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 Wgg production: Quartic Gauge Couplings and the Radiation Zero Paul BellManchester HEP Christmas Group MeetingJanuary 2006

Activities to Date 2001 2002 2003 2004 2005 PhD, University of Birmingham Anomalous quartic gauge couplings at OPAL in the nngg final state ATLAS study of Wgg production: quartic gauge couplings and radiation zero System test of the ATLAS barrel SCT QA testing of the ATLAS SCT end-cap modules CERN fellowship SCT offline software, conditions database issues ATLAS SCT EC assembly & integration 1 2 3

1. ATLAS SCT End-Cap: Assembly and Integration

1. ATLAS SCT EC Assembly and IntegrationIntroduction: ATLAS and the SCT

1. ATLAS SCT EC Assembly and Integration

1. ATLAS SCT EC Assembly and Integration • 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 |h| < 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

1. ATLAS SCT EC Assembly and IntegrationEC Assembly: Liverpool and Nikhef

1. ATLAS SCT EC Assembly and IntegrationEC Assembly • Modules-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

1. ATLAS SCT EC Assembly and IntegrationEC Assembly

1. ATLAS SCT EC Assembly and IntegrationEC-C Programme at CERN 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

1. ATLAS SCT EC Assembly and IntegrationFinal 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

1. ATLAS SCT EC Assembly and IntegrationThe EC Area in SR1, CERN Reception, assembly and integration take place inside the EC area of SR1

1. ATLAS SCT EC Assembly and IntegrationThe EC Area in SR1, CERN 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)

1. ATLAS SCT EC Assembly and IntegrationThe EC Area in SR1, CERN Space in EC area is limited so we hope to expand into the barrel area once the SCT barrel is integrated to the TRT A second cantilver stand will be installed: work on the two end-caps will be in parallel

1. ATLAS SCT EC Assembly and IntegrationTesting After Final Assembly 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.

1. ATLAS SCT EC Assembly and IntegrationIntegration Stage • 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...

1. ATLAS SCT EC Assembly and IntegrationIntegration Stage • 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 • SCT load then transferred from beam to trolley • Survey stage

1. ATLAS SCT EC Assembly and IntegrationCombined Testing Combined testing takes place in the test area of SR1 (same for barrel and EC)

1. ATLAS SCT EC Assembly and IntegrationCombined 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 above • TRT 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??

1. ATLAS SCT EC Assembly and IntegrationSummary • 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 BaseOverview of SCT Offline Reconstruction Software Algorithms in the ATLAS software environment: ATHENA Data Taking The bytestream converter takes incoming "raw" data and outputs Raw Data Objects (RDOs) From the RDOs first make clusters of hits, then space points combining data from both sides of a module Finally perform the tracking (combined with other detectors) Simulated Data Digitization CONDITIONS DB 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.

2. SCT Software and the Conditions Data BaseRole of Conditions Data • 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 BS converter Tracking Clusterization Digitization

2. SCT Software and the Conditions Data BaseUse of Conditions Data Base During Commissioning • 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 • 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....

2. SCT Software and the Conditions Data BaseDetails: Data in COOL • 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)

2. SCT Software and the Conditions Data BaseDetails: Reading Data in ATHENA • 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.

2. SCT Software and the Conditions Data BaseSummary • 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

3. Wgg Production: Gauge Couplings and Radiation Zero

3. Wgg ProductionIntroduction: Some Physics SM electroweak lagrangian: 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-couplings in the SM, giving rise to: TGCs: WWg, WWZ QGCs: WWWW, WWZZ, WWgg, WWZg

3. Wgg ProductionQuartic 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 must conspire with the g/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.

In addition to being sensitive to a possible AQGC, Wgg 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→em or mn) and low partonic centre-of-mass required contains a radiation zero in the SM 3. Wgg ProductionIntroduction to Wgg Production Wgg production is sensitive to a possible AQGC vertex of the form WWgg NB: this vertex is one of the allowed in the SM but may receive anomalous contributions

3. Wgg ProductionSignal Simulation Monte Carlo has been provided by O. Eboli, Sergio Lietti (Sau Paulo) Includes all tree level diagrams leading to the l±ngg final state, with l = e, m: • ISR, FSR, TGC and SM AQGC term + the possible AQGC diagram MC includes anomalous contribution from lagrangian term where anomalous coupling parameters b0 and bc = 0 in SM ⇒ cross-section varies quadratically with these parameters MC has been interfaced to ATLFAST in the ATHENA environment • Inclusive as possible set of cuts are applied on ATLFAST quantities (no proper trigger study) • Two photons: PTg > 15 GeV, | hg |<2.4 • One electron or muon: PTl > 25 GeV, | hl |<2.4 • Missing energy: PTmiss> 20 GeV • Separations: DRlg > 0.8, DRgg > 0.4 • Plus cut on W transverse mass: MTW > 65 GeV • (removes events where photons come from final state charged lepton)

3. Wgg ProductionSM Background Simulation • Principal backgrounds to Wggare expected to arise from Wg + jet and W + 2jet events in which one or both jets are mis-identified as a g • This mis-identification occurs with probability 1/Rjet where Rjet is the g-jet rejection factor • Since cross-sections for W(g) events are orders of magnitude higher than Wgg, need high jet rejection factor if backgrounds are to be controlled Evaluate the backgrounds as follows: • Generate a large number of Wg + jet and W + 2jet events • For Wg + 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/ Rjet)2 • Still using Rjet = 1300: this needs to be optimised

3. Wgg ProductionATLFAST Distributions Events in 30fb-1 Point are signal + bkg Signal Wjj background Wgj background pTg (MeV) Mgg (MeV) In 30fb-1 (3 years of low luminosity running) for e± and m± 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%

3. Wgg ProductionStudying the AQGCs Transverse energy of highest energy photon, pT, and invariant mass of photon pair, Mgg, offer good sensitivity to the AQGC (e- channel only shown, 30fb-1) Sensitivity is in high pT region and for high gg invariant masses (very little SM signal or background here) Study not complete but first indications based on maximum likelihood analysis are limits on b0 around 1×10-4, an order of magnitude tighter than the current LEP limits. pTg Solid line: SM (b0 = bc = 0) Dashed lines: ± b0 AQGC Mgg ATLFAST 10.0.1

3. Wgg ProductionThe Radiation Zero: Theory In addition to sensitivity to the quartic gauge couplings, the Wgg final state also offers the chance to observe a "radiation zero". Theory: • In the SM, the amplitude for qqgWg vanishes for cosqW* = -1/3 where q* 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 Wgg 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 Dy(gg,W) = ygg – yW, or Dy(gg,e) = ygg – ye where ygg, 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, qgg, is increased

3. Wgg ProductionThe Radiation Zero at ATLAS Events in 30fb-1 ygg - ye 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

3. Wgg ProductionThe Radiation Zero at the Tevatron (Baur et al) Recap: theory says that the 2 photons must be collinear to observe the zero and indeed the dip can be seen only for cos(q)gg > 0 from hep-ph/9702364 cos(q)gg ygg – yW

3. Wgg ProductionRadiation Zero in Wgg 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 pp not pp, expected dip to be symmetric in Dy = ygg – ye but with similar behaviour wrt the photon opening angle as seen at Tevatron Similar behaviour seen with an alternative generator → tried to reproduce Baur's results at generator level by modifying Eboli's MC for the LHC to simulate Tevatron... cos(q)gg ygg – yele

Tevatron Comparison @ Generator Level Left: Results from hep-ph/9702364 (photon opening angle in lab frame) Below: Results from Eboli MC cos(q)gg ygg – yW

Tevatron Comparison @ Generator Level 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) cos(q)gg ygg – yW

3. Wgg ProductionRadiation 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(q)* > 0 cos(q)gg ygg – yele

3. Wgg ProductionRadiation 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(q)* > 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 cos(q)gg ygg – yele

3. Wgg ProductionSummary • 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 • Wgg offers chance to probe WWgg 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 Wgg 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

Cantilevers, Conditions Databases and Gauge Couplings