NIKHEF B-field monitors Paul Balm November 11 th, 1999

Outline Introduction The system –Hall head, conditioner, etc. –Cabling & location of equipment Calibration Read-out Installation and schedule Conclusion

Introduction Hall probes providing actual 3D-measurement of B-field, complementing the solenoid current measurement and field map Located in the clearance between fiber tracker and solenoid location of probes

System overview Basic measurement device is a Hall head –contains three Hall ‘probes’ for each of the three directions and a temperature sensor Hall head read out by a conditioner, containing an ADC Conditioners read out from read-out PC –connection provided by CAN-bus network

The Hall head 0.59 inch 0.39 inch 0.16 inch

CAN-bus Noise pick-up: –No ground loops (opto-coupled) –Shielded housing of the nodes –Only active when read out; power may even be disconnected while taking data Support on longer term: –Used in automobile industry –ATLAS default bus

Location of equipment CFT/SMT conditioners CAN node C.C. Read-out PC Ethernet connecting to EPICS Strips with Hall heads Hall heads: –in clearance solenoid/CFT: held by locator strips, 6 locations in , 6 in z –on CC face: held by studs, locations to be finalized Conditioners on the face of CC CAN nodes on top of CC Read-out PC “far away”

Calibration Performed at CERN –Hall head will be rotated in magnetic field, range 0-2 Tesla –Procedure repeated at various temperatures –Provides calibration tables to be used by read- out software Comparison to field map –fringe field is a problem

Installation and schedule Already done:Design is fixed, prototypes assembled Ongoing:(Preparation for) Calibration at CERN Installation of strip-holders in solenoid Dec ~15:System test at NIKHEF January:Calibration ready System arrives at Fermilab Read-out software components put together February:Full (calibrated) system test in solenoid “Final” installation after installation of CFT

Conclusions Ready in February/March 2000 (personal estimate November 1999) Work to be done: –system test at NIKHEF in December –perform tests in solenoid field –work out comparison field map –details of read-out Sheets available at