Development ofthe Cylindrical Detector System
for an experimental searchfor kaonic nuclei
at J-PARCFuminori Sakuma, RIKENFuminori Sakuma, RIKEN
for the J-PARC E15 Collaborationfor the J-PARC E15 Collaboration
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J-PARC E15 ExperimentCylindrical Detector System•Cylindrical Drift Chamber (CDC)•Z-Vertex TPC
SummaryThe Third Joint JPS/DNP Meeting (Hawaii 2009), Oct. 13-17, 2009
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J-PARC E15 Experimentsearch for K-pp bound state using 3He(K-,n) reaction
K-3He Formation
exclusive measurement byMissing mass spectroscopy
andInvariant mass reconstruction
Decay
K-ppcluster
neutron
p
p
-
Mode to decay charged particles
Missing
mass
Spectroscop
y
via neutron
Invariant
mass
reconstructio
n at J-PARCat J-PARC
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J-PARC E15 Setup
1GeV/cK- beam
p
p
n
mass resolution for K-ppinvariant mass= 19MeV/c2 (CDC = 250m)missing mass (for 1.3GeV/c neutron)= 9.2MeV/c2 (ToF = 150ps)
NeutronToF Wall
CylindricalDetectorSystem
Beam SweepingMagnet
K1.8BR Beam Line
flight length = 15m
neutron
Beam trajectory
CDS &target
SweepingMagnet
NeutronCounter
Beam LineSpectrometer
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Cylindrical Detector System (CDS)Solenoid Magnet
Cylindrical Drift Chamber
L3He Target System
Z-Vertex TPC
B
Hodoscope Counter
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Cylindrical Drift Chamber (CDC)
hexagonal cell (drift length 9mm)15 layers (r = 19.0548.45cm)7 super layers (AUVAUVA)
made of Aluminum and CFRP# of wires : 8136 (read-out : 1816ch)solid angle = 2.6Ar:C2H6=50:50
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CDC (Cont’d)preamp cards and cables are attached
TDC’s in the counting room LVDSECL converters at the exp. hall
•Chip : CXA3183Q (SONY, low noize ASD IC, =16nsec)•Output : LVDS differential•Gain : 0.8V/pC at preamp8m
cables60m
cables
LVDSECL
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CDC Study with Cosmic-Ray
Intrinsic spatial resolution ~200Intrinsic spatial resolution ~200mm
CDC works good with expected performances
efficiency
x-t correlation
residual
resolution=206m
--- cosmic-ray run
stereo stereo
(using 90Sr)
T.Hiraiwa (Kyoto-u)K.Tsukada (RIKEN)
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Z-Vetex TPC (Z-TPC)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 5 10 15 20 25 30 35
reso
luti
on(m
m)
z(cm)
longitudinal
transverse
gas:P10 (150V/cm)
expected resolution (w/o B-field)
however, r-resolution is limited by pad size, e.g., 20.0/sqrt(12) = 5.8mm
To improve z-resolution,Z-TPC is newly constructing
z(p-): 7mm 2mmw/o
Z-TPCw/
Z-TPC
~500mm
~300mm
280
mm
170
mm
readout-pad•pad size:20x4mm•# of pad:4x4x9=144
field strip•double sided flexible print circuit board•8mm strip•10mm pitch
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Z-TPC (Cont’d)a double TGEM structure is used for amplificationSony ASD chips are used for our preamp at first (No dE/dx)in the future, fast FADC or ASDQ chips will be used to measure dE/dx
TGEM for Z-TPC
readout part
preamps
frame
field cage
Z-TPC will be ready in this yearZ-TPC will be ready in this year
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10cm10cm
HV
Thick-GEMa robust, simple to manufacture, high-gain gaseous electron multipliercost-effectively fabricated from double-clad G10 plates, using standard printed circuit board (PCB) techniquesholes are mechanically drilled (and the hole’s rim is chemically etched to prevent discharges)easy to operate and feasible to cover large areas, compared to the standard foil GEM
Thick-GEM @ RIKEN
11mm
2mm
2mm
drift mesh
TGEM #1
TGEM #2
R/O pad ASD
Edrift
Etrans
Etrans
55Fesetup
=150V/cm
=2.5*VGEM V/cm
=5*VGEM V/cm
w/ Rims
w/o Rims
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Thick-GEM StudyType Comment hole drim pitch thick size
TGEM1 w/ rim
0.3mm
0.05mm
0.6mm 0.4mm
100mmX
100mmTGEM2 w/o rim X
RETGEM Carbon X
H-RETGEM C+Cu hybrid XRETGEM: carbon electrodesH-RETGEM: carbon and copper electrodes on each side
The TGEMs reach effective gain of ~104, that is of practical use
It seems that the RETGEMs and hybrid RETGEMs work good
goalgoal ~10~1044
M.Tokuda (Tokyo-TECH)
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Thick-GEM StudyType Comment hole drim pitch thick size
TGEM1 w/ rim
0.3mm
0.05mm
0.6mm 0.4mm
100mmX
100mmTGEM2 w/o rim X
RETGEM Carbon X
H-RETGEM C+Cu hybrid X
start gain ~ 2x104
start gain ~ 4x103
RETGEM RETGEM relative gain
energy resolution
TGEM1TGEM1relative gain
energy resolution
start gain ~ 2x104
start gain ~ 4x103
TGEM2TGEM2relative gain
energy resolution
start gain ~ 2x104
start gain ~ 4x103
start gain ~ 2x104
start gain ~ 4x103
H-RETGEM H-RETGEM relative gain
energy resolution
RETGEM: carbon electrodesH-RETGEM: carbon and copper electrodes on each side
all TGEMs keep almost constant gain after initial gain dropall TGEMs keep almost constant gain after initial gain drop
instableinstablestable, but, there are no reproductive stable, but, there are no reproductive
repeatability of the repeatability of the RETGEMsRETGEMs
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Thick-GEM StudyType Comment hole drim pitch thick size
TGEM1 w/ rim
0.3mm
0.05mm
0.6mm 0.4mm
100mmX
100mmTGEM2 w/o rim X
RETGEM Carbon X
H-RETGEM C+Cu hybrid X
instability in the TGEM with rims is caused by charge up of the insulator?
lack of productive repeatability of RETGEM is caused by drilling process?
…
We have to study TGEM/REGEM in more detail
problems to be solved!problems to be solved!
RETGEM: carbon electrodesH-RETGEM: carbon and copper electrodes on each side
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Summary
J-PARC E15 experiment– Search for the simplest deeply-bound kaonic nuclear state,
K-pp, by in-flight 3He(K-,n) reaction
Detector construction is in progress– Solenoid Magnet, CDC, Z-TPC, CDH, 3He Target, and other
detectors– CDC works good with expected performances– Z-TPC will be completed in this year– TGEM study is ongoing…
Instability of TGEM with rims Lack of productive repeatability of RETGEM
The goal is to develop the “stable” TGEM/RETGEM.The goal is to develop the “stable” TGEM/RETGEM.
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J-PARC E15 Collaboration
backup
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Physics Motivation
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QGP neutronstar
SPS, RHIC, LHC
KEK-PS
W.Weise NPA553, 59 (1993).
E549@KEK-PS FINUDA@DANE
DISTO@SATUREN
OBELIX@CERN-LEAR
T.Yamazaki, A.Dote, Y.Akiaishi PLB587,167(2004).
We need conclusive evidence!
deeply-bound kaonic nuclear states exist?
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vtxK-pp vtx
p
p-
n~1300MeV/c
~400MeV/c~150MeV/c
~500MeV/c
Expected Kinematics for K-pp Decay
p
p -
binding energy = 100MeV/c2
Isotropic decay of K-pp with forward neutron
Calculated using Geant4
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Hodoscope Counter (CDH)expected pID using ToF measurements
CDH system has been mounted inside the Solenoid Magnet
CDH is used for the charged trigger and particle identification.
Plastic Scintillator : 99x30x700 mm3 ( W X T XL ) Configuration : 36 modulesPMT: Hamamatsu H8409 (fine mesh) x 72int = 76psec
Feb. 2009
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Kaon Decay Veto Counterreduce fake triggers caused by decay of K- beamrequirements for the detector
•inside CDC & magnetic field•small and compact
plastic scintillators embedded with wavelength shifting (WLS) fibers are in progress
Feb. 5-8, 2008test experiment atLNS, Tohoku Univ., Japan
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layernumber
wiredirection
super-layer number ofcells
radius [cm] cell width[degree]
drift length[cm]
offset angle[degree]
tilt angle[degree]
1 X 19.05 0.83 02 X’ 20.4 0.89 03 X 21.75 0.95 04 U 24.85 0.87 3.725 U’ 26.2 0.91 3.926 V 29.3 0.92 3.957 V’ 30.65 0.96 4.128 X 33.75 0.88 09 X’ 35.1 0.92 0
10 U 38.2 0.80 3.4311 U’ 39.55 0.83 3.5512 V 42.65 0.84 3.5913 V’ 44 0.86 3.7114 X 47.1 0.82 015 X’ 48.45 0.85 0
A3 180 2 0
U2 150 2.4 7.2
V2 160 2.25 6.75
V1 100 3.6 10.8
A2 120 3 0
A1 72 5 0
U1 90 4 12
Detailed Cell Configuration
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Calculated using Geant4generated at the center of CDS0<p<1 GeV/c, flat distribution60<<120 degree, flat distributionaccepted = track with a CDH-hit
decay
proton>250MeV/c, kaon>150MeV/c, pion>50MeV/cenergy loss
magnetic field = 0.5T
Geometrical Acceptance
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mass resolution K-ppp p
w/o chamber-resolution
5.8 MeV/c2 1.6MeV/c2
w/ chamber-resolution 18.7MeV/c2 2.5MeV/c2
invariant mass resolution for K-pp and
momentum resolution for , K, pCalculated using Geant4
Expected Spectrometer Performance
Invariant mass of p (MeV)
0 channel channel
K-pp= 60 MeV
we can distinguish the two non-mesonic decay modes for K-pp
– K-pp p p-p
– K-pp 0p p p-p