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LCLS Undulator Systems Beam Loss Monitor. William Berg ANL/APS Diagnostics Group. 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.
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LCLS Undulator SystemsBeam Loss Monitor William Berg ANL/APS Diagnostics Group
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).
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.
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.
ANL Draft BLM Budget • 425kM&S Total: • 325k Detector Development • detectors • mounting and slide systems • cables and fiber • 100k Controls Interface Box
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
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.
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).
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).
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
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)
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.
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.
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)
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
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).
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
Locking Pin Detail (moves with undulator) Flex Joint Spherical Bearing
Beam Loss Monitor - Undulator Hardware (m. brown) In Undulator Hall Long Haul Cables
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
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
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