Transcript Beam optics from the main

2002/7/2 NuFact02@CERN
JHF2K neutrino beam line
A. K. Ichikawa
KEK
• Overview
• Primary Proton beamline
• Target
• Decay Volume
• Strategy to change peak energy
•Summary
Overview of experiment
Conventional nm beam of ~1GeV
Super-K: 50 kton
Water Cherenkov
Kamioka
~Mt “Hyper
Kamiokande”
JAERI
(Tokai-mura)
0.75MW 50 GeV PS
4MW 50GeV PS
1st Phase
 nm→ nx disappearance
 nm→ ne appearance
 NC measurement
2nd Phase
CPV
proton decay
Off Axis Beam
Osc. Prob.=sin2(1.27Dm2L/En)
Target Horns
Decay Pipe
q
 Quasi Monochromatic Beam
 x2~3 intense than NBB
osc.max.
(ref.: BNL-E889 Proposal) Far Det.
Dm2=3x10-3eV2
L=295km
nm
OA1°
OA2°
OA3°
Tuned at oscillation maximum
Exp’ed # of evts(1yr,22.5kt)
~4500 nm tot
(OAB 2degree)
~3000 nm CC
ne contamination ~0.2% at nm peak
~102
x (K2K)
Expected spectrum
(OAB2o)
Overview of Facility
Primary Proton
beamline
JHF
E(GeV)
Int.(1012ppp)
Rate(Hz)
Power(MW)
NuMI
(FNAL)
K2K
Target Station
50
330
120
12
40
6
0.275
0.75
0.53
0.45
0.41
0.0052
Decay
Volume
m pit
SK
280m Near Detector
Beam Axis
50GeV PS
Overview -Primary proton beamline-
Preparation section
Arc
R=106m
Single turn fast extraction
8 bunches/~5ms
Final Focusing
Section
3.3x1014proton/pulse
3.94 (3.64) sec cycle
1ｙｒ≡1021proton on target(POT)
 e=6p mm.mr

Beam loss
50GeV ring
0.5W/m
PQ1
PQ2B
PH3
PQ5 PV2
PQ4B
PQ4A
PV1
PQ3B
PQ3A
PQ2A
PD1
1.92 deg. bend
PH2
PH1
PD2
1.92 deg. bend
A
サブトンネル
B
サブトンネル
Fast ext.(kicker, septum)
1.125kW (0.15%)
Matching section
(ctrl’ed loss by collimator)
0.75kW (0.1%)
サブトンネルD
サ
C
ル
ネ
トン
ブ






No way to know absolute beam loss
Assumed by HAND
Assure hands on maintenance (1W/m)
Shielding design based on the assumption
Same order as KEK-PS beam line
 ~102 relative suppression!!Challenging
放射化物保管室
Preparation section
Make the matching with the Arc.
Consists of normal conducting magnets.
V
Collimator/shield
monitor
10cm
10cm
H
Acceptance : 60p mm.mrad (cf Acc. design = 6p mm.mr)
Waist mode & normal mode.
e=24p
Matching
Point
Primary Beamline –ArcQ
B
B
Q
FODO lattice x 10,
about 80o bending
Bends by
3m long 4 T superconducting magnet.
+ 1m long Q-superconducting magnet.
Bore : ~180mmf
Y
Normal Mode
2cm
2cm
To prevent the quenching,
the beam size and halo should be small.
Matching Point
beam ellipse is tilted
to achieve small size.
X
Beam halo study using Geant
Magnet geometry and field are
set via data file.
Preparation section
applicable to different
beamlines.
Arc
60p mm.mr beam
1,000 events
100p mm.mr beam
500 protons
Beam Direction
For both SK and possible HK.
Decay pipe
Target Station
Off Axis Beam
Plan to change the axis by moving horns or w/ dipole after horns.
Service pit
Side View
concrete
iron
OAB 2o, 2.5o, 3o
Target
Graphite (or Be) is a unique solution. ← Heat problem
(except for liquid target)
density
Interaction length
Melting point
Thermal conductivity
Thermal expansion
Yang Modulus
Sound velocity
~1.8 g/cm3
79g/cm2 (44cm)
>3000
o
~ 115W/m・K
4.2×10-6/ o C
~ 1E10 Pa
7,400 m/s → 3.7 cm/5ms
Energy deposit in the target
Graphite(r =1.81g/cm3)
2cmf target, sbeam=0.4cm
3cmf target, sbeam=0.6cm
J/cm3 /spill
Maximum  460J/cm
3
J/cm3 /spill
Maximum  300J/cm3
Temperature in the target (FEM
analysis)
f = 30mm, L = 1000mm
~ 70 C @ surface
Time Evolution
beam direction

~ 230 C @ r = 0, z ~ 300mm

230 C
230 C
r=0mm,z=300mm
70 C
r=1.5mm,z=300mm
4 8 12
43 C
32
(Sec.)
Target
-for 4MW-
Not yet considered well.
Radiation cooling, Liquid target………
Decay Volume
Top view
6.6m
Concrete shield
Side View
w/ additional 60cm thick concrete,
it can accept ~4MW beam.
To SK/HK OAB 2 o
OAB3 o
m-pit
Decay Volume –Cooling53
°
FEM analysis for
4MW beam
Concrete
Iron
~600 o
Collimator after Horns
concrete
Service pit
iron
Important
Side View
for DV
W/m3
For 0.75MW beam
z(m)
Strategy to change peak energy
One method is changing the beam axis.
The other….
OAB+Bending Magnet
Dipole magnet
gap 1m×1m×1m
OAB vs OAB+Bending
By T.Oyabu
No need to access target and horns.
Easy to change the peak energy
Summary
JHF will produce 0.75 MW 50 GeV proton beam.
Quasi Monochromatic Beam with off-axis method.
Peak Energy can be tuned
by changing axis or w/ bending magnet.
Facility is being designed to accept 0.75 MW beam
while keeping extendibility for 4 MW beam.
Supplement
2cm
Waist mode
Y
X
3cmf@target
Arc section
Total Length=37.5m
Vertical bending
magnets
200mf
120mmf
200mf
120mmf
4m
Applicable to 6p mm.mr<e<24p mm.mr
Size (radius) dependence of
neutrino yield
f=1cm
f=2cm
f=3cm
f=1cm
f=2cm
f=3cm
Al target
Maximum energy deposit
of aluminum target (3cmf)
~ 700J/cm 3 /spill
→ 290°/pulse
Thermal stress
E
P=
 α(T  T0 )
1-2ν
P
Pressure
Young modulus
E
Poisson ratio
ν
Linear expansion rate
α
T ,T0 Temperature
P ~ 12MPa
10.8GPa
0.2
6 
4.2  10 / C
235 C,25 C
Small enough
Simulation results (by ANSYS)
are almost consistent (or smaller).
Dynamic thermal stress can be reduced
by splitting the target in a few cm pieces.