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A Student on MICE

A Student on MICE. Adam Dobbs, Imperial College Goldsmith’s Particle Physics Summer School 21 st July 2009. Outline. 1. Why MICE? - a brief overview of the Standard Model - n eutrino m asses and oscillations - the neutrino factory and muon cooling What is MICE?

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A Student on MICE

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  1. A Student on MICE Adam Dobbs, Imperial College Goldsmith’s Particle Physics Summer School 21st July 2009

  2. Outline 1.Why MICE? - a brief overview of the Standard Model - neutrino masses and oscillations - the neutrino factory and muon cooling • What is MICE? - muon ionisation cooling – what we hope to show - MICE design - schedule • Life on MICE (what I do) - the office - accelerator beam loss and MICE particle rate • Conclusion - where we’ve been - why I like what I do A Student on MICE, A Dobbs

  3. Introduction to the Standard Model Neutrino masses and mixings The Neutrino Factory 1. Why MICE? A Student on MICE, A Dobbs

  4. The Standard Model of Particle Physics • A mathematical model of matter and forces at the most fundamental level currently known (with the notable exception of gravity) • Extraordinarily good agreement with experiment • Held good for the last 40 years • ... but not a “final theory” A Student on MICE, A Dobbs

  5. ντ d t s νe τ b νµ u c s = 1/2 s = 1/2 s = 1/2 s = 1/2 s = 1/2 s = 1/2 s = 1/2 s = 1/2 s = 1/2 s = 1/2 Q = -1/3 Q = 0 Q = +2/3 Q = -1/3 Q = +2/3 Q = -1/3 Q = 0 Q = 0 Q = +2/3 Q = -1 m = 104 MeV m < 0.17 MeV m = 1.27 GeV m = 2.4 MeV m = 4.2GeV m < 15.5 MeV m = 171.2 GeV m = 1.777 GeV m < 2.2 eV m = 4.8 MeV γ e z0 g H w± G µ s = 1 s = 2 s = 1 s = 1 s = 1/2 s = 1 s = 0 s = 1/2 Q = 0 Q = 0 Q = 0 Q = ±1 Q = 0 Q = -1 Q = 0 Q = -1 m > 112 GeV m = 0 m = 91.2 GeV m = 80.4 GeV m = 0.511 MeV m = 0 m = 0 m = 105.7 MeV “Fundamental” Particles Quarks Leptons Fermions Higgs EM Weak Strong Gravity Bosons A Student on MICE, A Dobbs

  6. Interactions Image courtesy of Wikimedia Commons A Student on MICE, A Dobbs

  7. Beyond the SM: Neutrino Mass and Mixing • SM had assumed neutrinos to have a zero mass • First evidence against this came in 1960s when Ray Davis at the Homestake mine experiment observed a deficit in the number of solar neutrinos detected from that predicted by the standard solar model → “The Solar Neutrino Problem” A Student on MICE, A Dobbs

  8. The Plot Thickens • Missing neutrinos and the mysterious appearance of neutrinos were subsequently noticed in neutrinos generated by cosmic rays hitting the atmosphere (Super Kamiokande, SNO), in nuclear reactors (KamLAND) and in particle accelerators (K2K) • What is the cause? Inside Super Kamiokande, a 50,000 ton water Cherenkov detector based in the Mozumi Mine, Japan A Student on MICE, A Dobbs

  9. Solution: Neutrino Oscillations • All the information about a quantum system is held in a mathematical entity known as the wavefunction, ψ • Neutrino mass (eigen)states are not the same as neutrino weak flavour (eigen)states... • ...but they are related... • ... its a questions of hats A Student on MICE, A Dobbs

  10. The Mixing Matrix or How the hats are related , and are CP violating phases where ... yes ... lets not think too hard about this... See “Where have all the neutrinos gone” on Thursday The Point: the neutrino weak force states are a combination of the neutrino mass states and we want to know exactly how by measuring the four parameters A Student on MICE, A Dobbs

  11. Oscillations Graphically: Flavour = combination of masses Consider 2 neutrino case for simplicity. When a neutrino has just been formed in a weak interaction the neutrino is in a pure single flavour state, which is a combination of two mass states: + = A Student on MICE, A Dobbs

  12. Probing Oscillations: The Neutrino Factory • The Neutrino Factory is a proposed next generation high intensity neutrino source • Allow us to study the mixing parameters to greater precision • Only one of various contenders for a next generation neutrino source... but probably the best (but probably the most difficult to realise too) A Student on MICE, A Dobbs

  13. How does it work? • Get a beam of protons and zap them into a target... • ... which generates pions... • ... which will then decay into muons... • ... which are put into a big storage ring until... • ... the muons decay to neutrinos! Feynman diagram for muon decay A Student on MICE, A Dobbs

  14. Near Detector Muon Decay Ring (muons decay to neutrinos) To Far Detector 1 R109 To Far Detector 2 What does it look like? A Student on MICE, A Dobbs H− LEBT RFQ Chopper H−Linac Synchrotrons Stripping Foil [below ground ] RF Phase Rotation FFAG I (3-8GeV) Solenoidal Decay Channel (in which pions decay to muons) Target (produces pions from protons) Proton Beam Dump FFAG II (8-20GeV) Muon Cooling Ring FFAG III (20-50GeV) Solenoidal Muon Linac

  15. OK, but what does all this have to do with small rodents? • Once the muon beam has been generated from the pions it needs to be cooled, sort of shrunk, so that it will fit into the other NF components further downstream, before decaying into neutrinos • Cooling becomes even more necessary when considering a future muon collider • Conventional beam cooling using EM fields does not work because of the short muon life time • Enter MICE... A Student on MICE, A Dobbs

  16. Muon Ionisation Cooling MICE layout MICE Schedule 2. What is MICE? A Student on MICE, A Dobbs

  17. A Little Accelerator Physics • MICE stands for the International Muon Ionisation Cooling Experiment • “Cooling” refers to the phase space compression or emittance reduction of the muon beam • Phase space here refers to the normal position space x, y, z and the momentum space x’, y’, z’ of the beam of particles • The emittance of a beam refers to how much volume a beam occupies in this phase space A Student on MICE, A Dobbs

  18. x’ x y x z Emittance Part of Phase Space Real Space b a Beam - the slope of the particle trajectory relative to the axis A Student on MICE, A Dobbs

  19. Ionisation Cooling • Pass the beam through an absorber e.g. liquid hydrogen, lithium hydride • The particle beam ionises the medium, the beam particles losing energy and momentum in all directions • Re-accelerate the beam in the beamline direction (z) only, using a radio frequency electric field • Muon ionisation cooling has never been demonstrated before... but concept is simple v LiH2 RF v v A Student on MICE, A Dobbs

  20. MICE Goals • Produce a functional Neutrino Factory cooling channel (the factory itself will require multiple channels). Specifically: • Produce an input muon beam of momentum between 140 to 240 MeV / c , and a tuneable emittance between 1 to 12 π mm rad • Measure the emittance before and after cooling to a precision of 1 part in 1000 • Produce an approximately 10% cooling effect A Student on MICE, A Dobbs

  21. MICE Home • Based in the UK at Rutherford Appleton Laboratory, Didcot • Uses the ISIS 800MeV synchrotron accelerator as a proton source • Possible site for the Neutrino Factory A Student on MICE, A Dobbs

  22. MICE Layout D = Dipole bending magnet Q = Quadrupole magnet DS = Decay solenoid GVA1 = Scintillator counter CKOV = Cherenkov detector MICE Target Pion capture with Q1-3 ISIS MICE D1 Q4-6 Q7-9 D2 Dipoles → bend the beam Quadrupoles → focus the beam DS Tracker GVA1 CKOV A, B A Student on MICE, A Dobbs

  23. What it looks like A Student on MICE, A Dobbs

  24. The Finished Product A Student on MICE, A Dobbs

  25. MICE Aspirational Schedule A Student on MICE, A Dobbs

  26. The Office Beam Loss 3. Life on MICE A Student on MICE, A Dobbs

  27. The Office Arrive Scribble a bit Look for some interesting weather Sit here Use these Read this Go home A Student on MICE, A Dobbs

  28. MICE in ISIS • MICE is an unique experiment on ISIS – the only one capable of disrupting the synchrotron • The MICE target causes a measure of disruption to the ISIS beam and thus a possible increase in the radioactivity present MICE Everyone else A Student on MICE, A Dobbs

  29. Beam Loss and Particle Rate • In fact, the more beam loss we produce in ISIS, the more particles we get down the MICE beamline – something we badly need (our current particle rate is far too low) → a tension of needs exists • As a result beam loss in ISIS must be monitored and studied in relation to the MICE target • Part of what I do A Student on MICE, A Dobbs

  30. Beam Loss Simulation: ORBIT • ORBIT = Objective Ring Beam Injection & Tracking • Particle tracking code used by ISIS to simulate their machine • Built under C++ and SuperCode • Free • It has issues... A Student on MICE, A Dobbs

  31. Short-Fat Target A Student on MICE, A Dobbs

  32. Long-Thin Target A Student on MICE, A Dobbs

  33. Cylindrical Target A Student on MICE, A Dobbs

  34. Beam Loss Data Analysis • 39 ionisation chamber beam loss monitors positioned around the ISIS ring • Noisy data – use averages to extract signal • Look for affects solely due to the MICE target - remove background signal due to normal ISIS beam loss • Target position and dip time also recorded A Student on MICE, A Dobbs

  35. The ISIS Spill and Beam Loss Beam Intensity (V) Target Position (V) Total Beam Loss (V) Spill with MICE target present Spills without MICE target present A Student on MICE, A Dobbs

  36. Beam Loss and 3rd Order Polynomial Fit Total Beam Loss (V) 3rd order polynomial fit to MICE specific beam loss Losses due to beam extraction Losses due to beam injection A Student on MICE, A Dobbs

  37. Data reduction: 1 point per dip A Student on MICE, A Dobbs

  38. Its Useful Too: Target Melt Event 8mm Ti Melting Point = 1660 0C A Student on MICE, A Dobbs

  39. Beam Loss Vs Particle Rate A Student on MICE, A Dobbs

  40. Where we’ve been Why I like what I do 4. Conclusion A Student on MICE, A Dobbs

  41. Where We’ve Been • Introduction to particle physics and the Standard Model • Neutrino mass and oscillations • The Neutrino Factory to further investigate oscillations • MICE to demonstrate cooling needed for a NF • MICE – what, when • MICE and ISIS beam loss issues A Student on MICE, A Dobbs

  42. Why I like what I do • “Fill the earth and subdue it” - Genesis → Physics • Physics is challenging, beautiful, useful and even fun • If you still don’t like it, a physics degree equips you for many professions • ... and you don’t have to get up too early in the mornings A Student on MICE, A Dobbs

  43. Thank you!

  44. Masses = Combination of flavours = + = + Flavour 1 components constructively interfere, flavour 2 components destructively, hence the neutrino is a pure flavour 1 state A Student on MICE, A Dobbs

  45. Different masses travel at different speeds Because the different mass states travel at different speeds, the phases between the two changes → flavour 1 components no longer interfere purely constructively, flavour 2 components no longer interfere purely destructively. A Student on MICE, A Dobbs

  46. Relative amounts of each flavour component change with time So our neutrino now has components of both flavour 1 and flavour 2. The amplitude of the wave for each flavour dictates the probabilty that when the neutrino is detected it will be observed as that flavour. The mixings angles dictate how these amplitudes vary over time. A Student on MICE, A Dobbs

  47. KamLAND: Observation of Oscillation A Student on MICE, A Dobbs

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