K2K?? SciBar???????????

1
K2K?? SciBar???????????
????????????????

• ??? ?? ??

2
Contents

• K2K experiment
• SciBar detector readout system
• Cosmic ray trigger system
• Timing calibration
• Conclusion

3
K2K Experiment
SciBar detector
SciFi detector
Super-Kamiokande
1kt water cherenkov detector
Pure ?µ
?µ
L 250km
Near Detectors
MRD(Muon Range Detector)
K2K experiment uses neutrinos made by the
accelerator
KEK 12GeV PS
Pure ?µ beam whose Flux and energy are well
known, can be obtained .
4
Neutrino Oscillation
Square mass difference(eV2)
Flight length (km)
Oscillation Probability

Neutrino energy (GeV)
Mixing angle
Data
K2K current status
0.6 GeV
Best Fit
Best fit
?m2 2.810-3(eV2) sin22T 1.0
No oscillation
En
5
Neutrino interaction
CC-QE Interaction

• Assuming Charged Current Quasi-Elastic
  interaction
• Dominant process around 1GeV neutrinos.
• Oscillation maximum 0.6GeV
• Non-QE interactions are backgrounds for En
  measurement

CC-nonQE Interaction
m
nm
N
pion
nucleon
6
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
• 720p.e./MIP/cm (2 MeV)
• Detect 10 cm track
• Distinguish proton from pion by using dE/dx
• ?High 2-track CC-QE efficiency
• ?Low non-QE backgrounds

Extruded scintillator (15t)
EM calorimeter
3m
Multi-anode PMT (64 ch.)
3m
1.7m
Wave-length shifting fiber
Just constructed in this summer!
7
Detector Components
DAQ board
64ch MAPMT
Front-end board
8
Scintillator WLS Fiber
Scintillator
1.8 mmf

• Size 1.32.5300 cm3
• Peak of emission spectrum 420 nm
• TiO2 reflector (white) 0.25 mm thick

300 cm
1.3 cm
2.5cm
Wave-length Shifting Fiber

• Kuraray
• Y11(200)MS 1.5mmf
• Multi-clad
• Attenuation length 3.6m
• Absorption peak 430nm
• Emission peak 476nm

Charged particle
9
Multi-anode PMT

• Hamamatsu H7546 type 64-channel PMT
• 2 x 2 mm2 pixel
• Bialkali photo-cathode
• Compact
• Low power lt 1000V, lt 0.5mA
• Typical gain 6 x 105
• Cross talk 3
• Gain uniformity 20 (RMS)
• Linearity 200 p.e. _at_ 6 x 105

Top view
10
Readout Electronics
1.2ms
hold
? charge
VATA Chip
PMT signal
Front-end board
VA/TA chip
11
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 front-end boards(864ch)
16ch2 TA signal
12
Scintillator Installation
64 X and 64 Y layers
X and Y planes were glued
13
WLS Fiber and PMT installation
14
Logic Diagram for Cosmic Ray Trigger
Identification of hit track
Make coincident with two trigger signals
Top
112 TA
Trigger Board
7 DAQ Board
56 Front-end Board
56 MAPMT
Master trigger board
Timing Distributor
TRG
Side
112 TA
Trigger Board
7 DAQ Board
56 Front-end Board
56 MAPMT
Distribute signals made from the trigger signal
to other modules
Top view
Side view
We use half of the TA channels (224ch/448ch) for
cosmic ray trigger.
15
Trigger Board
Output 1ch
input 128 ch (168)
Output 16 ch
FPGA decide to make trigger signal.

• VME 9U module

• Front panel input 128 (168) ch LVDS/ECL

• Back plane output 16ch LVDS/ECL

• Using FPGA, trigger logic can be easily
  implemented for any combinations of 128 inputs.

16
Timing Distributor
Daughter board
16ch NIM I/O
8ch LVDS I/O
162ch LVDS/ECL Input
FPGA

• VME 6U module to distribute timing signals made
  by trigger system to DAQ backend boards

• 4ch NIM I/O on main board 2 daughter boards

Daughter board
162 ch LVDS/ECL Input
16ch NIM I/O

• Flexible data processing is realized using FPGA.

17
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 ORed signals from TA1 (fast-triggering
  ASIC) are trigger board input signals.

18
Trigger Design

• Trigger is generated, based on the hit pattern
  identification.

Preparing hit patterns, track pattern matching
them is selected.

• Track which is less than 45 degree of zenith
  angle is taken.

Zenith angle gt 45 degree
Zenith angle lt 45 degree

• Pre-scale factor can be set on the hit pattern
  to make hit distribution uniformly.

19
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.

Current Status
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.
20
Angle distribution of cosmic ray event
taken by commissioning trigger
Zenith angle(degree)
60
0
Horizontal line
-60
-80
0
80
Azimuth angle (degree)
21
Hit distribution of cosmic ray event
taken by commissioning trigger
250
250
Vertical position(cm)
Horizontal position(cm)
150
150
0
0
80
160
80
160
Z(cm)
Z(cm)
?
?
22
Event display of cosmic ray event
Side View
Top View
µ
µ
23
TQ Distribution
Correction function ?T A/(ADC B) C
A,B,C const
?T T(X12Z1) T(X12Z2)
?T(nsec)
?T(nsec)
25
25
?T 1719.8/(ADC 65.5)-5.6
10
10
-5
-5
600
0
300
0
300
600
ADC
ADC
24
Time Resolution
?T T(X12Z1) T(X12Z2)
Before TQ correction
After TQ correction
count
count
Time resolution s/v2 2.83 nsec
Time resolution s/v2 1.70 nsec
?T(nsec)
?T(nsec)
25
Light velocity in the fiber
y15z8
?T(nsec)
?T(nsec)
0.05847E-01 0.8594E-03
Light velocity in a fiber 17.2 nsec/cm
?x(cm)
?x(cm)
26
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.

Next step
Ability of direction ID by using TOF will be
estimated.
27
CC-QE candidate

• Area of circle is proportional to ADC
• Hits along the proton track are larger

Top view
Side view
p
µ
µ
p
28
3-Track Event
Top view
Side view
1
3
3
2
2
1
29
Neutral Current p0 Candidate
Top view
Side view
Vertex!
e
e
?
?
p0
p0
?
e
e