1. Accelerator Based Particle Physics Experiments
Su Dong
Stanford Student Orientation
SLAC session
Sep/16/2010

2. 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 ?

3. Accelerator Based Particle Physics Programs
Expt
Description
Data Period
ATLAS
pp TeV at LHC
2010-
BaBar/
superB
at SLAC B-factory/
e+e- super B factory at Frascati
/ ??
APEX/HPS
Heavy Photon Search at Jlab
2010/2012-
SiD
Silicon Detector for ILC ??
SLD
e+e- -> e- beam

4. LHC

5. Physics Road map and Detector Evolution
Stage 1:
Stage 2: 2020
Stage 0: 2012
2010
2020
2015

6. Physics Opportunities
SLAC physics strategy:
Initial emphasis on physics signature tools (b-tag,jet/missingEt) and trigger. Use Standard Model measurements with early data to validate these tools to prepare for searches of new physics beyond Standard Model.
Current SLAC physics analyses
New physics search and top cross section measurement with b-tag and missing Et
Search for long lived new particles
Lepton jets
Heavy fermions->same sign dileptons
Boosted W
Close collaboration with SLAC theory group
Higgs particle
SuperSymmetry
Large extra-dimensions
The unexpected…

7. SLAC Involvement in ATLAS
2 Faculty + 1 Panofsky fellow
17+ Staff physicists & professionals
7 Postdocs
6 Grad students
& Tier2 computing center staff
Experimental Involvement
Pixel vertex detector and tracking
High Level Trigger and DAQ
Simulation
Tier-2 computing center
ATLAS Detector Upgrades
Opportunities to develop wide variety of experimental skills

8. Contact Info
Dr. Charlie Young
Prof. Su Dong
Prof. Ariel Schwartzman
(resident at CERN)
Dr. Andy Haas
Detailed info on for students:

9. PEP-II
& Frascati

10. BaBar Physics
CP violation in B0 decays

11. BaBar Analysis Opportunities
Data taking ended Apr/08.
465M BB events
630M cc events
460M tt events
Largest sample of Upsilon resonance data
2-photon, ISR
Analysis topics:
ISR->hadronic final states
B/D decay Dalitz analysis
Radiative B decays
fDs
Charmonium like resonances
Prof. David Leith
Dr. Blair Ratcliff

12. Focusing DIRC prototype now in Research Yard
Radiator:
1.7 cm thick, 3.5 cm wide, 3.7 m long fused silica bar (the same used in the BaBar DIRC).
Optical expansion region:
filled with mineral oil to match the fused silica refraction index (KamLand oil).
include optical fiber for the electronics calibration.
Focusing optics:
spherical mirror with 49cm focal length focuses photons onto a detector plane.
Now being tested with new electronics:
8/6/2018

13. Focusing DIRC prototype photon detectors Nucl. Inst. &Meth
Focusing DIRC prototype photon detectors Nucl.Inst.&Meth., A 553 (2005) 96
1) Burle MCP-PMT (64 pixels, 6x6mm pad, sTTS ~50-70ps)
snarrow ≈70ps
time (ns)
Timing resolutions were obtained using a fast laser diode in bench tests with single photons on pad center.
2) Hamamatsu H-8500 MaPMT (64 pixels, 6x6mm pad, sTTS ~140ps)
snarrow ≈140ps
time (ns)
3) Hamamatsu H-9500 Flat Panel MaPMT (256 pixels, 3x12mm pad, sTTS ~220ps)
snarrow ≈220ps
time (ns)
8/6/2018

14. Cherenkov light: tagging color by time
Chromatic growth rate:
s ~ 40ps/m
Analytical calculation:
dTOP/Lpath [ns/m] = TOP/Lpath(l) - TOP/Lpath (410nm)
Cherenkov angle production controlled by nphase:
cos c = 1/(nphaseb), nphase(red) < nphase(blue) => c < c
Propagation of photons is controlled by ngroup (≠ nphase) :
vgroup = c0 /ngroup = c0 /[nphase - phase
vgroup(red) > vgroup (blue)
Geant 4 - without and with pixilization:
Data from the prototype:
dTOP/Lpath [ns/m]
dTOP/Lpath [ns/m]
8/6/2018

15. Future
We are building a new full size prototype for Super B with new fused silica focusing elements
Will be starting tests in Cosmic Ray Telescope in the SLAC Research Yard this year
Excellent opportunity for hands-on R&D with a innovative new detector.
8/6/2018

16. HPS is a new, small experiment which offers the thesis student
exposure to all aspects of experimental particle physics, from
experiment design and optimization, to hardware construction, installation and commissioning, and data analysis. Rotation Projects:
John Jaros

17. What is a “Heavy Photon”?
A heavy photon (A’) is a new, ~100 MeV spin one, force-carrying particle that couples to an analogue of electric charge. Because it will mix with “our” photon, it couples to electrons, albeit weakly:
Heavy photons can be produced by electron bremstrahlung off heavy targets and they decay to e+e –
A heavy photon appears as an e+e- resonance on a large background of QED tridents.
Heavy photons can travel detectable distances before decaying, providing a unique signature.
g’ =  e

18. Why Consider Heavy Photons?
Are there are additional U(1)’s in Nature? If so, they’ll show up by mixing with “our” photon, inducing weak couplings to electric charge.
Heavy Photons could mediate Dark Matter annihilations. Their decays may explain excess high energy electrons and positrons in the cosmic rays; their interactions may account for the DAMA dark matter “detection”.
Pamela Positron Excess

19. SLAC Activities on HPS and APEX
SLAC Heavy Photon Group is engaged in two projects:
HPS (Heavy Photon Search) has just submitted a proposal to JLab
Review next week at JLab workshop; approval this Fall?
Hope to engineer, construct, test, install by Spring 2012
Building Si tracker/vertexer, targets, and SVT data acquisition system GOOD PROJECTS FOR ROTATION STUDENTS
APEX (A Prime Experiment) utilizes two large existing spectrometers in Jlab’s Hall A to search for heavy photons
SLAC built targets, helped with test run, and is developing analysis
SLAC will continue helping run and analyze APEX
Contact: John Jaros
Si Tracker
APV25 Readout