A Parasitic search for a muon EDM to 10 -xx e-cm using tracking Brendan Casey, Fermilab New (g-2) Collaboration Meeting 3/19/2011.

A Parasitic search for a muon EDM to 10-xx e-cm using tracking

Brendan Casey, FermilabNew (g-2)m Collaboration Meeting

3/19/2011

B. Casey, 3/19/2011 2

A universe with matter• Differences between matter and

antimatter interactions allowed a small amount of matter to escape annihilation in the early universe– (4-6)x10-11 baryon to photon ratio

• Observed CP violation in neutral meson mixing and decay only partially explains this– From CKM: < 6x10-27 baryons/photon

• Huet, Sather PRD51 379 (1995)

• New effects needed. A small permanent electric dipole moment (EDM) of elementary particles is a good candidate.– Violates P and T

s d

B. Casey, 3/19/2011 3

EDM expectations• The large anomalous CPV in

Bs mixing reported at the Tevatron + minimal flavor violation predicts EDMs are “around the corner!”– Gino Isidori, ICHEP 2010 plenary

talk

• Need lepton and quark EDM searches to distinguish new weak interaction from a small QQCD

• Need different leptons to determine if the new phase is universal

Muon may be the only competitive place we can study EDMs outside the first generation

Large Bs CPV shrinks available parameter space

Titaniumneutron

Mercury

10-25

10-30

Buras, Isidori, Paradisi arXiv:1007.5291

Bs CPV

Muon EDM milestones

B. Casey, 3/19/2011 4

10-19

10-20

10-21

10-22

10-23

10-24

Phys. Rev. D 80, 052008 (2009)

|dm|< 1.8 x 10-19 e-cm @ 95%

10-25

10-26

10-27

|dm|< 10-21 e-cm

Muon EDM milestones

B. Casey, 3/19/2011 5

10-19

10-20

10-21

10-22

10-23

10-24

Phys. Rev. D 80, 052008 (2009)

|dm|< 1.8 x 10-19 e-cm @ 95%

10-25

10-26

10-27

|dm|< 10-21 e-cm

Im

Re

am

hm

SM

|dm|~3 x 10-22 e-cm

Muon EDM milestones

B. Casey, 3/19/2011 6

10-19

10-20

10-21

10-22

10-23

10-24

Phys. Rev. D 80, 052008 (2009)

|dm|< 1.8 x 10-19 e-cm @ 95%

10-25

10-26

10-27

|dm|< 10-21 e-cm |dm|~3 x 10-22 e-

cm

|dm| < 10-24 e-cm: (m m / me)2

|dm| < 10-26 e-cm: (m m / me)

B. Casey, 3/19/2011 7

Experimental setup• Muon sees E field pointing into the ring• Muon EDM will tilt the precession plane• Results in an up-down asymmetry in the positron

decay angle, 90° out of phase

M. Sossong’s analysis note

B. Casey, 8/10/2010 8

Proposed update

• Previous measurement based on ~10 million reconstructed positron tracks

• Tracking detectors in front of all calorimeter stations could reconstruct ~1011 tracks in the new experiment– Factor 100 reduction in limit

Tracking volume

Muon orbit

Positron trajectory

B. Casey, 3/19/2011 9

Tracking design considerations

asymmetry

Convoluted with Michelle

Spectrum

• Effective maximum asymmetry– Optimize design for

positron momentum near 1.5 GeV

• Inherent angular spread in decay angle– Sets upstream

material budget: keep multiple scattering below this.

• Occupancy throughout the fill– Sets how early we can

take data

• Many more details outlined in Thursday’s talk

~11 mrad RMS

inherent decay

angle in positron decay

Limit per POT

B. Casey, 3/19/2011 10

We might have the statistics for 1 order of magnitude per 2 x 1020 POT

0 4 8 12 16 20 24 28 32 361E-24

1E-21

1E-18

x 1020 POT

|dm|

Tracking team

B. Casey, 3/19/2011 11

Actively investigating cathode strip chambers, straws, and readout electronics options either inside the vacuum or using vacuum

inserts

Starting to investigate plastic scintillator and Silicon options as well

Much more detail in Thursday’s detector team talk

Petersburg Nuclear Physics Institute 

B. Casey, 3/19/2011 12

EDM conclusions

• Best current knowledge indicates EDMs will be seen in experiments this decade

• To understand what we see requires a measurement of the muon EDM

• We know how to improve by (at least) 2 orders of magnitude by adding tracking stations to the new (g-2)m experiment

• This naturally progresses into a dedicated muon EDM experiment at Project X

B. Casey, 3/19/2011 13

Happy St. Patrick’s Day!

Katie, PonoDylan, Logan

3/17/2011