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"The Universe is not made of Atoms it is made of Stories"

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1 "The Universe is not made of Atoms it is made of Stories"
Particle Physics and Cosmology in the Age of the Large Hadron Collider (LHC) Lesson based on talks for 2008 Teachers Conference Kavli Institute UCSB Some slide have links to short informative videos. Teachers may skip these without any lose of continuity. Objectives: To understand what the LHC is To learn the major categories of sub atomic particles To understand what a particle detector is and its basic operating principles To understand what mass might be and how this might be solved at the LHC To understand the Hierarchy principle and how this might be solved at the LHC To understand dark matter and how this might be found at the LHC To understand the asymmetry in matter and antimatter Roughly once a second, a subatomic particle enters the earth’s atmosphere carrying as much energy as a well thrown rock. Somewhere in the universe, that fact implies, there are forces that can impart to a single proton 100 million times the energy achievable by the most powerful earthbound accelerators. James W. Cronin, Thomas K. Gaisser, and Simon P. Swordy,” Cosmic Rays at the Energy Frontier.” Scientific American (January 1977) Speakers at the KIPT teachers conference 2008 1. Ayana Holloway Arce (UC Berkeley) 2. Raman Sundrum (Johns Hopkins Univ.) 3. Kevin McFarland (University of Rochester) 3. James Wells (CERN & Univ. of Michigan) Note time frame for LHC on poster < 1x10-10s, Temp > 1015 K and energy > 100 GeV "The Universe is not made of Atoms it is made of Stories" Muriel Rukeyser

2 Solved and Unsolved The Standard Model answers many of the questions about the structure and stability of matter, but??? Are quarks and leptons actually fundamental, or are they made up of even more fundamental particles? Why can't the Standard Model predict a particle's mass? How does gravity fit into all of this? Why is there more matter than antimatter in the universe What is this "dark matter“? Standard model-The Standard Model of particle physics is a theory that describes three of the four known fundamental interactions between the elementary particles that make up all matter. What can we expect to learn at the LHC? What gives particles their mass. What dark matter is Solving the Hierarchy problem. Or how does gravity fit into the Standard Model Why there more matter than antimatter in the universe Each of these topics will be discussed in this lecture

3 Standard Model Particle Physics Review ”If I could remember the names of all these particles... I'd be a botanist!” Enrico Fermi Fundamental particles Quark Electron Hadron-Two types, experience strong interaction Baryon-made of three quark, fermions Proton Neutron Meson-made of quark and antiquark, bosons Pion Kaon Lepton-Three flavors, spin ½ does, does not experience strong interaction Muon Tau Neutrino-Three flavors, lepton Fermion-Obey Pauli exclusion principle odd ½ integer spin Lepton, quarks Baryon Boson-Do not obey Pauli exclusion integer spin Force carrier-Photon, W and Z particles, and Gluons Meson A good review of particles can be found at Also attached is a review sheet that goes along with this web site. Students should do this active before this lecture. Two good introductions to particle physics 1. Richard Muller Quarks, exchange forces and confinement ( (Start at 22min.) 2. You Tube video on quarks and leptons Students should know: What are Hadrons- Made up of quarks, e.g. proton (up and down only stable quarks) and mesons which are unstable 2. What are Leptons-fundamental particles, e.g. electron (Electron only stable lepton) 3. All neutrinos are stable 4. Fermions obey Pauli exclusion principle, bosons do not

4 Standard Model A good poster, one that can be ordered for the classroom. Can be used to reinforce previous slide. ( Review Lower right unsolved mysteries in physics List of quarks List of leptons Bosons Fermionos Source:

5 Large Hadron Collider (LHC) Solving the Unsolved???
Use google earth to zoom in on CERN, Switzerland ( A 12 min overview of CERN from PBS can be found at Some facts about the LHC 8 stories below surface 9,300 magnets Enough niobium-titanium wire to stretch to the sun and back five times. 3. 27-kilometer–long tunnel 4. Collisions up to 600 million times a second. 5. Heat, energy and densities near a trillionth of a second after the Big Bang 6. 15 years in the making 7. 60 metric tons of liquid helium required to cool its magnets 8. 20,000 tons of metal 9. $8 billion price tag Source: R. Cowen, E(14 trillion eV )=mc (close to the speed of light ) squared, Science News July 19, 2008 Vol.172

6 Overview of LHC Linear Accelerator-0.31c Booster-0.87c -0.92c
Proton Synchrotron PS-.996c Super Proton Synchrotron SPS-450 GeV LHC-2, 7 TeV beams of protons Good collision You Tube video: (31 sec.) hyperlinked to title in this slide. Protons come from hydrogen source (Start out here in diagram) Linear accelerator boosts speed to 0.31c Other boosters are synchrotrons A cyclotron uses a constant magnetic field and a constant-frequency applied electric field (one of these is varied in the synchrocyclotron), both of these fields are varied in the synchrotron. 4. Eventual energy 7TeV or c (notice easier to use TeV, also there is a homework question on this) 5. Beam size 40 μm less than size of human hair 3. Maximize luminosity 10-2 picobarns-1*s-1 luminosity measures the flux of particles A barn is a unit of area. 1 barn = 10-28 4. Collision 14 TeV-20 protons per collisions 5. Frequency of collisions (bunch crossing) 32 MHz 6. Challenge-How to do detect Collisions every 31 ns which is 1/32 MHz 7. Atlas is one of 4 major detectors (short video shows this)

7 Four main detectors at LHC
Four main experiments LHCb-designed to measure CP violation of heavy particles containing bottom quarks (why is there more matter than antimatter) Alice-Pb Pb collision study quark-gluon plasma Atlas-general purpose detector CMS-general purpose detector Short overview of LHC and position of detectors. Next three slides will emphasize importance of these detectors. These are a huge engineering challenges. 1. LHCb-Large hardron collider beauty (bottom quark) 2. Alice-A large ion collider experiment designed to study heavy ions. Lead Lead nuclei collisions 3. Atlas-Next slide 4. CMS-Compact Muon Solenoid Bunches of particles will pass through each other 30 million times per second . Each time they cross, there will be 25 collision. 25 x 30x106~ 1 billion collisions each second. This is equivalent to the data produced by 20 simultaneous telephone conversations by every man, woman and child in the world. A lot of data! 40,000,000 Mb of data every second. Wow! That’s a lot of CD’s After 1 year the amount of data will be 10 greater than all stored world wide web data Source:

8 Atlas The title ‘Atlas’ is linked to the following You Tube video Good video of Atlas about 7 min. 1. Make note of the E&M and Hadronic calorimeters. 2. Also make note of the Muon dectector These will be used in a homework/lab Also note size or person at the bottom of the dector! What will be seen at the LHC according to Ayana Holloway Arce (UC Berkeley) Light quarks (up and down) Virtual particles Antiquarks 6. 1TeV 7. Heavier quarks 8. Look to verify quantum theories by measuring probability distributions

9 Detector Cross section of a dectector- Again make note of the calorimeters and muon detectors Inner detector-The Inner Detector begins a few centimetres from the proton beam axis, extends to a radius of 1.2 meters, and is seven meters in length along the beam pipe. Its basic function is to track charged particles. Particles are tracked to 0.01 mm. Calorimeter-The calorimeters are situated outside the solenoidal magnet that surrounds the inner detector. Their purpose is to measure the energy from particles by absorbing it. (note two types of calorimeters) Muon Detector-The muon spectrometer is an extremely large tracking system, extending from a radius of 4.25 m around the calorimeters out to the full radius of the detector (11 m). This is designed to measure the momentum of muons Source:

10 Delphi Detector at CERN Z particle decay
E & M detector Quark jets (red and green spaghetti lines) Muons (green ++) Great exercise: In the picture above is actual data from CERN. The E&M detector, furthest two rings and the track detector, inner most two rings are turned on. My analysis is there are two quark jets. You can see some muons, ++, and a few neutral particles (straight lines). Also if you look at the starting energy, 91, and the detected energy, 77.6, you see some energy is missing. This may be due to a neutrino. Below are some of the detectors and how you can detect particles in this detector. More information is given in the attached homework document. VtxDet: the vertex detector TrDet: the track detector (TPC) EMCal: the electromagnetic calorimeter HaCal: the hadron calorimeter MuDet: the muon detector 1. Neutral particles are shown as straight lines 2. The key to identify electrons, positrons and photons is to look for energy depositions in the EM-calorimeter (large boxes). 3. A muon leaves a track in the track detector and a mark (a cross) in the muon detector. 4. Sometimes one can guess if there were neutrinos in an event by comparing the collision energy to the detected energy. 5. A quark will create a jet of many particles. Such a jet of particles usually consists of ten or more particles. 6. Tau particles will also decay before they can be seen in the detector. A tau particle decays into 1 or 3 charged particles plus a number of neutral particles. If several neutral particles are created, the decay will result into a mini-jet resembling the quark jets. However, the mini-jet from the tau particle has fewer particles, less than ten.

11 How particles acquire mass… Higgs Boson?
Standard theory tells us all particles have a zero rest mass Particles interacting with the Higgs field gives mass to a particle! Particles moving through a Higgs field can be modeled like resistance in a conductor. What is the Higgs particle (first 8 min.) Source: Raman Sundrum (Johns Hopkins Univ.) Teachers conference KIPT UCSB Time to switch topics and see what might be found at the LHC. We will start with the question of what causes mass? This would be a good time to have the students talk about their ideas of mass. Why do particles have mass? This hopefully will be solved at the LHC by finding the Higgs boson, or Higgs particle. Explain the Higgs field giving mass to a particle as a particle bouncing (interacting) with the Higgs field. This is shown in the cartoon at the lower right. Very similar to the model of electrical resistance. Different particles interact differently giving particle different mass. Notice a photon (in yellow) does not interact with the Higgs field. Below are two short videos about the Higgs. They don’t need to be shown, and could be given as homework. I find both videos very interesting, with the first one giving a good introduction to the Higgs field, and the second puts a face on the Higgs particle (interview with Peter Higgs). 1. The following is a short video on what is the Higgs particle. Physics for future Presidents Richard Muller talks about ‘What is the Higgs particle’ Watch the first 8 min. or so. 2. Peter Higgs is interviewed in this video (11 min.)

12 How to detect a Higgs particle at the LHC
This point in history should see a merger of radioactivity and E&M. (symmetry breaking) which leads to the Higgs mechanism. The LHC is poised to see this. One way the Higgs boson may be produced at the LHC. Two gluons decay into a top/anti-top quark pair The quark pair then combine to make a neutral Higgs Source: Raman Sundrum Higgs mechanism is space filled with a Higgs field. The Higgs field is produced by a Higgs particle. Might be seen in the LHC! The Higgs particle is short lived, and will be difficult to detect We are still not sure of Higgs mass but have a narrow range of values All particles should be massless in the Standard theory. The vacuum in space is not empty but is thought to be permeated with the Higgs field LHC should bring Higgs out of hiding (symmetry breaking) 6. LHC should produce a Higgs boson in 1 out of every 20 million million collisions. So with up to a billion collisions each second, a Higgs particle will be produced once a day.

13 Could a hidden dimension be seen at LHC?
Hidden Dimensions and Hierarchy (Raman Sundrum) The next topic will be; Can an extra dimension be seen at the LHC? Using the cartoon on the left, visualize along and between the mirrors (branes). This is our 3-D world and time (four dimensions, 3 space, 1 time). With the same cartoon now visualize perpendicular to the two mirrors. This is a possible 5th dimension. Probably less than cm How to detect this 5th dimension… When a quark and antiquark collide, it may be that a UV photon heads off into the 5th dimension. This is a KK or Kaluza Klein excitation. (cartoon on right). These excitations will show certain decays after some time in our 3D world (cartoon left). These decays could be seen in LHC, suggesting evidence for a 5th dimension. Notice that the energy of the KK excitation will be equal to the energy of the decay products. It turns out this 5th dimension must be <10-18 m Small dimension requires large energies, thus LHC! Lisa Randell’s book, Warped Passages: Unraveling the Mysteries of the Universe's Hidden Dimensions, Harper Perennial is a great introduction to this idea. Pp. 332 and following.

14 Warped compactification and the hierarchy problem…
The next problem, topic, is why is gravity so weak. Also called the hierarchy problem. Can this be solved at the LHC? First, In the picture above, notice gravity is not only acting vertically, but also in the ‘5th’ dimension. WoW! 1. Puzzle. Why is gravity so weak as compared to other forces (Weak, strong and EM). This is referred to as the Hierarchy problem 2. Extra dimension may solve Hierarchy puzzle… How? First a little about Warp compactification- Gravity can pull in the extra ‘5th dimension’ 2. Space time is highly curved in the 5th dimension. This is warped compactification 3. This leads to the next slide

15 Hierarch Problem Solved?
One solution to the hierarchy problem. We are now looking at what the 5th dimension might look like. 1. Continue to visualize gravity in 5th dimension. Here the gravition (purple) represents the strength or pull of gravity on a mass. Gravitons tend to localize to the left, close to mirror one. 2. The Higgs boson which creates mass tends to localizes on the right side, away from the gravitions. This separates the graviton (which pulls on mass) from the Higgs field (which creates mass), thus weakening gravity. 3. Note that the electron (yellow) is large on the left side, opposite of the Higgs field. This accounts for the low mass of the electron. This is a difficult concept. The important point is that gravity is separated from the Higgs field in the 5th dimension. This separation is thought to account for gravity being weaker than the other forces. Physicists will be looking for the KK or Kaluza Klein particles and evidence of the 5th dimension at the LHC.

16 Neutrinos Physics ‘You don’t work at the LHC’?
Produced in nuclear fusion (Sun) Product of radioactive decay (β decay) Produced by cosmic rays (protons) interacting with the atmosphere There are 3 flavors of neutrinos Kevin McFarland-neutrinos Switch to a topic related to the LHC, but not necessarily taking place there. Neutrinos!!! Graphic shows fusion of two protons (red spheres top) emitting neutrinos (ν) This slides bullets show some ways in which neutrinos are produced. What are neutrinos? Neutrinos are elementary particles that travel close to the speed of light, lack an electric charge, are able to pass through ordinary matter almost undisturbed and are thus extremely difficult to detect. Neutrinos make for very good probes in particle physics. Physicists also hope that by studying neutrino oscillation (later slide), the asymmetry in matter antimatter problem can be solved. Source: A couple facts about neutrinos Banana’s good source of K-40, β decay Three flavors of neutrinos-electron neutrino, muon neutrino, tau neutrino

17 Weak Force Beta Decay and the Neutrino
1013 times less than strong force (hence name) Range of weak interaction m Only weak force affects neutrinos (gravity has a very small affect) Weak force is the only interaction capable changing flavors (up quark to down) This slide shows some of the properties of the weak force along with Beta decay. Beta decay is an import source of antineutrinos. The weak force is probable the least talked about force. When a neutron converts into a proton, a down quark turns into a up quark. An antineutrino is thus produced in the decay of a neutron into a proton. Note heavy virtual mediating W boson. This can lead into a talk of the Heisenberg uncertainty principle.

18 Why study neutrinos? Matter Antimatter Asymmetry
Neutrinos may oscillate between the three flavors. Will this show why we see a large matter antimatter asymmetry in the universe? One of the unsolved theoretical questions in physics is why the universe is made chiefly of matter, rather than antimatter. In the standard model, all antiparticles are composed of antimatter Notice the upper picture from Fermi lab showing what looks like antimatter curling one way and matter curling the other. Notice similar size of curling path, but in opposite direction. This indicates two particles of similar mass but opposite charge. This is a great example of F=qv x B. 1. Neutrinos can be thought of as a puree or mixture of all three flavors 2. Neutrinos are thought to oscillate between each flavor with a certain periodicity. (bottom right picture) 3. New neutrino intensity frontiers are being looked into try and solve this antimatter, matter symmetry. 4. You need Mega Ton detectors and accelerators that produce lots of neutrinos in an intensity frontier. One such may be an NSF project, DUSEL. Leeds, SD. ( 5. It is hoped that these facilities will be able to show how neutrinos caused this asymmetry between matter and antimatter.

19 The search for Dark Matter
Cosmology requires the existence of dark matter How do we know this? Galactic rotation curves Collision of cluster galaxies Cosmic microwave background temperature fluctuations Last topic, What is dark matter, and how can we find some. Bottom line is we know it is out there, but don’t know what it is… Based on a lecture by James Wells Dark matter does not interact with electromagnetic force but does with gravity. Below are some reasons why we think there is dark matter. a. Galactic rotation curves b. CMB-Cosmic Microwave Background temperature fluctuations Collision of two galaxies 3. The next slides will talk a little about Galactic Rotation and collision of cluster galaxies as related to dark matter.

20 What is Dark Matter? Properties of simplest Dark Matter
Must be stable (have immutable qualities) Density 1 particle per hand Z2 charge invariance with an odd charge R-parity Possible Candidates Lightest Supersymmetric Particle (LSP) Lightest Kaluza-Klein Technibaryons Singlet Fermion Gravitons WIMP In the search for dark matter, we feel that dark matter must possess some of the following properties. If you want to talk more about these properties I have made a few notes below. I don’t think it is necessary… Important points is that dark matter must be stable… Picture above shows how dark matter may reside in outer regions of a galaxy. More on this in the next slide. LSP and WIMPS are the only two types of dark matter candidates discussed in this talk. Lighest Supersymmetric Particle or LSP is the most celebrated candidate for dark matter (more in a couple slides) WIMPs are another candidate and will be discussed in a later slides 1. Dark matter must possess, Z2 charge invariance. a. Z2 is a quantum numbers where the product is conserved*. This is also referred to as parity. *Most conserved quantum numbers are additive. Thus, in an elementary particle reaction, the sum of the quantum numbers should be the same before and after the reaction. Source: b. For dark matter Z2 is odd. Odd implies stable 2.Dark matter has the property of R-parity. a. R-parity is a conserved quantity of supersymmetry theory (hypothesized) This is a Z2 symmetry. Source: b. With R-parity being preserved, the lightest supersymmetric particle (LSP) can not decay. This lightest particle (if it exists) may therefore account for the observed missing mass of the universe that is generally called dark matter.

21 Existence of Dark Matter Galactic Rotation Curves
Kepler’s Law: rapid drop in V as D increases (1/D2) Solid body rotation: linear increase in V as D increases This is just one example of why we feel there must be dark matter. Rotational velocity vs. distance curves do not follow a Newtonian gravity law for rotation of galaxies. Dark matter in the halo of a galaxy may explain the observed galactic rotation curve (picture in last slide) a. Picture on left shows the expected (Following Kepler’s Law) and the Observed velocity vs. distance curve. There is little comparison between the two as you get further from the galactic center. b. Picture on the top right show a 1/r2 or Kepler’s Law for rotational velocity vs. distance (expected but not observed) c. Picture on bottom right shows what a solid body rotation velocity vs. distance plot would look like. Galaxies do not exhibit this type of motion 2. Use of radio telescopes to show galactic rotation curves: a great lab experience if resources are available! 2. East coast teachers: National Radio Astronomy Observatory, in Greenbank WV is a great field trip. Schedule time on the 4 m radio telescope, and create a galactic rotation curve. Students observe first hand that galaxy rotation curves do not follow Newton’s Law

22 Existence of Dark Matter Collision of Galactic Clusters
Artist's representation of the collision between two clusters in the Bullet Cluster Normal matter in the cluster, is shown in red and dark matter is shown in blue. The last image is showing the hot gas seen with the Chandra X-ray Observatory (pink) and the cluster mass as inferred by gravitational lensing (blue), which is mostly dark matter. Best evidence for dark matter to date Another example of the existence of dark matter Good video explaining Bullet Cluster and dark matter(4 min.). The image above is in the Bullet cluster showing two colliding galaxies. Dark matter and normal matter are torn apart by the tremendous collision of two large clusters of galaxies. The discovery, using NASA's Chandra X-ray Observatory and other telescopes, gives direct evidence for the existence of dark matter. 3. Best evidence to date for dark matter Full animations of the collision Scientific American Article and movie of colliding galaxy, dark matter

23 Search for Dark Matter NASA GLAST
Glast (NASA)Gamma-ray Large Area Space Telescope The GLAST space telescope, launched June 11, 2008, searching for gamma wave events, may also detect WIMPs. Supersymmetric particle and antiparticle collisions should release a pair of detectable gamma waves. The number of events detected will show to what extent WIMPs comprise dark matter. Here is still another way we are searching for dark matter. GLAST-searching for gamma waves. This may help in the detection of WIMPS. The cartoon in upper right, shows a simulation of two dark matter (WIMPS??) particles colliding and causing the emission of gamma rays. (yellow undulating lines) GLAST is designed to detect these gamma rays 2. WIMP- weakly interacting massive particles, are hypothetical particles serving as one possible solution to the dark matter problem. WIMPs have many of the properties of neutrinos except they are more massive and these slower Source: One other possible dark matter detection. 3. DAMA-reports possible results of dark matter. As earth orbits the sun, the flux of WIMPS from the galactic plane changes. ( , GLAST web site

24 Search for Dark Matter at the LHC
A proposed Feynman diagram of two protons colliding in the LHC producing a stable LSP (darkmatter). Possibly a neutralino. See: Something that could be seen at the LHC! SUSY-Supersymmetry LHC-Large Hadron collier LSP- Lighest Supersymmetric Particle Satisfies the basic properties of dark matter Must be stable (have immutable qualities) Density 1 particle per hand Z2 charge invariance with an odd charge R-parity

25 Summary LHC looks at <10-10 s after the Big Bang
LHC will produce energies near 14 TeV Atlas is one of the main detectors at the LHC Some unsolved physics problems that may be solved at the LHC Why is gravity so much weaker than the 3 other forces? Can the hierarchy principle solve this? What is mass? Will the Higgs particle be found? Why is there more matter than antimatter? Does this have to do with neutrino oscillation? What is dark matter and will we find any? GLAST and the LCH just might!

26 The next couple years in particle physics will be exciting!
These cartoons can be purchased at This slide can be removed if you are not interested in purchasing these

27 Homework (If this doesn’t work, try the link below) (hands on CERN WIRED) Galactic Rotation Lab (Great experience!) Particle Adventure Education material

28 References
Lesson based on talks for 2008 Teachers Conference Kavli Institute UCSB Dr. David Gross’s overview of the Future of particle physics and what can be expected from the LHC. (Start at 22min.) Richard Muller Quarks, exchange forces and confinement You Tube video on quarks and leptons Good collision You Tube video Good You Tube video of Atlas Physics for future Presidents Richard Muller talks about the Higgs particle What is the Higgs particle? What first 8 min. Peter Higgs-Interviewed (11 min.) PBS 12 min video on CERN Science Now dark matter and the Bullet Cluster

29 References Warped Passages: Unraveling the Mysteries of the Universe's Hidden Dimensions (Paperback) by Lisa Randall Paperback: 512 pages Publisher: Harper Perennial (September 19, 2006) ISBN-10: ISBN-13: Particle Physics A very short Introduction by Frank Close Oxford Press Chandra x-ray telescope Nasa Video/Audio podcast Dark Energy/Matter Search for composition of dark Matter PBS show Dark Matter

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