Post on 25-Jan-2016
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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