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- Intro
- Hazard Summary
- Pretty big table on page 5. Worth a glance
- Lists general types of hazards, what they could do, how we're controlling for them, how likely they are to happen, and severity/risk
- Definition of Risk on page 9
- Risk is a function of probability and severity (high severity + low probability = low risk, high + high = high, low + low = low)
- LAF Description
- LAF Subsystems
- Copper linac through the FEE, FACET-II facility, ESA, LCLS II RGD
- Copper
- 2856 MHz, room temp, klystrons, SLED cavities
- 25 feet under gallery
- Gallery has klystrons, SLED cavities/modulators, power supplies, cooling water systems
- 31 sectors (0 in the west, 30 in the east)
- Linac West (S0 - 9)
- decommissioned and removed for superconducting LCLS-II (currently under construction)
- Linac Middle (S10 - 19) and Linac East (S20 - 30) separated by concrete shielding wall and personnel passageway maze
- Can be operated independently
- But share control and water cooling systems
- People can't be in Linac East if Linac Middle is running
- prompt radiation risk exposure
- Max pulse rate is 120 Hz
- 30 Hz if 120 isn't needed or to reduce power consumption
- Linac East and Middle can be operated at different rates
- Usually 30 Hz for FACET-II (the usually is suspicious here considering we haven't run it yet)
- Usually 120 Hz for LCLS
- Linac Middle
- Max energy of ~16 GeV to FACET-II
- Positron beam coming in the future when they build a damping ring
- Not designed to go above 30 Hz
- Linac East
- Max energy of ~18 GeV to Undulator Complex (has two undulator systems)
- Generate coherent x-ray beams that can be sent to the NEH and FEH
- Has previously sent beam to ESA, but that's currently decommissioned
- Could be brought back if needed
- LCLS-II Injector
- Normal conducting laser-driven photocathode gun (186 MHz) followed by a buncher cavity
- Currently set up to deliver electrons to a Faraday cup for commissioning without additional accelerationThere's currently a concrete shielding wall immediately downstream of the Faraday cup
- Will be removed before the injector is connected to the superconducting linac
It's currently a Radiation Generating Device (not an accelerator)- Will be reclassified when it's connected to the linac
- Linac West
- LCLS-II injector through Sector 9
- Currently under construction
- FACET-II Injector
- At Sector 10
- Produces electrons for acceleration in Linac Middle & delivery to the FACET-II experimental area in S20
- Normal conducting S-band laser-driven photocathode gun
- Linac Middle
- Middle third of the linac, sectors 10 though 20
- Designed to accelerate, compress, & focus electron or positron beams to the FACET-II experimental area in S20
- Magnetic chicane bunch compressors in sectors 10 and 14 shorten the electron beams longitudinally (increasing intensity)
- Currently unable to produce positron beam
- Positron Source
- Can produce positrons by slamming electrons into a target near S19
- The target is a plate of high-density, water-cooled tungsten-rhenium
- It's slowly rotated so that the heat from the beam is dissipated over a higher area
- Target is followed by RF capture and acceleration sections that make a 200 MeV positron beam
- You can park all or some portion of the e- beam on (in?) the transport line from S19 to the target
- We currently can't transport, damp, or reinject positrons in to the linac (all that stuff was decommissioned)
- FACET-II Experimental Area
- In S20
- Beam transport and focusing system, followed by an area to mount experimental setups, followed by a beam dump
- The transport and focusing system has diagnostic devices and magnets
- Focuses the beam to a small spot size at the experimental setup
- Compresses the bunches longitudinally for "very" high peak current
- LCLS Injector
- S20
- Produces electrons for acceleration in Linac East
- Which drive the LCLS FELs in the Beam Transport Hall
- Normal-conducting, laser-drive photocathode S-band gun
- Linac East
- LCLS uses last kilometer of linac (S21 through 30)
- Produces ~2 to 17 GeV
- Dependent on number and configuration of klystrons
- Beam lines and shielding could safely transport and dissipate 25 GeV e- beam
- Magnetic chicane e- bunch compressors in S21 & 24 shorten the e- bunches longitudinally
- The chicanes divide Linac East into five LCLS areas:
- Linac-1 (L-1)
- Bunch Compressor-1 (BC-1)
- Linac-2 (L-2)
- Bunch Compressor-2 (BC-2)
- Linac-3 (L-3)
- Beam Switchyard
- BSY
- Provides switching, energy definition, collimation, and transport functions for LCLS and ESA beams
- Can send compressed e- bunches to either transport line to the BTH on a pulse-by-pulse basis
- Has beam dumps that can stop and safely dissipate e- beam
- A-Line to End Station A (ESA) and Beam Dump East (BDE)
- ESA is a facility for fixed target experiments
- A-Line transport system can deflect pulses from the primary beam to ESA on a pulse-by-pulse basis
- Only a small fraction of them though. Most of them continue to the LCLS HXR undulators
- Originally designed to handle beam power from the full linac (potentially more than 1 MW), so can safely handle Linac East beam
- A dump in the Northwest ESA wall can be used with low power beam
- Currently out of service, but could be easily brought back
- The Beam Transport Hall (BTH)
- Immediately east of the linac BSY
- Contains two LTU (Linac to Undulator) beam lines
- e- beam from the linac can be sent to either one
- Contains two undulator magnet systems
- HXR (Hard X-Ray) and SXR (Soft X-Ray)
- horizontal and vertical bending magnets can direct the beam to either
- Both go to the EBD (Electron Beam Dump)
- The east end has tune up dumps that provide temporary parking places for the e- beams upstream of the undulator magnets
- Undulators
- Series of magnets placed end-to-end along the beam line
- interleaved with quadrupole magnets, steering corrector magnets, and beam position monitors
- HXR Undulator
- approximately 32 magnetic segments
- each has a remotely adjustable horizontal gap
- produces a vertically polarized Free Electron Laser (FEL) beam
- selectable photon energies between 1 and 25 keV
- SXR Undulator
- approximately 20 magnetic segments
- each has a remotely adjustable vertical gap
- produces a horizontally polarized Free Electron Laser (FEL) beam
- selectable photon energies between 0.2 and 8 keV
- a magnetic chicane and photon filtering system in each undulator system provide self-seeding capabilities
- Byproducts
- low brightness spontaneous radiation beam
- broader spectral width and divergence
- lower brightness harmonics of main FEL beam
- Electron Beam Dump (EBD)
- After the undulators
- electrons and x-rays co-propagate to the dump magnets
- e- beams are deflected down into water-cooled Electron Beam Dumps
- designed to absorb the full beam power
- x-rays aren't deflected
- continue on to the experimental areas through the FEE (Front End Enclosure)
- The Front End Enclosure (FEE)
- first room downstream of the EBD (Electron Beam Dump)
- beam lines designed to transport photons, not electrons
- contains mirrors, optical elements, limiting apertures, attenuators, and diagnostic devices for each beam path
- can monitor the position and energy of individual pulses
- can send photons to two buildings, the NEH (Near Experimental Hall) and FEH (Far Experimental Hall), using mirror systems
- The FEH hutches (experimental areas) receive hard x-rays from the HXR undulator line
- The NEH has one hutch that can take hard x-rays from the HXR undulators, but the rest take soft x-rays from the SXR undulator line
- Each mirror system includes photon collimators to protect the beam line equipment from damage by the photon beam and to intercept bremsstrahlung radiation
- Sending beam to the FEE requires authorization from both the AOSD (Accelerator Operations and Safety Division) and the LCLS Directorate
- Safety controls for FEE operation are listed in the undulator complex BAS (Beam Authorization Sheet) and the FEE BLA (Beam Line Authorization)
- The details and hazard hazard analysis are in the LCLS SAD (Safety Assessment Document)
- Hazard Analysis
- ASE
- QA
- Post Ops
