1. FLASH Toroid Review Progress since last meeting in April Next steps Summary Johnny Ng FLASH Coll. Mtg. 7/25/03

2. 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)

3. Test Toroid Electronics Box Bob’s Lab Bench

4. 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

5. FFTB Beam Line Map (Not to Scale) “Green” Dump magnets E165 (Thin Target) Collimator PC 7.5 OD=1.2 inches New Ion Chamber Beam Loss Monitor beam New FLASH Toroid OD=7/8 inches Tunnel Entrance

6. 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)

7. 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 toroid  Signal/noise in FLASH Lo-Gain mode.  FLASH Hi-Gain mode: RMS ~ 3%  The current attenuator was still in place for this test !!!

8. Low current special run (current attenuator at front-end REMOVED - Run 507)  Signal clearly seen down to 2E7  Pulse shape comparable to off-time calibration signal  No RF noise from beam !  Detail features (“pre-shoot”?) need to compare 1-turn injection

9. 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.

10. NLCTA Beam Current Monitor Test Setup (C. Nantista, SLAC)

11. 50 W Matching Center conducting rod Calibration spool piece

12. 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