k2k実験 scibar前置ニュートリノ検出器 - osaka university · 2005. 8. 29. · k2k...
TRANSCRIPT
-
K2K実験SciBar前置ニュートリノ検出器読み出しシステムと時間情報の較正
久野研 田窪 洋介
-
Contents
• K2K experiment• SciBar detector & readout system• Cosmic ray trigger system• Timing calibration• Conclusion
-
K2K ExperimentSuper-Kamiokande
KEK 12GeV PS
Near Detectors
L = 250kmPure νμ
SciBar detector1kt water cherenkov detector
MRD(Muon Range Detector)
SciFi detector
νμ
K2K experiment uses neutrinos made by the accelerator
Pure νμ beam whose Flux and energy are well known, can be obtained .
-
Neutrino OscillationSquare mass difference(eV2) Flight length (km)
∆⋅ν
θE
Lm222 27.1sin2sin
Mixing angle
OscillationProbability =
Neutrino energy (GeV)
0
1
2
3
4
5
6
7
8
9
10
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5Eνrec
Events
Data
Best Fit0.6 GeV
No oscillation
Eν
K2K current status
Δm2 = 2.8×10-3(eV2)
sin22Θ= 1.0
Best fit
-
Neutrino interaction• Assuming Charged Current
Quasi-Elastic interaction– Dominant process around
1GeV neutrinos.• Oscillation maximum
~0.6GeV• Non-QE interactions are
backgrounds for Eνmeasurement
νµ
µ
proton
θµpµ
n
µµµ
µµν θcos
2/2
PEmmEm
n
n
+−−
=recE
CC-QE Interaction
νµ
µ
Npion
CC-nonQE Interaction
nucleon
-
SciBar detector• Extruded scintillator with WLS
fiber readout• Neutrino target is scintillator
itself• 2.5 x 1.3 x 300 cm3 cell• ~15000 channels• Light yield
7~20p.e./MIP/cm (2 MeV)• Detect 10 cm track• Distinguish proton from pion
by using dE/dxHigh 2-track CC-QE efficiencyLow non-QE backgrounds
ν
Extrudedscintillator(15t)
Multi-anodePMT (64 ch.)
Wave-lengthshifting fiber
EM calorimeter
1.7m
3m
3m
Just constructed in this summer!
-
Detector Components
DAQ board
64ch MAPMT
Front-end board
-
Scintillator & WLS FiberScintillator
• Size : 1.3×2.5×300 cm3
• Peak of emission spectrum : 420 nm
• TiO2 reflector (white) : 0.25 mm thick 1.3 cm
300 cm
1.8 mmφ
2.5cmWave-length Shifting Fiber
Charged particle• Kuraray– Y11(200)MS 1.5mmφ– Multi-clad
• Attenuation length ~3.6m• Absorption peak ~430nm• Emission peak ~476nm
-
Multi-anode PMT• Hamamatsu H7546 type 64-channel PMT
– 2 x 2 mm2 pixel– Bialkali photo-cathode– Compact– Low power : < 1000V, < 0.5mA– Typical gain : 6 x 105
– Cross talk : ~3%– Gain uniformity : ~20% (RMS)– Linearity : ~200 p.e. @ 6 x 105
Top view
-
Readout Electronics
mu
ltip
lexer
sample&holdslow shaper
preamp.
fast shaper discri.
CH1
CH2
CH32
VA serial output
TA (32ch OR)
hold
PMTsignal
∝ charge
1.2µs
VA/TA chip
VATA Chip
Front-end board
-
DAQ board• Control of VA readout sequence• Setting of VA trigger threshold• A/D conversion of VA serial output by FADC• 8 front-end board (8 MAPMT) are connected to
one DAQ board.8
fron
t-end
boa
rds(
8×64
ch)
16ch×
2 TA
sign
al
-
Scintillator Installation
64 X and 64 Y layers
X and Y planes were glued
-
WLS Fiber and PMT installation
-
Logic Diagram for Cosmic Ray Trigger
Master trigger board
TRG Timing DistributorTrigger Board
Identification of hit track Make coincident with two trigger signals
Distribute signals made from the trigger signal to other modules
7 DAQ Board
56MAPMT
56 Front-end Board
Trigger Board
7 DAQ Board
56MAPMT
56 Front-end Board
112 TA
112 TATop
Side
Top view Side viewWe use half of the TA channels (224ch/448ch) for cosmic ray trigger.
-
Trigger Board
inpu
t : 1
28 c
h (1
6×8)
Out
put :
16
ch
FPGA decide to make trigger signal.
Output : 1ch
• VME 9U module• Front panel : input 128 (16×8) ch LVDS/ECL
• Back plane : output 16ch LVDS/ECL• Using FPGA, trigger logic can be easily implemented for any combinations of 128 inputs.
-
Timing Distributor
• VME 6U module to distribute timing signals made by trigger system to DAQ backend boards
16
• 4ch NIM I/O on main board + 2 daughter boards
16ch NIM I/O
Daughter board
Daughter board
FPGA
16ch
NIM
I/O
×2c
hL
VD
S/E
CL
Inpu
t
16×2 ch LVDS/ECL Input
8ch
LV
DS
I/O
• Flexible data processing is realized using FPGA.
-
Requirement for Cosmic Ray Trigger
• Horizontally through-going muons are taken for calibration effectively.
• Distribution of cosmic ray hits is uniform.
• Decision time is less than 100 ns (due to the cable length of electron catcher)
• 32ch OR’ed signals from TA*1 (fast-triggering ASIC) are trigger board input signals.
-
Trigger Design
Preparing hit patterns, track pattern matching them is selected.•Trigger is generated, based on the hit pattern identification.
Zenith angle > 45 degree Zenith angle < 45 degree
• Track which is less than 45 degree of zenith angle is taken.
• Pre-scale factor can be set on the hit pattern to make hit distribution uniformly.
-
Achieved Performance & Current Status
Achieved performance• Decision time is 100 nsec.
• Single rate of one TA is about 100 Hz.
•Trigger rate is about 100 Hz.
• Data acquisition rate is about 20 Hz.
We now use a trigger logic for the commissioning. We make “or” signals of every other layer, and make coincident with those of the top and side separately. We make “and” signal of the top and side.
Current Status
-
Angle distribution of cosmic ray event
Azimuth angle (degree)
Zeni
th a
ngle
(deg
ree)
Horizontal line
taken by commissioning trigger
-80 0 80
-60
0
60
-
Hit distribution of cosmic ray eventtaken by commissioning trigger
Z(cm)
Hor
izon
tal p
ositi
on(c
m)
Z(cm)
Ver
tical
pos
ition
( cm
0 80 160 0 80 160
150
250
150
250
ν ν
)
-
Event display of cosmic ray event
Side ViewTop View
μ
μ
-
TQ DistributionCorrection function : ΔT = A/(ADC +B) + C A,B,C : const
ΔT = T(X12Z1) – T(X12Z2)
ADC ADC
ΔT(
nsec
)
ΔT(
nsec
)
0 300 600 0 300 600
-5
10
25
ΔT = 1719.8/(ADC +65.5)-5.6
-5
10
25
-
Time ResolutionΔT = T(X12Z1) – T(X12Z2)
ΔT(nsec)
coun
t
After TQ correction Before TQ correction
ΔT(nsec)
coun
t
Time resolution
σ/√2 = 2.83 nsec
Time resolution
σ/√2 = 1.70 nsec
-
Light velocity in the fiber
y15z8
0.05847E-01 ±0.8594E-03
Light velocity in a fiber = 17.2 nsec/cm
Δx(cm) Δx(cm)
ΔT(
nsec
)
ΔT(
nsec
)
-
Conclusion & Next step
• Cosmic ray data is taken by commissioning trigger and useful for timing and energy calibration, and so on.
• Timing correction was done by cosmic ray data.• Timing resolution is 1.70 nsec.
• Light velocity in a fiber is 17.2 nsec.
Ability of direction ID by using TOF will be estimated.
Next step
-
CC-QE candidate• Area of circle is proportional to ADC• Hits along the proton track are larger
Top view
μ
pν
Side view
μ
p
ν
-
3-Track Event
Top view
1
2
3 3ν
Side view
1
2ν
-
Neutral Current π0 Candidate
Top view Side view
Vertex!
π0
e
e
νγ
e
eγ
γ
νπ0
K2K実験 SciBar前置ニュートリノ検出器ContentsK2K ExperimentNeutrino OscillationNeutrino interactionSciBar detectorDetector ComponentsScintillator & WLS FiberMulti-anode PMTReadout ElectronicsDAQ boardScintillator InstallationWLS Fiber and PMT installationLogic Diagram for Cosmic Ray TriggerTrigger BoardTiming DistributorRequirement for Cosmic Ray TriggerTrigger DesignAchieved Performance & Current StatusAngle distribution of cosmic ray eventHit distribution of cosmic ray eventEvent display of cosmic ray eventTQ DistributionTime ResolutionLight velocity in the fiberConclusion & Next stepCC-QE candidate3-Track EventNeutral Current p0 Candidate