1. Targeting Monitor in K2K
Hiroyuki Noumi (KEK)
for M. Ieiri, BCG and K2K
Contents
Primary Beam Monitors
- SPIC/LS, CT/SEC
Targeting Monitor
- Motivation
CT for Secondary particles
- Response
- Analysis
Summary
○Beam line layout

2. Proton Beam Monitors - SPIC/LS/CT/SEC
Profile Monitors
SPIC:Segmented parallel Plate Ionization Chamber
LS: Luminescence Screen (Cr-doped Almina Ceramic Plate)
Intensity Monitor
CT: Current Transformer
SEC: Secondary Emission Chamber (for Supplement)

3. Proton Beam Monitors 400m 350m 0m 70m 208m
30 profile & intensity monitors are installed in the beam line
350m 0m
70m
208m

4. Beam Monitors - SPIC/LS/CT
Monitors in the Beam Pipe

5. Beam Monitors -at the Production Target
Target HORN
SEC
SPIC
SPIC CT
Beam LS
Monitors on the Slide Table

6. B-CT Response Beam Line CT (B-CT) Attenuator ADC LeCroys 2249W ~30 dB
Co-ax Cable (50W）
Attenuator
ADC
Beam Line
Counting House
Core:mm
N = 20 Turn
M=L/N
R=50W≫Rc

7. B-CT Response (Cont.) Signal fRF = 7.9 MHz ~1011p/V ~4×109p/pC
Raw Signal (No Attenuation)
ADC input
ADC Gate
CT signal
～1 μs
~1011p/V
~4×109p/pC

8. CT Response (Cont.) Current Sensitivity (Calculation)
C, mm(7.9MHz) for B-CT
Core Rel. Permeability

9. Targeting Monitor - Motivation
To monitor
Secondary Particles at Production
To be monitored…
○Production Efficiency
○Spatial Distribution
○Charge Distribution }
Targeting CT
Since CT(B-CT) worked fine,
we thought that we could monitor 2ndary particles at the production by using CT.
p Cherenkov Monitor for Pp vs qp
Work at Low Intensity
Need Off-line Analysis

10. Targeting CT -Setup CT Layout 2nd Horn 1st Horn B-CT CT-M CT-L movable
protons
B-CT
(for Normalization)
CT-M
CT-L
target

11. CT for 2ndary Particles Targeting CT Size Test by Dummy Current CT-L
I.D.
O.D.
CT-L
580
600
CT-M
204
224
B-CT
130
150
Size
Test by Dummy Current
Beam-Line CT
CT-L
CT-M
Coil material/dimension
Insulation
Core permability
204mm (I.D.)
580mm (I.D.)

12. Targeting CT -Setup (Cont.)
Targeting CT installed just behind the 1st HORN
1st Horn
CT-L
CT-M CT
2nd Horn

13. CT Response - Horn Current Dependence
Measurement
Monte Carlo Simulation
Charge Flux (N+ –N-) thru CT
(GEANT by T. Maruyama)
CT-L
Charge Flux in CT(Arbitrary)
CT-M
150
250
Horn Curr. (kA)

14. CT Response - Radial Position Dependence
Measurement
Monte Carlo Simulation
Charge Flux vs CT pos.
200
400
600
CT-L
CT-M
CT-L
CT-M
Charge Flux in CT(Arbitrary)
We found funny response on the CT radial position dependence.
Displacement from CL (mm)
Displacement from CL (mm)

15. CT Response - Radial Pos. Dependence in Diff. Horn Curr.
Measurement
Displacement from CL (mm)
Displacement from CL (mm)

16. CT Response - Radial Pos. Dependence in Diff. Horn Curr. (Cont.)
Monte Carlo Simulation
Particle Contents in CT-L
at Ihorn= 250kA
Charge Flux in CT(Arbitrary)
Displacement from CL (mm)
200
400
600 p
63% p+
30% m+ 3% e+
11%
S Pos.
107%
CT-L
Ihorn=150kA
Ihorn=250kA
CT-M p-
-1% m-
-0.1% e-
-6%
S Neg.
-7%
(preliminary)

17. CT Response - Other Result
Effect of LS out (~2.5g/cm2 removed from BL)
Signal
Increase
Normalized
CT-L
+2.8%
-2.1%
CT-M
+3.2%
-1.7%
Beam Transmission
+5.0%
---
Effect of Beam Incident-Angle Change
○ As the transmission is improved, CT-L/M outputs decrease.
The reason why…
Since the proton dominantly contributed to the CT output, the passing proton may decrease when transmission is improved.
As a result, the CT output decreases…???
No tilt
H-tilt
V-tilt
CT-L 1
+2%
+3%
CT-M
+0.8%
-2%

18. Summary B-CT works fine. Targeting CT has been examined.
- Its response can be understood well.
Targeting CT has been examined.
- CT signal increases linearly with Ihorn
- Radial Dependence of CT signal was observed
Simple Charge-Flux Distribution thru CT does not explain…
… For Further Understanding of the Response, we need to consider
1. Effect of the particles hit the core…?
2. Asymmetric current source out of CT…?
3. Misunderstanding of Low-E particle affects CT…?
- Other Result
Detect the CT-L/M output change when LS out
Targeting CT works at T-Station,
having some sensitivity to the primary beam condition on TGT.
CT is potentially useful for a targeting monitor.