Interconnecton. Lecture 8: Department of Physics and Astronomy

Transcription

1 Lecture 8: Interconnecton Department of Physics and Astronomy Texas A&M University & Department of Physics Kyungpook National University 1 So far

2 Recaps Lec 0: IceCube (HW 01) Lec 1: Introduction PPC, Higgs and SUSY Lec : Higgs Mechanism Lec 3: Higgs production and decay at the LHC Lec 4: Higgs searches at CMS Lec 5: Collider detectors (and CMS) Lec 6: CMS ECAL Lec 7: Lec 6 Review (HW 0) 3 Higgs Mechanism Closer look The illustration is not accurate. 4

3 Electron field Muon field Higgs Interaction Electromagnetic field + electron field [propagation of EM force Fundamental Interaction Higgs field s vacuum expectation is non-zero everywhere in the universe. Higgs field can interact with particle fields. Gives masses to all other particles (fermions) Muon field Electron field 5 Recap: CMS Higgs Summary We have observed a new boson with a mass of 15.3 ± 0.6 GeV at 4.9! * H H ZZ ( )( ) -1 CMS Preliminary s = 7 TeV, L = 5.05 fb -1 ; s = 8 TeV, L = 5.6 fb p-value Events / 3 GeV 1 Data Z+X 10 Z*,ZZ 8 m H =16 GeV 6 7 TeV 4e, 4, e 8 TeV 4e, 4, e 4 0 m 4l [GeV] [GeV] m 4l 6

4 Key Detector System for H Electromagnetic Calorimeter (ECAL) High energy resolution Fine segmentation H Low energy resolution Coarse segmentation H Illustrative purpose Let s check ECAL 7 Recap: Electromagnetic Cascade a 1 t max at b [Note] a difference between e and de dt a1 ( bt) e E0b ( a) bt 0 X 0 is a pretty good thickness. K. Nakamura et al. (Particle Data Group), J. Phys. G 37, (010) 8

5 PbWO 4 BGO Crystal Scintillators CeF 3 BaF CsI 1.5 X 0 Cubic Belle CsI(Tl) Full Size Samples L3 BGO CMS PWO(Y) Belle CsI(Tl): 16 X 0 L3 BGO: X 0 CMS PWO: 5 X 0 9 ECAL s Requirements Questions High energy resolution & fast response? Technologies? Fine granularity? Of order of lateral shower size find a typical lateral spread of EM showers The each tower size is of order of the lateral shower which is small enough to minimize an overlap with other particles from pile-up interactions. Uniformity? Calibration Radiation Hard? Limited lifetime 10

6 Calibration 11 Applications of Scintillators Medical application High energy physics Security check Nondestructive analysis Astro-particle physics,... Board inspection X-ray scanning Radiation monitoring Scintillation Detectors NaI(Tl) Spectrometer Scintillation Surveymeter 1

7 CMS Detector Some Details Inner ne Tracker System Pixel detector starts at ~ 4cm Outer silicon tracker ends at ~ 1m Tracks the trajectory of charged particles Electromagnetic Calorimeter (ECAL) Lead Tungstate crystals Designed to detect e s and s Hadron Calorimeter (HCAL) Brass and steel material sampled in with scintillators Designed to detect hadrons Solenoid Magnet 3.8 T strength for the precise measurement of particle momentum Muon Detector System Gas detectors 13 Calorimeter Tower Geometry A design to measure the direction of energy flow = 0 = lntan E tower =.704 E sin cos î E sin sin ĵ E cos kˆ tower tower Forward Calorimeter, not shown tower 14

8 ECAL Tower Geometry Crack -M4 -M3 -M -M1 η M1 +M +M3 +M4 5x0 0x0 0x0 0x Barrel (Ref : DN-010/01) Endcap(Ref : DN-010/005) Specification Gap(inter-crytal) Crack(intersupercrystal) Total 0.5 mm. mm 15 ATLAS vs. CMS magnet Note: the difference in its detector configurations 16

9 Collider Detectors Magnetic field ATLAS CMS CDF II D0 II T solenoid + toroid (0.5 T barrel 1 T endcap) Tracker Si pixels, strips + TRT σ/p T 5x10-4 p T EM calorimeter Hadronic calorimeter Muon Pb+LAr σ/e 10%/ E Fe+scint. / Cu+LAr (10λ) σ/e 50%/ E 0.03 σ/p T 50GeV to 1TeV (ID+MS) 4 T solenoid + return yoke Si pixels, strips σ/p T 1.5x10-4 p T PbWO4 crystals σ/e 3%/ E Brass+scintillator (7 λ + catcher) σ/e 100%/ E 0.05 σ/p T 50GeV to 1TeV (DT/CSC+Tracker) 1.4T solenoid T solenoid + toroid (1.8T) Si strips + drift chamber Pb+scintillator σ/e 13.5%/ E in barrel Iron+scintillator σ/e 50%/ E 0.03 in barrel Si strips + scintillating fiber U+LAr U+LAr (Cu or stainless in outer hadronic) Rapidities to 1.4 Rapidities to.0 17 Astronomical Dark Matter 18

10 Who Wanted Dark Matter? DM 19 I did [ While examining the Coma Galaxy Cluster (large cluster of galaxies - over 1,000 identified galaxies; mean distance from Earth is 99 Mpc or 31 million ly) in 1933, Zwicky was the first to use the Virial Theorem to infer the existence of unseen matter, what is now called Dark Matter. He was able to infer the average mass of galaxies within the cluster, and obtained a value about 160 times greater than expected from their luminosity, and proposed that most of the matter was dark. The same calculation today shows a smaller factor, based on greater values for the mass of luminous material; but it is still clear that the great majority of matter is dark. 0

11 Dark Matter in Spiral Galaxy Astrophysical Journal 159 (1970) 377 Rotation curve of a typical spiral galaxy: predicted (A) and observed (B). The discrepancy between the curves is attributed to dark matter. 1 Evidence for Dark Matter

12 More Evidence for Dark Matter 3 Dark Matter in the Universe Ordinary Matter (NASA s Chandra X Observatory) Splitting ordinary matter and dark matter Another Clear Evidence of Dark Matter (8/1/06) time Dark Matter (Gravitational Lensing) February 9, 008 Approximately the same size as the Milky Way Dark Particle Hunters 4

13 4 Properties of Cold Dark Matter It Doesn t Matter. Right, it doesn t shake hand with anyone easily. Two dark matter clusters (in blue) are just passing each other. It is a long-lived (stable) object. It s a Cold Matter. Yes, it is a relativistically slowly moving ( cold ) object. It s an Invisible Matter. Right, it doesn t respond to your flash light. This means it is a neutral object. So, It s a Cold Dark Matter (CDM). Can it be one of the known particles? Let s check out! 5 Quiz [Q] Can be the dark matter a Standard Model particle? [Recap: Dark matter particles] (1) Weakly interacting () Neutral (3) Heavy relativistically slowly moving [A] Quarks, electron, muon, and tau cannot be dark matter, because they are interacting via strong and/or electromagnetic forces. Neutrinos are too light. [Q] What should we do? [A] Expand the Standard Model framework based on a new symmetry, e.g., Supersymmetry or SUSY (next page) New particles, including a dark matter candidate 6

14 Spin (& charge) is a fundamental property and a powerful tool in information technology. See Lecture 1 by Prof. Sinova on Jan. 8. Supersymmetry (SUSY) Fermions Bosons A set of new particles, including a dark matter candidate 7 Interconnection 8

15 Particle Physics and Cosmology Astrophysics x f 1 ~ 0 h ~ 1 0 annv 0. 3 annv 8M 0.9 pb dx CDM = Neutralino ( ~ 0 1 ) SUSY SUSY is an interesting class of models to provide a massive neutral particle (M ~ 100 GeV) and weakly interacting (WIMP). 9 LHC Dark Matter and SUSY Now CMB ~ seconds annihilation combination Probing ~10-7 sec. after Big Bang 30

16 Connecting Particle Physics and Cosmology dn dt 3Hn v n Thermal Equilibrium n eq Annihilation Combination 31 DM Annihilation 3

17 DM Annihilation + Combination 33 Number density (n) dn 3Hn v dt n Cross section () SUSY Masses (at the LHC) ~ 0 1 h n eq ann D (SUSYmasses) h H /[100 kms Co-annihilation (CA) Process (Griest, Seckel 91) Mpc 1 1 ] 34

18 Possible Dark Matter Interactions 35 Hot Topic (Oct 9, 01) Today's High Energy Theory seminar will be given by Haibo Yu visiting from Michigan: Exploring Dark Matter From Colliders to the Cosmos Astrophysical and cosmological observations provide compelling evidence for the existence of dark matter in the Universe, but its particle physics nature remains mysterious. The weakly-interacting massive particle (WIMP) has been proposed as a dark matter candidate. In this talk, I will first show that particle colliders including the Tevatron and the LHC are powerful tools to hunt for WIMP dark matter. I will also discuss dark matter models beyond the WIMP paradigm and search strategies for them. Astrophysical objects such as neutron stars and dwarf galaxies provide natural laboratories for exploring dark matter beyond the WIMP. Date/time: October 9, pm. Room: MIST M10. 36

19 Hunt for Dark Matter Haibo Yu 37