HES-HKS & KaoS meeting

Toshi Gogami27/June/2012

Contents• SPL Magnetic field change by the effect of ENGE iron• SPL + ENGE GEANT4• The Helmholtz coil for bucking coil test

By on the line(Around SPL)

Line coordinates X [cm] Y [cm] Z[cm]

Minimum -40.0 0.0 15.0

Maximum 40.0 0.0 65.0

Saw By on the line

Setup

Setup1. SPL + ENGE(OFF)2. SPL + ENGE(ON)3. Only SPL4. SPL(8% up) + ENGE(OFF)

SPL + ENGE model

SPL model

ON : current onOFF : current offSPL is ON all the time

Setup

Setup1. SPL + ENGE(OFF)2. SPL + ENGE(ON)3. Only SPL4. SPL(8% up) + ENGE(OFF)

SPL + ENGE model

SPL model

ON : current onOFF : current offSPL is ON all the time

Comparison• Set1 & Set2 Effect of leaked field from ENGE• Set1 & Set3 Effect of ENGE iron• Set1 & Set3 & Set4 How much we can recover

the effect from the ENGE iron after increased current on SPL by 8%

Results

Comparison 1 (Set1 and Set2)

• ~ 10 G reduction in SPL• The effect is larger as closer to ENGE

Small effect

Closer to ENGE

SPL

Subtraction

SPL

Comparison 2 (Set1 and Set3)

• Up to ~ 0.3 T difference • Became 80 ~ 95% in SPL

Need to increase current for SPL to send beam to the beam dump

Closer to ENGE

SPL

Subtraction

100.0 + (Set1 – Set3) / Set3 * 100.0

Ratio

SPL

Due to meshing80 ~ 95%

Comparison 3 (Set1, Set3 and Set4)

• Recovered by <~5 % in SPL But hard to say it is good enough to send beam to the beam dump.

Closer to ENGESPL

Subtraction

100.0 + (Set1 – Set3,4) / Set3,4 * 100.0

Ratio

SPL

Set1 – Set4

Set1 – Set3

Set1 – Set4

Set1 – Set3

Summary of SPL+ENGE TOSCA calculation

• SPL field– Leakage field effect is ~10 G level in SPL.– Effect from ENGE iron• SPL field is no more uniform.• Very large ( up to ~0.3T difference from only SPL model)It is hard to find optimal current of SPL for sending

beam to beam dump only by seeing By in SPL. Need to see beam tracks in TOSCA and/or GEAMT4

What about the field clamp effect ??

SPL + ENGE GEANT4

Major update– Added

• Field map (SPL+ENGE combined , SPL 8% up)• Virtual detectors

– VD3 : before EDC– VD4 : after EDC– VD5 : after SS (1cm away from SS back face)

– Modified • Trigger• Sieve slit• Output tree

Distribution : spherical uniformNumber of events : 300pe : 0.27 ± 0.1 GeV/cθ : 0.1 ± 0.05 radφ : 1.57 ± 1.5 rad

Sieve slit pattern (1)• Distribution : spherical uniform• Number of events : 154k • Sieve Slit : ON• pe : 0.29 ± 0.1 GeV/c• θ : 0.1 ± 0.05 rad• φ : 1.5703 ± 1.5703 rad

VD0 VD5At VD0 SPL

ENGE

Sieve slit pattern (2)

Will be compared to real data !!!

x’ vs. y’ at the target x vs. x’ at the reference plane

Helmholtz coil for the bucking coil test

• Central magnetic field• Uniformity

By and uniformity from Chiba’s master thesis

TOSCA calculation of current vs. By

TOSCA calculation of current vs. By

Consistent with Chiba measurement

TOSCA calculation of uniformity

Consistent with Chiba measurement

Summary and To do• Summary

– TOSCA calculation• 8% up for SPL

– GEANT4• SS pattern can be seen.

• To do– TOSCA calculation

• Field clamp• Beam to beam dump

– GEANT 4 code of SPL + ENGE• Compare to real data

– Matrix tuning (Beginning of June - )• mtune

– Cross sections of Λ,Σ0 and 12ΛB g.s.

• Efficiencies (Trigger, Tracking, DAQ, K+ selection, Burned effects, absorption, decay….)

END

TOSCA calculation of current vs. By

Consistent with Chiba measurement