PPS and BCS Requirements for LCLS-II (Baseline) Stan Mao 06/10/2015

2 Outline D10 ST61, ST60, D2 MUON shielding  SLAC Radiation Safety System  LCLS-II PPS requirements  PPS shut-off mechanism  LCLS-II BCS requirements  BCS shut-off mechanism  BCS shut-off time  Access BTH fenced areas (PPS, BCS)  Summary

3 SLAC Radiation Safety Systems Access Control System (PPS) Radiation Control System Beam Containment System (BCS) Shielding Radiation Safety System Burn Through Monitors (BTM) Beam Shut- Off Ion Chambers (BSOIC) ACM, PIC, LIONS LCLS-II DOE Review, April 7-9, 2015

4 LCLS-II PPS Zones SC Linac PPS – From SC LINAC gun to FEE is one PPS zone ESB BTH UH Muon shielding BSY BTHW Dump FEE Undulator Complex PPS Zone (From BTHW to FEE) D2 Cu Linac PPS - access Undulator Complex PPS Zone with PPS stoppers D2 in

5 PPS Shut-off mechanism for SC LINAC D10 ST61, ST60, D2 MUON shielding Gun RF Power supply Off All RF off Injector PPS stopper In Beam from gun No beam No beam after PPS stopper Gun dark current No gun dark current No gun dark current after PPS stopper Dark current from RF devices No dark current from RF devices

6 Under Consideration D10 ST61, ST60, D2 MUON shielding  New PPS access options are being developed to compensate the baseline  SC LINAC gun local mode  Access to BTH during SC beam on BSY dump  Access to Sector 10 and upstream during FACET-II operation in FACET-II project

7 LCLS-II Beam Containment System (BCS) BCS monitoring will include measurements of the beam… 1)Current: Current Monitor (CM) Measure peak and average current 2)Energy: Magnet Current Monitor (MCM) Measure magnet current (main and trim) 3)Losses: Point beam loss monitor Protection Ion Chambers (PICs) or equivalent Line beam loss monitor Long Ion Chambers (LIONs) or equivalent Current Comparator Compare peak and average current between CMs BCS collimator system with BCS devices: contain the beam during mis-steering conditions, RP is working ESB 4) Cooling water Flow meters

8 BCS is critical radiation safety system for SC LINAC operation D10 ST61, ST60, D2 MUON shielding  LCLS-II beam power is much higher than in LCLS-I, but several systems and enclosures are preserved.  New controls and local shielding must be developed to compensate this  SC LINAC is capable to generate 1.2 MW beam. If spreader kicker time system fails, the kickers could deliver 300 kW beam from BSY dump line to SXR or HXR lines  the downstream beam dumps only absorb few hundred kW of the beam  Direct line from LINAC gallery to SC line through penetrations  Unknown dark current from gun and cryo modulator

9 LCLS-II BCS Specification D10 ST61, ST60, D2 MUON shielding  High beam rate (up t o1 MHz) requires fast BCS system  High power (up to 1.2 MW) requires high accuracy current monitor sensors  High power operation requires robust BCS system to limit beam power and losses, and to contain the beam  Fast BCS shut-off time needs to be 100 µS to protect the stoppers/ and dumps for 240 kW beam

BCS devices in SC LINAC injector area BCS LION Dark current block BCS CM PPS Stopper 10

BCS devices in SC LINAC L1, BC1, L2, BC2, L3, Dog-leg and LINAC (S13 – S27) CID Sector 10 Sector 11 Sector 13 Sector 4 Sector 2 Gun L0 L1 L2 L3 BC1B BC2B CEDOG DIAG0 CEBC1 CEBC2 DIAG1 CY11 CX11 CY12 CX12 CY21 CX21 CY22 CX22 CX13 11 BCS CM Magnet current monitors for CEDOG will be used as reference point to control SC LINAC energies. The currents of all magnets located downstream will be compared with these magnet currents by PLC. LCLS-I used one power supply for BTH dogleg BX31/BX33 and BYD.

12 2 ft D10 MUON shielding LCLS-I line DUMPLINE SXR line HXR line Current Monitor requirements 12 BSY Dump MUON shielding 2 ft MUON shielding Cu-LINAC line DUMPLINE SXR line HXR line Sector 28 Sector 29 5 kW limit Existing Interlocked to Cu LINAC 120 kW limit 300 kW limit

13 2 ft D10 MUON shielding LCLS-I line DUMPLINE SXR line HXR line ST61/ST60/D2 BCS magnet current monitor for magnets 13 BSY Dump MUON shielding 2 ft BSY Dump MUON shielding Cu-LINAC line DUMPLINE SXR line HXR line ST61/ST60/D2 Sector 28 Sector 29 Sector 30 BSY 1

BCS collimators DRAFT (To be determined by ray-trace studies) MUON shielding LCLS-I line DUMPLINE SXR line HXR line Sector 28 Sector 29 Sector 30 2 ft Collimator/BTM with PICs

Beam Transport Hall BTHW BTH SXR HXR Collimator/BTM with PICs Group LIONs are existing and will be repurposed to trip individually (for 35 W) and as Groups (for 75 W) Group MCM 15

Undulator Hall Undulator SXRSS PICs SXR HXR SXRSS HXRSS SXRSS SXRSS PICs Tune-up Dump and PICs Protection Collimator and PICs Tune-up Dump and PICs PICs located in the front of undulator PICs 16 Add one pairs of PICs in front of undulator for each line Use LIONs to protect BCS collimators

Dumpline DUMPLine SXR HXR BYD Magnet Set and PICs LCLS-II CM comparator Toroid 1 Permanent Magnet BYD Magnet Set and PICs Protection Collimator and PICs LCLS-II CM comparator Toroid 2 Protection Collimator and PICs LCLS-II CM comparator Toroid 1 LCLS-II CM comparator Toroid 1 PICs MCM 17 Both SXR and HXR lines have permanent magnets and safety dumplines Protection Collimator and PICs

BCS Shut-off mechanism BCS CM PPS Stopper 18 BCS fault from SC LINAC 1. Shut off laser No beam (<100 uS) 2. After Laser is shut off (10 uS), to check laser and BCS CM 3. If Laser intensity or BCS CM reading is still high (10 uS), interrupt Gun RF No beam and no dark current from Gun 1. Shut off Spreader kickers Beam to BSY dump (< 100 uS) Gun RF 4. If still has BCS fault (PICs and LIONs) from SC LINAC (50 mS), BCS send signal to PPS to shut off CM RF in 5 Second No CM RF

19 BCS Shut-off time D10 ST61, ST60, D2 MUON shielding  For those BCS devices used to protect BCS collimator or PPS stopper from radiation damage, the shut-off time should be equal or less than 100 µS Based on RP-RPG MEM-02, 240 kW LCLS-II beam (300 pC/pulse) will not damage (Al, Cu, SS, Nb, Ti) stoppers  For other BCS devices, the shut-off time should be equal or less than 600 mS for beam, and should be equal or less than 5 S for Cryo Modulator dark current

20 D10 ST61, ST60, D2 MUON shielding BTH beam losses, BTH PPS fenced areas and access requirements

21 LCLS-II DOE Status Review, Sept Oct. 2, 2014 LCLS-I: 6’ Long ION chambers -Normal Beam Loss* = 5 W (0.1 % bp) S.B. BTH -MCI: 100 kW  LIONs = 5 W -Beam Power = 5 kW LCLS-I: 5 W  Existing facility 6’ walls 6’ roof under SB 4’ roof elsewhere BTH \ LCLS-II shielding & BCS (slide from Mario Santana talk on LCLS-II DOE Status Review)

22 BTH \ LCLS-II shielding & BCS (slide from Mario Santana talk on LCLS-II DOE Status Review) LCLS-II: 6’ Local shielding around collimators, etc. 2 x 1 W/m Long ION chambers -Normal Beam Loss* = 1 W/m S.B. BTH 18’ -MCI: 2 MW No access to S.B. & trenches 32” additional concrete OR 18’ PPS fence Shielding on mazes and collimators,…  LION setting = 35 W 32” -Beam Power = 2 x 120 kW

23 2 ft D10 MUON shielding LCLS-I line DUMPLINE SXR line HXR line ST61/ST60/D2 Cu LINAC and SC Spreader lines 23 BSY Dump MUON shielding 2 ft BSY Dump MUON shielding Cu-LINAC line DUMPLINE SXR line HXR line ST61/ST60/D2 D10 Lambertson SXR Kicker OFF HXR Kicker off Lambertson D10 Sector 28 Sector 29 Sector 30 BSY 1

24 SC-HXR and SC-SXP operation Research Yard PPS Fence Research Yard PPS Fence interlocked to BSY kickers BCS LIONs set at 35 W 35 W

25 Cu-HXR operation BCS LIONs set at 5 W 5 W Kickers are off

26 Summary D10 ST61, ST60, D2 MUON shielding  LCLS-II beam power is much higher than in LCLS-I, but several systems and enclosures are preserved. New controls and local shielding are being developed to compensate this  LCLS-II baseline defined one PPS zone (from LCLS-II gun to FEE). It conflicts the LCLS-II commissioning plan, also may affect the LCLS-II operation.  BTH requires a PPS interlocked fence at 18 ft distance. Additional shielding is required at the mazes and at high beam loss points.  Robust, fast shut off, high accuracy and reliable BCS devices are being developed to contain SC LINAC high rate and high power beam

27 D10 ST61, ST60, D2 MUON shielding Back-up slide

28 BCS Shut-off mechanism (2) If BCS still fault after BCS Shut-off mechanism (1) D10 ST61, ST60, D2 MUON shielding BCS 100 µS Option Stage 120 µS Third Stage < 5 S Path Laser Laser shutter Pockels Cells or Acousto-optic Modulator Gun RF interrupted Shut off CM RF through PPS Injector PPS stopper In Beam from gun No beam from gun No beam after PPS stopper Gun dark current No gun dark current No gun dark current after PPS stopper Dark current from CM RF No CM dark current No CM dark current from L0