DELPHIDELPHI

involvement of the

Institute for High Energy Physics

of the

Austrian Academy of Sciences

DELPHI

L3

OPAL

ALEPH

W.Adam: DELPHI RECFA . Innsbruck, 26/03/04

Overview

One of two Austrian participations in the LEP programme(see also next talk on ALEPH)

The only Austrian institute in DELPHI (out of ~56) -member since the design phase

Typically 10 out of ~ 550 authors on DELPHI papers

Contributions to DELPHI construction and running budgets at the level of about 2%

External funding from Phase 1: Austrian Science Fund (FWF) Phase 2 (LEP II upgrade):

Austrian Ministry of Eduction, Science and Culture

Construction of detectors and electronics in collaboration with Austrian industry

W.Adam: DELPHI RECFA . Innsbruck, 26/03/04

Hardware - Contributions

Forward Chamber A

Silicon Tracker

W.Adam: DELPHI RECFA . Innsbruck, 26/03/04

FCA: Part of the forward tracking system Two arms with six layers of streamer tubes each Provided track trigger in the forward region and 4D track segments for

reconstruction (together with a 2nd set of drift chambers and the DELPHI TPC)

Designed, constructed andoperated by HEPHY for theDELPHI data-taking 1989 - 2000

Forward Chamber A

Mounting of one FCA moduleon the TPC endplate

W.Adam: DELPHI RECFA . Innsbruck, 26/03/04

Readout and Trigger Electronics

DELPHI electronics in the FASTBUS standard:

Multiplexing for parts of the forward chamber readout Design, construction and operation of the forward track trigger

at level 1 & 2: Linking hits in FCA and FCB with

momentum selection and check for compatibility with interaction point

Maintenance of the standard time digitizer “LTD” for the whole collaboration

FASTBUS multiplexer fordrift chamber signals

W.Adam: DELPHI RECFA . Innsbruck, 26/03/04

The forward part of the extended Silicon Tracker installed in the framework of the upgrade programme for LEP II : two crowns of pixel and two crowns of “mini-strip” detectors in

each endcap

Leading participation of Austria in the mini-strip system development of a simple and robust system with resolutions matched

to the effects of multiple scattering in the very forward region

single-sided detectors with 200m pitch glued back-to-back to provide

intersection points in 2D

Operated by the Silicon Tracker groupthroughout LEP II data-taking(1996-2000)

Very Forward Tracker

Forward region of a halfshellof the Silicon Tracker

Two crowns of mini-strips

W.Adam: DELPHI RECFA . Innsbruck, 26/03/04

Pattern Recognition& Track Fitting

Contributions to track reconstruction in DELPHI Introduction of the Kalman Filter

Proof of the equivalence of previously developed iterative track fitting algorithms with the Kalman filter (widely used outside HEP)

Use of the full advantage of the Kalman approach: flexibility and optimal estimates everywhere on the track by combining a filtering and smoothing stage

Development of an electron track fit Treatment of radiative energy loss in a least-squares track fit

Local pattern recognition in FCA resolution of ambiguities using a Hopfield-network

W.Adam: DELPHI RECFA . Innsbruck, 26/03/04

Application of the Kalman filter to vertex reconstruction equivalent to least-squares fit iterative procedure, suitable for attaching / detaching

tracks to / from a vertex

Robustified vertex fits Kalman filter with 2 tests of individual tracks Vertex fits based on the M-estimator algorithm

Application of these procedures to primary vertex reconstruction secondary vertex reconstruction in c- and b-events

Vertex Fitting

W.Adam: DELPHI RECFA . Innsbruck, 26/03/04

Physics Analyses LEP I

B-Physics: Early analysis of B-lifetime Exclusive reconstruction of rare B-decays,

e.g. search for charmless decays of B-hadrons

Exclusive decays of B-hadrons to J/ X Inclusive b decays to wrong sign

charmed mesons

Tau-production cross-section and

asymmetry measurement

Here & following pages: Analyses done by or with strong participation of HEPHY physicists

reconstruction ofdisplaced vertices

W.Adam: DELPHI RECFA . Innsbruck, 26/03/04

Physics AnalysesQCD

Multiparticle correlations in Z0 decays Angular correlations and correlation integral studies

3-jet events at s = MZ

comparison of the leading systems in gluon- and quark-jets Identified hadron spectra at LEP II

Pion, kaon and proton spectra in e+e- qq and hadronic W-decays

Using dE/dx (TPC) and Cherenkov angles (RICH)

Motivated by the temporary involvement of several Austrian physicists in the DELPHI RICH project

maximum of -log(2p/√s) vs. s

W.Adam: DELPHI RECFA . Innsbruck, 26/03/04

Physics AnalysesSearches

Search for a scalar top quark Analysis of the decay mode to b lepton sneutrino

in the first part of LEP II

Contributions to other searches at LEP II Higgs Excited leptons Technicolor

Excluded regionsin the techni-pion vs.

techni-rho mass plane

W.Adam: DELPHI RECFA . Innsbruck, 26/03/04

Co-ordination

Co-ordination & general tasks of HEPHY members :

Resonsibility for sub-detector operations and in global data-taking

Mandate in the DELPHI executive committee Co-ordination of LEP II analyses, responsible for

topologies with leptons or Emiss / searches for Exotica Co-ordination of the LEP working group for searches for Exotica

Activity now on the follow-up of the remaining publications

W.Adam: DELPHI RECFA . Innsbruck, 26/03/04

Outreach

Activities in Austria Since the end of DELPHI data-taking

detector parts have been prepared forpresentation to the public.

They form a key element of anexhibition shown at museums, high schools and universities.

DELPHI exhibition at CERN A specially prepared module of

the forward chamber will be shownin its original position on the DELPHIbarrel in the context of the permanentexhibition in the former DELPHI / now LHCB pit.

FCA on display

W.Adam: DELPHI RECFA . Innsbruck, 26/03/04

Summary

Some statistics (approximate numbers!) typically 10 HEPHY authors on ~ 350 DELPHI publications ~ 70 DELPHI notes (co-) authored by HEPHY physicists + DELPHI-related publications on detector development and

reconstruction algorithms ~ 14 diploma theses and 6 PHDs

Conclusion The participation in DELPHI was an important step in the

experimental programme of the institute. There were significant Austrian contributions to hardware,

software and analysis. The know-how gained in this way is now used for the next

generation of experiments with HEPHY-involvement.