1. A personal overview of particle physics activities at PSI
A. M. Baldini
INFN Pisa

2. Currently 2 mA (1. 2 MW) will be increased to 3 (1
Currently 2 mA (1.2 MW) will be increased to 3 (1.8 MW) in the near future

3. Two graphite targets M (mm), E(cm) from which several secondary beams are extracted
Named as p or m – E or M - #
e.g.: pE3
Roughly 107 m/s
70% of the beam is sent to SINQ, a neutron spallation source for materials studies, solid state physics...

4. e.g.Mass limits for Higgs Search
PSI has a tradition on precision measurements. Muon lifetime: MuLan and Fast
In V-A theory muon lifetime factorizes into a weak contribution plus radiative corrections.
e.g.Mass limits for Higgs Search
The Fermi constant is an input to all precision electroweak studies: Dr contains all relevant loop corrections: GF current precision constitutes a limit to these fits

5. MuLan at pE3
Surface muons (28.8 MeV/c) coming from p decay at rest on the surface of the E target
Scintillator tiles + PMTs arranged symmetrically to reduce unwanted muon polarization effects
Beam structure created artificially
20 muons of the DC beam are used every 10 muon lifetimes
1012 events collection: final 1 ppm measurement : improvement of one order of magnitude wrt previous measurements
Recent (2007) result: 11 ppm measurent (almost a factor 2 improvement): paper submitted to PRL

6. Dtm < 1ppm in future? FAST
Use of a pion beam (pM1): MHz
Array of plastic scintillating fibers read by multi-anode PMTs
No polarization problems
In principle should reach a 1 ppm GF measurement but it is having several problems with electronics
Dtm < 1ppm in future?
Radiative corrections would support another order of magnitude on tm (beyond 1 ppm) but that would go way beyond the precision of the other electroweak parameters

7. Another tradition: LFV searches by using muons: m+  e+ g search
Lab.
Year
Upper limit
Experiment or Auth.
PSI
1977
< 1.0  10-9
A. Van der Schaaf et al.
TRIUMF
< 3.6  10-9
P. Depommier et al.
LANL
1979
< 1.7  10-10
W.W. Kinnison et al.
1986
< 4.9  10-11
Crystal Box
1999
< 1.2  10-11
MEGA
~2010
~ 10-13
MEG
Two orders of magnitude improvement
several SUSY GUT and SUSY see-saw models predict BRs at the reach of MEG

8. SUSY SU(5) predictions BR (meg)  10-14  10-13
SUGRA indications
LFV induced by slepton mixing
MEG goal
Experimental limit (MEGA)
SUSY SU(5) predictions
BR (meg)   10-13
SUSY SO(10) predictions
BRSO(10)  100 BRSU(5)
R. Barbieri et al., Phys. Lett. B338(1994) 212
R. Barbieri et al., Nucl. Phys. B445(1995) 215
combined LEP results favour tanb>10

9. Connection with n-oscillations
Additional contribution to slepton mixing from V21 (the matrix element responsible for solar neutrino deficit)
J. Hisano, N. Nomura, Phys. Rev. D59 (1999)
Our goal
Experimental limit
tan(b)=30
tan(b)=1
After SNO
After Kamland
in the Standard Model !!

10. background signal   e g accidental   e n n   e g n n ee  g g
Signal and background
background
signal
  e g
accidental
  e n n
  e g n n
ee  g g
eZ  eZ g
physical
  e g n n
e+ + g
e+ + g n
e+ + n
qeg = 180°
Ee = Eg = 52.8 MeV
Te = Tg g

11. The sensitivity is limited by the accidental background
The n. of acc. backg events (nacc.b.) depends quadratically on the muon rate and on how well we measure the experimental quantities: e-g relative timing and angle, positron and photon energy
Effective BRback (nback/Rm T)
Integral on the detector resolutions of the Michel and radiative decay spectra

12. Required Performances
BR (meg)  reachable
BRacc.b.  and BRphys.b.  0.1 BRacc.b. with the following resolutions
FWHM
Exp./Lab
Year
DEe/Ee
(%)
DEg /Eg
Dteg (ns)
Dqeg
(mrad)
Stop rate
(s-1)
Duty cyc.(%) BR
(90% CL)
SIN
1977
8.7
9.3
1.4 -
5 x 105
100
3.6 x 10-9
TRIUMF 10
6.7
2 x 105
1 x 10-9
LANL
1979
8.8 8
1.9 37
2.4 x 105
6.4
1.7 x 10-10
Crystal Box
1986
1.3 87
4 x 105
(6..9)
4.9 x 10-11
MEGA
1999
1.2
4.5
1.6 17
2.5 x 108
(6..7)
1.2 x 10-11
MEG
2009
0.8 4
0.15 19
2.5 x 107
1 x 10-13
Need of a DC muon beam

13. Detector outline Experimental method
Stopped beam of  /sec in a 150 mm target
Solenoid spectrometer & drift chambers for e+ momentum
Scintillation counters for e+ timing
Liquid Xenon calorimeter for  detection (scintillation)
fast: 4 / 22 / 45 ns
high LY: ~ 0.8 * NaI
short X0: 2.77 cm

14. Particles intensity as a function of the selected momentum
The PSI pE5 DC beam
Primary proton beam
E target
Particles intensity as a function of the selected momentum m+
28.8 MeV/c muons from decay of  stop at rest: fully polarized
108 m/s could be stopped in the target but only 3x107 will be used because of accidental background

16. A new kind of calorimeter: experimentally measured resolutions
 - p  0 n e 0   
4.8 % FWHM
FWHM(T)  150 ps
x= mm

17. m radiative decay Laser LED g e m n n p0 gg alpha Nickel g Generator
Lower beam intensity < 107
Is necessary to reduce pile-ups
Better st, makes it possible to take data with higher beam intensity
A few days ~ 1 week to get enough statistics e m n n
(rough) relative timing calib.
< 2~3 nsec
Laser
PMT Gain
Higher V with light att.
Can be repeated frequently
p0 gg
p- + p  p0 + n
p0  gg (55MeV, 83MeV)
p- + p  g + n (129MeV)
10 days to scan all volume precisely
(faster scan possible with less points)
LH2 target
alpha
Xenon
Calibration
PMT QE & Att. L
Cold GXe
LXe e+ g e-
Nickel g Generator
Proton Acc
Li(p,)Be
LiF target at COBRA center
17.6MeV g
~daily calib.
Can be used also for initial setup
9 MeV Nickel γ-line on
off
3 cm
20 cm
quelle K Bi
NaI Tl
Illuminate Xe from the back
Source (Cf) transferred by comp air  on/off F
Li(p, 1) at 14.6 MeV
Polyethylene
Li(p, 0) at 17.6 MeV
0.25 cm Nickel plate

19. MEG time scale
Detectors commissioning going on: soon start of data taking
Goal: hope to get a significant result before entering the LHC era
Measurements and detector simulation make us confident that we can reach the SES of 4 x to meg (BR 10-13) and possibly below…
Revised
document
now
LoI
Proposal
Planning
R & D
Assembly
Data Taking

20. The future of LFV searches with muons
Accidental background: meg sensitivity not much below the MEG one. Maybe 10-14÷15 possible
me conversion in nuclei does not have this problem: single e+ sign.
Best present sensitivity achieved by SINDRUM II at PSI: <7 90% C.L.: W. Bertl et al., EPJ C47(2006) 37
 Decay In Orbit

21. Beam related background
Moderator: range  about ½ range 
SINDRUM
At higher muon rates ( 1011 /s) a good strategy (ex MECO) would be to use a pulsed proton beam and make measurements in a time window distant from the beam pulse
This will not be possible at PSI

22. An important project for PSI: the spallation Ultra Cold Neutron source

23. n EDM: P and T violating
1. At the UCN facility at the ILL (Grenoble) reactor
2. Move the spectrometer to PSI
2. Project, build and operate a new spectrometer (n2EDM) ay PSI later on

24. m edm: a possibility for the future at PSI
Theoretically related to m e g
Disentangle the EDM effect from the g-2 precession by means of a radial electric field: JPARC LOI (Jan 2003) for a dedicated experiment->10-24 e.cm level M. Aoki et al. + F.J.M. Farley et al., PRL (2004)
g-2 precession cancelled. Only the one related to the electric dipole moment, out of the storage ring plane, left: up-down detectors measure the asymmetry build up with time
High intensity beam of 0.5 GeV/c polarized muons (JPARC LOI)

25. PSI m edm (A. Adelmann and K. Kirch, hep-ex/0606034)
pm = 125 MeV/c , P ≈ 0.9 at mE1 beam line
= 1.57
B = 1 T
E = 0.64 MV/m
R = 0.36 m
A table-top experiment
in one year of running
4 orders of magnitude improvement

26. Muon EDM Limits
S. Eidelman et al., PLB 592(2004)1
Proof of the measurement principle to judge about the realization of much larger experiment
SM : < 10-36

27. Thank you and many apologies for not having been able to come to Fermilab