Transcript Mu2e Experiment and Issues Rick Coleman, Fermilab RESMM’12, February 2012 Mu2e talks  Today  Now: Mu2e Experiment and Issues  Overview, Status of Project,

Mu2e Experiment and Issues
Rick Coleman, Fermilab
RESMM’12, February 2012
Mu2e talks
 Today
 Now: Mu2e Experiment and Issues
 Overview, Status of Project, Production & Transport Solenoids
 16:30 Superconducting Magnets of Mu2e- Michael Lamm
 17:00 Mu2e Production Solenoid- Vadim Kashikhin
 Tuesday
 16:00 Radiation Studies for Mu2e Magnets- Vitaly Pronskikh
Special Thanks to: R. Bernstein, J. Miller, D. Glenzinski, for some material used
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Introduction
•
Mu2e experiment is a search for Charged Lepton Flavor Violation
(CLFV) via the coherent conversion of m-Ne-N
•
In wide array of New Physics models CLFV processes occur at
rates we can observe with next generation experiments
•
The proposed experiment uses current proton source at Fermilab
with some modifications
•
Target sensitivity has great discovery potential
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Beam Intensity and Pulsed Proton Beam
• Deliver high flux m- beam to stopping target
• proton flux ~6 x 1012 /sec at 8 GeV (8 kW)
•~2 x 1010 Hz m- , 1018 total, 4 conversion e- at Rme~10-16
•103 more muons than SINDRUM II previous best limt
• Pulsed Proton beam – Wait 670 ns to reduce prompt background,
extinction = 10-10 using Debuncher Ring and oscillating (AC) dipole
sweeper in external proton beamline
m(Al)=864 ns
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Pulsed Beam and Radiative Pion Capture Background
reduced 1011
Wait ~ 700 ns
time (ns)
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Protons from 8 GeV Booster to Mu2e
New beamline
shared by Mu2e
and g-2
Steve Werkema
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Muon Campus for Mu2e and g-2 with Cryo Plant
g-2 building (MC-1) has evolved to support needs of g-2 and Mu2e
• Low bay is Muon Campus Cryo Building
• Medium Bay will house beamline power supplies and equipment.
Compressed He
from existing TeV
compressors
New transfer line for
compressed He built
from recycled parts
Cold He lines
to experiments
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Three TeV refrigerators
installed in MC-1
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Schedule
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MELC at Moscow
1989
m/p ~ 10-4 vs
conventional ~10-8
MECO at BNL
1996-2005
COMET at J-PARC: proposal Nov 2007 & Mu2e at FNAL: proposal Oct 2008
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Mu2e Apparatus
Production
Solenoid
Production
Target
Transport
Solenoid
Detector
Solenoid
Stopping
Target
Collimators
Tracker
Calorimeter
(not shown: Cosmic Ray Veto, Proton Dump, Muon Dump, Proton/Neutron absorbers, Extinction Monitor, Stopping Monitor)
•
Mu2e experiment consists of 3 solenoid systems
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Mu2e Apparatus
Production
Solenoid
Transport
Solenoid
Detector
Solenoid
1.0T
em-, p2.5T
~5T
Production
Target
2.0T
Collimators
Stopping
Target
Tracker
Calorimeter
(not shown: Cosmic Ray Veto, Proton Dump, Muon Dump, Proton/Neutron absorbers, Extinction Monitor, Stopping Monitor)
•
Mu2e experiment consists of 3 solenoid systems
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Transport Solenoid
Inner radius=24 cm
Length=13.11 m
TS1: L=1 m
TS2: R=2.9 m
TS3: L=2 m
TS4: R=2.9 m
TS5: L=1 m
Goals:
—Transport low energy
m- to the detector solenoid
—Minimize transport of positive
particles and high energy particles
—Minimize transport of neutral particles- curved section
—Absorb antiprotons in a thin window
—Minimize particles with long transit time
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Charge, Momentum Selection and Rejection of Long-lived Particles
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Muon Fluxbefore and after Transport Solenoid
Negative Muons
p(MeV)
Positive Muons
p(MeV)
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Muons Reaching the Stopping Target in the Detector Solenoid
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Production Solenoid
L=
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radius
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Heat and Radiation Shield Dimensions from Simulation
25 kW
0.6 m
W
1.4 m
Cu
4m
8 kW
See Vitaly Pronskikh’s
talk
tomorrow
W
Cu
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Some Early Comparisons to MECO (2009)
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Study of Muon Yield vs Maximum Field in Production Solenoid
Muon Yield vs Bmax Production Solenoid
Graded Field Bmin =2.5 T
1.2
Relative Muon Yield
1
0.8
MECO
Mu2e
0.6
0.4
0.2
0
0
1
2
3
4
5
6
Bmax (T)
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Target z position Study (2009)
muon yield vs target position in Production Solenoid
1.2
Relative muon yield
1
0.8
Mu2e- g4beamline
0.6
MECO GEANT3
0.4
0.2
0
-2
-1
0
1
2
3
4
z (m)
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MECO
5200
1m
0m
1400
40
0
Joint Meeting in Berkeley Jan 2009
with COMET group- direct comparisons
difficult due to differing physics models
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COMET
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Sergei Striganov
improved
fit for Mu2e
2009, similar fits
by Bob Bernstein
File of pions
weighted
by HARP data
used
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Pion Production- what energies and angles are important?
Stopped Muon Yield vs Initial Pion Kinetic Energy
Stopped Muons per 1E6 incident protons
1000
~60% from 20-60 MeV kinetic energy
or p = 77- 143 MeV
100
10
1
0
40
80
120
160
200
240
280
320
360
400
440
480
520
560
600
Kinetic Energy (MeV)
Stopped Muon Yield vs Initial Pion Angle
Stopped Muons per 1E6 incident protons
300
250
200
150
100
50
0
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
cos angle
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MECO
Increase Field in Short PS from 4T to 5T max field
6
5
Use HARP
3
Bz(T)
4
Standard PS-5T
max
Mu- hitting stopping 1955
target
Mu- stopping
1280
Short PS- 4T max Short PS- 5T max
Relative stopped yield =1.00
1603
1917
970
1109
0.76
0.87
2
1
5000
4000
3000
2000
1000
0
-1000
0
-2000
z(mm)
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Optimize target z position for Stopped muon yield for L= 4m Mu2e PS
1
0.9
0.8
0.7
With this target location
muon yield is down ~ 7%
with L=4 m vs L=5.2 m (MECO)
0.6
0.5
0.4
0.2
1.2
2.2 z(m) 3.2
4.2
Some cost savings
reducing L, but most
important feature is
DPA requirements can be
satisfied in region where
proton beam exits PSsee Vitaly’s talk
tomorrow
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Production Solenoid- Some
Engineering Aspects – Heat Shield
8.3 kW current version
25 kW version
Requires Tungsten  $$$
Heat Transfer issues
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The Mu2e All-Bronze Heat and Radiation Shield Design
Exploded view showing radiation labyrinths and all parts
13.6 tons
12.4 tons
13.2 tons
6.6 tons
Bolt-on rails
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46 tons total
L. Bartoszek
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Status of Heat Shield Engineering
 We have to build drawings on all-bronze 8.3 kW
 3 cost estimates, very consistent, significant savings in 8.3
kW version over 25 kW version which uses tungsten
 Thermal analysis in progress, not expected to be a
problem
 Need to explore other materials (Copper, Copper/Nickel)
 Continue simulations to optimize design
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Backup Slides
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Electron Flash and Middle-Collimator
All particles
negative muons
electrons
e/m ~20 -> 1 & stopped m reduced 20%
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e- /m - flux entering the Detector Solenoid
e-
m-
Momentum (MeV/c)
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Time distribution entering Detector Solenoid
em-
Time (ns)
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Time vs p - negative muons reaching stopping target
MECO PS
Mu2e PS
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TS with gradient
t= ~200 ns
pp=54 MeV scatters to ~0 pitch angle
in pbar windowpbar window
TS without gradient
t= ~900 ns
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Study of the Production Solenoid
Gradient vs Muon Yield
normal time
distribution
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positive gradient
leads to long times
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