Taking the Muon for a Spin Thomas Gadfort Fermilab 47 th FNAL Users - - PowerPoint PPT Presentation

Taking the Muon for a Spin

Thomas Gadfort Fermilab 47th FNAL Users Meeting

Spin and the Muon Anomalous Magnetic Moment Measuring aµ with Polarized Muons The BNL Result and Goals for Fermilab Muon g-2 Last Summer and This Summer’s Big Move

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Spin and Its Observable Effects

In the Standard Model (SM), the muon is a point-like spin ½ particle.

With spin comes a magnetic dipole moment (MDM) of strength:

Dirac showed that g = 2 for the electron as observed.

The 1930‘s and 40’s saw several breakthrough measurements of the g- factor that lead to a new understanding of particles and substructure.

2

~ µ = g q 2m~ s

→ nucleon substructure

• Phys. Rev. 72 (1947)

→ QM corrections gp ≈ 5.6, gn ≈ −3.8

ge = 2.00229(8) ≈ 2(1 + α/2π)

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Spin and Its Observable Effects

In the Standard Model (SM), the muon is a point-like spin ½ particle.

With spin comes a magnetic dipole moment (MDM) of strength:

Dirac showed that g = 2 for the electron as observed.

The 1930‘s and 40’s saw several breakthrough measurements of the g- factor that lead to a new understanding of particles and substructure.

2

~ µ = g q 2m~ s

→ nucleon substructure

• Phys. Rev. 72 (1947)

→ QM corrections gp ≈ 5.6, gn ≈ −3.8

∗ `+ `+

ge = 2(1 + α 2π ) ≈ 2.00232

ge/2 = 1.001 159 652 180 73(28)

• D. Hanneke, S. Fogwell, and G. Gabrielse

PRL 100, 120801 (2008)

ge = 2.00229(8) ≈ 2(1 + α/2π)

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Understanding The Muon

There is a rich history of muon g-factor measurements starting in the 1950’s at Nevis.

Evidence that the muon is a fundamental particle.

The past 50 years have seen dramatic improvements in precision and experimental techniques.

3

gµ = 2(10%)

• Phys. Rev. 105, 1415–1417 (1957)

+ Hadronic + Hadronic + Weak

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Understanding The Muon

There is a rich history of muon g-factor measurements starting in the 1950’s at Nevis.

Evidence that the muon is a fundamental particle.

The past 50 years have seen dramatic improvements in precision and experimental techniques.

3

gµ = 2(10%)

• Phys. Rev. 105, 1415–1417 (1957)

+ Hadronic + Hadronic + Weak

CERN I

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Understanding The Muon

There is a rich history of muon g-factor measurements starting in the 1950’s at Nevis.

Evidence that the muon is a fundamental particle.

The past 50 years have seen dramatic improvements in precision and experimental techniques.

3

gµ = 2(10%)

• Phys. Rev. 105, 1415–1417 (1957)

+ Hadronic + Hadronic + Weak

CERN I

CERN II

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Understanding The Muon

There is a rich history of muon g-factor measurements starting in the 1950’s at Nevis.

Evidence that the muon is a fundamental particle.

The past 50 years have seen dramatic improvements in precision and experimental techniques.

3

gµ = 2(10%)

• Phys. Rev. 105, 1415–1417 (1957)

+ Hadronic + Hadronic + Weak

CERN I

CERN II

CERN III

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Understanding The Muon

There is a rich history of muon g-factor measurements starting in the 1950’s at Nevis.

Evidence that the muon is a fundamental particle.

The past 50 years have seen dramatic improvements in precision and experimental techniques.

3

gµ = 2(10%)

• Phys. Rev. 105, 1415–1417 (1957)

+ Hadronic + Hadronic + Weak

CERN I

CERN II

CERN III BNL

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

E821 Brookhaven Muon g-2

Muon injection greatly improved statistics. Continuously wound superconducting (SC) main magnet coils + tunable shimming kit ➝ Reduced multipole field terms.

4

Superconducting coil winding

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

E821 Brookhaven Muon g-2

Muon injection greatly improved statistics. Continuously wound superconducting (SC) main magnet coils + tunable shimming kit ➝ Reduced multipole field terms.

4

10

Dramatic improvement in field uniformity

Contours in [ppm]!

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Storage Ring Measurement Technique (I)

5

In a dipole magnetic field:

Muon momentum revolution frequency, ωC

ωC = eB mcγ

Muon spin revolution frequency, ωS

ωS = geB 2mcγ + (1 − γ) eB mcγ

Muon anomaly revolution frequency, ωa

ωa ≡ ωS − ωC = ✓g − 2 2 ◆ eB mc = aµ eB mc

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Storage Ring Measurement Technique (II)

6

Source of Polarized Muons

Measure Muon Spin

Weak decay correlates muon spin and electron momentum

Measure Positron Energy

µ νµ e ¯ νe

Highest energy positrons when spin and momentum are aligned.

µ νµ

Lucky break from parity violation

γµ(1 − γ5)

π

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Storage Ring Measurement Technique (II)

6

Source of Polarized Muons

Measure Muon Spin

Weak decay correlates muon spin and electron momentum

Measure Positron Energy

µ νµ e ¯ νe

Eelectron

Highest energy positrons when spin and momentum are aligned.

µ νµ

Lucky break from parity violation

γµ(1 − γ5)

π

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Storage Ring Measurement Technique (II)

6

Source of Polarized Muons

Measure Muon Spin

Weak decay correlates muon spin and electron momentum

Measure Positron Energy

µ νµ e ¯ νe

Eelectron

Count N(e) above fixed threshold. Oscillation rate ∝ aµ

Highest energy positrons when spin and momentum are aligned.

µ νµ

Lucky break from parity violation

γµ(1 − γ5)

π

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

The Wiggle Plot, ωa, ωp, and aµ

7

4 billion muon decays (≈15% yield >1.8 GeV positrons)

<A>=0.4

momentum cut

20 40 60 80 100 Counts per 150 ns 10

2

10

3

10

4

10

5

10

6

s) µ time ( 32 34 36 38 40 Counts per 150 ns 500 1000 1500 2000 2500 3000

3

x10 s) µ time ( 692 694 696 698 Counts per 150 ns 20 40 60 80 100 120

E821 data

⧳ — Data 5 Param Fit N(t) = N0e− t

γτ [1 + A cos(ωat + φ)]

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

The Wiggle Plot, ωa, ωp, and aµ

7

4 billion muon decays (≈15% yield >1.8 GeV positrons)

<A>=0.4

momentum cut

20 40 60 80 100 Counts per 150 ns 10

2

10

3

10

4

10

5

10

6

s) µ time ( 32 34 36 38 40 Counts per 150 ns 500 1000 1500 2000 2500 3000

3

x10 s) µ time ( 692 694 696 698 Counts per 150 ns 20 40 60 80 100 120

E821 data

⧳ — Data 5 Param Fit N(t) = N0e− t

γτ [1 + A cos(ωat + φ)]

⇒ ωp (⟨B⟩)

+

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

The Wiggle Plot, ωa, ωp, and aµ

7

4 billion muon decays (≈15% yield >1.8 GeV positrons)

<A>=0.4

momentum cut

20 40 60 80 100 Counts per 150 ns 10

2

10

3

10

4

10

5

10

6

s) µ time ( 32 34 36 38 40 Counts per 150 ns 500 1000 1500 2000 2500 3000

3

x10 s) µ time ( 692 694 696 698 Counts per 150 ns 20 40 60 80 100 120

E821 data

⧳ — Data 5 Param Fit N(t) = N0e− t

γτ [1 + A cos(ωat + φ)]

⇒ ωp (⟨B⟩)

+

aµ = ωa/ω0

p

µµ/µp − ωa/ω0

p

Add prior knowledge...

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

The Wiggle Plot, ωa, ωp, and aµ

7

4 billion muon decays (≈15% yield >1.8 GeV positrons)

<A>=0.4

momentum cut

20 40 60 80 100 Counts per 150 ns 10

2

10

3

10

4

10

5

10

6

s) µ time ( 32 34 36 38 40 Counts per 150 ns 500 1000 1500 2000 2500 3000

3

x10 s) µ time ( 692 694 696 698 Counts per 150 ns 20 40 60 80 100 120

E821 data

⧳ — Data 5 Param Fit N(t) = N0e− t

γτ [1 + A cos(ωat + φ)]

⇒ ωp (⟨B⟩)

+

aµ = ωa/ω0

p

µµ/µp − ωa/ω0

p

Add prior knowledge...

aE821

µ

= 0.00 116 592 089(63) aSM

µ

= 0.00 116 591 802(49)

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

The Wiggle Plot, ωa, ωp, and aµ

7

4 billion muon decays (≈15% yield >1.8 GeV positrons)

<A>=0.4

momentum cut

20 40 60 80 100 Counts per 150 ns 10

2

10

3

10

4

10

5

10

6

s) µ time ( 32 34 36 38 40 Counts per 150 ns 500 1000 1500 2000 2500 3000

3

x10 s) µ time ( 692 694 696 698 Counts per 150 ns 20 40 60 80 100 120

E821 data

⧳ — Data 5 Param Fit N(t) = N0e− t

γτ [1 + A cos(ωat + φ)]

⇒ ωp (⟨B⟩)

+

aµ = ωa/ω0

p

µµ/µp − ωa/ω0

p

Add prior knowledge...

aE821

µ

= 0.00 116 592 089(63) aSM

µ

= 0.00 116 591 802(49)

>3σ From SM Prediction!

aE821

µ

− aSM

µ

= 287 ± 80

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Explanations

Standard Model calculation is incomplete/wrong?

8

aµ = aQED

µ

+ aEW

µ

+ aHad

µ

• T. Aoyama, M. Hayakawa, T. Kinoshita, M. Nio Phys.
• Rev. Lett.109 111807

Calculated out to 5 loops!

287

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Explanations

Standard Model calculation is incomplete/wrong?

8

aµ = aQED

µ

+ aEW

µ

+ aHad

µ

2 loop calculation + known Higgs mass correction

287

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Explanations

Standard Model calculation is incomplete/wrong?

8

aµ = aQED

µ

+ aEW

µ

+ aHad

µ

Coming Soon: Constrain HVP with low energy e+e- ⇾ π+π- data, LbL needs first principles LatticeQCD.

Dominant source of uncertainty

287

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

New Physics?

Standard Model calculation is fine. We are just seeing new physics.

9

aµ = aQED

µ

+ aEW

µ

+ aHad

µ

+ aNP

µ

Dark Sector

A0

γ

µ µ

SUSY

µ µ

γ

˜ µ ˜ µ

˜ χ aµ value-added for LHC

1.0 1.2 1.4 1.6 1.8 2.0 10-9 10-8

2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9

GHh Æ ggLêGHh Æ ggLSM Muon magnetic moment dam 1s 1s

Giudice, Paradisi, Strumia ’12 Davoudiasl, Lee, Marciano ‘12

E141 E774 KLOE BaBar

ae aΜ

a

µ

explained

APEX Test MAMI 5 10 50 100 500 1000 1 10 7 5 10 7 1 10 6 5 10 6 1 10 5 5 10 5 1 10 4 mZd MeV

2

Zd

δaµ 𝝑2

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

New Physics?

Standard Model calculation is fine. We are just seeing new physics.

9

aµ = aQED

µ

+ aEW

µ

+ aHad

µ

+ aNP

µ

Dark Sector

A0

γ

µ µ

SUSY

µ µ

γ

˜ µ ˜ µ

˜ χ aµ value-added for LHC

A precise g-2 measurement is complimentary to Higgs measurements and a future LHC discovery.

1.0 1.2 1.4 1.6 1.8 2.0 10-9 10-8

2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9

GHh Æ ggLêGHh Æ ggLSM Muon magnetic moment dam 1s 1s

Giudice, Paradisi, Strumia ’12 Davoudiasl, Lee, Marciano ‘12

E141 E774 KLOE BaBar

ae aΜ

a

µ

explained

APEX Test MAMI 5 10 50 100 500 1000 1 10 7 5 10 7 1 10 6 5 10 6 1 10 5 5 10 5 1 10 4 mZd MeV

2

Zd

δaµ 𝝑2

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

The Fermilab Muon g-2 Experiment

Increased Statistics: Fermilab will

provide us with >20x more muons.

New segmented calorimeters, straw wire tracker, Fast muon kicker (and more). Long shimming period, magnet temperature stability, more in-situ calibrations (and more).

10

Goal: Resolve E821 3σ measurement with >5σ sensitivity

σaµ = 0.54 → 0.14 ppm

σωa = 0.18 → 0.07 ppm

σhBi = 0.17 → 0.07 ppm

σstat = 0.4 → 0.1 ppm

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

The Fermilab Muon g-2 Experiment

Increased Statistics: Fermilab will

provide us with >20x more muons.

New segmented calorimeters, straw wire tracker, Fast muon kicker (and more). Long shimming period, magnet temperature stability, more in-situ calibrations (and more).

10

Goal: Resolve E821 3σ measurement with >5σ sensitivity

σaµ = 0.54 → 0.14 ppm

σωa = 0.18 → 0.07 ppm

σhBi = 0.17 → 0.07 ppm

σstat = 0.4 → 0.1 ppm

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Fermilab Muon Campus

Fermilab will produce pions using 8.9 GeV protons impacting the former antiproton production target

Pions decay along long path ⇒ Pure muon beam. (E821 had large pion contamination). 11

M1 Line Target g-2 Hall M5 Line Delivery Ring M2/3 Line

Booster Delivery Ring MC1

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

New Calorimetry

Segmented Calorimeters and SiPMs

We will use a 9x6 array of PbF2 crystals with SiPM for light readout.

Segmentation reduces pileup (two positrons in same time window). Laser calibration system and lower energy thresholds

12

SiPM PbF2

σ(E) E = 2.8%

Measured Energy Beam Energy

SLAC Test Beam, Nov ’13

σpileup = 80(E821) → 40 ppb σgain = 120(E821) → 20 ppb

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

New Tracking Detectors

Straw tracking detectors will measure muon decay vertex and momentum.

Monitor beam profile fill-by-fill (required for ⟨B⟩ and ωa measurements) Measure pile-up ↔ calorimeter hits 13 PbF2 Calo Straws Central Orbit

e+

µ+

FNAL Test Beam, Jan/Apr ’14

σhBi = 30(E821) → 10 ppb σbeam = 50(E821) → 30 ppb

The Big Move From Long Island ...

14

BNL Fermilab

... To Fermilab

15

... To Its Final Resting Place in MC1

16

(from Brian Drendal) (from Lee Roberts)

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Summary

Fermilab muon g-2 will measure the muon anomalous magnet moment to sub-ppm level.

>5σ sensitivity to new physics!

CD-1 approval. CD-2/3 review this July. Magnet shimming and detector commissioning in 2015/2016.

Hopefully, stored muons in 2017.

17

“Magnetic Moment” from Two Brothers in Warrenville, IL

Luckily, we’ve got plenty to keep us busy

Back Ups

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Fast Muon Kicker

19

Fast muon injection kicker

Produce a fast (<150 ns) ≈11 mrad kick. to place muons on central orbit. Must turn OFF before 2nd orbit begins

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Fast Muon Kicker

19

Fast muon injection kicker

Produce a fast (<150 ns) ≈11 mrad kick. to place muons on central orbit. Must turn OFF before 2nd orbit begins

Central Orbit

Kickers

Time [ns]

0.2 0.4 0.6 0.8 1

• 200
• 100

100 200 300 400 500 600 700

PHYSICAL REVIEW D 73, 072003 (2006)

cyclotron period

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Fast Muon Kicker

19

Fast muon injection kicker

Produce a fast (<150 ns) ≈11 mrad kick. to place muons on central orbit. Must turn OFF before 2nd orbit begins

Central Orbit

Kickers → lost muons and large betatron oscillations

Time [ns]

0.2 0.4 0.6 0.8 1

• 200
• 100

100 200 300 400 500 600 700

PHYSICAL REVIEW D 73, 072003 (2006)

cyclotron period

E 8 2 1 k i c k

E821 dramatically underkicked muons

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Fast Muon Kicker

19

Fast muon injection kicker

Produce a fast (<150 ns) ≈11 mrad kick. to place muons on central orbit. Must turn OFF before 2nd orbit begins

Central Orbit

Kickers → lost muons and large betatron oscillations

Time [ns]

0.2 0.4 0.6 0.8 1

• 200
• 100

100 200 300 400 500 600 700

PHYSICAL REVIEW D 73, 072003 (2006)

cyclotron period

E 8 2 1 k i c k

E821 dramatically underkicked muons

FNAL kick

FNAL kicker uses a fast blumlien pulser

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Fast Muon Kicker

19

Fast muon injection kicker

Produce a fast (<150 ns) ≈11 mrad kick. to place muons on central orbit. Must turn OFF before 2nd orbit begins

Central Orbit

Kickers → lost muons and large betatron oscillations

Curved kicker plates allow for higher fields

Time [ns]

0.2 0.4 0.6 0.8 1

• 200
• 100

100 200 300 400 500 600 700

PHYSICAL REVIEW D 73, 072003 (2006)

cyclotron period

E 8 2 1 k i c k

E821 dramatically underkicked muons

FNAL kick

FNAL kicker uses a fast blumlien pulser

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Field Goals

20

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

g Does Not Equal 2

The 1930’s saw two unanticipated results for the g-factor of the proton (gp ≈ 5.6) and the neutron (gn ≈ -3.8).

Strongly suggests nucleon substructure.

In the late 1940’s another breakthrough measurement was made at Columbia by Kusch and Foley. Swinger showed this result to be consistent with QM + 1 loop correction.

21

• Phys. Rev. 72 (1947)

ge = 2.00229(8)

∗ `+ `+

ge = 2(1 + α 2π ) ≈ 2.00232

ge/2 = 1.001 159 652 180 73(28)

• D. Hanneke, S. Fogwell, and G. Gabrielse

PRL 100, 120801 (2008)

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Improvements with E821

Muon Injection

Previous experiments inject pions into storage ring. Only fraction of pion decays create “storable” muons. Direct muon injection also greatly reduces hadronic flash background on detectors. Requires fast kicker to place muons onto stable orbit.

Superconducting Inflector Magnet

Novel double cosine theta septum magnet creates field free region for injected muons. Avoids large gap in main magnet. Key design feature: traps its own fringe field using a SC shield. 22

Central Orbit Injected Muons

Kickers

𝝼 beam channel

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Spin and Its Observable Effects

In the Standard Model (SM), the muon is a point-like particle with precisely measured properties. The muon is a spin ½ particle and with spin comes a magnetic dipole moment (MDM).

Dirac explained in 1928 that g = 2 for the electron.

Dirac also postulated the existence of an electric dipole moment (EDM) of strength. The EDM of the electron, if present, is many

• rders of magnitude weaker than the MDM.

23

~ µ = g q 2m~ s

~ d = ⌘ q 2mc~ s

ACME Electron EDM (arXiv:1310.7534)

|de| < 8.7 × 10−29e · cm

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

−

π

s p

h = 1 h = 1

p

µ−

sµ−

ν −

ν −

Lucky break from parity violation

Measurement Technique

24

• 1. Source of Polarized Muons

(i.e., )

ˆ s · ˆ p ≈ 1

• 2. Magic Momentum Muons

(i.e., ɣ = 29.3 → p = 3.094 GeV/c)

~ !a = − q m " aµ ~ B − ✓ aµ − 1 2 − 1 ◆ ~ × ~ E c #

Vertical focusing w/ E field adds new term to oscillation frequency

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

−

π

s p

h = 1 h = 1

p

µ−

sµ−

ν −

ν −

Lucky break from parity violation

Measurement Technique

24

• 1. Source of Polarized Muons

(i.e., )

ˆ s · ˆ p ≈ 1

• 2. Magic Momentum Muons

(i.e., ɣ = 29.3 → p = 3.094 GeV/c)

~ !a = − q m " aµ ~ B − ✓ aµ − 1 2 − 1 ◆ ~ × ~ E c #

Vertical focusing w/ E field adds new term to oscillation frequency

• 3. Measure

Electron Energy

Another lucky break from parity violation Electron spin follows muon spin

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

−

π

s p

h = 1 h = 1

p

µ−

sµ−

ν −

ν −

Lucky break from parity violation

Measurement Technique

24

• 1. Source of Polarized Muons

(i.e., )

ˆ s · ˆ p ≈ 1

• 2. Magic Momentum Muons

(i.e., ɣ = 29.3 → p = 3.094 GeV/c)

~ !a = − q m " aµ ~ B − ✓ aµ − 1 2 − 1 ◆ ~ × ~ E c #

Vertical focusing w/ E field adds new term to oscillation frequency

• 3. Measure

Electron Energy

Another lucky break from parity violation Electron spin follows muon spin

Spin precesses because gµ ≠ 2

aligned

Harder electron spectrum when spin and momentum are aligned

Eelectron

(From Lawrence Gibbons)

a n t i

• a

l i g n e d

• 3. Measure

Electron Energy

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Measurement Technique

24

• 1. Source of Polarized Muons

(i.e., )

ˆ s · ˆ p ≈ 1

• 2. Magic Momentum Muons

(i.e., ɣ = 29.3 → p = 3.094 GeV/c)

~ !a = − q m " aµ ~ B − ✓ aµ − 1 2 − 1 ◆ ~ × ~ E c #

Vertical focusing w/ E field adds new term to oscillation frequency

• 3. Measure

Electron Energy

Another lucky break from parity violation Electron spin follows muon spin

Spin precesses because gµ ≠ 2

aligned

Harder electron spectrum when spin and momentum are aligned

Eelectron

(From Lawrence Gibbons)

a n t i

• a

l i g n e d

Count N(e) above fixed threshold. Oscillation rate ∝ aµ

• 3. Measure

Electron Energy

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

New Detector Elements

Straw Tracking System

Two straw wire tracking chambers will record positrons before hitting the calorimeters.

Allows non-destructive beam profile measurements

Reconstruct muon decay vertex. Assist in pileup determination. 25 PbF2 Calo Straws U-V planes Central Orbit

e+

µ+

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

New Detector Elements

Straw Tracking System

Two straw wire tracking chambers will record positrons before hitting the calorimeters.

Allows non-destructive beam profile measurements

Reconstruct muon decay vertex. Assist in pileup determination. 25 PbF2 Calo Straws U-V planes Central Orbit

e+

µ+

z

• B

s

• a

y x

• ⇾ Induces up-down asymmetry

in positron spectrum

Allows Muon EDM Measurement EDM tilts oscillation plane

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

New Ring Elements

New fast electrostatic kicker

Requirement: Produce a fast (<150 ns) ≈11 mrad kick. Otherwise, muon bunch will hit the inflector up return. Requirement: Can not perturb precision field.

E821 design produced insufficient kick

Result: Lost muons and large betatron oscillations. 26 E821

Time [ns]

0.2 0.4 0.6 0.8 1

• 200
• 100

100 200 300 400 500 600 700

PHYSICAL REVIEW D 73, 072003 (2006)

cyclotron period

E821 kick

New design creates a fast square pulse using 3 Blumleins. Curved kicker plates generate larger field / pulse.

FNAL kick

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Fermilab Muon Campus

Fermilab will produce pions using 8.9 GeV protons impacting the former antiproton production target

Yield is ≈10-5 π/POT within 2% of Pmagic = 3.094 GeV.

Pions travel through M2/M3 lines (900 m“decay pipe”) to delivery ring (DR) and accumulating muons (π→µ).

Nearly pure muon beam in DR (big improvement over E821).

After several turns in DR (to remove beam protons), muons are kicked into M5 beamline and into g-2 experimental hall.

27 M1 Line Target g-2 Hall M5 Line Delivery Ring M2/3 Line

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Fermilab Muon Campus

Fermilab will produce pions using 8.9 GeV protons impacting the former antiproton production target

Yield is ≈10-5 π/POT within 2% of Pmagic = 3.094 GeV.

Pions travel through M2/M3 lines (900 m“decay pipe”) to delivery ring (DR) and accumulating muons (π→µ).

Nearly pure muon beam in DR (big improvement over E821).

After several turns in DR (to remove beam protons), muons are kicked into M5 beamline and into g-2 experimental hall.

27 M1 Line Target g-2 Hall M5 Line Delivery Ring M2/3 Line

Booster Delivery Ring g-2 Hall

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

New Physics?

Standard Model calculation is ok. We are just seeing new physics.

28

aµ = aQED

µ

+ aEW

µ

+ aHad

µ

+ aNP

µ

aTGC WWγ

µ µ

W W

γ Dark Photons

A0

γ

µ µ

SUSY

µ µ

γ

˜ µ ˜ µ

˜ χ aµ value-added for LHC

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

New Physics?

Standard Model calculation is ok. We are just seeing new physics.

28

aµ = aQED

µ

+ aEW

µ

+ aHad

µ

+ aNP

µ

aTGC WWγ

µ µ

W W

γ Dark Photons

A0

γ

µ µ

SUSY

µ µ

γ

˜ µ ˜ µ

˜ χ aµ value-added for LHC

g-2 can disentangle allowed SUSY models

A precise g-2 measurement is very complimentary to a future LHC discovery.

μ

a

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Understanding The Muon

There is a rich history of muon g-factor measurements starting in the 1950’s at Nevis.

Evidence that the muon is just a heavy electron.

The past 50 years have seen dramatic improvements in precision and experimental techniques.

29

gµ = 2(10%)

• Phys. Rev. 105, 1415–1417 (1957)

+ Hadronic + Hadronic + Weak

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Understanding The Muon

There is a rich history of muon g-factor measurements starting in the 1950’s at Nevis.

Evidence that the muon is just a heavy electron.

The past 50 years have seen dramatic improvements in precision and experimental techniques.

29

gµ = 2(10%)

• Phys. Rev. 105, 1415–1417 (1957)

Muon spin rotation in magnetic field

Nevis

+ Hadronic + Hadronic + Weak

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Understanding The Muon

There is a rich history of muon g-factor measurements starting in the 1950’s at Nevis.

Evidence that the muon is just a heavy electron.

The past 50 years have seen dramatic improvements in precision and experimental techniques.

29

gµ = 2(10%)

• Phys. Rev. 105, 1415–1417 (1957)

CERN I

Muon in circular obits, spin precession relative to cyclotron frequency.

+ Hadronic + Hadronic + Weak

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Understanding The Muon

There is a rich history of muon g-factor measurements starting in the 1950’s at Nevis.

Evidence that the muon is just a heavy electron.

The past 50 years have seen dramatic improvements in precision and experimental techniques.

29

gµ = 2(10%)

• Phys. Rev. 105, 1415–1417 (1957)

Storage ring w/ vertical focusing + tying aµ to hyperfine splitting in muonium

CERN II

+ Hadronic + Hadronic + Weak

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Understanding The Muon

There is a rich history of muon g-factor measurements starting in the 1950’s at Nevis.

Evidence that the muon is just a heavy electron.

The past 50 years have seen dramatic improvements in precision and experimental techniques.

29

gµ = 2(10%)

• Phys. Rev. 105, 1415–1417 (1957)

CERN III

Electrostatic focusing w/ “Magic momentum” muons w/ ɣ = 29.3

+ Hadronic + Hadronic + Weak

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

Understanding The Muon

There is a rich history of muon g-factor measurements starting in the 1950’s at Nevis.

Evidence that the muon is just a heavy electron.

The past 50 years have seen dramatic improvements in precision and experimental techniques.

29

gµ = 2(10%)

• Phys. Rev. 105, 1415–1417 (1957)

BNL

+ Hadronic + Hadronic + Weak

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

−

π

s p

h = 1 h = 1

p

µ−

sµ−

ν −

ν −

Lucky break from parity violation

Measurement Technique

30

• 1. Source of Polarized Muons

(i.e., )

ˆ s · ˆ p ≈ 1

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

−

π

s p

h = 1 h = 1

p

µ−

sµ−

ν −

ν −

Lucky break from parity violation

Measurement Technique

30

• 1. Source of Polarized Muons

(i.e., )

ˆ s · ˆ p ≈ 1

• 2. Vertical Focusing

(i.e., trapped muons)

~ !a = − q m " aµ ~ B − ✓ aµ − 1 2 − 1 ◆ ~ × ~ E c #

Using quad E field adds new term to

• scillation frequency

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

−

π

s p

h = 1 h = 1

p

µ−

sµ−

ν −

ν −

Lucky break from parity violation

Measurement Technique

30

• 1. Source of Polarized Muons

(i.e., )

ˆ s · ˆ p ≈ 1

• 2. Vertical Focusing

(i.e., trapped muons)

~ !a = − q m " aµ ~ B − ✓ aµ − 1 2 − 1 ◆ ~ × ~ E c #

Using quad E field adds new term to

• scillation frequency

If ɣ = 29.3 (pµ = 3.09 GeV/c) ⇒ Cancels new term These are “Magic Momentum” muons

Thomas Gadfort “Taking The Muon For a Spin”, 2014 Users Meeting

−

π

s p

h = 1 h = 1

p

µ−

sµ−

ν −

ν −

Lucky break from parity violation

Measurement Technique

30

• 1. Source of Polarized Muons

(i.e., )

ˆ s · ˆ p ≈ 1

• 2. Vertical Focusing

(i.e., trapped muons)

~ !a = − q m " aµ ~ B − ✓ aµ − 1 2 − 1 ◆ ~ × ~ E c #

Using quad E field adds new term to

• scillation frequency
• 3. Measure Muon

Spin Precession

Weak decay correlates muon spin and electron momentum

If ɣ = 29.3 (pµ = 3.09 GeV/c) ⇒ Cancels new term These are “Magic Momentum” muons