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. • ANL Budget: M&S (325k detector, ctls interface box 100k). • Detector Schedule: (design: nov-dec,drawings: dec-feb,pro/fab/assy: feb-jun,del: july, inst: aug-sep). • 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. BLM 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 of 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.*Beam Current threshold determination? • 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. ANL Draft BLM Budget • 425kM&S Total: • 325k Detector Development • detectors • mounting and slide systems • cables and fiber • 100k Controls Interface Box

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: J. Dooling W. Berg J. Bailey J. Dooling L. Moog L. Emery M. Santana * J. Vollaire * B. Yang A. Brill L. Erwin R. Keithley J. Morgan M. Brown * R. Diviero J. Dusatko * S. Norum * A. Pietryla * 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 Machine Integration. • Simulations and Analysis Group: J. Dooling • Provide collaborative blm simulation support and test analysis. • Test and Calibration Group: B. Yang • Provide beam based hardware testing programs and calibration plan.

9. System 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. • 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).

10. Detector Design Highlights • Cerenkov Radiation Based (x-ray beam noise immunity). • Employs PMT for high sensitivity to beam losses. • Dynamic detector (tracks with undulator) 100mm stroke. Undulator position (in/out) detection will be used to set the corresponding mps threshold levels. • Manual static insertion option via detachable arm for special calibration and monitoring. • Large area sensor (coverage of the full horizontal width of the top and bottom magnet blocks). • Fiber Out for low gain upgrade (full integration and dyn range diagnostic), control system expandable to 80 channels. • Radiation hard components (materials and electronics).

11. BLM Interconnect Diagram m. brown

12. Interface Box Location

13. Plan View of Short Drift

14. BFW Pump Out Port Relocation

15. Removable Pin for Manual Insertion

16. Undulator Inserted Position

17. Undulator Retracted Position

18. Pin Function

19. Detector Pin Detail

20. Rendering of Detector

21. Cross Section of BLM Detector

22. Cerenkov Radiator

23. Magnet Block Sensor Coverage

24. Proposed PMT Device -04 (420nm)

25. Vendor List • Radiator Substrate water jet and final polish (lap and flame) (quartz)- VA Optical • Radiator AlSi coating – Eddy Company • Radiator Material - Corning • PMT and Magnetic Shield - Hamamatsu • Connectors: • SMA Fiber Feed through) -Thor Labs • High Voltage Feed through - Kings • SMB Signal Fed through - AMP • Fiber Optic Cable (heartbeat) Fiber (fused silica) - Stocker Yale • Fiber Optics Cable, UV Grade – Coastal Connections • Signal Cable – Belden • Body Fabrication- M1, High Tech, AJR Industries • Miscellaneous Hardware (fasteners, o-rings, flex coupling, spanner wrench) – McMaster-Carr • Linear Bearing Assembly – IKO International • Spherical Bearing – Aurora Bearing

26. UV Grade Fiber

27. Fused Silica Radiator

28. BLM System Support Focus Topics • Funding of beam based prototyping and test program. • Implementation of upstream calibration foil (alt. profile monitor/halo). • BFW prototype tolerance verification (system tolerance in LTT)

29. BLM Summary • Undulator magnets protection is critical for machine commissioning period. • BLM system is now defined as a component of the mps (descope) with an upgrade path to a diagnostic (low gain detector). • Calibration plan and hardware is vital to proper system operation (threshold detection will use empirically derived levels). • Schedule for development of the blm program is very aggressive and funding is limited.

30. Detector Summary • Building a detector based on cerenkov radiation and PMT detection. • 36 distributed channels (2 static devices) capable of single pulse detection (up to full rep rate) with rate limiting reaction. • Detectors dynamically track with undulator position with manual detach option to remain in a fully inserted static position. • Adjustable PMT sensitivity with remotely controlled high voltage power supply. • Keep alive system test (led pulser) before each beam pulse. • All Vendors have been identified, Quotes in progress, Drawing set being reviewed. • Installation does not require access into the vacuum system or removal of other components.

31. End of Presentation

33. Parts Animation

34. Undulator System

35. 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). • BFW prototype verification (system tolerance LTT)

36. 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). • Quotes in progress • Drawing set being reviewed

37. 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).

38. Undulator Hardware

39. 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

40. Segment Design Layout m. brown

41. Locking Pin Detail (moves with undulator) Flex Joint Spherical Bearing

42. Beam Loss Monitors using Link Nodes

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

44. Proposed PIC / BLM Timing

45. Link Node Block Diagram

48. 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

49. 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

50. 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