# Presentation: 533346

## 8 GeV Multi- Mission Injector Linac 

- G. William Foster

- 15 Jan 2002

## Proton Driver II Design Study

- Initiated by Fermilab Directorate
- Goal is 5x more protons in Main Injector.
- Side-by-side studies *(including cost)* of:
- 8 GeV Booster Synchrotron
*8 GeV Superconducting Linac*
- Main Injector modifications for IBEAM ~ 2 Amp
*FNAL needs a “Main Injector Sized” project ~2005*

- 15 Jan 2002

## OUTLINE

- 8 GeV Linac Concept
- Primary Parameters
- Technical Subsystems
- Cost Estimate
- Other Missions for 8 GeV Linac
- Concluding Remarks

- 15 Jan 2002

## 8 GeV Injector Linac Concept

-  1) Copy SNS Linac up to 1.2 GeV
- 	*(Reduced beam current and relaxed schedule allow some design optimizations)*
-  2) Use  “TESLA”  Cryomodules  from  1.2  8 GeV
-  3) H- Injection at 8 GeV in Fermilab Main Injector
-   “Super-Beams” in Main Injector:
*	**2 MW Beam power, small emittances, and minimum (1.5 sec) cycle time*
- Other possible missions for unused linac cycles:
- 8 GeV  program, 8 GeV electrons ==> XFEL, etc.

- 15 Jan 2002

## 8 GeV Injector Linac - Possible Sitings

- 15 Jan 2002

## 8 GeV Linac Siting for Design Study

- 15 Jan 2002

## 8 GeV Linac Parameters

- 15 Jan 2002

## Benefits of 8 GeV Injector

- Benefits to  and Fixed-Target program
- solves proton economics problem:  > 5E18 Protons/hr at 8 GeV
- operate MI with small emittances, high currents, and low losses
- Benefits to Linear Collider R&D
- 1.5% scale demonstration of TESLA economics
- Evades the Linear Collider R & D funding cap
- Simplifies the Linear Collider technology choice
- Establishes stronger US position in LC technology
- Benefits to Muon Collider / ****-Factory R&D
- Establishes cost basis for P-driver and muon acceleration
- Benefits to VLHC: small emittances, high Luminosity
- ~4x lower beam current reduces stored energy in beam
- Stage 1: reduces instabilities, allows small beam pipes & magnets
- Stage 2: injection at final synchrotron-damped emittances

- 15 Jan 2002

## Main Injector with 8 GeV Linac

- 1.5 Second Cycle time to 120 GeV
- filling time 1 msec or less
- no delay for multiple Booster Batches
- no beam gaps  for “Booster Batches” -- only Abort gap
- H- stripping injection at 8 GeV
- 25 mA linac beam current
- 90-turn Injection gives MI Beam Current  ~2.3 A
*( SNS has 1060 turn injection at 1 GeV )*
- preserve linac emittances ~0.5 (95%) at low currents
- phase space painting needed at high currents
*   **** **can put a frightening amount of beam in MI*

- 15 Jan 2002

## 120 GeV Main Injector Cycle with 8 GeV Synchrotron

- 15 Jan 2002

## 120 GeV Main Injector Cycle with 8 GeV Linac, e- and P

- 15 Jan 2002

## 8 GeV Linac Allows Reduced MI Beam Energy without Compromising Beam Power

- MI cycles to 40 GeV at 2Hz, retains 2 MW MI beam power

- 15 Jan 2002

## Running at Reduced Proton Energy Produces a Cleaner Neutrino Spectrum

- Running at 40 GeV reduces tail at higher neutrino energies.
- Same number of events for same beam power.
*(Plot courtesy Fritz & Debbie)*

- 15 Jan 2002

## Cost Estimates

- 1)  Scaled from TESLA costs
- 2)  Scaled from SNS actual costs
- 3)  Design Study Cost Estimate.
- use SNS & actual costs where reasonable
- independent, bottom-up cost estimates elsewhere
- no unproven technology or speculative cost scaling

- 15 Jan 2002

## Rough Cost, Scaled from TESLA

- TESLA Project Cost (European)	          $3B
- subtract damping rings, IR, Injector	       $2.5B
- US Cost Basis (x2) for bare linac	          $5B
- Scale to 7 GeV    (7/500) = 1.4%	       $70M
- TESLA Quantity Discount (7/500)-0.074 =1.37    $100M
- Include Fixed Project Cost  ($50M??)   **$150M**

- 15 Jan 2002

## Rough Cost, Scaled from SNS

- SNS Project Cost				$1300M
- SC Linac Cost	 (approx, incl. civil)	  $250M
- Scale SCRF by energy (7.6/0.8)	       x10
-  	 							**$2.5 B**
*There are many good technical reasons why the TESLA linac should be cheaper.  But how much? *
*Detailed breakdowns are needed to address the *
*apparent disconnect between TESLA and SNS costs.*

- 15 Jan 2002

## Cost Basis for 8 GeV Linac

- SNS _Actual_ Costs for:
- Niobium & Finished Cavities (industrially produced)
- Cavity tuners, RF Couplers, assembly labor, etc.
- Klystrons, circulators, water loads etc.
- FNAL in-house cost estimates for:
- TESLA-style Cryostat and Assembly Labor
- TESLA-Style RF distrib. from U.S. vendor pricing  (much cheaper if offshore pricing used)
- Cryogenics and Cryoplant (agrees w/SNS actuals)
- Modulators based on FNAL-built units for TTF
- Civil Construction, controls, & PM based on FMI

- 15 Jan 2002

## 8 GeV Linac Cost Estimate

- $283M  (x 1.3 Contingency) = $369M** **

***...******so this ***_***is***_*** a Fermilab Main Injector sized project.***

- 15 Jan 2002

## DISCLAIMER

- The cost estimate has not been reviewed
- Or exhaustively error-checked
- And may easily change 10-20% by time of final report
- But I believe it is OK.

- 15 Jan 2002

## Primary Parameter: 	CHARGE PER PULSE

**1.5 E14 protons (H-) per pulse**
- (same as SNS,   approximately 2.5x TESLA)
*... **as specified by charge for Design Study.*
- Equivalent of ~ 35 FNAL Booster Batches / pulse
- = 5x Main Injector design current
- = 25 mA  x  1 msec

- 15 Jan 2002

## Primary Parameter: 	LINAC PULSE LENGTH

**1 msec Beam Pulse   ==> 25 mA Current**
- ~ same pulse width as SNS and TESLA
- Many RF components & beam physics calculations (SNS) exist for this pulse width
- Conclusion of study is that 2.5 msec x 10mA might have been a better choice (==> fewer Klystrons)
*(Technical questions for longer pulse include cavity resonance control, cryogenics, and  H- injection)*

- 15 Jan 2002

## Primary Parameters: REP RATE & BEAM POWER

**10 Hz Rep rate   ==> 2 MW Beam Power**
- 	  (TESLA XFEL: 10 Hz;        SNS:  60 Hz)
- Only 0.7 Hz is necessary to fill Main Injector
- Existing 8 GeV experiment (BoonE) can only handle ~2Hz  (400kW)
- Modest cost increase between 0.7 Hz and 10 Hz
- Reason for 10 Hz is for use w/ electrons &/or “SNS”
- Operating Wall Power  = 2 MW standby + 1 MW/Hz

- 15 Jan 2002

## Primary Parameter:      Acceleration of  e-,  H-,  & P

**Linac Specified to Accelerate H- and e- only**
- 8 GeV Protons can be accumulated from H- in MI or Recycler, providing intense (10usec) beam spills
- Avoids pulsed (reversing) magnets in transport lines
- Interleaved e- running requires phase jump of cavities
- Costs for fast ferrite Phase Shifters needed to run e- are         $4M-$16M depending on detailed specifications
- Costs for XFEL lab considered to be “off budget”

- 15 Jan 2002

## Which Optimizations of SNS are worth it?

**1)  TESLA-style RF fanout**
- drive many (8-12) cavities from single big klystron
- must complete SNS development of fast phase shifter
**2)  Eliminate warm Cavity-Coupled Linac (CCL)**
- Use Beta=0.47, 805 MHz Superconducting cavities developed for RIA project by NSCL/Jlab/INFN
- Similar cryomodules & RF as Beta=0.61, 0.81 cavities
- SNS considered this but dropped due to schedule
**3) Use TESLA-style cryomodules with cold quads**
- longer cryomodules lower heat leak & fewer end costs
**4) Civil construction for fewer klystrons per meter**

- 15 Jan 2002

## Layout of 8 GeV Linac

- Copy SNS 402.5 MHz RFQ & DTL up to 87MeV
- 805 MHz Superconducting Linac up to 1.2 GeV
- Three sections: Beta = 0.47,  0.61,  0.81
- Use cavity designs developed for SNS & RIA
- TESLA-style cryomodules for higher packing factor
- 1.2 GHz “TESLA” cryomodules from 1.2-8 GeV
- This section can accelerate electrons as well
- RF from one Klystron fanned out to 12 cavites

- 15 Jan 2002

- 15 Jan 2002

## Linac:  0 - 87 MeV

- Direct Copy of SNS Design:
- H- Ion Source
- RF Quadrupole (RFQ)
- Simplified LEBT (buncher only)
- Drift Tube Linac (402.5 MHz Normal Conducting)
*SNS work provides technical existence proof*

- 15 Jan 2002

## At Reduced RF Duty Cycle of ~1%, the Front End is a Commercial Product

**CUSTOM LINAC SYSTEMS**
- AccSys’ proprietary and patented linac technology can provide a wide range of ion beams and energies for specialized applications in research and industry. AccSys experts will design a system to customer specifications consisting of a carefully selected combination of our standard modular subsystems: radiofrequency quadrupole (RFQ) linacs, drift tube linacs (DTL), rf power systems and/or other components such as high energy beam transport (HEBT) systems and buncher cavities.
***Radio Frequency Quadrupole Linacs***

- AccSys’ patented Univane (US Patent No. 5,315,120) design provides a robust, cost-effective solution for low-velocity ion beams. This unique geometry incorporates four captured rf seals, is easy to machine, assemble and tune, and is inexpensive to fabricate. The extruded structure, which is available in lengths up to three meters, can accelerate ions injected at 20 to 50 keV up to 4 MeV per nucleon. Cooling passages in the structure permit operation at duty factors up to 25%.

- Drift Tube Linacs provide a cost-effective solution for ion beam energies above a few MeV per nucleon. Designed to accelerate ions from an RFQ, the DTL’s permanent magnet focusing and high rf efficiency result in a minimum cost per MV. AccSys’ patented drift tube mounting scheme (US Patent No. 5,179,350), which is integral to the twin-beam welded vacuum tank, provides excellent mechanical stability and low beam loss.

***Drift Tube Linacs***

*D. Young’s work...*

- 15 Jan 2002

## Commercially Available Front-End Linac (AccSys)

- Don Young has verified the applicability of the AccSys RFQ/DTL to various PD scenarios.
- This is a real product.  Accsys has shipped multiple RFQ/DTL units for medical purposes in recent years.      IUCF injector uses one.
- Vendor Estimate  $20M for turn-key operation @87MeV.   (Less if FNAL provides the RF)
- This is very interesting for FNAL to pursue no matter what becomes of PD2 study.

- 15 Jan 2002

## AccSys Source/RFQ/DTL

- Appears to have shorter length and lower price than cloning the SNS Linac, _*for 10 Hz operation*_

- AccSys PL-7 RFQ with one DTL tank

*D. Young’s work...*

- 15 Jan 2002

## Transition from Copper to SC Linac

- Conventional Alvarez DTL is cost effective    for E < ~ 100 MeV
- Above 100 MeV cavity-coupled linac (CCL) is best *copper* solution (e.g. FNAL linac upgrade)
- SNS chose CCL from 87-190 MeV, but recognized that money could be saved by using SC cavities in this energy range (no R&D Time)
-    *The 8 GeV linac eliminates the CCL by using  SC cavities (subsequently developed for RIA).*

- 15 Jan 2002

## CRYOMODULES

- _BIG Differences between SNS & TESLA_
- Key Specification:
- SNS Cryomodules can be swapped out in _*~1 shift*_
- TESLA cryomodule replacement takes *~*_*25 days*_ *
- comes from having 2.5 km section of linac w/o bypass line
- 8 GeV LINAC:  _*~2 day*_ repair time specified
- possible because linac sector is much shorter ~300 m
*(M. Geynisman)*

- * http://tesla.desy.de/new_pages/TESLA_Reports/2001/pdf_files/tesla2001-37.pdf

- 15 Jan 2002

## SNS/CEBAF Cryomodules

- Warm-to-cold beam pipe transition in each module
- 2K Coldbox, J-T & HTX in each Cryomodule
- Bayonet disconnects at each coldbox
- Only 2-4 cavities per cryomodule    (f.f.~ 50%)
*Expensive Design forced by fast-swap requirement*

- 15 Jan 2002

## TESLA-Style Cryomodules for 8 GeV( T. Nicol )

- Design conceptually similar to TESLA
- No warm-cold beam pipe transitions
- No need for large cold gas return pipe
- Cryostat diameter     ~ same as LHC
- RF Couplers are KEK/SNS design, conductively cooled for 10 Hz.              *(R. Rabehl)*

- 15 Jan 2002

## 9 Cell Beta=1 Cavities, 1207.5 MHz

***9 Cell Beta=1 Cavities, 1207.5 MHz***

- 15 Jan 2002

## Scaling of TESLA Cryomodules for 1-8 GeV

- _Frequency_: 1300 MHz  1207.5 MHz
- for compatibility with 805 MHz front-end Linac
- 1.2 GHz cavities must be ~ 8% larger than TESLA
- 8 Cavities per Cryomodule not 12 (TESLA)
- _Accelerating Gradient for Protons _
- Eacc ~ 23 MeV/m (Epeak~45MV/m)
- Protons Linacs must run off-crest for phase stability (cos ~ 0.9)
- _Number of Quadrupoles_
- 8 GeV requires 2 quads per 16m cryomodule not 1/3
- Quads must be long ~1m to avoid H- stripping from B-field
- _Vacuum Breaks_: every ~ 80m not 500m  (design choice)

- 15 Jan 2002

## Cryomodule Technical Parameters

- 15 Jan 2002

## Self-Consistent Accelerator Physics Design(Jim MacLachlan)  

-    Had to increase number of quads to get to good design...

- 15 Jan 2002

## Quadrupole Technical Parameters

- 15 Jan 2002

## Superconducting Cavity Gradients

- 8 GeV design
- assumes *peak*
- field in cavities
- of 45 MV/m.
- SNS:
-     37.5 MV/m
- TESLA(500):
- 	47 MV/m
- TESLA(800):
- 	~70 MV/m

- 15 Jan 2002

## Cavity Technical Parameters

- 15 Jan 2002

## SNS Cavity Fabrication

- Deep drawing & machining

- Dumb-bells

- Frequency adjust

- Welding

- SNS =0.61

- Tuning

- 15 Jan 2002

## SNS  = 0.81  Tests at TJNAF

**Eacc > 20 MV/m for protons **
**is now reasonable design goal**

*[ from N. Holtkamp Nov ‘01 SNS Review]*

- 15 Jan 2002

## SNS Cavity Costs

- We have graciously been given access to SNS actual costs for ~110 completed SCRF RF cavities, tanks, tuners, couplers, etc. including final chemistry and assembly labor.
*(Thanks to N. Holtkamp, E. Daly, Katherine Wilson)*
- The 8 GeV Linac needs 416 cavity assemblies                       $35M for 8 GeV Linac
- This assumes:
- no quantity discount or rebate for existing tooling
- that 1.2 GHz  9-cell cavities are the same price as 805 MHz  6-cell SNS cavities of same length

- 15 Jan 2002

## 8 GeV Cryomodule Costs

- Costs for SNS cavity assemblies and RF power couplers integrated into TESLA-style cryomodules were estimated by T. Nicol (TD)
- Tom is the project manager for US LHC cryostats
- USLHC requires ~270m of cryostats, 8 GeV ~ 650m
- Final Cost including cavities, cryostats, RF couplers, EDIA & labor, no contingency:
- 52 Cryomodules @ $1093k ea. = $57M
*... **this is the biggest single cost component*

- 15 Jan 2002

## Cryomodule Cost Estimate

- 15 Jan 2002

## CRYOGENICS & CRYO PLANT

- 8 GeV Linac Cryoplant is ~ same size as SNS
- Linac is longer: 8 GeV vs. 1 GeV
- RF Duty Cycle is smaller 1% vs. 6%
*Dynamic heat load is about the same*
- 8 GeV Linac Static heat leak per meter                  is similar to TESLA (TTF)
- No bayonet or cold box heat loads per cryomodule
*Standby heat load  < ~  SNS*

- 15 Jan 2002

## CRYOGENICS & CRYO PLANT

- Arkadiy Klebaner (BD) is doing detailed analysis of 8 GeV linac cryogenic requirements & cost
- Tom Nicol(TD): cryostat detailed design & costs
- Tom Peterson (TD): System Heat Loads
- Michael Geynesman (BD): cool-down calcs.
- Roger Rabehl (TD): power Coupler calcs
*These guys are the top draft choices and really*
*they know what they are doing.*

- 15 Jan 2002

## Cryoplant and Distribution Box 

- Cryoplant Process Flow

-    Distribution Box and Transfer Line Flow Schematic

- 15 Jan 2002

## Cryomodule Coolant Flows needed for 48-hour Module Replacement

- It appears we can meet the  48-hour target using LN2/GHe precooling and warm-up heaters
- Thermal stresses may be an issue

- 15 Jan 2002

## Cryogenic Technical Parameters

- 15 Jan 2002

## SNS CHL Facility

_*8 GeV Linac Cryoplant will be comparable ~$15M*_

- 15 Jan 2002

## RF System for 1 8 GeV Linac

- Must assume TESLA-style RF distribution works
*This will require fast phase shifters for individual cavity control*
- One TESLA multi-beam Klystron per ~12 Cavites
- 24 Klystrons  10 MW each
- 288 total 1207 MHz power couplers  600kW each
- Modulators are identical to TESLA modulators
- Rough Cost:  $1.5M / RF station    $45M
- (TESLA costs & scaling rule* gives ~ $31M)
- 					*cost proportional to (quantity)-0.074

- 15 Jan 2002

## TESLA Tunnel & Klystrons

- 15 Jan 2002

## RF Fan-out for 8 GeV LinacA. Moretti, D. Wildman

- 15 Jan 2002

- 15 Jan 2002

## RF Power Budget & Coupler Power

- 15 Jan 2002

## RF Distribution Technical Parameters

- 15 Jan 2002

## RF - Klystrons

- 402.5  MHz / 2.5 MW   (7 total)
-  805    MHz / 5.0 MW  (10 total)
- 1207.5 MHz / 10 MW  (36 total)

- SNS Actual

- TESLA Design
- Scaled by ~ 7% from 1.3GHz

- 15 Jan 2002

## Klystron Technical Parameters

- 15 Jan 2002

## Klystron Cost Estimate

- 15 Jan 2002

## Modulators for Klystrons

- Biggest single component in RF costs
- Pfeffer, Wolff, & Co. (FNAL BD) have been making TESLA spec modulators for years
- FNAL Bouncer design in service at TTF since 1994

- 15 Jan 2002

## Modulator Circuit

- IGBT / Capacitor Discharge circuit
- Bouncer to maintain flat top
- Redundant Switch with Ignitron Crowbar
- Pulse Transformer 10kV to 130 kV (typ.)

*H. Pfeffer, D. Wolff, & sons.*

- 15 Jan 2002

## Modulator Cost Estimate

- 15 Jan 2002

## RF Phasing in Linac for Protons vs. Electrons

- Cavity cell length changes as proton accelerates
- not all cavities can be same design
- lose some gradient by running off design 
- Protons are non-relativistic
- energy error  downstream phase error
- Protons run off-crest
- only get ~85% of accelerating gradient at crest
- more sensitive to phase errors
- Must change cavity phases to accelerate electrons and protons on alternate cycles

- 15 Jan 2002

## CAVITY MICROPHONICS

- Cavity Bandwidths     are  ~ 1 kHz   (Q~106)
- Mechanical vibrations can shift resonant freq. by comparable amount.
- Produces large shift in required *phase* and *amplitude* of RF drive
- Codes exist to simulate impact on proton beams from measured (SNS/TESLA) microphonics.

- 15 Jan 2002

## Tuners and Cavity Resonance Control

- TESLA R&D has shown that piezoelectric tuners can correct for Lorentz detuning and cavity microphonics in a 1 ms pulsed SC linac.
- SNS Cavity assemblies used for cost basis include *both* Mechnical and Piezoelectric tuners
- RF phase and amplitude control provided for individual cavities via fast ferrite phase shifters.
- Simulation (& SNS experience) needed to determine bandwidth requirement of shifters.

- 15 Jan 2002

## Fast Ferrite Phase Shifter R&D

- Provide fast, flexible drive to individual cavites of a proton linac,  when one is using TESLA-style RF fanout.
- Also needed if Linac alternates between e and P.
- The fundamental technology is proven in phased-array radar transmitters.
- This R&D was started by SNS but dropped due to lack of time.  They went to one-klystron-per-cavity which cost them a lot of money (~$20M).

- 15 Jan 2002

## “SNS March 2000” Design, 12 Cavities / KlystronIndividual + Collective Cavity Control

- SNS pursued & dropped due to lack of R&D time

- 15 Jan 2002

## SNS Final Baseline RF Design 1 Klystron Per Cavity, Individual Control

- Conceptually simpler but ~10x more Klystrons

- 15 Jan 2002

## RF Fanout at Each Cavity

- 15 Jan 2002

## ELECTRONICALLY ADJUSTABLEE-H TUNER

- FERRITE LOADED SHORTED STUBS
- CHANGE ELECTRICAL LENGTH DEPENDING ON DC MAGNETIC BIAS.

***TWO COILS***  PROVIDE INDEPENDENT
***PHASE AND AMPLITUDE *** CONTROL OF CAVITIES

- Attractive Price Quote from AFT
- (<<  Klystron)

- 15 Jan 2002

## Phase and Amplitude Tuner Specs

*...**tuner bandwidth has significant impact on cost*

- 15 Jan 2002

## 805 MHz RF Distribution in Tunnel

- 15 Jan 2002

## RF Distribution Cost Estimate

- 15 Jan 2002

- 8 GeV Linac - Siting for Design Study (FESS)

- 15 Jan 2002

## Civil Construction Cost Estimate

- $56M  (x 1.3 conting.)  =  $73M

- 15 Jan 2002

## Main Injector Actual Civil Construction Costs               vs. 8 GeV Linac Estimate

- 15 Jan 2002

## Slide 79

- 15 Jan 2002

## 8 GeV  Klystron Gallery Floor Plan

- Linear array of equipment - simpler than SNS
- Much more room allocated for electronics     than TESLA design

- 15 Jan 2002

## SNS Tunnel & Klystron Gallery

*SNS:*
*One Klystron *
*every ~3m *
*along beam *
*line*
*(TESLA: 50m)*
*(8 GeV: 16m)*

- 15 Jan 2002

## Note on Klystron Location

- The Civil Construction (Klystron Gallery) costs could be reduced _a lot_ if we adopt the TESLA scheme of putting the Klystron and instrumentation electronics in the tunnel, and running a fat cable to a single building with all of the modulators in it.
- This may not be an acceptable technical risk.

- 15 Jan 2002

## Tunnel Cross Sections

- 15 Jan 2002

## FRONT END BUILDING

- 15 Jan 2002

## Front End Building Cost Estimate

- Cost Model is Main Injector MI-60 Service Building

- 15 Jan 2002

## LCW System from Fess

- 15 Jan 2002

## Cooling Water (LCW) Loads

- System designed for 15 degC Maximum Temperatue Rise

- 15 Jan 2002

## Site Work & Utilities:  $13M x 1.3 = $17.3M

- 15 Jan 2002

## MAIN  INJECTOR  CONNECTION

- 15 Jan 2002

## 8 GeV Injection Line Optics with Betatron and Momentum Collimation

- 15 Jan 2002

## Foil Stripping Collimation of H-

- Traditional collimation schemes incite multiple scattering & showers which result in some “damaged beam” transported down beam channel
- H- ions can be cleanly collimated with foil stripping followed by sweeping magnets
- A beam channel can be designed (BNL/SNS) which is incapable of transporting halo or off-momentum beam, (or damaged beam).

- 15 Jan 2002

## 8 GeV H- Stripping in Magnets

- B= 0.06 Tesla strips only 1E-6 of Beam in 10m length
- 500m Bend Radius is OK
- Stripped Beam Power is <1 Watt

- 15 Jan 2002

## H- Injection Layout Example

- Foil Stripping Injection at 8 GeV
- Slow orbit bump disappears as beam accelerates
- (fast, smaller orbit bump also required to escape foil)
- Injected beam misses nearest quad in MI straight section

- 15 Jan 2002

## H- Injection Painting(A. Drozhdin)

- Painting from 2pi into 40pi with 90-turn injection seems feasible
- Peak foil temperature ~2300 degC
-      (tolerable with new diamond foils from BNL)

- 15 Jan 2002

## Adiabatic Capture vs. Chopping

- Adiabatic Capture at 8 GeV (no 53 MHz RF chopping)
- We are less sensitive to injection losses than SNS’s (since EINJECTION << EFINAL)
- We have more time for Adiabatic Capture (100 ms)
- Simulations (K. Koba) indicate very high capture efficiency in shorter time.

- 15 Jan 2002

## SECONDARY MISSIONS

- _Main Mission:_ “Super-Beams” in Main Injector
- _Possible Secondary Missions:_
- 1)   8 GeV Neutrino Program
- 2)   8 GeV Spallation Neutron Source
- 3)   8 GeV Fixed-target Program
- 4)   -factory front end
- 5)   Electron Linac
- 6)   XFEL
- 7)   Recirculating microtron (pseudo-CEBAF)
- 8)   Pbar Deceleration
- 9)   TESLA damping ring preaccelerator linac .....
-                                     *...etc... etc...* *etc...*

- 15 Jan 2002

## Possible Secondary Mission #1: 8 GeV Neutrino Experiments

- 8 GeV beam for Mini-BooNE follow-on
- Interleave one 8 GeV cycle(s) with MI filling
- > 3.6E17 Protons/hr to *both* MI and BooNE
- Upgrade potential for >10 MW of 8 GeV beam
- ~ 20% efficiency wall power  beam
*Mini-BooNE confirms the LSND result, the 8 GeV linac could help increase statistics >20x.*

- 15 Jan 2002

## Demand Schedule for 8 GeV Protons

- 8 GeV
- Linac
- >1E18/hr

*R. Webber*

- 15 Jan 2002

## Possible Secondary Mission #2: 8 GeV Spallation Neutron Source

- Upgrade RF Duty cycle from 1% to ~5%
- RF, couplers, and cryo pipe sizes must anticipate this
- Add SNS-Style Accumulator Ring    (R ~ 50m)
- Biggest incremental cost will be Target facility

***8 GeV Linac has the potential be competitive as a pulsed neutron source,  if FNAL is interested...***

- (Installed Klystron peak power ~300MW vs. ~50 MW in SNS)

- 15 Jan 2002

## Possible Secondary Mission  #3: 8 GeV Fixed-Target Program

- Pion production per incident beam energy is maximized at ~6 GeV        *(N. Mokhov)*
-  Best source for precision , K experiments.
- The RF time structure (~50 psec bunches) would allow high-quality TOF separation of neutral K’s
- The Recycler might be used as 8 GeV stretcher ring to provide ~ continuous beams of protons.

- 15 Jan 2002

## Possible Secondary Mission  #4: Neutrino Factory

- Very Similar to 8 GeV Spallation Source
- (but shorter time spread on target)
- Possible to use _*same linac*_ to _*re-accelerate *_the muons after filling the accumulator ring?
- 1) use linac to fill the 8 GeV accumulator for ~1 msec.
- 2) rephase the cavities for muon acceleration (~0.2 ms).
- 3) bunch the accumulator beam and extract onto target.
- 4) debunch & cool the muons in couple sec
- 5) reaccelerate the muons in *same* linac at 8 GeV/turn.
- 		 *everything uses DC magnets.*

- 15 Jan 2002

## Possible Secondary Mission #5: 8 GeV Electron Linac

- At least 7 GeV of the linac can accelerate e-
- electrons run on-crest, so the gradient will be higher     9-10 GeV e-beams
- Re-phase the cavites for (multiple) pulses of electrons between proton injections to FMI.
- Many possible physics missions, test beams, etc.
- Smaller activation problems than proton beams
- An 8-GeV Linac and SCRF infrastructure makes FNAL a good site for a super-B-factory...

- 15 Jan 2002

## Possible Secondary Mission #6: X-ray Free Electron Laser (XFEL)

- There may be competition for XFEL’s in the U.S.
- FNAL may want to stay out (or collaborate).
- Concept of joint ANL-FNAL-DESY project, (sister XFEL’s at DESY and FNAL),  with ANL taking the lead on US XFEL user facility...?

- 15 Jan 2002

## Possible Secondary Mission #7: Recirculating Electron Linac

- A CEBAF-Style Recirculating Linac could be made with   ~  8 GeV per pass
- Smaller Duty Cycle than CEBAF,  but higher energy per pass.
- Either MI or MR tunnels could hold stretcher ring to provide ~ continuous beams of *electrons.*

- 15 Jan 2002

## Possible Secondary Mission #8: Antiproton Deceleration

- Scenario:
- 1) Electron-cool Antiproton Beams in Recycler
- 2) Ultra-cool core can be frictionally dragged away and separately extracted
- 3) Small emittances will decelerate efficiently   in large-aperture SC Linac
-  World’s best source of “stopped” antiprotons

- 15 Jan 2002

## VLHC and the 8 GeV Injector

- The small beam emittances obtainable with the 8 GeV Injector will make FNAL *by far* the best VLHC injector.
- Small Emittances  Small Beam Currents at fixed Luminosity
-  Small Stored Energy in Beams
-  Small instability problems in small beam pipes ( Small magnets)

- 15 Jan 2002

## Proton Driver vs. 8 GeV Injector

- There is little doubt that, in principle, a synchrotron is cheaper.
- If we are manpower limited:  an 8 GeV Linac has many fewer parts to design than a new Booster Synchrotron.
- The 8 GeV linac will probably be simpler to operate.
- The 8 GeV linac is more likely to produce smaller emittances, if that is the primary goal.
- It can accelerate electrons, and so has a broader range of uses.
*Difficulty with reconciling Proton Driver with B&B subpanel recommendations can be finessed by 8 GeV Linac.*

- 15 Jan 2002

## The Linear Collider & 8 GeV Injector

- If the plan is the LC, will be an advantage in asking for this $7B project to have already completed a _*~1% proof-of-principle facility*_ showing that we understand the performance and costs.
- However in the current political climate, it may be _*difficult to ask for a $100M+ proof-of-principle*_ facility as the _*leading edge of a $7B project*_  (GWF opinion).
- FNAL needs a construction project ~ 2005 when NUMI & LHC money starts vanishing.  _*Need to get a project into the pipeline NOW*__.__ _
- The 8 GeV linac has _*good, stand-alone physics missions*_ and will simultaneously _*provide $200M+ “LC R&D” funds*_ to demonstrate that we understand the performance and economics of big linacs.
- Since _*only the TESLA design can accelerate protons*_, it simplifies the LC technology choice, which can be made promptly and without contentious technology and cost comparisons.

- 15 Jan 2002

## Many Other Users of SCRF Linacs

- 15 Jan 2002

## The Linear Collider & 8 GeV Injector (cont’d)

**If TESLA is approved in the next couple of years,** then the 8 GeV Injector gives the US the opportunity to extract some benefit from our contribution to SCRF Linac technology. *(makes it easier to argue for a US contribution to TESLA if there is a simultaneous construction project with related technology in US)*
**If TESLA  is  NOT immediately approved,** and only TTF-2 and the 8 GeV Injector are completed,then by ~2009 this will leave the US holding the *strongest technological position to bid for the LC.**(and 8 GeV linac can be used for TESLA Damping ring pre-acc.)*
- The 8 GeV Linac holds the best promise of retaining the current construction slots in HEP (namely NUMI and the LHC),while remaining true to the strategic vision of the B&B subpanel.

- 15 Jan 2002

## PROJECT INFORMATION

- 30 Page Parameter List  (v1.8)
- (Soon) Cost Estimate Spread Sheet  w/ BoE
- ~ May 15th - Design Study Final Report
- 		*(delayed by Run II Travails...)*
- _http://tdserver1.fnal.gov/project/8GeVlinac_

- 15 Jan 2002

## CONCLUSIONS

- An 8 GeV Injector Linac will be a useful component at FNAL no matter what future machine is built.
- There are no technical difficulties, just further optimizations.  Can copy existing designs.
- It should make FNAL complex simpler to run.
- The cost will be similar to the Main Injector and Proton Driver.

- 15 Jan 2002