phys 3446 lecture #1brandta/savtwel/lectures/phys3446-lec1.pdf · phys 3446 lecture #1 wednesday...
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PHYS 3446
Lecture #1Wednesday January 18, 2012
Dr. Andrew Brandt
1. Syllabus and Introduction
2. High Energy Physics at UTA
Thanks to Dr. Yu for developing initial electronic version of this class
Please turn off your cell-phones, pagers and laptops in class
http://www-hep.uta.edu/~brandta/teaching/sp2012/teaching.html
My Background+Research
B.S. Physics and Economics College of William&Mary 1985
PH.D. UCLA/CERN High Energy Physics 1992
(UA8 Experiment-discovered hard diffraction)
1992-1999 Post-doc and Lab Scientist at Fermi National Accelerator Laboratory
-1997 Presidential Award for contributions to diffraction
-Proposed and built (with collaborators from Brazil) DØ Forward Proton
Detector
-Physics Convenor
-Trigger Meister
1999 Joined UTA as an Assistant Professor
2004 promoted to Associate Professor
2010 promoted to Full Professor
- Funding from NSF, DOE, and Texas approaching 10M$ as PI or Co-PI
Monday August 29,
2011
PHYS 1444-004, Dr.
Andrew Brandt
My Main Research Interests
• High Energy Physics (aka Particle Physics)
• Physics with Forward Proton Detectors (detect
protons scattered at small angles)
• Fast timing detectors (How fast? Really really fast!)http://www.youtube.com/watch?v=By1JQFxfLMM&feature=related
• Triggering (selecting the events to write to tape): at
ATLAS must choose most interesting 300 out of up to
40,000,000 events/sec
• Higgs Discovery
• Weapons of Mass Destruction
Monday August 29,
2011
3 PHYS 1444-004, Dr.
Andrew Brandt
(detection of)
Grading
• Only test is a Midterm: 25%
– No Final
– Test will be curved if necessary
– No makeup tests
• Homework: 20% (no late homework)
• Lab score: 25% (details soon)
• Project: 20% (a look at early ATLAS data
or a report/presentation on important events
in particle physics?)
• Pop Quizzes: 10%
Attendance and Class Style
• Attendance:
– is STRONGLY encouraged, to aid your
motivation I give pop quizzes
• Class style:
– Lectures will be primarily on electronic media
• The lecture notes will be posted AFTER each class
– Will be mixed with traditional methods
(blackboard)
– Active participation through questions and
discussion are STRONGLY encouraged
Physics History
• Classical Physics: forces, motion, work,
energy, E&M, (Galileo, Newton, Faraday,
Maxwell)
• In modern physics (Einstein, Planck, Bohr)
we covered relativity, models for the atom,
some statistical mechanics, and finished
with a bit of discussion about the nucleus
and binding energy circa 1930 when the
neutron was discovered
• What’s new since 1930?
Physics History
• I’m going to have to respectfully disagree
with you Leonard…
• 1937 muon discovered (who ordered that?)
• With advent of particle accelerators came
particle zoo
• There was a need to classify all the new
particles being discovered and try to
understand the underlying forces and theory
Course Material • Nuclear Physics
– Models of atom
– Cross sections
– Radiation
• High Energy Experiment
– Energy deposition in matter
– Particle detector techniques
– Accelerators
• HEP Phenomenology
– Elementary particle interactions
– Symmetries
– The Standard Model
– Beyond the Standard Model
High Energy Physics at UTA
UTA faculty Andrew Brandt, Kaushik De,
Amir Farbin, Andrew White, Jae Yu along with many post-docs, graduate and undergraduate students investigate the basic forces of nature through particle physics studies at the world’s
highest energy accelerators
In the background is a photo of a sub-detector of the 5000 ton
DØ detector. This sub-detector was designed and built at UTA
and is currently operating at Fermi National Accelerator
Laboratory near Chicago.
Structure of Matter
cm
Matter
10-9m
Molecule
10-10m 10-14m
Atom Nucleus
Atomic Physics
Nuclear
Physics
High energy means small distances
Nano-Science/Chemistry10-15m
u
<10-18m
QuarkBaryon
Electron
<10-19mprotons, neutrons,
mesons, etc.top, bottom,
charm, strange,
up, down
High Energy Physics
(Hadron)
(Lepton)
Periodic Table
All atoms are madeof protons, neutronsand electrons
Helium Neon
u
d
uu
dd
Proton NeutronElectron
Gluons hold quarks togetherPhotons hold atoms together
What is High Energy Physics? Matter/Forces at the most fundamental level.
Great progress! The “STANDARD MODEL”
BUT… many mysteries
=> Why so many quarks/leptons??
=> Why four forces?? Unification?
=> Where does mass come from??
=> Are there higher symmetries??
What is the “dark matter”??
Will the LHC create a black hole
that destroys the Earth?
NO! See: http://public.web.cern.ch/Public/en/LHC/Safety-en.html
Role of Particle Accelerators
• Smash particles together
• Act as microscopes and time machines
– The higher the energy, the smaller object to be
seen
– Particles that only existed at a time just after the
Big Bang can be made
• Two method of accelerator based
experiments:
– Collider Experiments: p p, pp, e+e-, ep
– Fixed Target Experiments: Particles on a target
– Type of accelerator depends on research goals
Fermilab Tevatron and CERN LHC• Currently Highest Energy
proton-anti-proton collider
– Ecm=1.96 TeV (=6.3x10-7J/p13M Joules on 10-4m2)
Equivalent to the K.E. of a 20 ton truck at a speed 81 mi/hr
Chicago
Tevatron p
p CDF
DØ
Fermilab: http://www.fnal.gov/ ; DØ: http://www-d0.fnal.gov/ CERN: http://www.cern.ch/ ; ATLAS: http://atlas.web.cern.ch/
• Highest Energy (proton-proton) collider since fall 2009
– Ecm=14 TeV (=44x10-7J/p1000M Joules on 10-4m2)
Equivalent to the K.E. of a 20 ton truck at a speed 711 mi/hr
Currently 7 TeV collisions
1500 physicists
130 institutions
30 countries
5000 physicists
250 institutions
60 countries
The International Linear Collider
33km=
21mi
European Design
500 GeV (800 GeV)
47 km
=29 mi
US Design
500 GeV (1 TeV)
• Long~ linear electron-position colliders
• Optimistically 15 years from now
• Takes 10 years to build an accelerator and the detectors
Dr.White is co-
spokesman
of SiD detector
Particle Identification
Interaction
Point
electron
photon
jet
muonneutrino (or any non-
interacting particle
missing transverse
momentum)
Ä B
Scintillating Fiber
Silicon Tracking
Charged Particle Tracks
Calorimeter (dense)
EM hadronic
Energy
Wire Chambers
Mag
net
Muon Tracks
We know x,y startingmomenta is zero, but
along the z axis it is not, so
many of our measurements are
in the xy plane, or transverse
DØ Detector
• Weighs 5000 tons
• As tall as a 5 story building
• Can inspect 3,000,000 collisions/second
• Record 100 collisions/second
• Records 10 Mega-bytes/second
• Recording 0.5x1015 (500,000,000,000,000)
bytes per year (0.5 PetaBytes).
30’
50’
ATLAS Detector
• Weighs 10,000 tons
• As tall as a 10 story building
• Can inspect 1,000,000,000
collisions/second
• Recors 200 -300 collisions/second
• Records 300 Mega-bytes/second
• Will record 2.0x1015
(2,000,000,000,000,000) bytes each year (2
PetaByte).
The Standard Model
• Current list of elementary (i.e. indivisible) particles
• Antiparticles have opposite charge, same mass
The strong force is different from E+M and gravity!new property, color chargeconfinement - not usual 1/r2
Standard Model has been very successful
but has too many parameters, does not
explain origin of mass. Continue to probe
and attempt to extend model.
UTA and Particle Physics
Fermilab/Chicago
CERN/Geneva
ILC? U.S.?
Building Detectors at UTA
High Energy Physics Training + Jobs
EXPERIENCE:
1) Problem solving
2) Data analysis
3) Detector construction
4) State-of-the-art high speed electronics
5) Computing (C++, Python, Linux, etc.)
6) Presentation
7) Travel
JOBS:
1) Post-docs/faculty positions
2) High-tech industry
3) Computer programming and development
4) Financial
DØ Forward Proton Detector (FPD)
• Quadrupole Spectrometers
• surround the beam: up, down, in, out
• use quadrupole magnets (focus beam)
- a series of momentum spectrometers that make use of accelerator
magnets in conjunction with position detectors along the beam
line to measure the momentum and scattering angle of the proton
• Dipole Spectrometer
• inside the beam ring
in the horizontal plane
• use dipole magnet
(bends beam)
• also shown here: separators (bring beams
together for collisions)
A total of 9 spectrometers comprised of 18 Roman Pots
Data taking finished, analysis in progress (Mike Strang Ph.D. 2006)
Detector Construction
At the University of Texas, Arlington (UTA), scintillating and optical
fibers were spliced and inserted into the detector frames.
The cartridge bottom containing the detector is installed in the Roman
pot and then the cartridge top with PMT’s is attached.
One of the DØ Forward Proton Detectors built
at UTA and installed in the Tevatron tunnel
FermilabDØ
High-tech fan
Tevatron: World’s 2nd Highest Energy
Collider
Elastic Scattering Cross Section (FPD)
Single Diffractive Cross Section (FPD)
Arnab Pal (UTA PhD student)
ATLAS Forward Protons: A (10)
Picosecond Window on the Higgs Boson
Andrew Brandt, University of Texas at Arlington
A picosecond is a trillionth of a second.
This door opens ~once a second, if it opened
every 10 picoseconds it would open a hundred
billion times in one second (100,000,000)
Light can travel 7 times around the earth in
one second but can only travel 3 mm in 10 psec
Yes, I know it’s a door, not a window!
27January 12, 2010 Andrew Brandt SLAC Seminar
Central Exclusive HiggsAFP concept: adds new ATLAS sub-detectors at 220 and 420 m
upstream and downstream of central detector to precisely measure the
scattered protons to complement ATLAS discovery program.
These detectors are designed to run at a luminosity of 1034 cm-2s-1 and
operate with standard optics (need high luminosity for discovery physics)
Ex. The leading discovery channel for light SM
Higgs, H , has a branching ratio of 0.002!
You might ask: “Why build a 14 TeV collider and have 99% of your energy taken
away by the protons, are you guys crazy or what??”
beam
p’
p’AFP Detector
LHC magnets
The answer is “or what”!—ATLAS is routinely losing energy
down the beam pipe, we just measure it accurately!!!
420 m 220 mH
Note: the quest for optimal S/B
can take you to interesting places:28
n=1 n>>1
Cerenkov Effect
Use this property of prompt radiation to develop a fast
timing counter
particle
Photocathode
Dual MCP
Anode
Gain ~ 106
Photoelectron
V ~ 200V
V ~ 200V
V ~ 2000V
photon
+
+
e-
Faceplate
MCP-PMT
Micro-Channel Plate
Photomultiplier Tube
(MCP-PMT)
Ultra-fast Timing Issues
• 3 mm =10 ps
• Radiation hardness of all components of system
• Lifetime and recovery time of tube
• Backgrounds
• Multiple proton timing
Time resolution for the full detector system:
1. Intrinsec detector time resolution
2. Jitter in PMT's
3. Electronics (AMP/CFD/TDC)
4. Reference Timing
31January 12, 2010 Andrew Brandt SLAC Seminar
Laser Tests
Study properties of MCP-PMT’s:
1) How does timing depend on gain and number of pe’s
2) What is maximum rate? How does this depend on various
quantities?
3) Establish minimum gain to achieve timing goals of our detector
given expected number of pe’s (~10). Evaluate different electronics
choices at the working point of our detector
4) Eventually lifetime tests
***Ongoing laser tests very useful in developing the fastest time of
flight detector ever deployed in a collider experiment
32
LeCroy Wavemaster
6 GHz Oscilloscope
Laser Box
Hamamatsu
PLP-10
Laser
Power
Supply
33
laserlenses
filterMCP-PMT
beam splittermirror
PTF
Picosecond Test Facility
featuring initial
Undergraduate
Laser Gang (UGLG)
Undergraduate Laser
Youths? (UGLY)
January 12, 2010 Andrew Brandt SLAC Seminar
Timing vs Gain for 10 m Tube
Measured with reference tube using CFD’s and x100
mini-circuits amps, with 10 pe’s can operate at ~5E4 Gain
(critical for reducing rate and lifetime issues) With further
optimization have obtained <25 ps resolution for 10 pe’s.
34
35
0
5
10
15
20
25
30
35
40
45
0 20 40 60 80 100 120
Tim
e R
esolu
tion
(p
s)
#PE
HV 2350
HV 2450
HV 2650
HV 2750
HV 2850
Timing vs. Number of PE’s
No dependence of timing on gain if sufficient amplification!
Aside: Measuring Speed of EM Waves
• We noted that
ground plane
oscillations on
reference tube
were picked up
by second tube
• Used this to do a
3% measurement
of speed of light
(Kelly Kjornes)
36
Moving 2nd tube 2 feet from reference tube shifts pick-up
oscillation pattern by 2.05 ns
New Multi-Channel Laser Setup
37January 12, 2010 Andrew Brandt SLAC Seminar
Pre-lecture Conclusions
• Nuclear and Particle picks up where
Modern Physics left off
• One of the current frontiers of physics is
high energy or particle physics: very
interesting (I think!)
• Nobel Prize possibilities
• Other interesting areas of physics at UTA
include nano-bio physics, astrophysics,
nano-magnetism, etc.
Summary
• If you are here to learn about Nuclear/Particle Physics this should be an interesting and fun class, if you are here because you need four hours of physics….
a) get out while you still can OR
b) it will still be an interesting and fun class (up to you)
• It is an opportunity to learn about high energy physics from a high energy physicist
• Lab takes time, there will be reading outside of main text
• See me if interested in UG research project in particle physics
Monday August 29,
2011
40
Why Do Physics?
• To understand nature through experimental observations and measurements (Research)
• Establish limited number of fundamental laws, usually with mathematical expressions
• Explain and predict nature
⇒Theory and Experiment work hand-in-hand
⇒Theory generally works under restricted conditions
⇒Discrepancies between experimental measurements and theory are good for improvement of theory
⇒Modern society is based on technology derived from detailed understanding of physics
Exp.{
Theory {
PHYS 1444-004, Dr.
Andrew Brandt
Monday August 29,
2011
41
Why Do Physics Part Deux
PHYS 1444-004, Dr.
Andrew Brandt
http://www.aps.org/publications/apsnews/200911/physicsmajors.cfm
2008/2009 Graduates
1.7% unemployment
While engineering
starting salaries are
typically higher than
physicists, mid-
career salaries are
virtually identical
101k$ for engineering
99k$ for physics
Monday August 29,
2011
42
What Do Physicists Do?
PHYS 1444-004, Dr.
Andrew Brandt