Transcript Slide 1

`Your Vision of a Future Tevatron
Program’ (request from Chris)
Henry Frisch
University of Chicago
Patrick Huber
Fermilab 3/4/2010
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I. Run the Tevatron Until We Are
Sure We Don’t Need It
1. There are key precision measurements that it will be a very long time, if
ever, before they are done better at the LHC than at the Tevatron –
e.g. the W mass and the top quark mass.
2. Even if the LHC is able to measure these more precisely, the
systematics of the measurements at the LHC and the Tevatron will be
quite different- there is a good chance that the tension between the
EWK precision fits and the LEP limit on the Higgs mass will endure, and
being sure that there is no problem in MW or Mtop is critical.
3. There are many models that have light new physics- the Tevatron is a
better match to MET ~ MW/4 and light masses (few GeV to EWK scale)
for track-based triggering and soft electron reconstruction, among
other soft (low Pt) things.
4. We have finally entered the realm of diboson and Higgs cross-sectionsstill many signatures to explore. The SM Higgs is only one of many
possibilities, e.g.- and tools are still getting better. Why quit now?
Fermilab 3/4/2010
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II. Make adiabatic improvements and
necessary replacements/upgrades
1. Systematic program to get detector efficiencies to PRL
(not to tape) up to 90% (`hammering down highest nails’)many small nagging losses.
2. Make tests of luminosity leveling- opposition was from bphysics, but would help in quality of high-Pt data, analysis,
and (I still believe, but could be wrong) efficiency.
3. I don’t know about silicon lifetime- need to ask experts- I
think other sub-systems are ok (e.g. CEM goes down slowly
but steadily, COT and magnet seem to be holding up)
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III. Assign technical staff to run the
detectors instead of constant shuffling of
responsibilities
1. Heard often that `there aren’t enough people to run the
detectors’.
This is true in the present model, which is mind-blowingly
inefficient. In the present model, institutions are still
responsible for sub-systems built years (decades in some
cases) earlier. Maintaining these systems is neither
interesting nor easy to do well- yet we persist at it. Not
surprisingly, it’s hard to find enough people to do it. The
ones we do find are completely unskilled and are short-term.
The lab needs to make a new model, the `John Roof’ model, in
which permanent staff are assigned to run, maintain, and
improve the operation of the detectors. This is possible- it
would only take a management decision that this is a
priority.
Fermilab 3/4/2010
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IV. Make qualitative improvements in
capability (i.e. non-adiabatic)
EXAMPLES (these need evaluation by collaboration godparent
committees or equiv.- these are ones I know a little about,
probably good others)
1. New silicon systems with better spatial resolution (cancelled
by previous management)
2. New TDC’s for the COT for faster readout (cancelled by
previous management), less deadtime (more b-physics data)
3. 3-10-psec TOF for K-pi separation for quark-flavor
identification (e.g. ttbar -> e nu b bbar c sbar).
4. New SVT track-based trigger.
Build on ILC detector development advances- incorporate
them into the Tevatron program. (takes careful evaluation)
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What follows is completely
ignorant, and may be much too
late, and in any case impossible
to turn the ship around to given
the momentum (inertia), but in
the abstract still seems to me to
be the right answer: so, be
forgiving (Chris asked for `vision’)
Fermilab 3/4/2010
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IV. Upgrade the pbar source
1. I don’t know much about this- but there are many
exceptionally talented folks at the lab and elsewhere who
do. If there were serious support for this, how much could
be gained? (again, question of money, talent, and
commitment- I just have no idea of the curve of gain vs
money and time, e.g. I would ask Paul Derwent, Rol Johnson,
and Chuck Ankenbrandt, for starters.)
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V. Go for USA as Number 1 Again
(we owned the podium- want it back).
Go for the energy
frontier- that’s
where the big
questions will be
answered, if at all.
Go back to 1984 pbar
workshop at UC,
and (one) start of
the SSC tragedy.
Pbarp at 1033 and
42 TeV reaches 21
TeV in q-qbar vs
7.8 for pp at 1034.
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VI. Followed by a Muon Collider
• Long-term goal of the lab should be a muon collider,
IMHO (15-20 years out?)
• But we cannot afford a long gap of a weak or narrow
program in the interim- neutrino program is not broad
enough, both in opportunities for young folks and in
basic questions being asked, to support the effort
until we get to the next step.
• And it’s a long ways to a muon collider (I’m no
expert- Rol, who is, says not and is actually doing
something about it, and I don’t know, but would be
nice to be on a path that seems broader and richer
while we develop one.
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Back to IV. Pbar-p at 42 TeV
1. Has to be innovative, much lighter weight than SSC, ILC, or LHC.
2. Has continuity with Tevatron program- upgrading pbar source, build a
new detector with ILC technologies (`CD0F’?), 4th-gen detector.
3. Not a new proposal- 1984 Workshop, work by Ernie Malamud, othersjust not taken seriously.
4. Requires robust, relatively simple (no pushing boundaries) magnet
design. Much simpler than LHC 2-in-1 high-field magnets.
5. Probably requires horizontal drilling (not tunneling) of small-diameter
tunnel and robotic installation.
6. Local opposition existed for Fermilab- not guaranteed, but was
overcome then. (I think this is a red herring).
7. Present political climate receptive to `We want to be Number 1 again’
argument- not to Theta13 muttering.
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THE END
“You could be up to your belly-buttons in (SUSY) and not know it..”- C. Prescott
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BACKUP SLIDES
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Precision Measurements of MW
and MTop
Much as the case for Babar was made on the closing of the CKM
matrix, one can make the case that closing the MW - MTop-MHiggs
triangle is an essential test of the SM.
All 3 should be measured at the LHC- suppose the current central
values hold up, and the triangle doesn’t close (or no H found!).
Most likely explanation is that precision MW or MTop is wrong.
The systematics at the Tevatron are completely different from those
at the LHC- much less material, known detectors, qbarq instead of
gg, # of interactions, quieter events (for MW).
=>Prudent thing to do is don’t shut off until we see MW - MTopMHiggs works.
Remains to be proven that the LHC can measure MW and MTop
better than the Tevatron (maybe eventually, but not soon is my
guess)
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Low-mass/low met BSM
LHC has much more reach- but there may be regions
of rel. soft things (e.g. met~20) that will not be top
priority at CERN and where light new physics can
hide. LHC is not optimum for this physics- Tevatron
complements it well. This is physics that may not get
done if not at Fermilab, and has discovery potential.
1. Triggering at EWK-scale values of MET (M_W/4)- interesting
mass region based on MW-mtop, models of light objects at low
cross-sections.
2. Identification of soft electrons and taus from new light objects
in EWK events (too much material, multiple interactions)- region
not yet explored well
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Tevatron aspects complementary to LHC
strengths to compare capabilities
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Obvious ones (pbar-p,..)
Electron, photon, tau ID
has much less materialultimate MW, H->taus,?
Tau-ID; photon/pizero
separation (shower max)
Triggering at
met~20GeV
Triggering on b, c quarks
(SVT)- also (?)
hyperons,…
Fraction of a radiation length
traversed by leptons from W decay
(CDF Wmass analysis)- << 1 X0
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The attraction of hardware upgrades
(this is a little over the top- ignore it if you want to, please)
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Could even imagine
bigger upgrades- e.g.
may want to
distinguish W->csbar
from udbar, b from
bbar in top decays,
identify jet parents,..
Outfit one of the 2
detectors with particle
Id- e.g. TOF with s
<= 1 psec:
Collect signal here
Incoming particle makes light in window:
Micro-channel Plate/Cherenkov Fast Timing Module
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Geometry for a Collider Detector
2” by 2” MCP’s
Beam Axis
Coil
“r” is expensive- need a thin segmented
detector
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Summary
1. Tevatron running well – expect >= 1.5-2 fb-1/yr/expt of all goes
well (could even be somewhat better- there are more pbars).
2. Experiments running pretty well and producing lots of hands-on and
minds-on opportunities (lots of room for new ideas, analyses, and
hardware upgrades (great for students!)
3. Doubling time for precision measurements isn’t set by Lum- set by
learning. Typical time constant ~ one grad student/postdoc.
4. Precision measurements- MW, Mtop, Bs Mixing, B states- MW and
Mtop systematics statisics-limited
5. Can make a strong argument that pbar-p at 2 TeV is the best place
to look for light SUSY, light Higgs,…; as met at EWK scale,
(MW/2, Mtop/4) doesn’t scale with mass, root-s, and tau’s (maybe
b’s) are better due to lower mass in detector, and SVT and L1
tracking triggers,
6. All of which implies keep the Tevatron running until we know that we
don’t need it (and keep Fermilab strong for the ILC bid too!)
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A real CDF Top Quark Event
T-Tbar -> W+bW-bbar
Measure transit time here
(stop)
W->charm sbar
B-quark
T-quark->W+bquark
T-quark->W+bquark
TRIDENT
B-quark
Cal. Energy
From electron
W->electron+neutrino
Fit t0 (start) from all tracks
Can we follow the color flow
through
kaons, charm, bottom? TOF! 19
Fermilab
3/4/2010
Peak Lum of 3E32
40-50 pb-1/wk times 40 weeks/yr = 2 fb-1/year delivered per exptThere are more pbars even now. Peak lum problem =>Luminosity leveling?
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BUT: don’t focus on big improvements- steady improving X running=>smarts
The Learning Curve at a Hadron Collider (tL)
Take a systematics-dominated measurement: e.g. the W mass.
Dec 1994 (16 yrs
ago)`Here Be Dragons’
Slide: remarkable
how precise one
can do at the
Tevatron
(MW,Mtop, Bs
mixing, …)- but has
taken a long timelike any other
precision
measurements
requires a learning
process of
techniques,
details, detector
upgrades….
Theorists too(SM)
Electron+
Electron-
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A real CDF Top Quark Event
T-Tbar -> W+bW-bbar
Measure transit time here
(stop)
W->charm sbar
B-quark
T-quark->W+bquark
T-quark->W+bquark
TRIDENT
B-quark
Cal. Energy
From electron
W->electron+neutrino
Follow the color flow!
Fit t0 (start) from all tracks
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Luminosity vs Time
CDF
Run II
Run II So Far
Delivered Lum
D0
(CDF+D0)/2*
Xmas
week
Note patternintegral grows
when you don’t
stop, with
increasing slope
> 40 pb-1/wk/expt
Fermilab 3/4/2010
*(Protons are
smaller on this
side (joke))
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