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This preliminary report discusses the requirements and specifications of the Beam Containment System (BCS) for the LCLS Project. The BCS is designed to confine the beam within approved channels and protect personnel from prompt radiation. It includes mechanical devices like collimators and beam dumps, as well as protection devices such as ion chambers.
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BCS Requirements for LCLS Project- preliminary report Alberto Fasso, Stan Mao, Noriaki Nakao, Sayed Rokni, Heinz Vincke Radiation Protection Department Stanford Linear Accelerator Center October 20, 2005
Beam Containment System (BCS) Personnel Protection System (PSS) keep people away from prompt radiation Beam Containment System (BCS) keep prompt radiation away from people BCS is a combination of mechanical devices (e.g., collimators and beam dumps) and associated protection devices (e.g., current toroids or ion chambers) that assure that a beam is confined to an approved beam channel at an approved allowed beam power
BCS Policy Radiation Safety Systems ES&H Division, SLAC-I-720 0A05Z-002, Technical Basis Document
BCS Device To monitor and limit the beam power (energy) in a beamline to the allowed value Average Current Monitor, Rep Rate Monitor, Meter Relays To limit the losses along a beamline that is operating at its allowed power Pulse-to-Pulse Comparator, Protection Ion Chambers (PICs), Long Ion Chambers (LIONs) To prevent the beam from escaping Beam Containment Collimators/stoppers with BTM/PICs To protect safety-related beamline components from damage Protection Ion Chambers (PICs), Flow switches Radiation level detection devices BSOICs Monitoring system
To define BCS Specification Need help from beamline physicists Operation and access modes – containment area Define allowed beam, beam losses, and maximum credible beam power (MCBP) Ray-trace studies Burn-through analysis Trip mechanism to be designed by LCLS
Components along the LCLS LCLS Injector LINAC BSY/LCLS Beam Transport Hall (BTH) Undulator Hall (UH) Electron Dump/Dump line Front End Enclosure (FEE) Near Experimental Hall (NEH) X-ray Transport Optics Diagnostic (XTOD) Far Experimental Hall (FEH)
LCLS beam parameters Injector: e- 135 MeV, 16 W LINAC: e- 15 GeV, 5 kW MCB: e- 15 GeV, 150 kW X-ray: photon 140 keV (Ec), 2.7 W FEL: photon 8.2 keV (1st Harmonic), 0.3 W
BSY/LCLS Hazard: Sources: 5 kW of beam loss in single beam dump (SBD), radiation outside the end-plug Energy chicane bends the beam, the beam could direct to the end-plug in the case of the chicane failure Maximum Credible Beam (MCB) to the dump: 15 GeV, 150 kW Requirements Three ACMs upstream of the 55’ muon shielding Two PICs and one BTM on the SBD dump, flow switches BCS collimators with PICs/BTMs to prevent the beam from hitting the concrete wall (considering the failure of the energy chicane)
Beam Transport Hall Hazards: Sources: 5 W loss at any point, 417 W on tune up dump Radiation outside the BTH Requirements LIONS limit the beam loss at 5 W Two PICs and one BTM on the tune up dump, flow switches, Rate monitor BSOICs on each service building and each maze and each end-plug
Front End Enclosure Hazards: High energy bremsstrahlung – 800 mW Spontaneous X-ray – 2.7 W Free Electron Laser – 0.3 W (high power density) Requirements Protection against FEL (burn through shielding and PPS stopper, BCS collimators) BCS collimators with BTMs for two-collimator system BSOICs
LCLS Injector shielding wall Hazards: Radiation generated during PEP-II/LINAC operation. Shielding allows access to the vault during PEP-II and LINAC operation Requirements Two protection ion chambers (PICs) - installed One BSOIC - installed
LCLS Injector Hazards: Radiation generated during the LCLS Injector operation from beam losses on Faraday Cups, OTRs, dump may reach the laser room above through penetrations Maximum Credible Beam (MCB) to the dump: 104 MeV, 4.74 kW Requirements Two PICs and one BTM on the dump if the dump power capability is less than MCB, flow switches Average Current Monitor (ACM) to be determined One BSOIC in Laser room
LINAC Hazards: Sources: Beam loss in collimators located in LCLS Bunch compressor (BC) 1 and 2, temporary dump near BC1 Radiation in the linac klystron gallery through penetrations Requirements Two PICs and one BTM on the temp dump if the temp dump power capability is less than MCB PICs on Jaws of BC1 and BC2
Undulator Hall Hazard: 5 W loss at any point Radiation in the service buildings through penetrations Requirements LIONs limit the beam loss at 5 W BOICSs on each service building
Electron Dump/Dumpline Hazards: Sources: 30 W loss at any point, 5 kW on the dump Requirements Two ACMs upstream of the dump one BTM on the dump, flow switches BCS collimators with PICs/BTMs Safety dump with PICs/BTMs Meter Relay BSOICs
Near Experimental Hall Hazards: High energy bremsstrahlung – 17 µW Spontaneous X-ray reflected by one mirror is scattered by an object inside the hutch Free Electron Laser reflected by one mirror is scattered by an object inside the hutch Requirements Protection against FEL (burn through shielding and PPS stopper, BCS collimators)
X-ray Transport Optics Diagnostic (XTOD) Hazards: Spontaneous X-ray reflected by two mirrors is scattered by an object Free Electron Laser reflected by two mirrors is scattered by an object Requirements BCS collimators Protection against FEL (burn through shielding and PPS stopper, BCS collimators)
Far Experimental Hall Hazards: Spontaneous X-ray reflected by two mirrors is scattered by an object inside the hutch Free Electron Laser reflected by two mirrors is scattered by an object inside the hutch Requirements BCS collimators Protection against FEL (burn through shielding and PPS stopper, BCS collimators)