flash toroid review progress since last meeting in april next steps summary johnny ng flash coll....
TRANSCRIPT
FLASH Toroid
• Review
• Progress since last meeting in April
• Next steps
• Summary
Johnny NgFLASH Coll. Mtg. 7/25/03
FLASH Toroid Electronics
Work done by Bob Simmons (SLAC BCS Group)
Specs: Sensitivity Range: 1E7 – 1E9 elec. Accuracy: 1% Calibrations via charge inj.:
•electronics only•toroid + electronics
Noise Achieved in lab: 1.5E5 elec.
(April 2003)
Test Toroid
Electronics Box
Bob’s Lab Bench
Progress since April Meeting
• Fabrication:– New toroid built;– Whole assembly installed on beamline
• Parasitic beam test in FFTB (June 2003)– Readout using FLASH DAQ (2249W ADC)– High current: basic operations, long term
stability– Low current: noise/sensitivity
FFTB Beam Line Map (Not to Scale)
“Green” Dump magnets
E165(Thin Target)
CollimatorPC 7.5
OD=1.2 inches
New Ion ChamberBeam Loss Monitor
beam
New FLASHToroid
OD=7/8 inches
Tunnel Entrance
High current beam test
Data set spans more than 24 hours
Excellent correlation with standard toroid: RMS ~ 0.2%
Charge injection calibration stable to 0.4% (RMS)
(current attenuator used to avoid saturation)
Low current beam test(current attenuator at front-end was still in place)
Excellent correlation with standard toroid down to N=5E9: RMS ~ 0.6%
Issues for N<5E9:Digitization noise in standard toroidSignal/noise in FLASH Lo-Gain mode.
FLASH Hi-Gain mode: RMS ~ 3%
The current attenuator was still in place for this test !!!
Low current special run
(current attenuator at front-end REMOVED - Run 507)
Signal clearly seen down to 2E7Pulse shape comparable to off-time calibration signalNo RF noise from beam !Detail features (“pre-shoot”?) need to compare 1-turn injection
Next Steps
• Absolute calibration in-situ– Network analyzer scans
– Pulse current measurements traceable to NIST
• Other tests– Linearity studies using pulser
– Calibration using 1-turn winding:
systematic effects?
• Useful RF techniques involved; could be a nice
project for a student.
NLCTA Beam Current Monitor Test Setup(C. Nantista, SLAC)
50 Matching
Center conducting rod
Calibration spool piece
Summary
• New FLASH toroid monitor and electronics for low-current built and tested successfully
• Some beam test results:– Excellent long-term stability
– No evidence of beam-related RF noise
– Clear sensitivity down to 2E7
• Next– Absolute calibration
– More systematic studies