MUON Physics Program at Fermilab

Eric Prebys, FNAL

Summarizing steering committee working group, chaired by W.

Molzon and A. de Gouvea

3/28/2008E. Prebys - PAC Presentation

Two classes of muon experiments have been identified as particularly promising for an intensity-based program e conversion

A dramatic improvement in the search charged lepton flavor violation (CLFV)

Broadly sensitive to new physics Complementary to proposed e searches (eg, MEG) Can exploit voluminous work done for MECO proposal at BNL

Anomalous muon magnetic moment (g-2) Already shows hint of possible new physics Can transport apparatus from previous experiment at

Brookhaven Significant improvements in experimental technique and

theoretical uncertainty


Forbidden in Standard Model Observation of neutrino mixing shows this can occur at a very small rate

Photon can be real (->e) or virtual (N->eN)

3

e

0Z

First Order FCNC: Higher order dipole “penguin”:

e

Virtual mixing

W

54

2

3,22

21* 10

32

3)(

i W

ieii M

mUUeBr


3/28/20084

Courtesy: A. de Gouvea

?

?

?

Sindrum IIMEGA

MEG proposal

We can parameterize the relative strength of the dipole and four fermi interactions.

This is useful for comparing relative rates for NeN and e

E. Prebys - PAC Presentation

1

10-2

10-16

10-6

10-8

10-10

10-14

10-12

1940 1950 1960 1970 1980 1990 2000 2010

Initial mu2e Goal

- N e-N

+ e+ + e+ e+ e-

K0 +e-

K+ + +e-

SINDRUM II

Initial MEG Goal

10-4

10-16

3/28/2008 5E. Prebys - PAC Presentation

3/28/2008

Rate limited by need to veto prompt backgrounds!

12103.4capture

Ti

TieTiR e

High energy tail of coherent Decay-in-orbit (DIO)


3/28/20087

Eliminate prompt beam backgrounds by using a primary beam with short proton pulses with separation on the order of a muon life time

Design a transport channel to optimize the transport of right-sign, low momentum muons from the production target to the muon capture target.

Design a detector to strongly suppress electrons from ordinary muon decays

~100 ns ~1.5 s

Prompt backgrounds

live window


8

MECO spectrometer design

for every incident proton 0.0025 ’s are stopped in the 17 0.2 mm Al target

foils


3/28/20089

Deliver beam to Accumulator/Debuncher enclosure with minimal beam line modifications and no civil construction.

Recycler(Main Injector

Tunnel)

MI-8 -> Recycler done for NOvA

New switch magnet extraction to P150 (no need for kicker)


3/28/200810

Exploit NOvA accelerator modifications and post-Run II availability of Accumulator and Debuncher rings to mount a ->e conversion experiment patterned after MECO 4x1020 protons in ~2 years Measure

Single event sensitivity of Re=2x10-17

90% C.L. limit of Re<6x10-17

Improvement over existing limit of more than four orders of magnitude (one order of magnitude in effective mass reach)

ANY signal = Beyond Standard Model physics

capture Al

AlAl

e

R e


Example Sensitivities*

CΛ = 3000 TeV

-4HH μμμeg =10 ×g

Compositeness

Second Higgs doublet

2Z

-17

M = 3000 TeV/c

B(Z μe) <10

Heavy Z’, Anomalous Z

coupling

Predictions at 10-15

Supersymmetry

2* -13μN eNU U = 8×10

Heavy Neutrinos

L

2μd ed

M =

3000 λ λ TeV/c

Leptoquarks

*After W. Marciano


3/28/200812

The Project X linac would provide roughly a factor of ten increase in flux. Or could allow this experiment to run concurrently with

other experiments requiring similar intensity Investigating scheme for proton delivery Direct extraction from Recycler? Injection into Accumulator, then manipulate as before?

Also investigating improvements to muon transport efficiency based on muon collider/neutrino factory R&D

The combination of increased flux and efficiency could potentially push the 90% C.L. sensitivity to ~10-18


13

1992 MELC proposed at Moscow Meson Factory

1997MECO proposed for the AGS at Brookhaven as part of RSVP (at this time, experiment incompatible with Fermilab)

1998-2005intensive work on MECO technical design: magnet system costed at $58M, detector at $27M

July 2005 RSVP cancelled for financial reasons

2006MECO subgroup + Fermilab physicists work out means to mount experiment at Fermilab

June 2007 mu2e EOI submitted to Fermilab

October 2007 LOI submitted to Fermilab

Fall 2008 mu2e submits proposal to Fermilab

2010 technical design approval: start of construction

2014 first beam

To lowest order, the muon magnetic moment (g) is 2 g is perturbed by contributions from virtual loops, from both

the Standard Model and (possibly) beyond. The calculation and measurement of the “anomalous

magnetic moment”

stands as one of the most precise tests of the Standard Model

14

2

2g


B

QED

Z

Weak Had LbL

Had VP

Had VP

muons

hadrons

ee

eesR

m

,had sRssK

dsa2

1

KEY REGION

2006 plot


R-parity conserving Supersymmetry (vertices have pairs)

And the diagrams are amplified by powers of tan (here linearly)


is determined from the ratio of the muon precession frequency (a) and the magnetic field (B).

17

Momentum

Spin

e

a


18

K. Hagiwara, A.D. Martin, Daisuke Nomura, T. Teubner

Compare

TIME

Rep.Prog.Phys. 70, 795 (2007).

)4.3( 10)88295()theor.()expt.(

ppm) 48.0(10)6.5.(11658180)theor.(

ppm) 54.0(10)3.6.(11659208)expt.(

11

10

10

Theory+exp. input


Increase muon flux with better beam optics

Decrease contamination with long transport channel

Improve injection kicker to increase number of stores


Ankenbrandt and Popovic, Fermilab

g-2

Test Facility

Booster-era Beam Transfer Scheme

Rare Kaon Decays

Alternative ?


Event Method

Geant simulation using new detector schemes

Energy Method

Same GEANT simulation


22

Phase 1: + measurement to 0.1 ppm statistical Requires Nova type upgrades, beam manipulations and

~4x1020 p Can do in pre Project X era

Phase 2: - measurement to 0.1 ppm (or lower) Requires many more protons due to xsection for -

Would benefit from Project X

Phase 3: All “integrating” with much higher proton beam and restricted storage ring acceptance to lower systematics

Requires Project X



σsystematic 1999 2000 2001 Future

Pile-up 0.13 0.13 0.08 0.04

AGS Background 0.10 0.10 0.015*

Lost Muons 0.10 0.10 0.09 0.04

Timing Shifts 0.10 0.02 0.02

E-Field, Pitch 0.08 0.03 0.06* 0.05

Fitting/Binning 0.07 0.06 0.06*

CBO 0.05 0.21 0.07 0.04

Beam Debunching 0.04 0.04 0.04*

Gain Change 0.02 0.13 0.13 0.03

total 0.3 0.31 0.21 ~0.09

3/28/2008 23


Future

3/28/2008 24


This CMSSM calculation: Ellis, Olive, Santoso, Spanos. Plot update: K. Olive

gaugino mass

scal

ar m

ass

Excluded for neutral dark matter

1

2

With new experimental and theoretical precision and same a

Present:a = 295 ± 88 x 10-11

Futurea = 295 ± 39 x 10-11

Topical Review: D. Stöckinger hep-ph/0609168v1

Here, neutralino accounts for the WMAP

implied dark matter density

3/28/2008 25

Precision muon measurements offer powerful tools for the investigation of physics beyond the Standard Model.

Both the e conversion experiment and the g-2 measurement fit well into an intensity-based program at Fermilab.

These programs have the potential for a staged approach, beginning in the NOvA era and expanding in the Project X era.

3/28/2008E. Prebys - PAC Presentation 26

January 31 2008William Molzon, UC Irvine Muon

Physics at Fermilab 28

MEG experiment (running) at Paul Scherrer Institute: →eto ~10-13

Difficult to improve beyond that (perhaps to 10-14) due to accidental backgrounds

Reprise of MECO/mu2e at BNL Fermilab has better time structure, duty cycle, running time per year, higher

intensity COMET at JPARCMuon beam flux, time structure similar to MECO design sensitivity below 10-16

Detectors displaced from stopping target to reduce rates PRISM/PRIME at JPARCVery different muon beam: FFAG storage ring for

phase rotation, very intense pulses at low frequency (<1kHz)

Very small, narrow momentum spread beam, thintarget, detector arrangement similar to COMET

Would require new building, technical advances Prime disadvantage of both COMET and PRISM/PRIME is conflict with running neutrino beam

29

Examples with >>1 (no e signal):LeptoquarksZ-primeCompositenessHeavy neutrino

SU(5) GUT Supersymmetry: << 1

Littlest Higgs: 1

Br(e)

Randall-Sundrum: 1

MEG

mu2e

10-12

10-14

10-16

10-1110-1310-15

R(TieTi)

10-13 10-11 10-9

Br(e)

10-16

10-10

10-14

10-12

10-10

R(TieTi)


http://www.ippp.dur.ac.uk/~georg/sps/sps.html

10-11 units

29331816.513549086169237173-90

Compare to present a =295 ± 88

Next stage to a < ±39

Snowmass Points and Slopes:

MUON Physics Program at Fermilab

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