LINX LINear collider IR X-ing facility at SLAC Snowmass 2001 July 11 Andrei Seryi, SLAC for NLC collaboration

Why do we need IR-FF test facility? IR and FF are one of the most critical areas of LC Prior to start of construction, need to build and refine full scale engineering prototypes and perform adequate tests

LINX letter of intent

LINX engineering test facility e+e- collisions at SLC with ~50nm beams NLC 250 GeV 300/2 360/3.5 same 0.11mm 245/2.7nm 7.5e9 Beam Energy: 30 GeV DR emittances: gx,y=1100/50E-8m FF emittances: gx,y=1600/160E-8m IP Betas: x=8mm y=0.1mm Bunch length:  z=0.1 - 1.0mm IP spot sizes: x,y=1500/55nm Beam currents: N= 6e9 Test stabilization techniques proposed for future linear colliders and demonstrate nanometer stability of colliding beams Investigate new optical techniques for control of beam background Provide a facility where ultra-small and ultra-short beams can be used for a variety of other experiments

LINX IR and optics LINX FF NLC FF LINX IR

Nanometer stability of colliding beams Beam-beam deflection gives 1nm stability resolution BPM res Colliding beams provide a Direct Model-Independent test of any engineering solutions to the final doublet stability problem Not possible at FFTB

Controlling beam background with nonlinear elements Tail Folding via Octupole Pairs has the promise of relaxing collimation depths Confidence that comes from an Actual Demonstration may permit a great savings in collimator design, radiation shielding, and muon shielding

Technical feasibility of LINX Parasitic to PEP-II Operation: 30 HZ, 30 GeV Damping Rings: Typical SLC run: gex,y =2900/150E-8m-rad Typical FFTB gex,y = / 90E-8m-rad => need x2-3 improvement “Best” SLC gex,y = / 70E-8m-rad LINX: Reduced rep rate allows “long store” AND simple rewiring allows shift of magnetic center of QFs in ring to act as combined function magnets and to decrease ex,y by x3 Linac: No different than 1994-1997 FFTB runs and recent (E150,E157) FFTB plasma experiments Arcs: 30 GeV running reduces SR emittance growth to ~0 Final Focus: Optics are “EASY”; need only: New doublet w/ sextupoles New octupole pair to investigate tail control

Ultra-short & -low emittance beams Producing NLC-like beams increase confidence in the program Various tests relevant to NLC or exploiting the short bunches may be performed: Plasma wakefield acceleration studies Traveling focus study Low latency Feed-forward orbit correction Collimator tests Instrumentation test-bed Gamma-gamma collisions

What else can be done @ LINX? Tests of fast feedforward Tests of traveling focus (allows to play with by/sz) Position of focus is moving during collision [Balakin 91]

DECISION POINT TO PROCEED & CONSTRUCT DOUBLET LINX staging Step 1: Successfully transport e+ and e- beams to the north and south beam dumps respectively. Step 2: Demonstrate that the SLC beamlines can still deliver high quality colliding beams. DECISION POINT TO PROCEED & CONSTRUCT DOUBLET Step 3: Produce ultra-short beams. Step 4: Evaluate the effectiveness of background suppression with the new Final Focus optics. Step 5: Produce ultra-low emittance beams. Step 6: Develop fast intra-pulse feedback hardware INSTALL NEW DOUBLET Step 7: Produce < 100 nm vertical beam size at the IP. Step 8: Demonstrate nanometer stabilization at the IP.

LINX timeline

Summary LINX engineering test facility is been considered to be created at SLAC on the base of existing hardware it will help to: Test stabilization techniques proposed for future linear colliders and demonstrate nanometer stability of colliding beams Investigate new optical techniques for control of beam background Provide a facility where ultra-small and ultra-short beams can be used for a variety of other experiments We are in the process of restoration the SLC arcs vacuum and hardware, and evaluating technical feasibility of the proposal

Summary Effective design of an Interaction Region of a linear collider is a challenge, but the IR is also special because its problems are common in any incarnation of linear collider and the solutions that may be found will be applicable to any design, regardless of the choice of RF technology. The NLC collaboration is addressing the Worldwide Linear Collider community to consider participation in the LINX test facility. We believe that this test facility is of significant scientific importance and that such participation will be for our mutual benefit.

Let’s submit the LINX letter of intent jointly ! Summary Preliminary discussion shows positive reaction from our colleagues from CERN, DESY and KEK Let’s submit the LINX letter of intent jointly ! Lets joint our efforts and build it !

Acknowledgement Special thanks to Leif Eriksson, Lew Keller, Rainer Pitthan and many other people who are working on evaluation of technical feasibility of LINX The tail folding development by octupoles were inspired by earlier enthusiastic work of Reinhard Brinkmann, Dick Helm, Rainer Pitthan, Frank Zimmermann and other people F. Zimmermann, “Octupoles in Front of the Final Doublet”, NLC Accelerator Physics Note, July 14, 1998. R. Pitthan, “Using Octupoles for Background Control in Linear Colliders - an Exploratory Conceptual Study”, SLAC-PUB-8402, 1999. R.Brinkmann, “An Effective Acceptance Expander for the FFS”, presented at Beam Delivery and Interaction Region Workshop, July 2000, Thanks to all who expressed interest and support the LINX proposal