Future Directions in Experimental Nuclear and Particle Physics

Transcription

1 Future Directions in Experimental Nuclear and Particle Physics Robert Bacher Bacher at the Caltech Synchrotron Barry Barish Bacher Symposium Caltech 5-Nov-05

2 Bacher and the Energy Frontier In the Spring of 1949, the Institute announced plans to build a one-billion volt ("1 BeV") electron accelerator. Robert Bacher, chairman of Caltech's Physics Division, stated: "The purpose of the new accelerator will be to seek additional knowledge about the nature of the forces that hold atomic nuclei together." The new accelerator, the synchrotron, would be the most powerful machine of its type ever built. 5-Nov-05 Bacher Symposium 2

3 Photoproduction of Excited States of the Nucleon Bacher 5-Nov-05 Bacher Symposium 3

4 This led to higher energy machines: Electron-Positron Colliders ADA Bruno Touschek built the first successful electron-positron collider at Frascati, Italy (1960) with help from Bob Walker (Caltech) and others Eventually, went up to 3 GeV 5-Nov-05 Bacher Symposium 4

5 But, not quite high enough energy. 3.1 GeV and Burt Richter Nobel Prize SPEAR at SLAC Discovery Of Charm Particles 5-Nov-05 Bacher Symposium 5

6 The rich history for e + e - continued as higher energies were achieved DESY Petra Collider 5-Nov-05 Bacher Symposium 6

7 Electron Positron Colliders The Energy Frontier 5-Nov-05 Bacher Symposium 7

8 The Future Three Complementary Probes Neutrinos as a Probe Particle physics and astrophysics using a weakly interacting probe High Energy Proton Proton Colliders Opening up a new energy frontier ( ~ 1 TeV scale) High Energy Electron Positron Colliders Precision Physics at the new energy frontier 5-Nov-05 Bacher Symposium 8

9 What makes the sun shine? 4 1 H 4He + 2e v e + energy 5-Nov-05 Bacher Symposium 9

10 Neutrinos observed from the sun! Koshiba Davis and Bahcall Superkamiokande 5-Nov-05 Bacher Symposium 10

11 But, too few neutrinos If neutrinos have mass, then as conjectured earlier by Bruno Pontecorvo, neutrinos could oscillate from one type to another. In this case, some of the original electron neutrinos made in the sun convert to other neutrinos on trajectory to the earth 5-Nov-05 Bacher Symposium 11

12 Puzzle resolved neutrinos oscillate SNO (Canada) used D 2 0 to detect other neutrino types KamLAND used terrestrial neutrinos from reactors, observes oscillations (McKeown) 5-Nov-05 Bacher Symposium 12

13 Neutrinos The Future Long baseline neutrino experiments Create neutrinos at an accelerator or reactor and study at long distance when they have oscillated from one type to another. MINOS C Peck, H Newman, D Michael 5-Nov-05 Bacher Symposium 13

14 Neutrinos The Big Questions Why are neutrino masses so small? Are the neutrinos their own antiparticles? What is the separation and ordering of the masses of the neutrinos? Neutrinos contribution to the dark matter? CP violation in neutrinos, leptogenesis, possible role in the early universe and in understanding the particle antiparticle asymmetry in nature? 5-Nov-05 Bacher Symposium 14

15 Accelerators and the Energy Frontier Large Hadron Collider CERN Geneva Switzerland H Newman, E Hughes 5-Nov-05 Bacher Symposium 15

16 Accelerators and the Energy Frontier International Linear Collider B Barish 5-Nov-05 Bacher Symposium 16

17 Why e + e - Collisions? elementary particles well-defined energy, angular momentum uses full COM energy produces particles democratically can mostly fully reconstruct events 5-Nov-05 Bacher Symposium 17

18 Electroweak Precision Measurements 6 4 Winter 2003 theory uncertainty Δα (5) had = ± ± Without NuTeV What causes mass?? The mechanism Higgs or alternative appears around the corner 2 Excluded Preliminary m H [GeV] 5-Nov-05 Bacher Symposium 18

19 How do you know you have discovered the Higgs? Measure the quantum numbers. The Higgs must have spin zero! The linear collider will measure the spin of any Higgs it can produce by measuring the energy dependence from threshold 5-Nov-05 Bacher Symposium 19

20 What can we learn from the Higgs? Precision measurements of Higgs coupling can reveal extra dimensions in nature Straight blue line gives the standard model predictions. Range of predictions in models with extra dimensions -- yellow band, (at most 30% below the Standard Model The red error bars indicate the level of precision attainable at the ILC for each particle 5-Nov-05 Bacher Symposium 20

21 Direct production from extra dimensions? Linear collider New space-time dimensions can be mapped by studying the emission of gravitons into the extra dimensions, together with a photon or jets emitted into the normal dimensions. 5-Nov-05 Bacher Symposium 21

22 Is there a new symmetry in nature? Supersymmetry The breaking of the symmetry between electromagnetic and weak interactions though the Higgs mechanism introduces several anomalies, which point towards physics beyond the standard model. A particularly attractive scenario is supersymmetry (SUSY), which would eliminates the anomalies from the Higgs section and predicts SUSY partners for all known particles. These particles should be detected at the LHC and ILC 5-Nov-05 Bacher Symposium 22

23 few GeV Designing a Linear Collider pre-accelerator source KeV damping ring few GeV few GeV GeV final focus extraction & dump bunch compressor main linac collimation IP Superconducting RF Main Linac 5-Nov-05 Bacher Symposium 23

24 Superconducting RF Cavities High Gradient Accelerator 35 MV/meter km linear collider 5-Nov-05 Bacher Symposium 24

25 Improved Processing Electropolishing Chemical Polish Electro Polish 5-Nov-05 Bacher Symposium 25

26 Internationl Linear Collider Timeline Global Design Effort Project Baseline configuration Reference Design Technical Design ILC R&D Program Expression of Interest to Host International Mgmt

27 Conclusions We have determined a number of very fundamental physics questions to answer, like. What determines mass? What is the dark matter? Are there new symmetries in nature? What explains the baryon asymmetry? and others discussed by Gukov We are developing the tools to answer these questions and discover new ones Neutrino Physics Large Hadron Collider International Linear Collider The next era of particle physics will be very exciting 5-Nov-05 Bacher Symposium 27

28 Bacher s Legacy Identify the most fundamental physics questions and develop (or use the tools) needed to address those questions Those principles have guided the Caltech nuclear and particle physics efforts for several decades and will continue into the future. 5-Nov-05 Bacher Symposium 28