Higgs particle discovery and measurements - a breakthrough in physics

Transcription

1 Higgs particle discovery and measurements - a breakthrough in physics The Standard Model of elementary particles Large Hadron Collider at CERN and its experiments Discovery of the Higgs boson Particle Physics technologies find medical applications Elżbieta Richter-Wąs Institute of Physics, Jagiellonian University

2 4-th of July 2012, ATLAS and CMS experiments at Large Hadron Collider at CERN announced observation of a new particle, consistent with predicted by so called Higgs mechanism. F. Englert P.Higgs 2

3 Nobel Prizes in Elementary Particle Physics GREEN - theoretical BLUE - experimental M. Gell-Mann 1964: Higgs mechanism was born 1957 C. N. Yang, T. Lee 1965 S. I. Tomonaga, J. Schwinger, R.P Feynman 1969 M. Gell-Mann 1976 B. Richter and S. Ting 1979 S.L. Glashow, A. Salam, S. Weinberg 1980 J. Cronin, V. Fitch 1984 C. Rubbia, S. van der Meer 1988 L. M. Lederman, M. Schwartz, J. Steinberger 1990 J. Friedman, J. Kendall, R. Taylor G. Charpak 1995 M. Perl, F. Reines G. thooft, M. J. Veltman D. J. Gross, H. D. Politzer, F. Wilczek 2008 Y. Nambu, M. Kobayashi, T. Masakawa 2013 F. Englert and P. Higgs Detectors -> medical applications 2012: Higgs particle was discovered 3

4 Quantum mechanisc Standard Model of elementary particles Matter particles (< cm) Force carriers Higgs particle Has a special role, it is neither a matter particle nor a force carrier. 4

5 Mass (giga-electron-volt) Mass Spectrum of Elementary Particles If the mass of the W boson was smaller, time of the combustion would be shorter and at lower temperature Sun shield Mass of the electrons is times smaller than mass of W, but if it was exactly zero there would be no atomic binding. If the masses of elementary particles were different the Universe, as we know it, would not exist. m = 0 5

6 Symmetry Broken symmetry Mass Symmetries in the system dictate conservation laws Discrete symmetry in art (*) E. Noether (1918) H. Weyl (1918, 1929) Hermann Weyl (1918 /1929) Symmetries in the system dictate interaction laws J. Goldstone (1961), Y. Nambu (1960) Spontaneously broken symmetry ( hidden symmetry ) in the quantum system can generate mass. Meta-stable conditions: Once the ball falls down, the symmetry of the system is spontaneously broken and system is in the stable conditions. (*) hexagonal design (Chinese paper window support) 6

7 Vacuum Concept of the field Higgs mechanism Michael Faraday (1845) Introduced concept of field into description of magnetic interactions. Magnetic field has a source. Force lines of the magnetic field In classical understanding vacuum = empty space, or state of energy = 0. In quantum mechanics vacuum is full of life. Just bubbling with creation and annihilation of matter particles. Symmetries dictate laws of interactions. Stable state of vacuum does not necessarily has an energy = zero. Higgs mechanism (1964): Quantum vacuum is not empty, is full of the Higgs field. This field has no structure nor sources. After symmetry is spontaneously broken, field is not neutral anymore and interaction of elementary particles with this field gives masses to the elementary particles. This mechanism predicted also the existence of a massive scalar particle, so called, Higgs particle which is the quantum fluctuation of the Higgs field. 7

8 Theory has to be verified by experiment It doesn t matter how beautiful your theory is, it doesn t matter how smart you are. If it doesn t agree with experiments, it s wrong. R. Feynman R. Feynman There was no good idea how to observe the Higgs field. For several decades also discovery of the Higgs particle seemed to be beyond technological reach of experiments. 8

9 How are we probing elementary particles, how are we exploring structure of Universe? Big-bang Large distances events far apart in time Virus Radius of Earth Distance Earth-Sun LHC Galactica Universe cm LHC: Super microscop which creates Conditions as s after Big-Bang Short distances very large energies 9

10 CERN European Laboratory for Particle Physics CERN was founded in 1954: ( Science for peace ) Today: 21 member states, more than users Mont Blanc Jezioro Genewskie CERN 38 państw CERN s primary mission is SCIENCE. Main area of research ATLAS Collaboration is particle physics study of the fundamental constituents of matter and the forces acting between them. 10

11 LHC (Large Hadron Collider) Mont Blanc Lake Geneva ATLAS CMS 27 km circuit 100m underground 27 km długości 100m pod ziemią LHC One of the most ambitious projects in Science 11

12 Proton-proton collisions We accelerate two beams Składniki protonu Proton bunch Colliding protons Interacting quarks Proton-Proton 1380 bunches/beam Protons/beam 1.7 pęczków/wiązkę Beam energy 4 TeV ( = MeV) Protonów/pęczek Energia wiązki Each proton is moving close to the speed of light and carry energy of a fly. It turns around the ring with a frequency of 1100 times/second. Beam cross-section at collision point: 16mm (4 times smaller than diameter on human hair). Each beam has energy of TGV train (200m) moving with the speed of 155km/hour (360M Jule). Production and decay of a new particle Such event in 1/10 12 of interactions 12

13 ATLAS detector and collaboration ATLAS detector: 42m length, 22 m diameter; 3000 km of cables outputting electronic signal; more than 10 8 readout channels; precision in positioning of some elements is about microns. Atlas Collaboration: More than 3000 physicists, engineers and technicians, including more than 1000 PhD students; 178 institutions from 38 countries; Polish groups: IFJ-PAN, AGH and Institute of Physics UJ 13

14 ATLAS detector ATLAS Analysis of the registered event: In 3 years each experiment registered on the disc more than of interesting events = 20 PB (10 15 bytes) of data. If written on the CD discs, it would make a tower 20 km in high. 14

15 How did we observe Higgs particle? Probability < that it is not a statistical fluctuation of the background. Analysed are multi-dimensional distributions. ~450 registered Higgs particle decays look similarly. It was complex, one detectable Higgs particle produced every collisions. 15

16 Measuring properties of the Higgs particle Mass = ( ± 0.3% ) GeV Quantum state J PC = 0 + Interacts with elementary particles Interaction strenght is proportional to their mass. All experimental observations so far are consistent with the predictions of the Higgs mechanism! The next step will be to confirm that the Higgs particle interacts with itself as predicted. 16

17 Large Hadron Collider is operating again Event recorded at a collision energy of 13 TeV ( x2 more than so far) More than 1000 papers published by 4 LHC experiments. We are starting now the route to UNKNOWN! maybe we will be able to understand why there is such asymmetry between matter and anti-matter in the Universe? Will we ever understand what is a dark-matter and dark-energy which are 95% of the Universe Is the value of the vacuum of the Higgs field associated with the cosmological constant in Einstein equation?

18 Particle physics technologies find medical applications G. Charpak (Nobel Prize in Physics, 1992) For invention of multi-wire chamber detectors (1968); Made possible to increase data collection speed by factor 1000 and improve significantly spatial resolution. Widely used technology in Particle Physics Exp.; Found its applications in medicine and biology. (Randomly picked article ) G. Charpak, Pressurized xenon wire-chamber gamma camera, allowed for using short-lived radionuclei 178 Ta, which greatly reduced radiation dosimetry and allowed for brief duration of data acquisition. The wire chamber camera is starting to be utilized in number of clinical areas. 18

19 Particle physics technologies find medical applications Large Hadron Collider is operating again Accelerating particles beams: ~ accelerators worldwide ~ used for medical applications LHC CERN has been collaborating to the design and testing of two last generation dual facilities, designed to provide proton and carbon ion beams: CNAO (Pavia) and MedAustron (Austria). On site, CERN transforms Low Energy Ion Ring (LEIR) into biomedical facility. One of the facilities at CERN generates custom radioisotopes for clinical research. 19

20 Particle physics technologies find medical applications Digital imaging -> medical diagnostics eg. PET (Positron Emission Tomography) Detecting particles Frontier machines like LHC push particle detectors beyond state-of-art to achieve needed resolution and speed, fuelling new developments in medical imaging. One example are LYSO crystals used for modern PET and PET/CT scanners. Faster and more sensitive detectors allow for in-vivo monitoring in real time during therapeutic irradiation: AX-PET, Medpix, Crystal Clear, EVISION, 20

21 Particle physics technologies find medical applications Data analysis techniques in the Grid-based distributed computing systems Unprecedented is amount of data processed by LHC experiments Epidemiology Genetics MammoGrid Monte Carlo simulation tools ( Geant4, Fluka) developed for particle physics volumes of ATLAS detector Used to model sources and geometries which have moving parts. Allows to simulate interactions of all particles type (electrons, positrons, photons, etc.) with composite matter 21

22 Discovery of the Higgs boson is a turning point. After 50-years last building block of Standard Model has fallen into place and opened the door to something completely new. What we know is a droplet, what we don t know is an Ocean Isaac Newton ( ). Research is a long and endless path. It is very difficult to predict what would be the effect of todays discoveries in fundamental science 50 years from now. However, tools and technology developed today in one discipline, continuously find applications and provide inspirations elsewhere, often in unexpected places. 22

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26 (Almost) Final Run-I Coupling Results 26

27 When elementary particles 1995 have been 1979 discovered?

28 Many possible extensions to probe 28

29 LHC probes this energy range, about s Evolution of the Universe

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