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The silicon detector of the muon g-2 experiment at J-PARC. Vertex 2011, Rust June 24, 2011 Tsutomu Mibe (KEK) for the J-PARC muon g-2/EDM collaboration. Particle dipole moments. Hamiltonian of spin 1/2 particle includes. Magnetic dipole moment Electric dipole moment. - PowerPoint PPT Presentation
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The silicon detector of the muon g-2 experiment at J-PARC
Vertex 2011, RustJune 24, 2011
Tsutomu Mibe (KEK)for the J-PARC muon g-2/EDM collaboration
1
Particle dipole moments
Magnetic dipole moment g = 2 from Dirac equation, in general g≠2 due to quantum-loop effects
= + + + …
Example : electron
Hamiltonian of spin 1/2 particle includes
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Magnetic dipole moment
Electric dipole moment
a “anomalous magnetic moment”
Anomalous magnetic moment : g-2• Standard model can predict g-2 with ultra high precision
• Useful in searching for new particles and/or interactions
• Experiment has reached the sensitivity to see such effects...
0.24ppb0.54ppm
Dal(SM)/al
4.5 ppb0.41ppm
Dal(exp)/al
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DHMZ, Tau 2010 workshop
a exp – a
SM = (296 ± 81) 10 –11
(259 ± 81) 10 –11
3.2~3.6 ”standard deviations“ To be confirmed by new experiments
HLMNT,Tau 2010 workshop
Muon anomalous spin precessionin B and E-field
• Muon spin rotates “ahead” of momentum due to g-2 >0.• Precession frequency
• BNL E821– Focusing electric field to confine muons.– At the magic momentum
g = 29.3, p = 3.094 GeV/c (a m -1/(g2-1) ) = 0
4
c
EB
c
EaBa
m
e
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12
c
EB
c
EaBa
m
e
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12
Safely be neglected with current upper limit on EDM
Continuation of the experiment at FNAL is planned.
Compact storage ring
– Suited for precision control of B-field• Example : MRI magnet , 1ppm local uniformity
• Completely different systematics than the BNL E821 or FNAL
Our approach
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80 cm
Hitachi co.
14m
BNL E821 (FNAL ) J-PARC g-2
P= 3.1 GeV/c , B=1.45 T P= 0.3 GeV/c , B=3.0 T
Our approach (cont’)
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c
EB
c
EaBa
m
e
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12
Zero Focusing Electric field (E = 0 )
Ultra-cold muon beam (pT/p < 10-5) by utilizing the laser resonant ionization of muonium makes it possible to realize such experimental condition.
Equations of spin motion is as simple as at the magic momentum
BBa
m
e 2
BNL, FNAL, and J-PARC
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BNL-E821 Fermilab J-PARC
Muon momentum 3.09 GeV/c 0.3 GeV/c
gamma 29.3 3
Storage field B=1.45 T 3.0 T
Focusing field Electric quad None
# of detected m+ decays 5.0E9 1.8E11 1.5E12
# of detected m- decays 3.6E9 - -
Precision (stat) 0.46 ppm 0.1 ppm 0.1 ppm
Bird’s eye photo in Feb. 2008
J-PARC Facility(KEK/JAEA)
Material and Life Science Facility
Neutrino Beam To Kamioka
Main Ring (30 GeV 50 GeV)
Hadron Hall
LINAC
3 GeVSynchrotron
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9
New Muon g-2/EDM Experiment at J-PARC with Ultra-Cold Muon Beam
Surface muon
Ultra Cold m+ Source
Muon LINAC (300 MeV/c)
Muon
storage
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Resonant Laser Ionization of Muonium (~106 m+/s)
Graphite target (20 mm)
3 GeV proton beam ( 333 uA)
Surface muon beam (28 MeV/c, 4x108/s)
Muonium Production (300 K ~ 25 meV⇒2.3 keV/c)
New Muon g-2/EDM Experiment at J-PARC with Ultra-Cold Muon Beam
Surface muon
Ultra Cold m+ Source
Muon LINAC (300 MeV/c)
Muon
storage
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Resonant Laser Ionization of Muonium (~106 m+/s)
Graphite target (20 mm)
3 GeV proton beam ( 333 uA)
Surface muon beam (28 MeV/c, 4x108/s)
Muonium Production (300 K ~ 25 meV⇒2.3 keV/c)
New Muon g-2/EDM Experiment at J-PARC with Ultra-Cold Muon Beam
Silicon Tracker
66 cm diameter
Surface muon
Ultra Cold m+ Source
Muon LINAC (300 MeV/c)
Muon
storage
Super Precision Magnetic Field(3T, ~1ppm local precision)
Injection, kicker and positron detector
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Muon beam is injected here
mm
mm
Magnet coil
detectorkicker
Expected time spectrum of me+nn decay
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dm=2E-20 e・ cm
Up-d
ow
n a
sym
metr
y
g-2 precession spectrum Parasitic EDM search in up-down asymmetry
Time
High energy positron tends to be emitted in the direction of muon spin.
wa
∝ED
M
Requirements Detector should be efficient for
Positron track with p = 200 - 300 MeV/c in 3T solenoidal B-field
Immune to early-to-late effect The decay positron rate changes by
two orders of magnitude. 1.6 MHz/strip 10kHz/strip for 200 um
pich Silicon strip. The positron detector must be stable
over the measurements.
Zero E-field (<<10-2 V/cm) at muon storage area
Not spoil the precision B-field ( <<0.1ppm) at muon storage area
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Number of eventAbove threshold
Analyzingpower
300MeV/c200MeV/c100MeV/cpth(e+)
1.6 MHz
0.01 MHz
rate per 200 mm strip
Muon life time 6.6 ms
g-2 silicon tracker• Tracking vanes made of
Double-sided Silicon strip sensor– Anticipating excellent
stability and high granularity
• Number of sensors– 384 for 24 vanes*
• Number of channels– 0.2 mm pitch– 288k for 24 vanes
• Detector area– 0.12 * number of vanes [m2]– 2.9 m2 for 24 vanes
– * design studies in progress to determine these parameters 15
g-2 silicon tracker
576 mm
580
mm
g-2 silicon vane
front back
The detector model• A GEANT4 model made of DSSD sensors (300mm thick) has
been developed.– Dynamical Si response yet to be implemented (as discussed by Zbynek
Drasal on Wed)
• Track-finding performance is a key in the tracker design– Maximum ~10 tracks/10 ns– Algorithm based on the Hough transform in “zf” plane is being explored.
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Example event display
Signal e+ (>150MeV)BG e+ (<150MeV)
Lead developers: Kazu Ueno (RIKEN) Hiromi Iinuma (KEK)
Top view Side view
Evaluation of DSSD sensor
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HPK’s Belle-II DSSD sensor (discussed by Markus Fridel on Tue) was used to evaluate timing response of the sensor.A fast shaping ASD was wire-bonded to a part of strips (3x16 strip)
Belle-IIDSSD
Bias
XY stage
ASDASD
p-side
Special thanks toToru Tsuboyama (KEK)and Belle-II SVD group
Belle II Silicon Vertex Detector
Sensors from HPK
• Technical details (layers 4,5,6):• Dimensions: 59.6 x 124.88 mm2
• p-side:- Readout pitch: 75 µm- 768 strips
• n-side:- Readout pitch: 240 µm- 512 readout strips n-side- Atoll p-stop scheme
21 June 2011 18Markus Friedl
First look at signal from sensor
• Full depletion above 60 V• Well identified signals from 90Sr as
well as IR laser with a rise time of 10 nsec
• Plan to investigate timing response as a function of bias voltage, instantaneous rate, and temperature.
• Plan to perform a beam test at CERN in collaboration with the SiLC.
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20 mV/div40 ns/div
Test pulse (7fC)
IR laser (1060nm), n-side
Front-end electronics• Muon spill comes in every 40 msec.
We measure decay positrons for first 33 msec.
• Data acquisition sequence resembles to that of LC. The SiLC collaboration led by Aurore Navarro-Savoy (Paris) has been developing FEE for LC.
• R&D started to adopt the SiLC front-end technology to this experiment (French-Japan collaborative research program, 2011-2012).
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Summary
• A new muon g-2/EDM experiment at J-PARC:– Off magic momentum– Ultra-slow muon beam + compact g-2 ring– Start in 2016– Complementary to FNAL g-2
• Silicon tracker for g-2– Not quite a vertex detector, but a tracker for
incoming low energy positrons– Stringent requirements on early-to-late effect, E-field
and B-field– Conceptual design and R&D are in progress
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