# Presentation: 773468

## Eric Prebys, FNAL
Summarizing steering committee working group, chaired by W. Molzon and A. de Gouvea

- Eric Prebys, FNAL
- Summarizing steering committee working group, chaired by W. Molzon and A. de Gouvea

- 3/28/2008

- E. 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

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## 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)

- First Order FCNC:

- Higher order dipole “penguin”:

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

- Courtesy: A. de Gouvea

- Sindrum II

- MEGA

- MEG proposal

- This is useful for comparing relative rates for NeN and e

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## Initial mu2e Goal 

- 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

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## Rate limited by need to veto prompt backgrounds!

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

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## 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 

- 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

- E. Prebys - PAC Presentation

## MECO spectrometer design

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

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

- 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)

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## 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 Re=2x10-17
90% C.L. limit of Re<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

- 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 Re=2x10-17
- 90% C.L. limit of Re<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

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## Example Sensitivities*

- Compositeness

- Second Higgs doublet

- Heavy Z’,        Anomalous Z    coupling

- Predictions at 10-15

- Supersymmetry

- Heavy Neutrinos

- Leptoquarks

- *After W. Marciano

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## 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

- 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

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## Slide 13

| 1992 | MELC proposed at Moscow Meson Factory |
| --- | --- |
| 1997 | MECO proposed for the AGS at Brookhaven as part of RSVP   (at this time, experiment incompatible with Fermilab) |
| 1998-2005 | intensive work on MECO technical design:  magnet system costed at $58M, detector at $27M |
| July 2005 | RSVP cancelled for financial reasons |
| 2006 | MECO 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

- 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

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## 3/28/2008

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

- R-parity conserving Supersymmetry (vertices have pairs)

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

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

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

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## Compare

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

- TIME

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

- Theory+exp. input

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## Increase muon flux with better beam optics

- Decrease contamination with long transport channel
- Improve injection kicker to increase number of stores

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## Booster-era Beam Transfer Scheme

- g-2

-  Test Facility

- Rare Kaon Decays

- Alternative ?

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## Phase 1:  + measurement to 0.1 ppm statistical

- 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*_

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## E. Prebys - PAC Presentation

| 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 |

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## Future

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## gaugino mass

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

- scalar mass

- Excluded for neutral dark matter

- 1

- 2

- With new experimental and theoretical precision and same a

- Present:
- a = 295 ± 88 x 10-11

- Future
- a = 295 ± 39 x 10-11

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

- Here, neutralino accounts for the WMAP implied dark matter density

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## 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.

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## MEG experiment (running) at Paul Scherrer Institute: →eto ~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 JPARC
Muon beam flux, time structure similar to MECO design
sensitivity below 10-16
Detectors displaced from stopping target to reduce rates 
PRISM/PRIME at JPARC
Very different muon beam: FFAG storage ring forphase rotation, very intense pulses at low frequency (<1kHz)
Very small, narrow momentum spread beam, thintarget, 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

- William Molzon, UC Irvine                                           Muon Physics at Fermilab

- MEG experiment (running) at Paul Scherrer Institute: →eto ~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 JPARC
- Muon beam flux, time structure similar to MECO design
- sensitivity below 10-16
- Detectors displaced from stopping target to reduce rates
- PRISM/PRIME at JPARC
- Very different muon beam: FFAG storage ring forphase 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

## Examples with >>1 (no e signal):
Leptoquarks
Z-prime
Compositeness
Heavy neutrino

- Examples with >>1 (no e signal):
- Leptoquarks
- Z-prime
- Compositeness
- Heavy neutrino

- SU(5) GUT Supersymmetry:  << 1

- Littlest Higgs:   1

- Br(e)

- Randall-Sundrum:   1

- MEG

- mu2e

- 10-12

- 10-14

- 10-16

- 10-11

- 10-13

- 10-15

- R(TieTi)

- 10-13

- 10-11

- 10-9

- Br(e)

- 10-16

- 10-10

- 10-14

- 10-12

- 10-10

- R(TieTi)

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## Snowmass Points and Slopes:

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

**10****-11**** units**

**293**
**318**
**16.5**
**135**
**490**
**86**
**169**
**237**
**173**
**-90**

**Compare to present ********a******** =295 ****± 88**

**Next stage to ******** ********a******** < ****±****39**

**Snowmass Points and Slopes:**