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  • Peter 70's birthday 2009
    Peter, the ITC and the Heavy Flavors
    ¿ El ALEPH?-repetí.
    Sí, el lugardondeestán, sin confundirse, todos los lugares del orbe, vistosdesdetodos los ángulos
    From El Aleph, J.L. Borges
    ”Aleph? ” I repeated. Yes, the place where they are, without confusion, all the places of the world, viewed from all angles
  • Peter 70's birthday 2009
    Aleph was a gifted Collaboration also because there were few high charismatic people capable to indicate the direction of the path to the success of the experiment and to inspire the young fellows.
    Peter was one of those people.
  • Peter 70's birthday 2009
    Brief history of ALEPH and Peter
    • The Collaboration was initiated in 1980 and is still producing papers.
    • More than 30 institutions from western Europe, USA and China
    • Took data at LEP from 1989 to 2000
    • Produced some 300 papers, 21 with more than 100 citations
    Peter joined the ALEPH collaboration in 1983 after the demise of ELECTRA. He inspired the design of its Inner Trigger Chamber and directed its construction, in ALEPH he served as Spokesman, Chair of the Institution Board and Chair of the Editorial board.
    At Imperial we had worked hard for ELECTRA but realism had caused us to examine the other experiments should there be disappointment.
    Which of them had the same basic physics goals, which had a niche where our expertise would be valuable? Aleph satisfied both goals and the niche we saw was the tracking area close to the interaction
    point, building on the two wire chambers we had produced for TASSO.
  • The Design of the ITC
    Peter 70's birthday 2009
    At that time there was the reasonable fear that TPC could not work close to the beam line because of possible problems with space charge. In addition the TPC had a very long drift time, and could not be used for triggering. The proposal of the Imperial College group was to build a wire chamber that could satisfy the the following requirements:
    Provide tracks for the 1st Level Trigger
    Provide tracking from the beam pipe to the first TPC pads at 30 cm radius.
  • The ITC Tracking
    Peter 70's birthday 2009
    The ITC was a 2 m long chamber with axial wires which provided up to 8 accurate r-ϕ points.
    For the trigger, the r-ϕcoordinate is given by the wire number and the z by the time difference of the arrival time at the two ends of the wire.
    The tracking resolution in r-ϕwas 100 μm
    and the z resolution was 3 cm.
  • ITC Triggering
    Peter 70's birthday 2009
    The ITC was able to trigger both in r-ϕ and in r-z. But the r-ϕ was more critical for the performance. The trigger information was selecting tracks with momentum > 1 GeV and was selecting the ECAL sector that the track could reach. This was the ALEPH main trigger.
    With the exception of purely neutral final states the ITC trigger fired for virtually every interaction used in Aleph results.
    ALEPH PERFORMANCE PAPER
    Leptonic events have a lower multiplicity than hadronicevents, and so require larger redundancy. For muons threetriggers are used: the muon-track, electron-track, and back-to-back triggers. [ALL BASED ON ITC]The combined efficiency of these triggersis very near to 100%; the first is measured to be largerthan 99.8% and all three of these triggers are present inmore than 98% of muon pair events. The same triggers areused to select tau events, again achieving close to 100%efficiency.
  • Peter and ITC
    Peter 70's birthday 2009
    ITC was responsibility of a single institution ….
    …… and Peter was identifying ITC, the ALEPH Imperial College group
    and himself as one unique entity. It was (in) the center of ALEPH.
    At the end of ALEPH operation 945 of 960 wires were still operational and no wire broke.
    No more than 10 days of run were lost in more than 10 years because of ITC problems.
    BILL, Geoff, Ray, David, Marco, Dave, Roger, Dave, Ann, Dave, Julia, Andy.
  • Peter and Bill in ECHENEVEX
    Peter 70's birthday 2009
    July 1996
  • ITC Installation 26 Oct. 1988
    Peter 70's birthday 2009
    ALEPH Note 82-91
    The whole operation turned out to be rather tense. One of the problems was the large number of people present, with ill-defined roles.
  • Had Peter ever a doubt on the ITC ?
    Peter 70's birthday 2009
    ………………………
    The truth is that Peter always suffered when comparing the 21 TPC space points with the 8 ITC r-phi points !
  • ALEPH Event Display
    Peter 70's birthday 2009
  • Peter in between Online and Operation
    Peter 70's birthday 2009
    In the beginning of 1989 the ALEPH control room was organized in two kingdoms: Online and Operation. The former responsible of collecting the data and putting them to tape, the latter responsible for all aspects of data monitoring and run organization.
    The ALEPH spokesperson and founder – a very wise and strong man – had designed the managerial structure and chosen the main (also strong) characters. Unfortunately the interface was not working and ALEPH was not in condition to collect data smoothly.
    .
  • Peter in between Online and Operation
    Peter 70's birthday 2009
    I remember a secret meeting (May 1989 ?) with Jacques, Lorenzo, Klaus, Peter and myself where we concluded that something had to change and proposed the figure of “Run Coordinator” to govern the two kingdoms. Peter was selected by us to be the first Run Coordinator.
    There was only one small detail: we had to communicate this decision to Jack.
    It was at that moment that I understood why I (young and inexperienced) was called in that meeting. The four old men looked at me and said: you go.
  • The first Z: 14th of July 1989
    Peter 70's birthday 2009
    Peter did a remarkable job in reconciling the different characters and in building up the correct team spirit that lasted for 10 years in the ALEPH control room.
    ALEPH was ready for the pilot run that showed the readiness of the ALEPH tracking detectors that were able to measure the first Z at 13h15 of the first day of beam.
    At the first CERN seminar ALEPH reported the number of neutrinos with a luminosity error of 2%, compared to 5% of OPAL and DELPHI and none of L3.
  • Peter and the Z lineshape
    Peter 70's birthday 2009
    In a nut shell: he could not care less.
    His only interest was to collect data at the peak at the highest possible rate and to measure heavy flavors with ALEPH.
    And this is a remarkable story of some 10 publications in two years produced by the ALEPH Heavy Flavor group led by Peter.
    Robert, Alain, Pierre, Roberto, Vivek, Dave, Roger, Paul, Marcello………
  • Early ALEPH Publications on HF
    Peter 70's birthday 2009
    Heavy Flavor Production In Z Decays.
    TOPCITE = 100+
    Measurement of B - anti-B mixing at the Z.
    TOPCITE = 50+
    Measurement of the B hadron lifetime.
    TOPCITE = 50+
    Measurement of the forward - backward asymmetry in Z ---> b anti-b and Z ---> c anti-c.
    TOPCITE = 50+
    Production and decay of charmed mesons at the Z resonance.
    TOPCITE = 50+
    Evidence for b baryons in Z decays.
    TOPCITE = 50+
    Measurement of B - anti-B mixing at the Z using a jet charge method.
    TOPCITE = 50+
    Observation of the semileptonic decays of B(s) and LAMBDA(b) hadrons at LEP.
    TOPCITE = 50+
    Updated measurement of the average B hadron lifetime.
    TOPCITE = 50+
  • HF Identification
    Peter 70's birthday 2009
    After R_L cut
  • Measurement of Rb
    Peter 70's birthday 2009
    where the systematic error is dominated by the knowledge of the blepton B.R.
    High or vsp fit ? This was the the question most asked by Peter in the HF meetings 1
    with electrons
    submitted 25/4/1990
  • ICHEP 1990 Singapore
    Peter 70's birthday 2009
    high pt-leptons
  • ICHEP 1990 Singapore
    Peter 70's birthday 2009
  • First precise measurement of χat LEP
    Probability to PB
    The French fit :
    Peter 70's birthday 2009
    submitted 20/12/1990
  • Measurement of the FB Asymmetry
    Peter 70's birthday 2009
    High Pt sample
    submitted 23/4/1991
  • Measurement of the FB Asymmetry
    Peter 70's birthday 2009
    The big fit in pt and p
    submitted 23/4/1991
  • Asymmetry today
    Peter 70's birthday 2009
    20 times smaller than the early measurements
  • ITC measures the b-hadron lifetime
    Peter 70's birthday 2009
    impact parameter divide by error
  • Peter 70's birthday 2009
    Early Aleph days
    1986
  • CERN February 1991
    Peter 70's birthday 2009
  • Bari 1995
    Peter 70's birthday 2009
  • Peter 70's birthday 2009
    … all nice stories have an end
    …. also ALEPH….
    …..but memories stays forever in our heart……