large acceptance and high extinction pion/muon beamline for the meco experiment at bnl
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MSI-05 KEK, 1-4 March 2005. Large Acceptance and High Extinction Pion/Muon Beamline for the MECO Experiment at BNL. Yannis K. Semertzidis Brookhaven National Laboratory. LFV: Physics Reach LFV Experimental Techniques MECO Experiment at BNL Intensity, Collection Efficiency - PowerPoint PPT PresentationTRANSCRIPT
Yannis K. SemertzidisBrookhaven National Laboratory
MSI-05 KEK, 1-4 March 2005
•LFV: Physics Reach•LFV Experimental Techniques•MECO Experiment at BNL•Intensity, Collection Efficiency•Extinction Issues
Large Acceptance and High Extinction Pion/Muon Beamline for the MECO
Experiment at BNL
Muon to Electron COnversion (MECO) Experiment
Boston University
R. Carey, V. Logashenko
J. Miller, B. L. Roberts,
Brookhaven National Laboratory
K. Brown, M. Brennan, G. GreeneL. Jia, W. Marciano, W. Morse, P. Pile, Y. Semertzidis, P. Yamin
Berkeley
Y. Kolomensky
University of California, Irvine
C. Chen, M. Hebert, P. Huwe,
W. Molzon, J. Popp, V. Tumakov
University of Houston
Y. Cui, N. Elkhayari, E. V. Hungerford,
N. Klantarians, K. A. Lan
University of Massachusetts, Amherst
K. Kumar
Institute for Nuclear Research, Moscow
V. M. Lobashev, V. Matushko
New York University
R. M. Djilkibaev, A. Mincer, P. Nemethy, J. Sculli
Osaka University
M. Aoki, Y. Kuno, A. Sato
University of Virginia
C. Dukes, K. Nelson, A. Norman
Syracuse University
R. Holmes, P. Souder
College of William and Mary
M. Eckhause, J. Kane, R. Welsh
Three Generations…leptons quarks
G=1 e e u dG=2 c sG=3 t b
Lepton Number isConserved…
MECO is searching forthe COHERENTconversion of ein the field of anucleus (Al, Ti).
2
2
2W
mM
Rate
Neutrino Oscillations:
Y. Okada: “Large effectsare expected in wellmotivated SUSY models”
Supersymmetry Predictions for e Conversion
Process Current Limit
SUSY level
10-12 10-15
10-11 10-13
10-6 10-9
+ e
- -N e N
Rem (GeV) 100 200 300 100 200 300
0 0
MECO single event sensitivity
10 -11
10 -13
10 -15
10 -19
10 -17
10 -21
Re
Rem (GeV)
SUSY: EDM, MDM and Transition Moments are in Same Matrix
Experimental Method• Low energy muons are captured by a target
nucleus. They cascade to 1s state rapidly.
• They either decay in orbit: with a lifetime of ~0.9s for Al (in vacuum:2.2 s)
• They get captured by the nucleus:
• or …they convert to electrons: N N'(Z-1) [ p n]- -
Ee = m c2 – Ebinding – Erecoil
= 105.6 – 0.25 – 0.25 MeV
ee
NeN
We want to measure Re with Sensitivity:
• High Proton Flux, High Muon Collection Efficiency, goal: ~1011muon stops/sec
• High Background Rejection, High Extinction
17102)1,(),(
ZNZNNeNR e
Need
1
10-2
10-4
10-16
10-6
10-8
10-10
10-14
10-12
1940 1950 1960 1970 1980 1990 2000 2010
MECO Goal
History of Lepton Flavor Violation Searches
- N e-N + e+ + e+ e+ e-
K0 +e-
K+ + +e-
E871
SINDRUM2PSI-MEG Goal
MEGA
SINDRUM 2
Expected signal
Prompt backgroun
d
Muon decay in orbit
Cosmic raybackgroun
d
Experimental signature is
105 MeV e- originating ina thin stopping target
MECO Requirements• Increase the muon flux (graded solenoid, MELC
design), collect ~10-2 muons/proton
• Use pulsed beam with <10-9 extinction in between for prompt background rejection
• Detect …only promising events defines detector geometry; resolution requirements
• Use cosmic ray veto
Number of - per InteractionComparison with Data…
GHEISHADATAGCALORFLUKA
Kinetic Energy [GeV]
Pio
ns/G
eV
Prediction for MECO Beam By V. Tumakov
The MECO Apparatus
Proton Beam
Straw Tracker
Crystal Calorimeter
Muon Stopping Target
Muon Production
Target
Muon Beam Stop
Superconducting Production Solenoid
(5.0 T – 2.5 T)
Superconducting Detector Solenoid
(2.0 T – 1.0 T)
Superconducting Transport Solenoid
(2.5 T – 2.1 T)
Collimators
Proton Beam
Charged particle’s helix conserves flux…
R2B is constant
i.e. in a graded solenoid transverse momentum is transformed into longitudinal increasing its collection efficiency.
BPT
2
is constant too,
Magnetic Field Overview
•Curved sections
Curved sections
Detector region
Curved sections
Production region
5T
3T
1T
Distance along beam path [m]100 20
Magnetic field vs distance
At 3.3 Tesla: 75% of muon capture efficiency of 5 Tesla.
Goals:–Transport low energy -
to the detector solenoid –Minimize transport of
positive particles and high energy particles
–Minimize transport of neutral particles
–Absorb anti-protons in a thin window
–Minimize long transittime trajectories
Muon Beam Transport with Curved Solenoid
2.5T
2.4T
2.1T
2.1T 2.0T
2.4T
Sign and Momentum Selection in the Curved Transport Solenoid
2 2s t
s
1+ p2p1 sD= × × p0.3B R
e-
-
e+
+
Time [ns]
Momentum and Time Distributions in MECO Muon BeamR
elat
ive
Flux
Momentum [MeV/c]
e-
e+
Part
icle
s/pr
oton
/ns
Transported and stopped muons
Transported muonspectrum
Stopped muonspectrum
Stopping Target and Experiment in Detector Solenoid
1T
1T
2T
Electron Calorimete
r
Tracking DetectorStopping Target:
17 layers of 0.2 mm Al
Magnetic Spectrometer for Conversion Electron Momentum Measurement
• Measures electron momentum with precision of about 0.3% (RMS) – essential to eliminate muon decay in orbit background
• 2800 nearly axial detectors, 2.6 m long, 5 mm diameter,0.025 mm wall thickness – minimum material to reduce scattering
• position resolution of 0.2 mm in transverse direction, 1.5 mm in axial direction
Electron starts upstream,
reflects in field gradient
Two Tracking Detector option are being considered
–Longitudinal geometry with ~3000 3m long straws–Transverse geometry with ~13000 1.4 m straws Both geometries appear to meet physics requirements
Longitudinal Tracker
Spectrometer Performance Calculations
FWHM ~900 keV
10
1.0
0.1
0.01 103 104 105 106
Aiming for ~200 KeV resolution
Calorimeter
/ E 3.5% Estimated
PbWO4 crystals cooled to -23 °C coupled with large area avalanche photodiodes meet MECO requirements, with efficiency 20-30 photo e-/MeV
Expected Sensitivity of the MECO ExperimentMECO expects ~ 5 signal events for 107 s running for Re = 10-16
Contributions to the Signal Rate FactorRunning time (s) 107
Proton flux (Hz) (50% duty factor, 740 kHz micropulse) 41013
entering transport solenoid / incident proton 0.0043
stopping probability 0.58 capture probability 0.60Fraction of capture in detection time window 0.49Electron trigger efficiency 0.90Fitting and selection criteria efficiency 0.19Detected events for Re = 10-16 5.0
Expected Background in MECO ExperimentMECO expects ~0.45 background events for 107 s with
~ 5 signal events for Re = 10-16
Source Events Comments decay in orbit 0.25 Dominant background; resolution
Tracking errors < 0.006Radiative decay < 0.005Beam e- < 0.04 decay in flight < 0.03 Without scattering in stopping target
decay in flight 0.04 With scattering in stopping targetdecay in flight < 0.001Radiative capture 0.07 From out of time protons; extinctionRadiative capture 0.001 From late arriving pionsAnti-proton induced 0.007 Mostly from
Cosmic ray induced 0.004 Assuming 10-4 CR veto inefficiencyTotal Background 0.45 Assuming 10-9 inter-bunch extinction
Required Extinction vs Time
MECO at Brookhaven National Laboratory
•Extinction of 10-9
Extinction at the AGS of BNL
Use 6 buckets, only two of them filled with beam. Time between filled buckets: s
AGS Ring20TP 20TP Extinction of 10-9
MeasurementTime
What is Planned for the AGS Ring
• Use a 60KHz AC Dipole Magnet (CW). Resonance at the vertical betatron frequency
• Use a pulsed Strip-line kicker to kick the full buckets into stable orbits.
• Need 1-50ms to drive particles off (driven by the strip-line kicker)
Mike Brennan (1998)
s
Removing Out-of-Bucket Protons in the AGS
Extinction measurements:•Initial test at 24 GeV with one RF bucket filled yielded <10-6 extinction between bucketsand 10-3 in unfilled buckets
•A second test at 7.4 GeV with a single filled bucket found <10-7 extinction
magnetic
kick
AC magnet
Buckets at AGS with h=6, W. Glenn
Buckets are connected creating unstable fixed points.
One or Two filled buckets? (W.Glenn)• At Injection the proton phase space is large
(scales as 1/). While waiting for the second injection (~0.2s) protons hop into the next buckets…
-1
-0.5
0
0.5
1
-3.14 -1.57 0 1.57 3.14
phi
d ph
i/dt
coasting
max dB/dt
,x
,y
In :
In :
x n
y n
xx
yy
Coasting bucket
Accelerated bucket
Preventing Bucket Contamination:
We are planning
• To study the one vs two filled buckets in the AGS ring with simulation and beam.
• Measure extinction in the AGS to 10-9
• Use external monitor and use an external extinction device as “insurance”.
RSVP/MECO Milestones
Milestone
Cost Baseline April `05HEPAP review 2005$15M for FY2005 for RSVP, available after baseline/HEPAP review decisionsPresident’s request for RSVP for FY2006 $42M
Start data taking 2011