LCLS Undulator Systems Beam Loss Monitor Control Interface

1. LCLS Undulator SystemsBeam Loss Monitor Control Interface Josh Stein LCLS Undulator Controls CAM/TL Bill Berg ANL/APS Diagnostics Group Arturo Alarcon SLAC Controls

2. Undulator Protection Requirements • Inputs to inhibit the e-beam • Primary protection from a number of Beam Loss Monitors (BLMs) along the undulator • Secondary protection from control system monitoring of • BPM orbit • Magnet power supply status • Magnet mover status • Long-term monitoring of the radiation dose • Dosimeters attached to the magnets

3. BLM Specification • A single BLM will be placed in each of the gaps between undulator modules. • Design is to maximize the sensitivity of the monitor • Located as close as possible to the beam axis as the vacuum chamber allows • Choose a sensitive Cerenkov medium coupled to a high gain photomultiplier tube • The detector will not be segmented to provide transverse position information of the losses

4. BLM Rolls Out with Undulator Magnet • The BLM is mounted to tightly surround the vacuum pipe near the beam finder wire • It is on a linear slide so that it can be moved off the beam when the undulator magnet is rolled out • An detachable arm makes the BLM and magnet roll out together • The BLM will automatically be less sensitive to beam loss when the undulator is in the out position • The BLM can be manually inserted on the beam pipe for special calibration procedures

5. BLM reliability and self test • Each loss monitor is equipped with a LED that flashes between beam pulses. • Provides a pre-beam test of the BLM system before beam is sent through the undulator • Provides a stay-alive signal for the control system to monitor the BLM system during operation

6. BLM dynamic range • For simplicity and cost the BLM will be optimized for maximum sensitivity • And allowed to saturate the signal if a large loss occurs • The trip threshold is still exceeded if the device saturates so the MPS will still trip and protect the undulator • Monitoring of the loss signal to integrate the dose received by the undulator will not be valid if the device saturates • However, if large losses are anticipated such as when the beam finder wires are inserted, the gain of the PMT will be reduced to prevent saturation.

7. BLM Signal Monitoring • The BLM has a fast, dedicated link to the MPS to shutoff the beam within 1 pulse • The local MPS link node chassis also has a ‘slow’ network connection to the control system via channel access • Allows monitoring of the BLM level at any time • Reads back and controls the PMT voltage • Controls the LED test pulse • Controls the threshold set point for MPS trips

8. 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 cable interface box 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 to 16 channels)

9. 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

10. Undulator Hardware

11. Beam Loss Monitors using Link Nodes

12. Beam Loss Monitor - Undulator Hardware (m. brown) In Undulator Hall Long Haul Cables

13. BLM Interconnect Diagram m. brown

14. Future expansion • The link node chassis can handle more than the present number of installed BLMs • During commissioning a long fiber BLM will also be tested • It is compatible with the link node chassis controls

15. 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).

16. Summary • Undulator magnets protection is critical for machine commissioning period. • Schedule for development of the blmprogram 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 detection). • 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 with empirically derived levels).

17. End of Presentation

18. Supporting slides

19. Segment Design Layout m. brown

20. Interface Box Location

21. Plan View of Short Drift

22. BFW Pump Out Port Relocation

23. Removable Pin for Manual Insertion

24. Undulator Retracted Position

25. Undulator Inserted Position

26. Rendering of Detector

27. Cross Section of BLM Detector

28. Proposed PMT Device (420nm)

29. Proposed PIC / BLM Timing

30. Link Node Block Diagram

31. MPS Overview (m. brown)

32. System Roll

33. 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 (325 detector ctls/mps 175). • Schedule: (design: n-m, test: f-m, fab: m-j, 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).

34. 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.

35. 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.

36. 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

37. Draft schedule

38. 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

39. 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 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.

40. 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, 100mm stroke (tracks undulator) with undulator position detection (in/out) for adjusting mps threshold levels. • Large area sensor (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. • Calibrated using upstream reference foil (initial use of simulation based levels). • MPS threshold detection and beam rate limiting. • 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 (600-1200Vdc out). • Single pulse detection, level measurement, and mps action at max rep rate via dedicated mps link. • Radiation hard detector (materials and electronics). • Monitoring live single shot signal levels (dedicated) and recording of integrated values to one second.