Introduction to LHC Aug. 25, 2015 CMSDAS @ KNU, Daegu, KOREA Inkyu Park University of Seoul Disclaimer • Language . English or Korean? Official language is English, but most of students in this classroom are Korean • Credits . Many of pictures, plots, ideas were from Frank Zimmermann’s 2015 CERN Summer school Chandra Bhat’s 2015 CMSDAS Daniel Brant’s 2010 CAS @ Varna 2015-08-25 CMSDAS - LHC primer 2 Menu del Dia • What is Particle Physics? How? . A brief history of Particle Physics • Accelerator basics . Accelerator or Collider? • LHC primer For today . Beam parameters . Luminosity, cross section, Pileup . Run history • Future accelerators . LHeC, FCC, … 2015-08-25 CMSDAS - LHC primer 3 What is Particle Physics? How? What is Particle Physics? Leon Lederman’s definition: “Particle physics is a search for the most primitive, primordial, unchanging and indestructible forms of matter and the rules by which they combine to compose all the things of the physical world. It deals with matter, energy, space, and time. The objectives of particle physics are to identify the most simple objects out of which all matter is composed and to understand the 1922- 1988 forces which cause them to interact and Leon Lederman "for the neutrino beam method combine to make more complex things.” and the demonstration of the doublet structure of the leptons through the discovery of the muon neutrino" What are the elementary building blocks? How do they interact with each others? 2015-08-25 CMSDAS - LHC primer 5 How to do Particle Physics? • To know about the elementary building blocks . Just look inside, if not possible, smash it • Then, how? . According to the method of smashing, one can define the era of Particle Physics! From the radio active source to the accelerator 2015-08-25 CMSDAS - LHC primer 6 See it or smash it • See 반사되어 오는 정보를 인식하는 것 . Probes EM wave, Light 전파망원경 Electron, Proton 망원경 anything . De Broglie wave 맨눈 풉 흀 = 광학현미경 풑 전자현미경 가속기+검출기 2015-08-25 CMSDAS - LHC primer 7 A brief history of Particle Physics • 불의 발견: Discovery of Fire . using chemistry (~1900) discovery of atoms • 석기시대: Stone age . using radioactive rays (~1920) discovery of nuclear • 수렵생활: Hunter-gatherer’s era . using cosmic rays (~1950) discovery of new particles • 농경시대: Agrarian era . using accelerators (~present) creation of elementary particles 2015-08- 25 CMSDAS - LHC primer 8 Discovery of Atom 1766-1844 1834-1907 John Dalton Dmitri Mendeleev Atoms are periodic Inner structure 2015-08-25 CMSDAS - LHC primer 9 Discovery of nuclear 금박 알파입자 방사선원 납상자 형광스크린 2015-08-25 CMSDAS - LHC primer 10 Discoveries from cosmic rays: 풆+, 흁, 흅 1883-1964 1936 1905-1991 1936 Victor Hess Carl David Anderson 1932: Discovery of Positron 1936: Discovery of Muon 1903-1969 1950 1947: Discovery of Pi meson Cecil Powell 2015-08-25 CMSDAS - LHC primer 11 Creation of elementary particles ퟏ (푩풒풓)ퟐ 푬 = ퟐ 풎 1929년 Ernest Lawrence 1900 1910 1920 1930 1940 1950 1960 1970 -----+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+--- + 풆 풑 풏풆 흁 흅푲 횲횺횵 풑 흂풆 흆흎휼흓훀 ⋯ 가속기의 등장으로 엄청나게 많은 소립자들을 발견하게 된다. cyclotron synchrotron 2015-08-25 CMSDAS - LHC primer 12 Another way of smashing Today’s main topic Collider 2015-08-25 CMSDAS - LHC primer 13 Accelerator basics Basic physics • Energy: eV . 1eV=1.6x10-19J MeV, GeV, TeV, … – Mass and momentum are often written in GeV too. But it really means GeV/c2 for mass and GeV/c for momentum. • Electromagnetism . 푭 = 풒푬 to accelerate particles . 푭 = 풒풗푩 to bend particles But in reality, much more complicate Beam dynamics. 2015-08-25 CMSDAS - LHC primer 15 Linac, Cyclotron or Synchrotron? • All about size and Bremsstrahlung! beam out 자기장 Linac (deflection) Synchrotron 전기장 Cyclotron (acceleration) beam injection 2015-08-25 CMSDAS - LHC primer 16 Why use collider? • Fixed target . 푬푪푴~ ퟐ풎푻푬풃풆풂풎 7TeV beam will make 푬푪푴~ퟏ. ퟐTeV • Collider . 푬푪푴 = ퟐ푬풃풆풂풎 7TeV beam will make 푬푪푴~ퟏퟒTeV Q) What will be the beam energy to get 푬푪푴 = ퟏퟒTeV in Target experiment? A) ? 2015-08-25 CMSDAS - LHC primer 17 Synchrotron components • Magnets . Dipole to bend . Quadrupole to focus Sextupole, Octupole, Decapole, etc. • RF cavities . to accelerate • Cryogenics . For superconducting . For cooling the machines • Beam diagnostics . to monitor the beam movement 2015-08-25 CMSDAS - LHC primer 18 From the beginning to now The first cyclotron (1930) The latest synchrotron (2010) D~11cm, E~1.1 MeV D~9km, E~7TeV after 80 years, 105 x larger and ~107 x more energetic 2015-08-25 CMSDAS - LHC primer 19 LHC primer LHC, where? 50-175m underground 2015-08-25 CMSDAS - LHC primer 21 Aerial view N LHC SPS PS 2015-08-25 CMSDAS - LHC primer 22 PS and Booster PSB PS 2015-08-25 CMSDAS - LHC primer 23 LINAC to LHC Large Hadron Collider LINAC2: Proton starting point LINAC3: Ion Super Proton starting point Synchrotron 7km 450GeV Proton booster Low-Energy Ion Proton Synchrotron 1.4GeV Ring 2015-08-25 CMSDAS - LHC primer 628m, 25GeV 24 LHC in numbers by • Total mass of protons = 0.00000000047 grams • Proton speed = 1B km/h (99.9999991% of c) . 0.0001s = time taken by proton to circle the ring. • 362MJ = collective energy of LHC's protons at top speed. 88,000t = total weight of the aircraft carrier USS Ronald Reagan. 361MJ = energy of the USS Ronald Regan at 5.6 knots. • US$4.1 billion = cost of building the LHC. US$4.5 billion = cost of the USS Ronald Regan. • 9,000 m3 = total volume of the LHC‘s vacuum systems. 4,650 m3 = interior volume of the Big Ben clock tower • 14 years = time taken to build LHC. 13 years = time taken to build Big Ben. • 0.000000002g = amount of hydrogen consumed each day . 0.75g = amount of hydrogen needed to fill a party balloon. 1 MY = time needed for LHC to use a party balloon's of hydrogen. • 10-13 atm = vacuum of the LHC's beamline. 10-12 atm = atmospheric pressure on the Moon. • 8.3 tesla = field of each of the LHC's 1232 dipoles. 1 tesla = strength of a typical scrapyard electromagnet 2015-08-25 CMSDAS - LHC primer 25 LHC in numbers • For engineers . ~9000 magnetic elements . 1720 Power converters . 7568 Quench det. systems . 1088 Beam position monitors . 4000 Beam loss monitors . 150 tonnes Helium, ~90 tonnes at 1.9 K • For historians . 1983 first LHC proposal, launch of design study . 1994 CERN Council approval . 2010 first collisions at 3.5 TeV beam energy . 2015 collisions at roughly design energy • For scientists . ~10,000 users . ~1000 journal papers so far 2015-08-25 CMSDAS - LHC primer 26 Important parameters for us • Beam properties . Beam type Protons, electrons, heavy ions… . Beam energy 풔: MeV, GeV, TeV, … . Beam parameters Number of bunches Bunch intensity (#of particles in a bunch) Beam crossing angle, emittance, beta • Luminosity . ℒ: 풄풎−ퟐ풔−ퟏ . Integrated luminosity: 풑풃−ퟏ, 풇풃−ퟏ 2015-08-25 CMSDAS - LHC primer 27 Beam energy • 7 TeV beam! What does it really mean? . Proton mass ~ 1GeV/c2 negligible Kinetic energy dominant 푬 = 휸풎풄ퟐ ퟕ푻풆푽 . 휸 = = ퟕퟎퟎퟎ 푳푯푪 ퟏ푮풆푽 휷푳푯푪 = 0.99999999 . 휸푺푷푺 = ퟒퟓퟎ 휷푺푷푺 = 0.99999753 2015-08-25 CMSDAS - LHC primer 28 Beam parameters • Understanding beam bunch 11 20휇푚~푚푚 1.15x10 protons 30cm (1ns) 7.5m (25ns) 2808 bunches make ~ 21km Up to 3564 bunches ~ 27km 2015-08-25 CMSDAS - LHC primer 29 Bunch structure • 25 ns bunch spacing • ~2800 bunches • nominal bunch intensity 1.15 x 1011 protons per bunch 1 PS batch 1 SPS batch (72 bunches) (288 bunches) Abortgap 21 km 2800 bunches 2015-08-25 CMSDAS - LHC primer 30 Bunch crossing angle work with a crossing angle to avoid parasitic collisions. 25 ns, 7.5 m separation: 10 -12 s at 25ns ≈ 30 long-range collisions per IP at 50ns ≈ 15 geometric luminosity reduction factor 2015-08-25 CMSDAS - LHC primer 31 Understanding Luminosity • Event rate: how frequently events happens? (# of events per second) . 푹 = ℒ × 흈 얼마나 많은 양의 빔을 쪼였는가? ℒ (luminosity) 입자들이 얼마나 반응하는가? 흈 (cross-section) – Naturally the dimension is “cm-2s-1” some refer as 풅푹 instead of R 풅풕 2015-08-25 CMSDAS - LHC primer 32 Cross-section • Target dN . area=A, thickness=dx, n atoms/m3 Total atoms in the target = n A dx A . cross-section of each atom = 흈 N Total cross-section of the target = 풏흈푨풅풙 dx • Beam . N particles enter in A and dN interact 풅푵 푵 = 풏흈푨풅풙 푨 = 풏흈풅풙 풅푵 . − = 풏흈풅풙 푵 = 푵 풆−풏흈풙 푵 ퟎ • Dimension of cross-section = [L]2 −ퟐퟒ ퟐ −ퟐퟖ ퟐ . Unit: 1 barn = 1b = ퟏퟎ 풄풎 =ퟏퟎ 풎 10fm ퟏ/ퟑ 풓 = 풓ퟎ푨 의 식을 고려하면 1b은 A=100인 핵. ퟏퟎ−ퟏퟐ풄풎 = ퟏퟎ−ퟏퟒ풎 = ퟏퟎ풇풎 2015-08-25 CMSDAS - LHC primer 33 Barn? 2015-08-25 CMSDAS - LHC primer 34 proton cross-section 풅푵 • Event rate, = 푹 = ℒ × 흈 풅풕 . ℒ: 단위면적, 단위시간당 입사하는 입자 수 0.1barn 70mb 1초에 1025개를 쏘아야 1번 충돌이 난다. 2015-08-25 CMSDAS - LHC primer 35 Calculation of luminosity • In fixed target experiment easy 휎 −ퟏ −ퟑ ퟏ 푙 . ℒ = 횽흆푻풍 [푻 푳 푳 ] • For collider complicate 타깃도 움직이는 빔이다 ퟐ 푵ퟏ푵ퟏ풏풃풇 푵 풏풃풇휸 . ℒ = ∗ ∗ 푭 = ∗ 푭 ퟒ흅흈풙흈풚 ퟒ흅휺풏휷 N number of particles per bunch nb number of bunches / beam f revolution frequency σ* beam size at interaction point F reduction factor due to crossing angle ε emittance 흈∗ = 휷∗휺 휺풏 = 휺휷휸 εn normalized emittance = 휺휸휷 β* Lattice beta function at IP 2015-08-25 CMSDAS - LHC primer 36 Emittance & beta • Beam movement along its central path . Emittance: transverse & longitudinal “low” emittance small beam size, small momentum spread . Beta: transverse beam size^2/emittance Small beta beam is squeezed 2015-08-25 CMSDAS - LHC primer 37 Beta* • Beta* means beta at IP 휷∗ 흈 ퟐ흈 IP 2015-08-25 CMSDAS - LHC primer 38 Pile-up! • Multiple events in a photo .