PETRA

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PETRA TASSO
November revolution of 1974 and the observation
of jets in ee- collisions at SLAC in 1975, made
existence of quarks as real objects part of
particle physicists world-view.
End 73/early 74 PETRA_at_DESY and PEP_at_SLAC
were being developed
Emphasis was on ep with an ee- option
- this quickly changed after 1974!
Even after jets, J/ y etc., theoretical situation
unclear Cabibbo at the 1976 Frascati meeting on
PETRA detectors listed physics objectives as
R, mult. scaling, jets(2 jets), new narrow
resonances, heavy leptons, weak int.,something
new!
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PETRA TASSO
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TASSO DC
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PETRA TASSO
Five experiments approved - CELLO, JADE, Mark
J, PLUTO, TASSO TASSO Aachen-Bonn -DESY-IC-Ox
ford- RAL-Wisconsin
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First data
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First data
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First data
1. Top
2. TOP
3. T o p
Jets were only 3 years old and QCD 1 year older
QCD was far from being accepted as THE theory
of strong interaction.
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Expectations
However, it wasnt that the theory predictions
didnt exist - they just werent widely
known/appreciated Ellis, Gaillard Ross 76
predicted planar events, growth in ltptgt
and at sufficiently high
energy, explicit 3-jet
structure
At TASSO, exceptionally good contacts between
theorists (Ellis, Gaillard .) and experimenters
(Wiik, Wolf) meant that we were perhaps more
aware than most of these ideas Also, TASSO was
optimised for hadronic final state particle
i.d. , so jets were central to our physics
programme.
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Gluon discovery
Wu Zobernig (1979) - pointed out the best way
to observe 3-jet planar
structures the smoking gun of
the gluon. SPEAR had 7.4 GeV and
resolved 2-jets,
back-of-envelope phase-space gt
22 GeV required to see 3-jets.
From Jan- April, TASSO ran below 17 GeV. Clear
two jet structures, pt distributions etc
measured. In late April more r.f. added and we
started taking data at 27.4 GeV.
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Gluon discovery
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Gluon discovery
Paul, Gunter Wolf myself, showed a variety of
plots which, taken together, were convincing
evidence that the gluon had been discovered.
In the August Fermilab LPS, the other experiments
also had evidence the papers followed in
September
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Gluons and QCD
Spin 1 gluon Coupling constant Flavour
Independence
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Vertex Detectors
Story now returns to PETRA. In Jan. 81 I was
measuring ? and b lifetimes using only the
TASSO DC CPC - the resolution at vertex was
cm, but we managed! Guenter came in and asked
why we couldnt build a VXD like MARK IIs.
Alfred Ladage had idea to construct a VXD made
of straws with central anode. UK groups led by
David Binnie had more conventional design
with drift cells. Both were at 4 bar pressure.
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Vertex Detectors
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TASSO VXD
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TASSO VXD
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VXD Planning
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VXD Installation
VXD installed inside TASSO and taking data by
mid-December 1982 - less than 2 years since we
had first begun to think about it.
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VXD Physics
Eventually we found where VXD was and used it for
physics.
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Lifetimes
Tau,B mesons, Ds, D
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TASSO Collaboration
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The early meetings