eRHIC with nonscaling FFAGs Dejan Trbojevic 1 Nonscaling

e-RHIC with non-scaling FFAG’s Dejan Trbojevic 1

Non-scaling FFAG for e. RHIC • Introduction to a concept of non-scaling FFAG • Requirements for the e. RHIC • Arc single ring to accept 2. 4 -10 Ge. V electron beams • 1. 9 Ge. V Linac • Going around detectors • Matching the straights to arcs • Summary and required future work Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 2

What is the non-scaling FFAG? • The first one is presently being built in UK: “EMMA” • Orbit offsets are proportional to the dispersion function: Dx = Dx * dp/p • To reduce the orbit offsets to +-6 cm range, for momentum range of dp/p ~ +- 60 % the dispersion function Dx has to be of the order of: Dx ~ 6 cm / 0. 6 ~ 10 cm • The size and dependence of the dispersion function is best presented in the normalized space and by the H function: = Dx / x and = D’x x + x Dx x with H: H = 2 + 2 Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 3

Basic properties of the NS-FFAG A. Particle orbits B. Lattice Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 4

Basic properties of the NS-FFAG Concept introduced 1999 at Montauk meeting –Trbojevic, Courant, Garren) using the light source lattice with small emittance minimized H function Muon acceleration - Extremely strong focusing with small dispersion function. - large energy acceptance. - tunes variation - very small orbit offsets - small magnets Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 5

Recent example of the muon acceleration collaboration with the Muon. inc Orbits magnified 100 times From 2. 5 Ge. V- 10 Ge. V Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 6

New Concept: Multipass Linac with racetrack FFAG 20 Cavities Chicane Non-scaling FFAG arc 20 Cavities Chicane Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 7

Layout of the RHIC tunnel Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 8

Possible locations of the magnets Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 9

Previous solution (PAC 07) Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 10

Previous work on the non-scaling FFAG in RHIC tunnel Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 11

Layout of the Arc in RHIC Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 12

Design of the arcs – from the densely populated FODO cells for the 2 - 10 Ge. V electrons N=648 cells L=3. 6965 m R 1=381. 23249 m LBD=1. 6 m LQF=1. 0 m 3 2. 81 m For the dp/p=[0, -80 %] BBD = + 0. 078 T BQF = + 0. 199 T Orbits are magnified 1000 times 762. 46 m 3 r= GF= 9. 15 T/m GD= - 5. 4 T/m @ electron energy=3. 8 Ge. V Bmax=0. 078 - 5. 4 *(-0. 048)=-0. 34 T Bmax=0. 199 +9. 15*(-0. 069)=-0. 43 T Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 13

Design of the arcs – from the densely populated FODO cells for the energy range of 2. 4 -> 10 Ge. V electrons Orbits in the arc cell – there are 648 cells in the whole ring Bd/2 Bf Bd/2 44 mm 0. 8 m 0. 5483 m 1. 0 m 0. 8 m 3. 696228 m Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 14

Design of the arcs – from the densely populated betatron functions vs. momentum Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 15

Design of the arcs – from the densely populated betatron functions vs. momentum Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 16

The linac – triplets with cavities Qd Qf Cavity Qf Qd 10 Ge. V 2. 4 Ge. V 7. 393 m Gf =15. 8 T/m Gd=-10. 4 T/m Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 17

Superconducting linac: Betatron Function dependence on energy Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 18

New concept of the linac – Tunes per Linac cell Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 19

Matching cell – arc to linac The matching cell length is: L=2 * 3. 696 m = 7. 393 m Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 20

Design of the large cells – match to the linac 0. 8 m 1. 0 m 0. 8 m Orbit offset are identical to the arc orbit offsets 7. 393069 m Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 21

Design of the arcs – Matching to the linac Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 22

Larger cells to match to linac from arcs Orbit offsets are zero Lp_cell q=qo= 2 p/648 Ln_cell q=-qo= -2 p/648 Lp_cell q=qo= 2 p/648 Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 23

Creating the 4. 6 m around the detectors 4. 6 meters 4. 6 m Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 24

The whole ring with two straight sections - linacs 229 meters Separation Of 4. 6 meters Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 25

The whole ring with two straight sections - linacs 229 meters Separation Of 4. 6 meters Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 26

The linac Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 27

Time of flight – Path length dependence on energy Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 28

Summary: • The non-scaling FFAG concept could be applied for e. RHIC within the existing tunnel. • The non-scaling FFAG arc has been constructed to accept in a single pipe electrons in energy range from 2. 4 – 10 Ge. V with a circular 10 Ge. V electron orbit, maximum orbit offsets of ~70 mm for the lowest energies, and with the maximum magnetic fields of 0. 4 T at the lowest energy. The magnetic field strengths for the 10 Ge. V electrons are B max< 0. 2 T. • A new concept of energy recovery linac with small changes in the betatron functions for the six times in energy range has been presented for the first time. • Possibilities of bypasses and time of flight adjustments have been explored. • Matching between the arcs and straight sections for linac needs to be improved. • A special beam line to send electrons towards the detector need to be designed. Dejan Trbojevic EIC Collaboration Meeting, Hampton University, Virginia May 19, 2008 29