MICE: THE FIRST COOLING FRONTIER

V. Blackmore

18th May, 2010

SUMMARY

Physics at a NFBenefits of a Muon ColliderCreating and Cooling MuonsMICEFuture

2/20

PHYSICS AT A NF Neutrino flavours are a superposition of mass

eigenstates:

Measure sin2213, even if 13 is small. Determine mass hierarchy. Search for CP violation in the lepton sector.

3

2

1

231313122323121323121223

231323131223122313121223

1312131312

ccsscescsccess

scssseccsscesc

ssccc

ii

iie

phase violatingCP

sin

cos

ijij

ijij

s

c

m1

m3

m2

or

3/20

Search for “wrong sign” muons: An initial beam of +, produces 50% e and 50%

Clean experimental signature and extremely low backgrounds

Can measure values of sin2213 down to O(10-4)

NF PHYSICS SENSITIVITY

N HadronShower

ee

ee

e

No oscillation With oscillation

CP1

e

e

N

N

Figure from FNAL-TM-2259

4/20

NF AND MUON COLLIDER COMPONENTS Bright, intense neutrino beams and step

towards a muon collider…

NeutrinoFactory

MuonCollider

Image from M. Zisman, Muon Collider Physics Workshop 2009

5/20

Image from M. Zisman, Muon Collider Physics Workshop 2009

BEN

EFIT

S O

F A

MU

ON

CO

LLID

ER

• Muons suffer little synchrotron radiation loss.

• Smaller energy spread at Interaction Point for precision energy scans

• RF (expensive!) used efficiently, giving a compact footprint.

• ratio makes the Higgs coupling 40’000 larger.

emm

6/20

CREATING MUONS

p

Target Decay Channel

To

Acc

eler

ator

Resulting muon beam has a large spread in energy and momentum.

This is difficult to accelerate!(Plus, they don’t live long...)

p

p

7/20

e

LIOUVILLE’S THEOREM

Emittance = area of phase space ellipse

xp

zpxp

p

p

p

8/20

LIOUVILLE’S THEOREM

“The particle density in phase space is constant unless acted on by non-conservative force.”

xxxx xzxxzxz 22 )()(2)(

Emittance = constant

9/20

COOLING

We must violate Liouville’s Theorem!...not that it hasn’t been done before.

Cooling is a reduction in emittance.

10/20

TRADITIONAL COOLING

Electrons in a damping ring

Ions cooled by pre-cooled electron beam

Amplifier

Transverse Pickup

TransverseKicker

Stochasticcooling

Muons are too heavy.

Muon is short lived.

cool

ing

11/20

IONISATION COOLING

Absorber

RFAbsorber

RF

Largeemittance

Small(er)emittance

12/20

MUON IONISATION COOLING EXPERIMENT

Aim: Build a section of cooling channel Master engineering and operation Measure cooling with high precision

Experience feeds back into NF and collider design

13/20

MICE HALL AT RAL

14/20

Cooling is balanced by multipleCoulomb scattering

Equilibrium emittance = minimum emittance a material can provide:

Low (strong focusing), large X0 and dE/dz (H2 is best)

XmEEN

dz

dE

dz

d n

0rel3

2

)GeV 014.0( 2

2rel

1

COOLING vs. HEATING

dz

dEXm

n

0rel2

GeV 014.02

equil ,

Cooling Heating

15/20

THE COOLING CHANNEL

16/20Liquid Hydrogen

AbsorberFocus Coils RF

MIC

E M

AG

NETIC

FIE

LD

o Muons produced with large emittance

o Need to contain beam and provide tight focussing at absorbers

o SFoFo lattice

o Magnetic field reverses at absorbers to prevent build-up of canonical angular momentum.

matched in tracker

abs = 42cm

Image from M. Rayner, MICE Collaboration Meeting, March 2010

17/20

TH

E R

EA

L M

ICE B

EA

M

o The current MICE muon beam.

o Characterised using the TOFs by M. Rayner (Oxford)

Images from M. Rayner, MICE Collaboration Meeting, March 2010

3 fit3 fit

Preliminary!

18/20

CO

OLIN

G IN

MIC

E

o Real beam simulations

o Beam inflated by diffuser

o Emittance reduced in absorbers.

o Energy replaced by RF

TOF

Diffuser

Absorber

RF

Absorber

Absorber

RF

MICE should work!

Preliminary!

19/20

Images from M. Rayner, MICE Collaboration Meeting, March 2010

THE FUTURE

Image from B. Palmer, Muon Collider Physics Workshop 200920/20

THE FUTURE

20/20

EXTRA

LIOUVILLE’S THEOREM

xxxx xzxxzxz 22 )()(2)(

rms,

2

rms,

rms,

2

x

xx

x

xxx

x

xx

xx

x

x

x

x

xx

xxx

x

NEUTRINO OSCILLATIONS

Suppose neutrinos {1, , } have different masses {m1, m2, m3}. Each neutrino flavour is a mix of these. E.g. in a two flavour system:

Probability for a to oscillate to e is:

2

1

cossin

sincos

e

parameter mixing neutrino 2sin

energy, Neutrino

detector, tosource from Distance

27.1sin2sin

2

22

21

2

222

mmm

E

L

E

LmP e

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