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

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)

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

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

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

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

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

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

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

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

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.)

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

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)

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)

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

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)

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%

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.