Rails are installed on the floor and aligned

parallel to SCT EC cylinder• ID trolley with TRT inside is installed on rails


• Trolley passes over SCT• SCT load then transferred from beam to

trolley• Survey stage


Combined Testing

Combined testing takes place in the test area of SR1 (same for barrel and EC)


Combined Testing

Combined testing takes place in the test area of SR1 (same for barrel and EC)

Plan to read out one quadrant through all disks (easily enough readout for this, though not for whole EC)

Could envisage with the 6 weeks allowed:

1. Standalone Verification

• SCT (TRT off) initial verification of function of the SCT with TRT present:usual tests of noise performance: 5 days

• TRT verification (with SCT off) similar to aboveTRT will use at least 2/32 of total phi, either in 1 or 2 slices: 5 days

2. SCT-TRT Pseudo-Combined

• SCT tests with TRT powered and not triggered/triggered 5 days

• TRT tests with SCT powered and not triggered/triggered/pairs of triggers 5 days

3. SCT-TRT Synchronous Readout 2 weeks

• EC operating with synchronous trigger

• Cosmics running??


Summary

• The SCT is part of the ATLAS inner (tracking) detector and consists of 4 nested barrels and two end caps

• End-caps consisting of 9 disks and 988 modules are being assembled in Liverpool (EC-C) and Nikhef (EC-A)

• EC-C will be delivered to CERN mid-February; EC-A in mid-March

Five stages prior to installation in pit

1. Reception testing (focus on cooling circuitry + electrical functionality)

2. Transfer to cantilever beam and assembly of thermal enclosure

3. Testing inside thermal enclosure (including noise performance)

4. Integration with TRT

5. Combined testing with TRT

Assembly of two end-caps will proceed largely in parallel and current estimates predict EC-C will be ready for installation by September

2. SCT Software and the Conditions Database

2. SCT Software and the Conditions Data Base

Overview of SCT Offline Reconstruction Software

Data Taking

The bytestream converter takes incoming "raw" data and outputs Raw Data Objects (RDOs)

From the RDOs first make clusters of hits, then spacepoints combining data from both sides of a module

Finally perform the tracking (combined with other detectors)

Simulation

Input is Monte Carlo events, simulated in GEANT4 model of SCT geometry and material

Front-end response to the hits modelled in a digitization algorithm (SCT_Digitization)

RDOs from the digitization algorithm then passed through same reconstruction chain.

Algorithms in the ATLAS software environment: ATHENA

Simulated Data

Digitization

CONDITIONS DB

The offline reconstruction needs to know:

• which readout channel is connected to which module

• the precise alignment of the detectors

• which channels are dead or noisy

Furthermore, for accurate simulation the SCT_Digitization algorithm must know, e.g.:

• which modules and readout chips on the modules are active

• the noise levels within/across the modules

• the threshold settings (binary readout)

• which channels are dead or noisy

Without these data we are simulating a perfect ATLAS, not the ATLAS we have built

The conditions database is the resting place for any data required by offline software


Role of Conditions Data

Digitization

Clusterization

Tracking

BS converter

In the 2004 CTB run, limited use was made of the "Lisbon implementation" of the conditions database

• dead and noisy channels found in offline monitoring masked in clusterization• channels masked in the DAQ also masked in digitization for accurate simulation• cabling stored in a text file – only 8 modules

SCT/TRT barrel combined test will take cosmic ray data in Feb 2006⇒ want to exercise much fuller use of conditions data

Now using the final version of the database: COOL


Use of Conditions Data Base During Commissioning

So far have implemented:

• description of cosmic setup (the 504 barrel modules)

• access to all module configuration data in digitization (thresholds, chips active, bias voltages...)

• implementation of masked channels in digitization

⇒ now allowing accurate simulation of cosmic events....

COOL Basics

• Data are stored in COOL in folders which contain payloads

• The payloads can be integers or floats or pointers to data outside of COOL

• Data are stored using the principle of "intervals of validity"e.g. a bias voltage for a particular detector can have some value for a period from (run1, event1) to (run2, event2). For a given (run, event) the DB returns the valid value.

SCT Configuration

• For the SCT, in our use of COOL, we are currently restricted to configuration data (which is a subset of conditions data)e.g. threshold is a configuration, but noise is a condition

The SCT configuration is recorded in an xml file which is read in by the DAQ at start of a run – this file contains all cabling information, power supply settings and a complete description of all modules (in fact, what comes out of the production DB from the QA)

Tool exists (Shaun Roe) to put this into COOL, so then its there ready for ATHENA (me) to pull out whats needed

Other people are now looking at putting the remaining conditions data to COOL, e.g the results of calibration scans (noise values)


Details: Data in COOL

Made a "tool" which can be called in the digitization algorithm to access the SCT configurations stored in COOL

The tool offers the following methods:

• getModuleSn(location(layer, phi, eta))- returns the serial number of a module at a certain geometrical location

• getModuleData(module_serial_number, data_requested)- returns the module-level conditions data given a serial number, eg, bias voltage

• getChipData(module_serial_number, chip, data_requested)- returns the chip-level conditions data given a serial number and chip number

With these methods it is possible to access any piece of configuration data

Actual use of the data is currently restricted to the masked channels: no hits are simulated in those channels masked in the DAQ (masking has so far been randomly applied at the 1% level in all simulations)

Implementation of use of other data remains to be done – the interface is there.

NB: these features are specific to the cosmic running (barrel only) and cannot be extended to whole of ATLAS while some end-cap modules remain unmounted.


Details: Reading Data in ATHENA

• ATLAS simulation and reconstruction software all runs in the ATLAS software environment ATHENA

• The algorithm SCT_Digitization simulates response of the modules to charged particles

• Conditions data is particularly important to correctly model the characteristics of the SCT in the digitization algorithm if we are to simulate the ATLAS we have built

• For the cosmic run, now have the data in COOL describing complete configurations of all the 504 barrel modules in the setup

- thresholds- bias voltages- masked channels- cabling- ....

• A tool has been provided in ATHENA to access these data and make them available in SCT_Digitization


Summary

3. W Production: Gauge Couplings and Radiation Zero

3. WProduction

Introduction: Some Physics

where in the second to last term

Last term arises since generators of the SU(2)L symmetry do not commute (non-Abelian)

⇒ this is the origin of the self-couplingsin the SM, giving rise to:

TGCs: WW, WWZ

QGCs: WWWW, WWZZ, WW, WWZ

SM electroweak lagrangian:

3. WProduction

Quartic Gauge Couplings• Studying form and strength of TGC and QGC couplings tests whether fundamental

interactions really are described by non-Abelian SU(2)L × U(1)Y gauge structure

• In addition, QGCs may "provide a window on the mechanism responsible for the spontaneous breaking of the electroweak symmetry":

To conserve unitarity in W+W- scattering events the SM Higgs exchange diagram mustconspire with the/Z exchange diagrams and the QGC process:

• Self couplings have not been measured precisely and are studied using "effective lagrangians": - write down the most general allowed lagrangian term and put limits on the coefficients.

W production is sensitive to a possible

AQGC vertex of the form WWthis vertex is one of the allowed in the SM but

may receive anomalous contributions

In addition to being sensitive to a possible AQGC, W production is an interesting process in itself:

– first sign of triple vector boson production (which have small cross-section) due to large branching ratio to measurable final states (W→e or ) and low partonic centre-of-mass required

– contains a radiation zero in the SM

3. WProduction

Introduction to W Production

Monte Carlo has been provided by O. Eboli, Sergio Lietti (Sau Paulo)

Includes all tree level diagrams leading to the l± final state, with l = e, :– ISR, FSR, TGC and SM AQGC term + the possible AQGC diagram

3. WProduction

Signal Simulation

MC includes anomalous contribution from lagrangian term

where anomalous coupling parameters 0 and c = 0 in SM

⇒ cross-section varies quadratically with these parametersMC has been interfaced to ATLFAST in the ATHENA environment

WWWWFF

WWFFL

c

0eff ~

Inclusive as possible set of cuts are applied on ATLFAST quantities (no proper trigger study)

• Two photons: PT > 15 GeV, | |<2.4

• One electron or muon: PTl > 25 GeV, | l |<2.4

• Missing energy: PTmiss> 20 GeV

• Separations: Rl > 0.8, R > 0.4

• Plus cut on W transverse mass: MTW > 65 GeV(removes events where photons come from final state charged lepton)

• Principal backgrounds to W are expected to arise from W + jet and W + 2jet events in which one or both jets are mis-identified as a

• This mis-identification occurs with probability 1/Rjet where Rjet is the -jet rejection factor

• Since cross-sections for W() events are orders of magnitude higher than W, need high jet rejection factor if backgrounds are to be controlled

Evaluate the backgrounds as follows:

• Generate a large number of W + jet and W + 2jet events

• For W + jet, for each event try the photon with every jet relabelled as (i.e., pretend that it is) a photon and for each time the event then passes the selection, accept it with weight 1/ Rjet

• For W + 2jet, for each event try every jet relabelled as a photon with every other jet also relabelled as a photon and for each time the event passes accept it with wieght (1/ R jet)2

Still using Rjet = 1300: this needs to be optimised

3. WProduction

SM Background Simulation

In 30fb-1 (3 years of low luminosity running) for e± and ± channels combined:

- signal events: 42.4 (assuming 80% efficiency for photons)

- background events: 35.9

* Also fully simulated 4000 e- events: evgen, simulation, digitization, recon. → AODs

- agreement with ATLFAST to 10%

p(MeV) M (MeV)

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30fb-

1Point are signal + bkgSignalWjj backgroundWj background

3. WProduction

ATLFAST Distributions

Transverse energy of highest energy photon, pT, and invariant mass of photon pair, M, offer good sensitivity to the AQGC

(e- channel only shown, 30fb-1)

3. WProduction

Studying the AQGCs

Sensitivity is in high pT region and for high invariant masses (very little SM signal or background here)

Study not complete but first indications based on maximum likelihood analysis are limits on 0 around 1×10-

4, an order of magnitude tighter than the current LEP limits.

Solid line: SM (0 = c = 0)Dashed lines: ± 0 AQGC

p

MATLFAST 10.0.1

In addition to sensitivity to the quartic gauge couplings, the W final state also offersthe chance to observe a "radiation zero". Theory:

• In the SM, the amplitude for qqW vanishes for cosW* = -1/3 where * is the angle between the q and the W in the parton CMS:

• In the case of two photons, the radiation zero is preserved in the limit that the two photons are collinear

A study of the radiation zero in the W case was reported in hep-ph/9702364 (1997)published in Phys.Rev. D56 by U. Baur et al

Shown here that radiation zero can be observed as a dip in the distribution of

y(,W) = y – yW, or

y(,e) = y – ye

where y, ye and yW are the rapidities of the two photon system, the e- and the W(considering e- case only)

It was observed that the radiation zero only gradually vanishes as the opening angle

between the two photons in the lab frame, , is increased

3. WProduction

The Radiation Zero: Theory

Again, this is only the electron channel, for 30inv fb: assuming the MC is correct and the backgrounds do not grow, the dip should be observable

yye

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1

3. WProduction

The Radiation Zero at ATLAS

from hep-ph/9702364

Recap: theory says that the 2 photonsmust be collinear to observe the zeroand indeed the dip can be seen only forcos() > 0

cos()

y – yW

3. WProduction

The Radiation Zero at the Tevatron (Baur et al)

3. WProduction

Radiation Zero in W at LHC (Generator Level)

Using the MC supplied by Eboli, obtained unexpected results:• Dip visible across the full

range of opening angles • Never anywhere in this range

is it very pronounced

Given that this is now ppnot pp, expected dip to besymmetric in y = y – ye butwith similar behaviour wrt thephoton opening angle as seen at Tevatron

Similar behaviour seen with analternative generator

→ tried to reproduce Baur's results at generator level by modifying Eboli's MC for the LHC to simulate Tevatron...y – yele

cos()

Tevatron Comparison @ Generator Level

Left: Results from hep-ph/9702364

(photon opening angle in lab frame)

Below: Results from Eboli MC

y – yWcos()

Left: Results from hep-ph/9702364

(photon opening angle in lab frame)

Below: Results from Eboli MC

Below right: Results from Eboli MC boosted to

parton centre-of-mass. i.e., the opening angle of

the photons is now in parton CMS, not the lab.

(Rapidity difference same in both frames)

Tevatron Comparison @ Generator Level

cos() y – yW

cos() y – yele

If I boost the LHC radiation zero plot to the parton CMS, the dip becomes much more apparent:

now clearly seen if the opening angle of the photons satisifies cos()* > 0

3. WProduction

Radiation Zero at LHC Revisited

cos() y – yele

3. WProduction

Radiation Zero at LHC Revisited

If I boost the LHC radiation zero plot to the parton CMS, the dip becomes much more apparent:

now clearly seen if the opening angle of the photons satisifies cos()* > 0

But, all very well when at generator level but of course we will not be able to make this transform on the data

Thus, if what I am showing is true, the radiation zero will be more difficult to observe than first thought

Open ended discussion with Eboli and Baur to try and understand this

• Quartic (and triple) gauge couplings intimitely connected to the non-Abelian symmetry of the SM and should be measured as closely as possible

• Quartic gauge couplings also connected to Higg's sector of SM

• W offers chance to probe WW coupling at the LHC and is an interesting SM process in itself: triple vector boson production with radiation zero

• I set out to study the QGCs: the radiation zero should drop out of any W study "for free"

• Unexpected predictions for the radiation zero have been obtained:

either an error on my part or a problem with either Eboli's or Baur's MC

– trying to resolve this

• Also has been an exercise for me in running full ATLAS simulation chain

• Unfortunately very little time permitted in the last year

3. WProduction

Summary

cantilevers, conditions databases and gauge couplings

Documents

sct cylinder

nikhef ec

liverpool ecc

macroassembly sites

end april3

schedule disk testing

finished disks

reception testing