UltraHighPrecision witha MuonStorageRingg2pc1.bu.edu/~roberts/epac.pdf · BOSTON UNIVERSITY BeamCentroidandScraping nsec Beam Centroid Position (cm) No Scraping, fβ = 472 kHz 7 kV

BOSTONUNIVERSITY

Ultra High Precisionwith a

Muon StorageRingThe Muon

Experiment

at Brookhaven National Laboratory

B. Lee Roberts

robert [email protected] http: //g2pc1.b u.edu/˜ r oberts/

Department of Physics

Boston University

B. Lee Roberts, EPAC02, 4 June 2002 – p.1/44

BOSTONUNIVERSITY

BNL AGSE821:

A New Precision Measurement of theMuon

Valueat the level of 0.35 ppm

Boston University, Brookhaven NationalLaboratory, Budker Institute of Nuclear Physics -Novosibirsk, Cornell University, FairfieldUniversity, KEK, KVI and Rijksuniversiteit -Groningen, University of Heidelberg,University of Illinois, University ofMinnesota, Tokyo Institute of Technology,

Yale University


BOSTONUNIVERSITY

E821Collaboration(4/02)R.M. Carey, X. Huang, A. Lam-Ng, I. Logashenko, J.P. Miller, J. Paley, B.L. Roberts,

-

BU G. Bennett, H.N. Brown, G. Bunce,

G.T. Danby, Y.Y. Lee, W. Meng, W.M. Morse,

D. Nikas, C. Özben, R. Prigl, Y.K. Semertzidis - BNL Y. Orlov - Cornell D. Winn

- Fairfield K. Jungmann, KVI G. zu Putlitz Heidelber g P.T. Debevec, F. Gray D.W.

Hertzog, C. Onderwater, C. Polly, M. Sossong - UIUC A. Yamamoto - KEK B. Bous-

quet, P. Cushman, R. McNabb, T. Qian, P. Shagin - Minnesota V.P. Druzhinin, G.V.

Fedotovich, B.I. Khazin, N.M. Ryskulov, Yu.M. Shatunov, E. Solodov - BINP M. Iwasaki

- TyTech H. Deng, M. Deile, S.K. Dhawan, F.J.M. Farley, V.W. Hughes,

S.I. Redin, E.

Sichtermann - Yale

Co-Spokesmen,

Resident Spokesman,

Project Manager


BOSTONUNIVERSITY

Outlineof theTalk

Brief Introduction to

,the Motivation and Theory Overview of the Experimental Technique The Precision Storage Ring Magnet Beam Dynamics in the

Storage Ring. Summary and Conclusions


BOSTONUNIVERSITY

Muon: (2

generation lepton)

(1) ! " #(2)

(3) $&% '( )* + , " ,-/. )0 1 ) 0 2(4)

Parity Violating Decay Polarized Muons

3 4 5 36 * " , ) ,-/. 7. (5)


BOSTONUNIVERSITY

Magnetic Moments, -Factors,etc. 8" 9 9 ) 8;:(6)8" - magnetic moment; - gyromagnetic ratio8;: is the spin.

Dirac Equation Predicts <

In nature radiative corrections make

.

γ

µαπg = 2 +

γ

µγ

Dirac

+ ...

Kusch and Foley,Schwinger, 1947


BOSTONUNIVERSITY

MagneticMoments:DefinitionsandValues

" 0 ) = > ? @ 0

(7)

" 7 ) = 7 A BDC @ 5 C EF 3 @ G # CH *

(8)

" ) = A " I ! ! ) = I

(9) I !KJ J J

(10)B. Lee Roberts, EPAC02, 4 June 2002 – p.7/44

BOSTONUNIVERSITY

Theoretical Valuefor L

Electron: To the level of the experimentalerror,

ppb

0 7 MON 3 H PQ3 @ P C P R 0 7 S > GN ?UTWV )

Contribution of virtual" , , etc. is

ppb. Muon: The Relative Contribution of heavierthings: X 7 X V

Which is easy to understand from theuncertainty principle.


BOSTONUNIVERSITY

Theoryfor Muon L

0 M 0 S 0 ?3 PU@ CH G 5 0 > 3 4

0 > Y ?6 # G 5 # 0 3 #Z @ P 0 M


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TheExperimentalTechnique[ [ [ [[ [ [ [\ \ \ \\ \ \ \] ] ] ] ]] ] ] ] ]] ] ] ] ]] ] ] ] ]^ ^ ^ ^ ^^ ^ ^ ^ ^^ ^ ^ ^ ^^ ^ ^ ^ ^

_ _ _ __ _ _ __ _ _ __ _ _ _` ` ` `` ` ` `` ` ` `` ` ` `

a a a a a aa a a a a ab b b b b bb b b b b bc c cc c cc c cc c cc c cc c cc c c d d dd d dd d dd d dd d dd d dd d d e e e e e e e e ee e e e e e e e ef f f f f f f f f

Ideal Orbit

KickerModules

π + +µ

p = 3.1 GeV/c

Pionsµ ν Inflector

Injection Orbit

Storage Ring

TargetProtons

from AGS

= 77 mm~

= 10 mradβ ~

B dl = 0.1 Tm~

β


BOSTONUNIVERSITY

InflectorGeometry

µ


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InflectorExit Geometry

µ

ρ =


BOSTONUNIVERSITY

SpinandMomentumPrecession

gih ) T gij ) T )T

g 8$ @ R3N Glk N C 8;m gon gij gih )

+−e

information

The highest energycarry the spin = ω µ

Momentum Spin


BOSTONUNIVERSITY

Theneedfor vertical focusing In

we store for X4000 turns. Magnetic focusing conflicts with the need toknow to 0.1ppm. Can we use an electric field?

Spin Motion in

8

and

8-fields:

8gn pq ) 0 8 0 T 8r 8

sutv T wx y 0 T


BOSTONUNIVERSITY

TheRing Layout

Q4

Q1

Q2

Q3

inflector

trolleydrive

tracebackchambersFBM

garagetrolley

FBM

quadscover43% ofthe ring

K2K3

K1

cryo pump


BOSTONUNIVERSITY

TheRing Lfunction

0

2.5

5

7.5

10

12.5

15

17.5

20

0 50 100 150 200 250 300 350

β

β

β(m

eter

s)

φ (degrees)


BOSTONUNIVERSITY

TheKickerPlates


BOSTONUNIVERSITY

TheKickerCurrentPulse

x

vacuum

T

CT

1:85

1000 pf

SCR

PowerSupply

~1500 V

"charge"

µ

11.5

20MM

80M10nf

Ω

Ω

Ω"charge now"

300 f

In air In oil

In

4

0

2

Kicker Current

Beam

200 400 600 800 1000time (ns)

Kic

ker

Cur

rent

(kA

)


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A Kicker Modulator


BOSTONUNIVERSITY

MagneticCircuits

z" ? E | # R3 >

µ ∼106

steel

µ = 1air

I Biron yoke

void in yoke

air gaps

pole piece

pole piece

field regionhigh quality


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Schematicof theMagnet

thermal

pole piece

polebump

wedge

current sheet

g−2 Magnet in Cross Section

dipole correction coil

beamregion

fixed

probesNMR

YOKE

inner coil

inner coil

programmable

An array of 17NMR probes on the

trolley maps the B Field in the storage region

= 7112 mmρ

insulation

outercoils


BOSTONUNIVERSITY

Installation of aPolePiece


BOSTONUNIVERSITY

TheNudeStorageRing


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StorageRing Parameters

Parameter Value Comments

(g-2) Frequency

~ Hz ~ s

Muon kinematics GeV/c s

Cyclotron Period ns

Central Radius mm

¡

T Storage Aperture

cm circle

In one lifetime: 432 revolutions around ring

14.7 (g-2) periods


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Mappingthe

¢

field.

NMR trolley, 17 probes to map the field.

366 fixed NMR probes monitor field stability.


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£ £ in 1999o = 0θ

o90

o180

o270

-2000

200 (ppm)BB- φ


BOSTONUNIVERSITY

¤ ¥ £ ¥ £ ¥ ¥

¦ §;¨ª© « ¬® ¯°± ² ¨

°³;´ °µ¶· ¸ «º¹ » °· ¼¾½ ¸ « ¿

x

y

xθr

One slice in azimuth.

Muon Distribution (V À ÁT Â ( 5 C # À Ã Â ( # GH À Ä


BOSTONUNIVERSITY

And is:

1ppm field contours

-5

-4

-3

-2

-1

0

1

2

3

4

5

-5 -4 -3 -2 -1 0 1 2 3 4 5x [cm ]

y [c

m]

2000

−1

+1

00

0

−1

+1

x (cm)-4 -3 -2 -1 0 1 2 3 4

y (c

m)

-4

-3

-2

-1

0

1

2

3

4

Multipole expansion of B field in 1999

0 ppm

1

1

0 0

-1 -2

2 3

2 3

-3 -4

Multipoles (ppm)

normal skew

Quad -2.23 2.17

Sext -1.15 2.52

Octu -1.33 1.85

Decu 0.92 0.95


BOSTONUNIVERSITY

ExperimentalSignalis Decay

e+

e+

Highest energy are along muon spin

momentum

spin

The Muon Rest Frame

µ +

νe

νµ

The electron carries the muon spin


BOSTONUNIVERSITY

The Å Energy SpectrumN

umbe

r of

Pul

ses

0.9 GeV

hardwarethreshold

softwarethreshold1.8 GeV

ÆÈÇ É ÆËÊDÌÊDÌ É ÍÍlÎ Ì ÏÑÐ ÒÓ

Ô Õ ÖØ× ÙÚÛÜÙÝ Ô Þß à Õ Ö Þß àá ß

Pulse finding

threshold

250 MeV

2NA

A

N (E)

x


BOSTONUNIVERSITY

TheDetectorGeometry

â ââ ââ ââ ââ âã ãã ãã ãã ãã ãmuon momentum

muon spin

e

Sci−Fi Calorimetermodule

p

spin backward, lesshigh energy e

spin forward, morehigh energy e

Measures Energyand time

digitizer400 MHz


BOSTONUNIVERSITY

Time Spectrum,

äå GeV

æèç éëê ì í î ïðòñOó ôõö æ ÷ùø ç éú1,394.5 million e + (1999 data)

time, µs

Ne+ /14

9.185

ns

600-6

99

500-5

99

400-4

99

300-3

99

200-2

99

100-1

99

25-99

µs


BOSTONUNIVERSITY

TheMuonDistribution+e Time Spectrum: t = 6 sµ

+e Time Spectrum: t = 36 sµ

datasimulation

The distribution ofequilibrium radii


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û Fitting FunctionNature gives us 5 parameters:æèç éëê ì í î ïðñOó ôõö æ ÷oø ç éúStorage ring plus bunched beam gives more:

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 0.5 1 1.5 2 2.5üýÿþC

BO

-(g-

2)G

ain

chan

ge CB

O

CB

O+

(g-2

)

Dou

ble

CB

O

Ver

tical

wai

st

Fla

shle

ts

Fourier Transform of

the residuals from a5−parameter fit

(from 1 detector).


BOSTONUNIVERSITY

WeakFocussing

ê electric quadrupole gradient; ó

ì æó é ê í ê

ê ê ó

Detector acceptance depends on . The beammoves radially relative to one detector with the“Coherent Betatron Frequency”

ê ê æó ó é

which amplitude modulates the í

signal.B. Lee Roberts, EPAC02, 4 June 2002 – p.35/44

BOSTONUNIVERSITY

TheTunePlane

ν − 4ν = −12ν = 1

2ν −

2ν =

13ν

− 2

ν =

2ν − 2ν = 0

ν + ν = 1

3ν +ν = 34ν + ν = 4

ν = 1

5ν = 2

3ν = 1

ν − 3ν = 0

2ν − 3ν = 1

0.90 0.95 1.000.850.25

0.80

0.50

0.30

0.35

0.40

0.45

ν

ν

n = 0.137n = 0.142

n = 0.122


BOSTONUNIVERSITY

Frequenciesin the ring.

Quantity Expression Frequency Period

ø ! "# û%$ 0.23 MHz 4.37 &s

# '! (*) 6.7 MHz 149 ns

ó # 6.23 MHz 160 ns

# 2.48 MHz 402 ns

# 0.477 MHz 2.10 &s

+, # 1.74 MHz 0.574 &s


BOSTONUNIVERSITY

FiberBeamMonitors

x monitor y monitor

calibrate

calibrate


BOSTONUNIVERSITY

Measuring theTunewith FBM

Harp 1 (Horizontal), Fiber 4 ns

a.u.

Harp 2 (Vertical), Fiber 4 ns

a.u.

0

1

2

3

4

5

6

7

8

9

2000 3000 4000 5000 6000 7000 8000 9000 10000

0

10

20

30

40

50

60

2000 3000 4000 5000 6000 7000 8000 9000 10000

x fiber

y fiber


BOSTONUNIVERSITY

BeamCentroid andScraping

nsec

Bea

m C

entr

oid

Pos

ition

(cm

)

No Scraping, f β = 472 kHz

7 kV Scraping, f β = 416 kHz

-1.5

-1

-0.5

0

0.5

1

1.5

1000 2000 3000 4000 5000 6000 7000

cbo − traceback

frequency (MHz)

fc(1 - 2√n)

fc(1 - √n)

Muon Fast Rotation Frequency

Proton Fast Rotation Frequency

0

1000

2000

3000

4000

5000

6000

7000

8000

0 1 2 3 4 5 6 7 8

FFT − fiber harpscbo − fiber harps


BOSTONUNIVERSITY

û í &

Remove offsets and divide to determine

ê ÷ø ÷.-From û%$ ê /

/ê & $&-

Add corrections for radial

0

-field and vertical

“pitching motion”. ( 1 2ó 2

ppm)


BOSTONUNIVERSITY

Agreementwith SM?

Experiment −

Theory = + 1.6 σ+µ

µ+

µ−

µ+

µ+

a µ

(5 ppm)

(13 ppm) E821 (97)

E821 (98)

(9.4 ppm)

(10 ppm)CERN

CERN

E821 (99)(1.3 ppm)

The

ory


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Agreementwith SM?

2σ +−

− 1 σ + 5.5 σto

requiring that

2000 answer

agree with ’99

result to

gives the range

of values

SM agreement

+µ

µ+

µ−

µ+

µ+

a µ

(5 ppm)

(13 ppm) E821 (97)

E821 (98)

(9.4 ppm)

(10 ppm)CERN

CERN

E821 (99)(1.3 ppm)

The

ory


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ConclusionsandOutlook

3 The storage ring, kicker, quadrupoles, allmeet their specifications in the

æ54 éexperiment.

Beam dynamics is quite important inunderstanding the data.

Two data sets are being analyzed:ppm from 2000 run.

ppm from 2001 run


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æ54 éexperiment.

3 Beam dynamics is quite important inunderstanding the data.

Two data sets are being analyzed:ppm from 2000 run.

ppm from 2001 run


BOSTONUNIVERSITY



æ54 éexperiment.

3 Beam dynamics is quite important inunderstanding the data.

3 Two data sets are being analyzed:1

ppm & 6from 2000 run.1 2

ppm & î from 2001 run


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ConclusionsandOutlook, ctd.3 Historically muon

æ54 é

has developed as adialog between experiment and theory.

It still is!

Whatever the final answer, it will provide animportant constraint on new theories.

There is a window for discovery.

This is clearly a work in progress! Both theoryand experiment will be refined in the nearfuture.

Stay tuned!


BOSTONUNIVERSITY


æ54 é


3 It still is!

Whatever the final answer, it will provide animportant constraint on new theories.



Stay tuned!


BOSTONUNIVERSITY


æ54 é


3 It still is!

3 Whatever the final answer, it will provide animportant constraint on new theories.



Stay tuned!


BOSTONUNIVERSITY


æ54 é


3 It still is!


3 There is a window for discovery.


Stay tuned!


BOSTONUNIVERSITY


æ54 é


3 It still is!



3 This is clearly a work in progress! Both theoryand experiment will be refined in the nearfuture.

Stay tuned!


BOSTONUNIVERSITY


æ54 é


3 It still is!



3 This is clearly a work in progress! Both theoryand experiment will be refined in the nearfuture.

3 Stay tuned!B. Lee Roberts, EPAC02, 4 June 2002 – p.44/44

Documents

UltraHighPrecision witha MuonStorageRingg2pc1.bu.edu/~roberts/epac.pdf · BOSTON UNIVERSITY BeamCentroidandScraping nsec Beam Centroid Position (cm) No Scraping, fβ = 472 kHz 7 kV