1. Requests of Future HEP e+/e-Facilities
Tor Raubenheimer
FACET2 Workshop
October 15, 2015

2. Critical Requirements for HEP facility
Outline
Critical Requirements for HEP facility
Energy
Luminosity
Cost
Credibility (laugh-factor)
Other issues:
Polarization, Lum. Spectrum, Stability, Operability, …
FACET2 Workshop, October 14, 2015

3. Dictated by the physics
Energy and Luminosity
Dictated by the physics
In general, L scaling as E2 is required however some situations may reduce this (e.g. studying known resonance)
10,000 events/yr  1x1034 at 1 TeV, 2.5x1035 at 5 TeV
Possible scenarios
500 GeV cms ILC is constructed Afterburner on ILC for 1 TeV cms Addition facility upgrades (PWFA-LC) to 3 ~ 5 TeV
ILC too expensive and FCC not pursued Start with 1 TeV PWFA-LC
FACET2 Workshop, October 14, 2015

4. Linear Collider Luminosity
Luminosity is critical in a linear collider
Physics studies have been based on ~1x1034 cm-2sec-1
Need large beam powers, large bunch charges, and small spot sizes
For example, at 1 TeV:
20 MW beam power, 1010 e+/e- per bunch, frep = 10 kHz, and sx/sy = 140 / 3 nm  1x1034 cm-2sec-1 within 1% of cms energy
Maintaining E2 scaling very challenging
All parameters pushed beyond state-of-the-art
Choose set that minimizes the pain!
FACET2 Workshop, October 14, 2015

5. Luminosity
Proportional to (Pbeam / sy) * (N / sx) but latter factor has strong impact on luminosity spectrum  Maximize (Pbeam / sy) Getting multi-MW beam power requires large amounts of AC power with both cost and environmental impact  Need efficient transfer from AC  Beam Minimizing spot sizes requires small emittances, strong focusing, and high stability  Flat beam emittance preservation and stability
FACET2 Workshop, October 14, 2015

6. Implications for the FACET/FACET2 program
Emittance preservation still needs study/demonstration
Further demonstration of drive/witness acceleration with high efficiency and witness low energy spread
Understand and demonstrate high-h positron acceleration
Demonstrate stable operation
Understand multi-bunch stability and plasma heating
Design studies are needed to illustrate feasibility for parameters beyond those accessible at FACET2
FACET2 Workshop, October 14, 2015

7. Credibility and Feasibility
Plasma collider huge undertaking that will require engagement of the HEP and Accelerator communities
By the end of FACET2 I think we should have reasonable answers to questions posed by reasonable people and not just cartoons
Tolerances, plasma stability, heat dissipation, drive beam merge/separation, cost-scale, …
A reasonable demonstration pathway, e.g. PWFA-FEL ?
FACET2 Workshop, October 14, 2015

8. FACET R&D Program from FACET proposal to DOE, July 2008
FACET2 Workshop, October 14, 2015

9. My References ILC Reference Design PWFALC: AAC’08: AAC’04:
A Beam Driven Plasma-wakefield Linear Collider from Higgs Factory to Multi-TeV, J.P. Delahaye, et al. (2014). ⁞
A Conceptual PWFA Linear Collider, C. Adolphsen, et al. (2009).
AAC’08:
R&D for Very high Energy Colliders, T.O. Raubenheimer (2008).
Design considerations for a Laser-Plasma collider, C. Schroeder, et al. (2008).
AAC’04:
An Afterburner at the ILC: The Collider Viewpoint, T.O. Raubenheimer (2004).
Advanced Accelerator System Requirements for Future Linear Colliders, G. Dugan (2004).
FACET2 Workshop, October 14, 2015

10. Summary Huge opportunity to define ‘conceptual’ PWFA-LC
Both systematic experimental studies and design
Show significant cost benefit of new technology
1st focus should be on emittance preservation
Critical for any application (LC, FEL, high brightness source, …)
2nd priority on narrow spectrum and then high efficiency
Spectrum also applicable to any application
Efficiency necessary for large applications such as LC
3rd priority positron acceleration
Necessary for LC applications
In parallel, need to prioritize pre-conceptual design
Too many hand-waving answers to engage realistic people
FACET2 Workshop, October 14, 2015

11. FACET2 Workshop, October 14, 2015

12. Future Facility Costs
The energy and luminosity requirements for future colliders are severe
Constituent energy ~1 TeV and luminosity >1x1034 cm-2s-1
Achieving these parameters will be expensive
There is some cost scale that decreases the probably of approval
Crude model comparing projects in 2020$
ILC estimate from Mike Harrison at FNAL P5 meeting
SSC value of 10B$ to be completed in (seemed OK)
Estimated construction costs in FY2020 $
All costs escalated to 2020$ using 3.5%
FACET2 Workshop, October 14, 2015

13. Linear Collider Cost Drivers
ILC costs provide basis for optimization
60% of costs are in ML
15% in the long RTML, and 7 km damping rings
Power handling ~5%
Detector and IR Hall add another ~10%
ILC Costs by Sub-system (from RDR)
FACET2 Workshop, October 14, 2015

14. Facility Cost Goals
Goal: reduce LC cost by an order of magnitude – tough!
Can benefit from optimization all subsystems
New acceleration systems
Improved focusing concepts
Improved beam generation
Facility costs scale roughly with power consumption and facility size
High gradient can reduce site length – are components cheaper?
Improved efficiency, better sources, or improved focusing can reduce power consumption
All DOE projects must optimize life cycle costs
Inflated annual energy costs ~1$ (2020$) per Watt
Energy costs an order of magnitude smaller than capital cost in ILC design  important factor in a future design
FACET2 Workshop, October 14, 2015