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Shintakemonitor and the background estimation
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Use 2nd harmonics of YAG laser (532nm) FFTB used 1st YAG (1064nm) ... Time distribution monitored via oscilloscope and compared with Monte Carlo simulation. ... – PowerPoint PPT presentation
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Title: Shintakemonitor and the background estimation
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Shintake-monitorand the background estimation
Taikan SUEHARA (The University of Tokyo)
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Shintake-monitor upgrade
- Shorter wavelength
- Use 2nd harmonics of YAG laser (532nm)
- FFTB used 1st YAG (1064nm)
- Fringe stabilization
- In FFTB, 17 nm jitter in 6 sec. 22 nm in 25
sec. - Some feedback system ?
- Moving fringe pattern
- in FFTB, they moved electron beam instead of
fringe. - Use pockels cells or delay line (planning)
- ?-ray detector
- Compton energy is very low (28MeV max.)
- Background is more severe
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Schedule
- The FFTB Shintake-monitor arrival from SLAC (June
05) - Background study _at_ ATF ext. line (June 05)
- Shintake-monitor optics electronics test
(August 05) - Shintake-monitor upgrade (fall 05)
- Install on beam line (summer 06 ??)
- Beam ON (?)
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Interaction of beam halo with beam pipe
- Charge distribution of the beam (x y)
- Center of the beam gaussian
- Beam tail also gaussian ?
- If gaussian, interaction is negligibly small
(with proper distance of materials from beam
line) - Measurement of charge of beam halo_at_ ATF ext.
line - Using wire scanner
- Measure charge of 5 10 s
- We use s as that of center of the beam(gaussian
fit)
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Beam halo meas. result
Gaussian distribution damps a factor of 1000 for
every sigma, but it only damps s-4
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Integral beam halo estimation
Beam halo seems not to be negligible, We need
some beam collimeter optics ! (they did in FFTB)
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Radiation from beam dump
- Background measurement from beam dump
- Using CsI calorimeters installed around dump.
- Time distribution monitored via oscilloscope and
compared with Monte Carlo simulation. - Distance and angle dependence of charge and
timing of signal also checked.
Detector position
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Raw signal
100ns grid
Beam timing
CsI output
PMT without CsI
Prompt Peak
Delayed Peak
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Monte Carlo simulation(GEANT4)
prompt peak
delayed peak
Prompt delayed peak observed in both
measurement and simulation.
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Position dependenceof each signal
- Prompt signal
- Bigger signal near beam dump
- Timing is faster at upstream of beam line
- ?Combination of photons from beam line and
beam dump - Delayed signal
- Delay is larger at detector far from dump
- Interaction of slow neutron around detector
- Not affect for Shintake-monitorbecause of large
time delay(we can easily eliminate this by
timing gate)
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Next beam time (6/6)
- To measure beam halo (confirmation)
- Distribution of vertical beam halo
- Energy of beam halo no idea
- Outside 10 sigma Inside 5 sigma
- Difference between MW(04)X
- Dependence of beam parameter(Charge,Beam size, )
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Next beam time (6/6)
- To understand signal around beam line beam dump
- Timing separation of prompt signal
- Plastic scintillator ? (use XTFs ?)
- Air-cherenkov detector ?
- Lead glass detector ?
- Beam line signal (far from dump)
- Attenuation of distance
- Direction of particle
- Simulation
- Effect of shield
- Position dependence on prompt signal
