Core neutron measurement
with sampling calorimeter
“Cerberus”
in neutral beam line for KOTO
experiment
Miki Sasaki
( Yamagata Univ.)
10th Mar. 2015@ELPH Workshop C010
Beam line for KOTO
γ absorber sweeping magnet
e±,µ±,π±,p...
target(Ni/Pt)
KL,n,γ
16°
experiment
area
30GeV proton
20m
collimator
x or y profile
# of event
• Produce small size of neutral beam with collimation
system (7.9µ str)
• Small halo n
• halo n/K0L = 0.70±0.05x10-3 (< 1.0x10-3)
• halo n/core n = 2.70±0.11x10-52 ( ~1.0x10-5)
core
halo
halo
mm
KOTO schedule
• 2009
-
construction of KL beam line at J-PARC
- beam survey
• 2010
-
construction of CsI Calorimeter
- engineering run
- beam survey
• 2011
-
construction detecters
- engineering run
!
…
Beam survey experiment
10
104
3
10
102
10
1
-1
10
0
2
4
all particles
102
10
neutron
0
KL
charged particles
1
10-1
10-2
6
8
10
momentum (GeV/c)
-200-150-100 -50 0
50 100 150 200
X (mm)
10
neutron
K0L
5
10
X profile (T>0.01GeV,Z=21m)
Intensity (/mm/1.0x10 P.O.T.)
neutron momentum
Intensity (/mm/1.0x10 P.O.T.)
9
intensity (/0.01GeV/c/1.0x10 P.O.T.)
Beam line simulation by GEANT3
Y profile (T>0.01GeV,Z=21m)
all particles
102
10
neutron
0
KL
charged particles
1
10-1
10-2
-200-150-100 -50 0
• Measurement of KL beam to verify M.C.
• Beam profile
• Neutron, KL ,gamma flux and momentum
50 100 150 200
Y (mm)
Sampling calorimeter Cerberus
(Pb 4mm+Scinti 3.7mm)/layer
#1
#2
(Fe 4mm+Scinti 3.7mm)/layer
#3
#4
#5
#6
sensitive area : 40*40 cm2
(beam size 15*15 cm2)
18X0,0.7λI
29X0,3.5λI
sampling calorimeter
to measure neutron flux and energy
2009
K0L measurement
core n, γ
measurement
upstream
downstream
Beam profile
measurement
n/γ separation
(Pb 4mm+Scinti 3.7mm)/layer
#1
#2
(Fe 4mm+Scinti 3.7mm)/layer
#3
#4
γ
n
18X0,0.7λI
γ
n
29X0,3.5λI
#5
#6
Neutron trigger
module
n-trigger
1
2
3
Rear layer
beam
2
5
6
3
4
7
8
5
6
8
7
#1F
or
#1R
#2F
#2R
or
...
Front layer
1
4
#6R
• Modules are divided to the front and the rear layer.
• n-trigger→(#2F || #2R || … || #6R) &! (#1F || #1R)
Beam information
★ Feb.01-03 2010 (1kW run)
target
γ abs
Ni
0cm
7cm
Pt
9cm
1kW
0cm
7cm
9cm
-
★ Oct. 2010 (Pt target run)
target
γ abs
Pt
0cm
7cm
9cm
100W
1kW
3kW
-
-
＊100W，1kW，3kW→intensity of primary proton
Time distribution of start channel
retime[16] {(trig&2)==2&&tdc[16] < 4095}
triggered by self timing
Entries
13609
Mean
30.83
RMS
41.7
Integral 1.361e+04
103
triggered by other start channel
102
cut
cut
10
accidental
~40nsec
accidental
1
-50
0
ontime
50
100
150
200
retime[16]
nsec
1kW, Ni target, abs 7cm
Accidental event
★on time event
n
p
1
2
3
4
5
6
3
4
5
6
★accidental event
n
n
1
2
Accidental cut
event
energy deposit of Cerberus
w/o accidental cut
10 3
10
w/ accidental cut
2
10
1
0
200
400
600
800
1000
1200
1400
MeV
100 W run
Time distribution of start channel
g
h
Entries92163
67791
Mean -2.388
1.547
RMS
10-1
1kW
100 W
10-2
• special low intensity
run
• 100 W
10-3
• # of primary proton ->
1.3×1011 protons／pulse
10-4
-100
27.89
10.97
-80
-60
-40
-20
0
20
40
Pt target, abs 7cm
60
80
nsec
• ~ KEK PS intensity
100 W run
events/20MeV/2.284×10^9P.O.T
total deposit energy
line→M.C
dot→red:data
GEANT4 and 100W data
are good agreement.
MeV
Target Pt, γ abs 7cm,beam intensity 100W
Measure the response function
• K1.1BR beam line(Nov. 2011 )
K1.1BR
• Beam test by charged particles
• p pi+ e+ 0.4GeV~1.0GeV
Cerberus #1 deposit energy
-1
10
MC
data
-2
10
• Now studying
• tune MC
10-3
1GeV π+
10-4
0
20
40
60
80
100
120 140
160
180
200
MeV
16
!
!
Summary
• Neutral beam line for KOTO were constructed
at J-PARC.
• Beam neutron were measured by sampling
calorimeter “Cerberus”.
• It seems to be in good agreement MC with
100W data.
• Response function of Cerberus were measured
by charged particles in K1.1BR beam line.