International Design Study of a Neutrino Factory .International Design Study of a Neutrino Factory

download International Design Study of a Neutrino Factory .International Design Study of a Neutrino Factory

of 38

  • date post

    27-Aug-2018
  • Category

    Documents

  • view

    213
  • download

    0

Embed Size (px)

Transcript of International Design Study of a Neutrino Factory .International Design Study of a Neutrino Factory

  • International Design Study of aNeutrino Factory

    J. Scott BergBrookhaven National Laboratory

    IPAC 201027 May 2010

  • Neutrino Physics

    Neutrinos have mass Mass and flavor eigenstates different Mixing matrix angles 12, 23, 13

    13 possibly zero, 23 near 45

    CP-violating phase (irrelevant if 13 zero) Squared mass differences

    |m221| |m2

    31|

    Sign of m231

    unknown

    2

  • Neutrino Properties3

    2

    1

    1

    2

    3

    e

    ma

    ss

    2

    3

  • Long Baseline NeutrinoExperiments

    Accelerator: make neutrinos in flavor eigenstate Mixture of mass eigenstates

    Neutrinos propagate to far detector Each mass eigenstate has different phase

    advance Phase advance: square of mass

    Detector: detect flavor eigenstate Detect corresponding lepton (e, )

    4

  • Neutrino Factory Goals

    Create high-energy muon beam Decay in ring, directed through earth to far

    detector Well-defined spectrum from muon decay

    creates and e Distinguish by sign of detected leptons

    Need magnetized detector

    5

  • Neutrino Factory vs.Superbeams

    Get results forsmallest 13

    Better precisionfor mixingparameters

    Especiallyinteresting ifnearlysymmetric

    105

    104

    103

    102

    101

    True value of sin2213

    0

    0.2

    0.4

    0.6

    0.8

    1

    Fra

    ctio

    no

    f

    CP

    SPL

    T2HK

    WBB

    NF

    BB

    GLoBES 2006

    6

  • Neutrino Factory AcceleratorComplex

    High-power proton driver, protons hit Target, producing pions decaying to muons Front end, reshapes and intensifies beam Acceleration, increase energy to 25 GeV Decay ring, neutrinos produced decay toward

    far detectors

    7

  • Neutrino Factory AcceleratorComplex

    12.625 GeV FFAG

    3.612.6 GeV RLA

    0.93.6 GeV

    RLA

    Linac to

    0.9 GeV Muon Storage Ring

    Muon Storage Ring

    Linac optionFFAG/synchrotron option

    Proton Driver

    Neutrino Beam

    Neutrino Beam

    Hg Target

    Buncher

    Bunch Rotation

    Cooling

    1.5 km

    755

    m

    1.1

    km

    8

  • International Design Study

    Goal: reference design report by end 2012 Basis for request to start project Costs at 30% level

    Interim design report by end 2010 Move from design to engineering Designs for all systems Cost estimates at 50% level

    Focus on baseline: one design!

    9

  • Baseline Parameters

    25 GeV muon beam, both signs Detectors at two distances

    30005000 km 70008000 km

    5 1020 muon decays per year per baseline Muon beam divergence of 0.1/

    10

  • High-Power Proton Driver

    Supply protons to target to produce pions Basic specifications:

    4 MW proton beam power Proton kinetic energy 5-15 GeV RMS bunch length 13 ns 50 Hz repetition rate Three bunches, extracted up to 80 s apart

    11

  • Muon Capture vs.Proton Energy

    0

    0.005

    0.01

    0.015

    0.02

    0.025

    0.03

    0.035

    0.04

    0 10 20 30 40 50 60 70 80 90 100

    Mes

    ons/

    prot

    ons/

    GeV

    Proton Kinetic Energy, GeV

    12

  • Muon Capture vs.Proton Bunch Length

    13

  • Proton Bunch Structure

    13 ns

    > 160 s

    20 ms

    14

  • Proton Driver Plans

    Will be upgrade to existing facility Important to understand contribution to cost of

    neutrino factory Individual laboratories will contribute

    Plan to upgrade to neutrino factoryrequirements

    Corresponding cost estimate

    15

  • Target

    Baseline is liquid mercury jet Avoid target damage

    Target in 20 T field: pion capture Demonstrated in MERIT experiment

    Proton beam pulses comparable to neutrinofactory

    Two bunches in rapid succession: no loss inproduction for second with spacing 350 s orless

    16

  • Mercury Jet Target Station

    IronPlug

    ProtonBeam

    NozzleTube

    SC-1

    SC-2 SC-3 SC-4SC-5

    Window

    MercuryDrains

    MercuryPool

    Water-cooledTungsten ShieldMercury

    Jet

    ResistiveMagnets

    SplashMitigator

    17

  • Target Plans

    Engineering of target station and components Jet nozzle: improve jet quality Ensure sufficient shielding of superconducting

    magnets Fluid dynamics/engineering of Hg pool

    Acts as beam dump Return Hg to loop

    18

  • Mercury Pool Dynamics

    19

  • Front End

    Pions (thus muons) start with large energyspread: reduce

    Neuffer phase rotation Uses high-frequency RF Does both signs

    Create 200 MHz bunch train Reduce transverse beam size

    Ionization cooling

    20

  • Pion Spectrum

    0

    50

    100

    150

    200

    250

    300

    0 0.2 0.4 0.6 0.8 1

    Mes

    ons/

    10M

    eV/G

    eV

    Kinetic Energy, GeV

    10GeV+50GeV+100GeV Beam-Mesons(Positives+Negatives) at 50m

    10GeV50GeV

    100GeV

    21

  • Phase Rotation

    ct

    E

    Drift rf-Buncher rf-Rotation

    22

  • RF in Magnetic Field

    RF cavities in magnetic field Large angular and energy acceptances

    Experiments: gradient reduced in magnetic field Dont have complete picture yet Ongoing experiments

    Change magnetic field orientation w.r.t.surface

    Gas-filled RF cavities Test different surface materials

    23

  • Ionization Cooling Lattice

    24

  • Gradient vs. Magnetic Field

    0 1 2 3 4Solenoid Magnetic Field (T)

    0

    5

    10

    15

    20

    25

    30

    35

    40

    45G

    radi

    ent (

    MV

    /m)

    25

  • Mitigation Strategies

    Reduce fields on cavities Increase distance to magnets Add bucking coils Add shielding to solenoids

    Magnetically insulated lattice: high-E fieldsurfaces parallel to B

    Make cavity from beryllium Fill cavities with pressurized hydrogen gas

    26

  • Front End Plan

    Mitigation often reduces performance Operation limits of cavities still unknown Baseline: choose technically optimal design

    Earlier Study IIa lattice Improved Neuffer phase rotation

    One alternative to understand penalty/cost ofmitigation

    27

  • Acceleration

    Efficiency: maximize passes through RF Four stages to get good efficiency

    Linac to 0.9 GeV Two RLAs: to 3.6 GeV and 12.6 GeV (4.5

    passes) FFAG to 25 GeV (11 passes)

    Use 200 MHz SCRF

    28

  • Acceleration

    12.625 GeV FFAG

    3.612.6 GeV RLA

    0.93.6 GeVRLA

    Linac to0.9 GeV

    29

  • AccelerationLinac and RLAs

    Lattices completely defined More detailed magnet designs Tracking beginning with soft ends

    30

  • AccelerationFFAG

    Many passes (11): no switchyard Injection/extraction challenging

    15 cm radius, 0.09 T field, 7 needed, 546 mring circumference

    Selected triplet lattice with long drifts Longer drifts ease injection/extraction Double cavity in long drift: better gradient

    Reduce longitudinal distortion: largetransverse amplitude

    31

  • AccelerationFFAG

    Add some chromaticity correction Modest amount: hurts dynamic aperture Helps longitudinal distortion

    Design kicker systems (magnet, power supply) Study lattice dynamics in EMMA experiment

    32

  • Decay Ring

    Long straights to maximize decays to detector High beta functions in straight: reduce

    divergence Less divergence, less flux uncertainty for

    given divergence uncertainty Excellent dynamic aperture

    33

  • Decay RingDynamic Aperture

    34

  • Decay RingDiagnostics

    Reduce flux spectrum uncertainty Polarimeter: measure decay electron spectrum

    Neutrino flux depends on polarization Detector transverse to beam, in matching

    section following weak bend In-beam He gas Cerenkov: beam divergence

    Emittance growth: verify if acceptable

    35

  • Decay RingPolarimeter

    36

  • Low-Energy Neutrino Factory

    Same as above but stopping accelerationearlier, different decay ring

    Competitive with high energy (and bestsuperbeams) if 13 large

    Interesting as part of staging Start with low energy Upgrade to high energy or larger detector

    depending on physics results Will be described in design reports

    37

  • Conclusions

    Neutrino factory: precision measurements ofneutrino mixing

    Well-defined scenario, lattices almost complete Continuing important R&D

    RF cavities in magnetic fields MICE cooling experiment EMMA: FFAG dynamics

    Starting engineering of components

    38