Transcript Particle Physics Experiments Su Dong Stanford Student Orientation SLAC session Sep/22/2011 The Fundamental Questions • Are there undiscovered principles of nature: new symmetries, new physical laws.

Particle Physics Experiments
Su Dong
Stanford Student Orientation
SLAC session
Sep/22/2011
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The Fundamental Questions
• Are there undiscovered principles of nature: new
symmetries, new physical laws ?
• How can we solve the mystery of dark energy ?
• Are there extra dimensions of space ?
• Do all forces become one ?
• Why are there so many kinds of particles ?
• What is dark matter ?
How can we make it in the laboratory ?
• What are neutrinos telling us ?
• How did the universe come to be ?
• What happened to antimatter ?
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The Fundamental Questions
• Are there undiscovered principles of nature: new
symmetries, new physical laws ?
• How can we solve the mystery of dark energy ?
• Are there extra dimensions of space ?
• Do all forces become one ?
• Why are there so many kinds of particles ?
• What is dark matter ?
How can we make it in the laboratory ?
• What are neutrinos telling us ?
• How did the universe come to be ?
• What happened to antimatter ?
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Current Particle Physics Programs
Accelerator
based Expt
Description
Data Period
APEX/HPS
Heavy Photon Search at Jlab
2011/2015-
ATLAS
pp collision @7-14 TeV at LHC
2010-
BaBar/
superB
e+e- @10GeV at SLAC B-factory/
e+e- super B factory at Frascati
1999-2008/
2016??
Non Accel.
Expt.
Description
Data Period
CDMS
Cryogenic Dark Matter Search
2001-
EXO
Neutrino-less double b decay search with
Enriched Xenon Observatory
2011-
A common primary goal is to search for physics
beyond the Standard Model
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ATLAS @ LHC
Physics Program in Full Swing
No new physics yet,
but Higgs hunting already getting interesting…
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2013
Stage 2:
2021
2010
Stage 1:
2017
Stage 0: 2013
Physics Roadmap and Detector Evolution
2017
2021
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Physics Preparation Examples
Pile up correction with Jet Vertex Fraction (JVF)
Jet
Energy
Scale
calibration
b-jet
trigger
menu
optimization
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Physics Analysis Examples
Boosted
Top in jet
substructure
analysis
Stopped long-lived particle search
SUSY
Search
with b+MET
and
simplified
models
Close collaboration with SLAC/Stanford theory community
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SLAC Involvement in ATLAS
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Faculty
16+ Staff physicists & professionals
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Postdocs
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Grad students
& Tier2 computing center staff
Experimental Involvement
• Pixel vertex detector and tracking
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•
•
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High Level Trigger and DAQ
Simulation
Tier-2 computing center
ATLAS Detector Upgrades
Opportunities to develop wide variety of experimental skills
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Examples of Experimental Activities
Pixel
clustering
Simulation:
muon trigger
background
2mm
Modern DAQ
concept for upgrade
Online beam spot
DOE Site Visit: Aug/2/2011 ATLAS
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Contact Info
Prof. Ariel Schwartzman
[email protected]
Prof. Su Dong
[email protected]
Dr. Charlie Young
[email protected]
Detailed info on ATLAS@SLAC for students:
http://www.slac.stanford.edu/exp/atlas/students/
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Detector R&D for
& superB @ Frascati
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BaBar DIRC ---> FDIRC
BaBar DIRC
(in 2 easy steps)
• R&D Complete 2010
1-st FDIRC prototype
• This full scale
device is nearly
complete now
FDIRC design for SuperB
DIRC provided the “world’s
best “ PID at BaBar. It was
stable and robust. But new
SuperB factories need devices
that work at even higher
backround levels.
Prototype verified the focusing
concept, use of highly pixilated
detectors, developed MC methods,
and demonstrated the previously
Performance: sqc ~ 9.5 mrads unobserved principle that the
chromatic error can be corrected
by timing. Performance: sqc ~ 9.5
Cherenkov Ring
mrads
=> 9.0 mrads after we
Imaging Particle ID
corrected for the chromatic error
- 3D imaging (x, y & time),
- 25x smaller volume and
- 10x faster than BaBar DIRC.
Performance: sqc ~ 9.5 mrads
=> 8.5-9 mrads if we correct for
the chromatic error.
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Status of Fused Silica FBLOCK & New Wedge
• Precise machining on a 5-axis NC machine finished.
• Presently FBLOCK & New Wedge are being polished
to final size and surface quality. Expect delivery in
3-6 weeks.
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CRT: our SLAC “test beam”
• Test setup is now ready for the bar box.
• FBOX support structure arrived at SLAC in July.
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Status of Electronics and Detector plane
Have already experience with
BLAB2 electronics used in
the 1-st FDIRC prototype:
Hope to add
Up to 16
additional
H-8500 tubes
15 H-8500
tubes exist now
French TDC/ADC electronics:
Will be used to develop and test electronics as
well as demonstrate overall FDIRC performance
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Opportunity to Join FDIRC R&D
• Fabrication, testing, electronics, photon detectors, software
development, and analysis. Precise role depends on timing and
level of the student’s participation.
Expected Schedule:
• Fabrication and assembly complete by early fall
• Software and analysis system development in parallel
• System cosmic ray test in the SLAC end station in early winter
• Data accumulation, analysis, and published results during 2012
Prof. David Leith
Dr. Blair Ratcliff
[email protected]
[email protected]
Dr. Jaroslav Va’Vra
[email protected]
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Introduction to Heavy Photons
• The Heavy Photon (A’) is a conjectured U(1) force particle, a
massive vector gauge boson which couples to an analogue of electric
charge
• The A’ kinetically mixes with the SM , inducing a weak coupling e
to electric charge, so heavy photons can be radiated by electrons,
and decay to e+e-.
• Are there more U(1)’s in Nature? They proliferate in BSM
theories. General considerations imply  ~ 10-3 and mA’ ~100 MeV.
• A’ may mediate Dark Matter annihilations and interactions, and
thereby account for excess HE e+e- in the cosmic rays and DAMA’s
direct detection!
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Heavy Photon Search
• The photon provides a “portal” to hidden sectors of the universe,
since by virtue of “kinetic mixing” it will weakly mix with hidden
sector vector gauge bosons and couple them to electric charge.
• Dark Matter may be part of such a “hidden sector”,
and may well couple to the hidden sector gauge boson, just as
charged particles in our sector couple to the photon.
• The Heavy Photon Search is a search for a massive vector
gauge boson which could mediate Dark Matter interactions with
regular matter, be produced in Dark Matter annihilations, and
be visible in our sector by decaying to electrons and positrons.
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HPS Setup
• An intense electron beam impinging on a thin target would
produce heavy photons. They are detected in a compact
spectrometer/vertex detector by measuring the invariant mass
and decay lengths of the e+e- pairs into which they decay.
• Heavy photons appear as a resonance above the copious
QED trident background. For small couplings , the finite A’
decay length provides a second signature.
QED
A’
• EM Calorimeter provides a fast trigger and electron ID.
• Small cross sections and high backgrounds demand large luminosities.
HPS survives beam backgrounds by spreading them out maximally in time,
capitalizing on 100% CEBAF duty cycle and employing high rate DAQ.
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’/  2
Present Limits, Region of Interest, HPS Reach
Both “naturalness”
arguments and fits to
astrophysical data
suggest
’/  2 ~ 10-4 – 10-10
mA’ ~ MeV - GeV
Bump Hunt
2.2 GeV
Vertex
6.6 GeV
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Schedule and Plans
• HPS Test Run was approved by JLAB and funded by DOE earlier
this year. (Full HPS was conditionally approved, depending on the
Test Run.)
• Design, construction, and preparations for analysis are underway
now, to be completed early next year. SLAC is collaborating with
JLAB, UCSC, Fermilab, and others on HPS.
• HPS Test Run will be installed and commissioned at JLAB during
Spring 2012 to test detector operations and search for low mass
heavy photons.
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Opportunities for Students
•
Rotation Projects are available on HPS this year
•
After the Test Run, lots to do:
2012
Analyze test run data
2012
Remove contingencies for full HPS
2013-14
Refine the design and construct full HPS
2015
Install HPS at JLAB
2015-16
Take data with HPS and analyze
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Ideal training for all aspects of HEP experimentation
Experiment design, planning, and simulation
Proposal writing and submission and defense
State of the art hardware construction and commissioning
Data taking and monitoring
Data Analysis
•
Contact: Prof John Jaros
[email protected]
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CDMS
Cryogenic Dark Matter Search (CDMS)
• Stanford and SLAC have leading roles in the CDMS
experiment, which seeks to directly detect the Dark
Matter that makes up ~25% of the universe
– 10 kg of new “IZip” Ge detectors will start taking data in
~2 months at the Soudan Underground Laboratory in
Minnesota
– 100 kg planned for deeper SNOLAB site in Sudbury Canada
– Sophisticated detector technology to provide robust
rejection of backgrounds – expect background-free
performance up to 1 ton.
2010 CDMS Collaboration Meeting at SNOLAB
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SuperCDMS Technology
• Identify Dark Matter by simultaneously measuring phonons and
ionization produced in Ge crystals
– Phonons heat tungsten strips kept at transition between normal and
superconducting state - acts as a “calorimeter” in the traditional sense
– Ionization signal helps distinguish electron recoils (highly ionizing largely background) from nuclear recoils from Dark Matter interactions
Collage of SLAC / Stanford Efforts in CDMS
Photolithographic detector fabrication
Adapt 10 mK dilution
refrigerator for
SNOLAB Test Facility
Automated inspection of detectors
SNOLAB mechanical
and electronic design
GEANT4 simulation of backgrounds and
phonon/charge propagation in 10 mK Ge
CDMS Contacts
Prof. Blas Cabrera
[email protected]
Dr. Richard Partridge
[email protected]
EXO
EXO-200 first result 2nbb
EXO
Is neutrino Dirac or Majorana ?
2nbb
0nbb
See more details in Prof. Giorgio Gratta’s
talk on Wednesday
Prof. Giorgio Gratta
[email protected]
Prof. Martin Breidenbach
[email protected]
Dr. Peter Rowson
[email protected]
The Fundamental Questions
• Are there undiscovered principles of nature: new
symmetries, new physical laws ?
• How can we solve the mystery of dark energy ?
• Are there extra dimensions of space ?
• Do all forces become one ?
• Why are there so many kinds of particles ?
• What is dark matter ?
How can we make it in the laboratory ?
• What are neutrinos telling us ?
• How did the universe come to be ?
• What happened to antimatter ?
There is a vibrant particle physics experimental program at
SLAC/Stanford seeking answers with variety of approaches
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