PRISM-FFAG

Akira SATO

Osaka University

FFAG03@KEK2003/7/7

ContentsContents

n Physics motivation® Lepton flavor violating process

n PRISM overviewn Construction of the PRISM-FFAG® RF design® Magnet design

n Summary

Physics motivation

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10- 1 4

10- 1 2

10- 1 0

10- 8

10- 6

10- 4

10- 2

1940 1950 1960 1970 1980 1990 2000

Upper limits of Branching Ratio

Y e a r

KL0 Æ me

K+ Æ pme

mAÆeA

m Æ eee

m Æ eg

History of LFV Search limits

Search forSearch forthe Lepton Flavor Violating Processthe Lepton Flavor Violating Process

n No evidence so far for chargedlepton

n Limits have been improvedsteadily® two orders of magnitude

per decaden Sensitivities are superb in muon

systems

n Getting harder® To obtain/handle more

intense muon

New physics beyond the standard model

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LFV in SUSY GUTLFV in SUSY GUT

n MECO@BNL,n MEG@PSI®Equivalent sensitivity

n Future experiment will cover most of

parameter spacewith PRISM

Hisano et al.

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mÆmÆee conversion in a conversion in a Muonic Muonic AtomAtom

n muonic atom (1s state)

n neutrinoless muon nuclear capture (= m-e conversion) physics beyond the Standard Model

muon decay in orbit

nucleus m-

nuclear muon capture

lepton flavors changes by one unit.

A negative muon stopped in some material :

Signal :Monochromatic electron 104.6MeV

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Requirements to a muon beamRequirements to a muon beamfor a next-generation me conversion searchfor a next-generation me conversion search

n High Intensity® The potential sensitivity achievable in searches for rare processes is ultimately limited

by the number of muons available. The muon beam intensity of 1011－1012 μ－/secshould be required, yielding about more than 1020μ－ per year.

n High Purity® Beam contaminations are necessary to be removed, to reduce any background associated

with them. It is already shown that the past experiments like SINDRUM-II have alreadyseen a background event just above the signal region, and they suspect that it comes frompion contamination in a beam through radiative pion capture. Therefore, it is the mostimportant to reduce pion contamination in a beam.

n Narrow Energy Width® Narrow energy spread of the beam will allow a thin muon stopping target to improve the

momentum resolution of e－ detection, which is limited by energy loss in the muonstopping target.

n High Resolution Spectrometer® To improve the intrinsic momentum resolution in an e－ spectrometer, it is critical to

construct a thin tracking chamber system.

PRISM overview

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PRISMPRISMPPhase hase RRotated otated IIntense ntense SSlow low MMuon sourceuon source

n intensity :1011-1012m±/sec

n muon kinetic energy :20 MeV (=68 MeV/c)® range = about 3 g

n kinetic energy spread : ±0.5-1.0 MeV® ±a few 100 mg range width

n beam repetition :about 100Hz

secondary muon beam channelHigh intensity Powerful proton driver Superconducting Solenoid MagnetHigh purityNarrow energy spread Phase rotation in FFAG

dedicated for the stopped muonexperiments.

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PRISM layoutPRISM layoutn Pion capture sectionn Decay sectionn Phase rotation section

FFAG advantages:n synchrotron oscillation

® need to do phase rotation

n large momentum acceptance® necessary to accept large momentumdistribution at the beginning to do phase rotation

n large transverse acceptance® muon beam is broad in space

Ring advantages:n reduction of # of rf cavitiesn reduction of rf power consumptionn compact

not in scale

FFAG as a phase rotator

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Phase RotationPhase Rotationmethod to achieve a beam of narrow energy spreadmethod to achieve a beam of narrow energy spreadn Phase Rotation = decelerate

particles with high energy andaccelerate particle with lowenergy by high-field RF

n A narrow pulse structure (<1 nsec)of proton beam is needed toensure that high-energy particlescome early and low-energy onecome late.

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rrin=460

rout=550cm

Half gap = 10 x (500/r)5 cm

m-

n GEANT3.21 simulation® FFAG Acceptance, Phase rotation® Muon yield, background rate

n Field gradient was made by gap size.n Magnitude of the field

® D : Bz = -0.0717(r(m)/r0)5 (T)® F : Bz = +0.435(r(m)/r0)5 (T)

® r0 = 5 m for 68MeV/c

n Using TOSCA 3D magnetic field map

1 Cell = 45.0 deg.Straight sect. = 16.49 D = 2.46 FD間 = 0.10 F/2 = 3.00

Simulation studies of phase rotator

DFD Triplet Magnet

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012345

Sinusoidal or Saw-tooth Sinusoidal or Saw-tooth

n RF : 5MHz, 128kV/m

ΔE/E = 20MeV+12%-10%

012

3

4

5

n RF : 5MHz, 250kV/m

ΔE/E = 20MeV+4%-5%

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Phase Rotation Simulation:Phase Rotation Simulation:Horizontal Phase SpaceHorizontal Phase Space

Initial Phase

After 1 turn

After 2turns

After 3turns

After 4 turns

After 5turns

54.4 61.2 68.0 74.8 81.6MeV/c

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Pulsed Proton Beam Facility at J-PARCPulsed Proton Beam Facility at J-PARC

50GeV-PS at J-PARCn High intensity 0.75 MW

® 1014proton/sec® Upgradable to 4x1014proton/sec

n A narrow bunched : for phase rotation

New Fast extraction line is necessaryLOI was submitted to J-PARC Request for A Pulsed Proton Beam Facility at J-PARC PRISM/PRIME, EDM ,g-2, Antiproton, NuFactJ

Fast Extraction

Slow Extraction

1ms 100 pulse

0.1s

Kicker

100 Hz is feasible

LOIs are available from :http://psux1.kek.jp/~jhf-np/LOIlist/LOIlist.html

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Muon LFVMuon EDMMuon g-2

Pulsed Proton Beam Facility at J-PARC (cont.)Pulsed Proton Beam Facility at J-PARC (cont.)

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Application List with PRISMApplication List with PRISM

n Particle, Nuclear Physics® Lepton flavor violation

n me conversion, PRIMEn m+ m- conversion

® m life time® m edm® g-2

n Material Science®Muonic X-ray, m sR

n Archeology

n Life science

® Living cell

® Brain scan

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Staging scenarioStaging scenario

n Muon Factory (PRISM,g-2)® Muon LFV® Muon g-2 (3 GeV/c beam line)

n Muon Factory-II (PRISM-II,g-2)® Muon EDM® Muon g-2 (6 GeV/c beam line)

n Neutrino Factory® Based on 1 MW proton beam

n Neutrino Factory-II® Based on 4.4 MW proton beam

n Muon Collider

Physics outcomeat each stage

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Muon Acceleration based ona series of FFAGs

FFAG-based Muon AccelerationFFAG-based Muon Acceleration

n FFAG Acceleration® Large Acceptance (eH,V, dp/p)® Muon cooling is not

mandatory (better ifavailable).

n Advantages® Costs saving

n Small # of RF cavitiesn no cooling needed.

® Simple and compact® Less R&D components

n Four FFAG rings

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Neutrino Factory at J-PARCNeutrino Factory at J-PARC

Schematic Layout of Nufact-J at J-PARC

Construction ofthe PRISM-FFAG

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PRISM layoutPRISM layoutn Pion capture sectionn Decay sectionn Phase rotation section

FFAG advantages:n synchrotron oscillation

® necessary to do phase rotation

n large momentum acceptance® necessary to accept large momentumdistribution at the beginning to do phase rotation

n large transverse acceptance® muon beam is broad in space

not in scale

FFAG as a phase rotator

A budget for the PRISM-FFAG has been approved !FY2003-FY2007

FFAG03@KEK2003/7/7

n To demonstrate® Phase rotation® Muon acceleration® (Muon ionization cooling)

n R&D components® RF with high

n 5MHz, 250kV/m® Large aperture Magnet

n multi coil

Construction of the PRISM-FFAG Construction of the PRISM-FFAGWe will construct a full size PRISM-FFAG

0 20 m5 10 15 05

10

15

Magnet PS

RF PS

RF AMP

Injection system

Extraction

Vacuum Pump

Only 1 RF cavity and 1 kicker will be constructed.Future budget -> Other RFs and kicker to upgrade to the full spec.

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J-PARC

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MA(Magnetic Alloy) CavityMA(Magnetic Alloy) Cavity for high field gradient (~300kV/m) at 5MHzfor high field gradient (~300kV/m) at 5MHz

n MA will be used for J-PARC synchrotron RF cavitiesn Characteristics of MA® Thin Tape , 18 mm® High Field Gradient

n Voltage limit: Brf <Bsat. (1T) and Voltage per layer < 5 V

® High Curie Temperature® Large core, Rectangular Shape® Large permeability(about 2000 at 5MHz)® Original Q value is small(0.6).® High Q is possible by cut core configuration® Thickness -35mm (50mm in future)

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High Gradient CavityHigh Gradient Cavity

1.00E+09

1.00E+10

1.00E+11

1 10 100 1000 10000Brf[Gauss]

up'Q

f

SY2N5C4M2-302FT-smallFT-large

Magnetic Alloys

Ferrites

B=V/wS=25kV/2pX5MHzX5cmX40cm=400Gauss250kV/m 4gap 5MHz

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MA Cavity using Cut CoreMA Cavity using Cut Coren Low Q=large inductance vs. Resonant frequency = 5MHz vs. RF power for 250kV/m

® Resonant capacitance > 50-100 pF by structure® Large inductance in case of no cut MA (not good).

n Can be reduced by using cut core

n Solution® Q=1 at 5MHz with Cut Core (1.5mm gap)

n C=100pF and Rp=500 W /gapn Or C=50 pF and Rp=1 k W/gapn To obtain 40kV/gap, 800kW is necessary.

|Z|

0

20

40

60

80

100

120

140

160

180

0 5 10 15

frequency(MHz)

Impe

danc

e (O

hm)

H=1H=2

Need a model cavity to confirm.Measured using a core for J-PARC cavity

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PRISM RFPRISM RF plan planAnode PS

Clover

cavity cavity cavity cavity

HeaterSG

AMPcondenser

AMPcondenser

AMPcondenser

AMPcondenser

driveAMP

Cooling

# of cores

Impedance

Gaps/cavity

Field gradient

Power tube

Air cooling

4 cores /gap（2.5-３ｃｍcore）

1k W/gap　以上

1 gaps, 31.25-kV/gap, 25cm

62.5- kV/cavity250- kV/m

EIMAC 4CW150KDC35-40kV900-kW(peak)

PRISM RF Plan

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MA coreMA core

MA core for 150MeV FFAG

1.7m x 0.985m x 30mm

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Multi coil typen demerit

® Not easy to design® Needs current control

n Merit® Flat gap, large gap→large acceptance

® k-value changeable

Pole shape typen merit

® Established scheme® Easy to design

n demerit® Has small Gap

→acceptance is limited by gapsize

® k-value unchangeable

PRISM-FFAG MagnetPRISM-FFAG Magnet

PoP150-MeV

PRISM-FFAG

New

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X400.0 X450.0 X550.0 X600.0 X650.0

Y-50.0

Y50.0

Y100.0

Z0.0

Z50.0

Z100.0

Z150.0

Z250.0

Z300.0

Z350.0

X400.0 X450.0 X550.0 X600.0 X650.0

Y-100.0

Y-50.0

Y50.0

Y100.0

Z

X400.0 X450.0 X550.0 X600.0 X650.0Y

Z100.0

Z150.0

Z250.0

Z300.0

Magnet design is undergoing.

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Acceptance SimulationsAcceptance Simulations

LargeLarge

FFAG03@KEK2003/7/7

0 20 m5 10 15 05

10

15

Magnet PS

RF PS

RF AMP

Injection system

Extraction

Vacuum Pump

Schedule of the PRISM-FFAG constructionSchedule of the PRISM-FFAG constructionn FY2003

® Lattice design, Magnet design® RF R&D

n FY2004® RFx1gap construction & test® Magnetx1 construction & field

meas.n FY2005

® RFx4gap tuning® Magnetx7 construction® FFAG-ring construction

n FY2006® Commissioning® Phase rotation

n FY2007® Muon acceleration® (Ionization cooling)

Important first step to Neutrino Factory

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SummarySummaryn PRISM® Super muon beam with new technology for stopped muon

experiments.® High intensity, high purity and narrow energy spread muon

beamn Staging Scenario to NuFact and muon collider® a important step for the future muon physics and the NuFact.

n A budget for the PRISM-FFAG has been approved. The PRISM-FFAG will be constructed by the end of 2007.® RF construction will start soon.® Lattice and magnet design will be finalized by the end of this

year.