LCLS Undulator Systems Beam Loss Monitor

1. LCLS Undulator SystemsBeam Loss Monitor William Berg ANL/APS Diagnostics Group

2. Introduction • Physics Requirements Document: Heinz-Dieter Nuhn 9-28-07 (prd: 1.4-005-r0 undulator beam loss monitor). • Scope Reduction: diagnostic to mps detector. • Purpose and Requirements. • Budget: M&S 500k (325k detector, ctls/mps 175k). • Schedule: (design: nov-mar, test: feb-mar, fab: mar-jun, inst: july). • Organization: 4 groups. • Group Definition: controls, detector, simulation, test & calibration. • Design Highlights and System Overview (detectors: dynamic 33, static: 2, r&d fiber:1). • Detector design details and focus topics. • Funds are limited and efforts need to be focused to minimize costs (h-dn). • Simulation of losses and damage in the undulator will proceed in parallel with the present effort (pk).

3. BLM Purposeh-dn • The BLM will be used for two purposes: • A: Inhibit bunches following an “above-threshold” radiation event. • B: Keep track of the accumulated exposure of the magnets in each undulator. • Purpose A is of highest priority. It will be integrated into the Machine Protection System (MPS) and requires only limited dynamic range from the detectors. • Purpose B is also desirable for understanding long-term magnet damage in combination with the undulator exchange program but requires a large dynamic range for the radiation detector (order 106 ?) and much more sophisticated diagnostics hard and software.

4. BLM requirements pk • Primary function of the BLM is to indicate to the MPS if losses exceed preset thresholds. • MPS processor will rate limit the beam according to which threshold was exceeded and what the current beam rate is. • The thresholds will be empirically determined by inserting a thin obstruction upstream of the undulator. • Simulation of losses and damage in the undulator will proceed in parallel with the present effort.

5. Draft Budget Breakdown • 500kM&S Total • 325k Detector Development • 25k Interface Box • 150k Control and MPS integration • 25k link node chassis • 25k long haul cables • 50k davis bacon labor • 15k ctl modules and signal conditioning electronics • 25k clean power distribution • 10k racks

6. Draft schedule

7. LCLS MPS Beam Loss Monitor System Engineer: W. Berg Cost Account Manager: G. Pile Technical Manager: D. Walters Scientific advisor: P. Krejcik* FEL Physics: H. Nuhn* Scientific advisor: B. Yang FEL Physics: P. Emma* Controls/MPS Group Lead (ctls) : J. Stein Lead (mps): A. Alacron* Testing and Calibration Group Lead: B. Yang Detector Group Lead: W. Berg Simulations and analysis Group Lead: M. White M. Brown * R. Diviero E. Norum S. Norum * B. Laird J. Dusatko* A. Brill L. Erwin R. Keithley J. Morgan J. Dooling B. Yang W. Berg J. Bailey J. Dooling L. Moog E. Norum M. White * Slac employee

8. MPS Beam Loss Monitor Group Functions • Controls Group:J stein, A. Alacron Develop BLM control and mps system: • Interface Box and Control. • PMT Signal Conditioning. • Control and MPS Integration and User Displays. • Detector Group: W. Berg Develop Detector and Interface. • Simulations and Analysis Group: M. White Provide collaborative blm simulation support and test analysis. • Test and Calibration Group: B. Yang Provide beam based hardware testing programs and calibration plan.

9. Design Highlights • 33 distributed detectors (one preceding each undulator segment), two static units (up and downstream of undulator hall). • One additional channel reserved for r&d fiber based system. • Dynamic detector (tracks with undulator) 100mm stroke. Undulator position (in/out) detection will be used to set the corresponding mps threshold levels. • Large area sensor (coverage of the full horizontal width of top and bottom magnet blocks). • Manual insertion option via detachable arm for special calibration and monitoring. • Fiber Out for low gain upgrade (full integration and dyn range diagnostic), system expandable to 80 channels. • MPS threshold detection and beam rate limiting. • Single pulse detection and mps action up to max 120Hz beam rep rate via dedicated mps link. • Monitoring of real time shot to shot signal levels and record integrated values up to one second. • Heart beat led pulser for system validation before each pulse up to full rep rate (pseudo calibration). • Remote sensitivity adjust (dynamic range) by epics controlled PMT dc power supply (600-1200V). • Calibrated using upstream reference foil (initial use cal will be determined from simulation studies). • Radiation hard detector (materials and electronics).

10. BLM Controls Architecture pk • The BLM PMT interfaces to the MPS link node chassis. • The IO board of the MPS link node chassis provides the ADC & DAC for the PMT. • A detector interface box (pmt, led pulser, sig con?) is the treaty point between the MPS and the undulator BLM. • There are 5 link node chasses serving up to 8 BLMs along the undulator (expandable from 8 to16 channels).

11. Undulator Hardware

12. Beam Loss Monitors with Link Nodes • Use Link Node to • support analog I/O IndustryPack modules • provide analog readouts to control system • set threshold levels • control HV power supplies • control LED Pulser

13. Segment Design Layout m. brown

14. BLM Interconnect Diagram m. brown

15. Interface Box Location

16. Plan View of Short Drift

17. BFW Pump Out Port Relocation

18. Removable Pin for Manual Insertion

19. Undulator Inserted Position

20. Undulator Retracted Position

21. Magnet Block Sensor Coverage

22. Rendering of Detector

23. Cross Section of BLM Detector

24. Proposed PMT Device -04 (420nm)

25. BLM System Support Focus Topics • 1. Assignment of Eric Norum to controls design oversight and testing. • 2. Funding of beam based prototyping and test program. • 3. Group Leaders to significantly step up direct involvement in system oversight, program implementation, and schedule tracking (controls: n. arnold, diag: g. decker, lcls: g. pile, ops/analysis: m. borland). • Active participation in simulations and simulation priority from slac. • Implementation of upstream profile monitor (halo or at min. cal foil). • Adequate analysis and shielding of upstream beam dump. • Develop long term collaboration plan for the pursuit of determining magnet damage mechanisms and thresholds via empirical methods. • Determine need and priority of BLM signal integration (diagnostic).

26. Summary • Undulator magnets protection is critical for machine commissioning period. • Schedule for development of the blm program is very aggressive and Funding is limited. • System design and fabrication must go in parallel with simulation and testing program. • Consider Minimum requirements for first level implementation. Taking advantage of existing mps infrastructure. • BLM system is now defined as a component of the mps with an upgrade path to a diagnostic (low gain detector). • 36 distributed channels (2 static devices) capable of single pulse detection and rate limiting reaction. • Detectors track with undulator position with detach option for manual operation. • Calibration plan and hardware is vital to proper system operation (threshold detection will use empirically derived levels).