FACET Accelerator Overview John Seeman for the FACET Study Group PPA Directorate Stanford Linear Accelerator Center DOE FACET Review February 19-20, 2008

Topics FACET accelerator overview Brief look at science program Changes since the SABER review of Dec 2006 Brief budget overview

FACET Accelerator Team Management: R. Erickson, S. Kahn, J. Jaros, D. MacFarlane, T. Raubenheimer, J. Seeman Mechanical engineers: L. Bentson, D. Blankenship, S. DeBarger, N. Li, H. Shin Area Manager: A. Baker, T. Graul Optics: Y. Nosochkov, M. Woodley, T. Fieguth Alignment: C. LeCocq Beam dynamics: K. Bane, P. Emma Radiation physics: J. Bauer, A. Prinz Personnel Protection System: P. Bong, K. Turner Experimental region: M. Hogan, D. Walz, M. Woods, C. Hast Physics consultants: R. Iverson, P. Krejcik

Overview There was a constant demand for electron and positron beams in the Final Focus Test beam (FFTB) and End Station A (ESA) from a wide variety of accelerator physics users. However, the FFTB has been removed to make room for the Linac Coherent Light Source (LCLS). ESA is still in use. Many locations at SLAC have been studied for FACET. The optimum location is Linac Sector 20 for the Accelerator Science Facility (ASF) where the FFTB accelerator beam capabilities (final focus) can be relocated in a straight forward fashion. FACET makes use of the PEP-II HER bypass line to take a damped e- beam to End Station A, independent of LCLS. The existing electron longitudinal bunch compressor at the 1/3 point in the linac can be modified to compress positron bunches, as well, opening new worldwide unique opportunities for accelerator research. A Hadron Production Facility (for single particles) can be added to the A-Line to ESA.

FACET Layout FACET has four areas: Hadron Production Facility FACET has four areas: Accelerator Science Facility (ASF) (Sector 20) e+ bunch compressor (Sector 10) Electron Bypass Line (EBL) extension to ESA Hadron Production Facility in A-Line to ESA

Basic FACET areas Final Focus (ASF) in Sector 20: Makes a small beam spot (<10 microns) for experimenters. Similar design and layout as FFTB final focus. Sector 10 compressor for e+: Allows the production of positrons by e- and the delivery of short bunch length e+ to the experimenter. Same design and layout as present e- compressor. Bypass line (EBL): Allows independent operation from LCLS. Use PEP-II HER injection bypass lines with 9 to 12 GeV e- with extension built to join to A-line transport to ESA.  The technology is the same as the former FFTB, SLC arcs, and existing PEP-II injection bypass lines. Many components salvaged from SLC, FFTB, and PEP-II.  Minimal design and engineering needed!

Proposed Construction Timeline Fall 2008: Installation of shielding wall in linac tunnel between Sectors 20 and 21. This allows tunnel installation work to proceed in Sector 20 while the LCLS injector and other downstream systems operate in 2009. January through September 2009: Installation of Sector 20 magnets and vacuum systems while LCLS commissioning activities proceed in downstream sectors. Fall 2009: Removal of existing components of the PEP-II injection transport systems in the BSY, as needed for FACET EBL. Modifications will be done to the common line vacuum system in the BSY. FY 2010: First operation of Sector 20 ASF final focus with electrons. Installation of positron compressor system in Sector 10. Fall 2010: Installation of the bypass line in the BSY and Hadron Production Facility. FY 2011: All FACET systems fully operational, independent of LCLS operations.

Basic FACET ASF Beam Parameters Beam Energy = 30 GeV Single bunch per pulse 30 Hz (120 Hz possible) Charge per bunch (e- or e+) = 1 x 109 to 3.5 x 1010 Bunch length = 15-30 microns Transverse spot size at experiment <10 microns Energy spread = 0.5 to 4 % (full width)

Sector 20 Final Focus

FACET Sector 20 Area e- e+ target

LCLS Injector (Sector 21) New FACET Wall

Linac Housing: Site of ASF

Linac Tunnel ASF has a bunch compression dog-leg beam line and a final focus for the experiment. Longitudinal space for experiments will be the same as the FFTB. Transverse space is adequate for accelerator experiments and many detector experiments. Electric carts can travel in the linac tunnel aisle now and will be able to after the ASF and experiments are installed.

Many places for User Counting Houses

Basic FACET EBL-ESA Beam Parameters Beam Energy = 9-12 GeV using PEP-II HER line Single bunch per pulse 30 Hz (120 Hz possible) Charge per bunch = 1 x 109 to 3.5 x 1010 Bunch length = ~1 mm Transverse spot size at experiment < 1mm Energy spread = <1 %

Extension of HER Line to A-Line

Plasma Wakefield Acceleration Studies (ASF) Electron acceleration Positron acceleration Drive witness beam tests Beam emittance preservation

Dielectric Wakefield Accelerators (ASF) Acceleration (e- and e+) CSR studies Coating optimization Beam propagation tests Theory/simulation cross checks Channel diameter optimization

Detector Development (ESA) Development of beamline instrumentation for ILC or other applications New position monitors Precise beam energy measurements Collimator wakefield studies Detector development for ILC, LHC and many other applications Proof-of-principle for new detectors Detector characterization and calibration EMI & radiation damage studies Gas/air fluorescence for particle astrophysics experiments

Material Science (ASF and ESA) Pulsed magnetic fields THz radiation Photon detector development Electronic structure of metals Ferroelectric switching

Old Proposal: SLAC Overview with SABER in SLC South Arc SABER consists of three main components: (1) Experimental area with final focus and beam dump in SLC South Arc tunnel. (2) Linac Pulse Compressor upgrade to compress positron bunches. (3) Bypass Line to deliver e- or e+ beams to SABER, bypassing the LCLS. (2) e+ e- (3) (1)

Old SABER: Reuse 1 km of PEP-II Injection Bypass Line Sector 20 (exists) Linac Sector 21-30 (exists) 51 Line (exists) South Arc (exists) Extraction Line (new) Re-injection Line (new) Drift Line (exists but 12  30 GeV) ~50 m ~1000 m ~50 m Drift Line: Reuse: Vacuum chambers, pumps and controls Beam position monitors Beam size monitors Steering corrector magnets Quadrupole magnets and power supplies New: Extra quadrupole magnets, power supplies, supports, water

Suggestions from SABER Review FACET team has answered the committee recommendations from the DOE “SABER” review held December 6-7, 2006: Broader science program: Added ESA beam for detector and accelerator studies. Added hadron production facility for single particle detector studies. New location and lowest cost: Final focus in Sector 20 saves bypass line upgrade costs and has easier beam tuning. (Saves 3.6 M$) ASF and ESA can operate simultaneously, independent of LCLS. Manage the construction as a project: Project management team is now proposed.

Budget changes from SABER  FACET (FY2007$) SABER budget total: 12.4 M$ South Arc final focus: 2.4 M$ Linac bypass line (30 GeV) upgrade: 8.3 M$ Positron Bunch Compressor: 1.5 M$ Personnel Protection System upgrade: 0.2 M$ FACET budget total: 15.5 M$ Sector 20 ASF final focus: 7.1 M$ Positron bunch compressor: 1.5 M$ EBL Bypass line extension to ESA (12 GeV): 4.3 M$ ESA Hadron Production Facility: 0.6 M$ Project management: 2.0 M$ Operations costs: ~6 M$ for 4 months for running both ASF and ESA together.

Conclusions FACET (ASF and ESA) is a solid advance over the old design. The breath of the experimental program has been significantly expanded. There are four components to the facility allowing staging of the program. FACET construction matches the LCLS staff ramp down plan and accelerator operations schedule. Budget estimates have been carefully managed to be as low as possible.