Ionization Cooling neutrinos colliders and betabeams David Neuffer

Ionization Cooling – neutrinos, colliders and beta-beams David Neuffer July 2009 1

Outline Ø Front End and Cooling – IDS neutrino factory § Study 2 A – ISS baseline example • Target-capture, Buncher, Rotator. Cooler § Shorter bunch train example(s) • n. B= 10, Better for Collider; as good for ν-Factory § Variation – 88 MHz Ø Rf cavities in solenoids – major constraint? § up to 15 MV/m, ~2 T § Alternatives • Use lower fields (B, V’), use “magnetic insulation” ASOL lattice, use gas-filled rf cavities Ø Large Emittance Muon Collider option Ø Low-Energy Cooling discussion § ERIT results § Ion cooling for Beta-beams 2

Official IDS layout 3

For IDS need baseline for engineering Neutrino Factory-IDS 4

ISS Study 2 B baseline Ø Base lattice has B=1. 75 T throughout buncher and rotator § rf cavities are pillbox § grouped in same-frequency clusters • 7 to 10 MV/m Buncher; 12. 5 Rotator • 750μ windows in “Rotator” § with 200μ to 395μ Be “windows”, Ø Cooling Lattice is alternatingsolenoid with 0. 75 half-period § 0. 5 m pillbox rf cavity § 1 cm Li. H absorbers § 15. 25 MV/m cavities 5

IDS - Shorter Version Ø Reduce drift, buncher, rotator to get shorter bunch train: § 217 m ⇒ 125 m § 57 m drift, 31 m buncher, 36 m rotator § Rf voltages up to 15 MV/m (× 2/3) Ø Obtains ~0. 26 μ/p 24 in ref. acceptance § Similar or better than Study 2 B baseline Ø Better for Muon Collider § 80+ m bunchtrain reduced to < 50 m § Δn: 18 -> 10 500 Me. V/c -30 40 m 6

Shorter Buncher-Rotator settings Ø Buncher and Rotator have rf within ~2 T fields § rf cavity/drift spacing same throughout (0. 5 m, 0. 25) § rf gradient goes from 0 to 15 MV/m in buncher cavities Ø Cooling same as baseline § § ASOL lattice 1 cm Li. H slabs (3. 6 Me. V/cell) ~15 MV/m cavities also considered H 2 cooling ASOL lattice Ø Simulated in G 4 Beamline § optimized to reduce # of frequencies Ø Has 20% higher gradient 7

Rf in magnetic fields? Ø Baseline has up to 12 MV/m in B=1. 75 T (in 0. 75 m cells) Ø short version has up to 15 MV/m in B=2. 0 T Ø Experiments have shown reduced gradient with magnetic field Ø Results show close to needed ? § 14 MV/m at 0. 75 T on cavity wall § half-full or half-empty ? Ø Future experiments will explore these limits § will not have 200 MHz in constant magnetic field until summer 2010 Ø Open cell cavities in solenoids? § did not show V’ /B limitation 8

Solutions to possible rf cavity limitations Ø For IDS, we need an rf cavity + lattice that can work Ø Potential strategies: § § Use lower fields (V’, B) Use Open-cell cavities? § Use non-B = constant lattices § § § • alternating solenoid Magnetically insulated cavities • • Is it really better ? ? ? Alternating solenoid is similar to magnetically insulated lattice Shielded rf lattices • low B-field throughout rf Rogers Use gas-filled rf cavities • but electron effects? 9

Lower-field (? ) Variant Ø Use B=const for drift + buncher § Low-gradient rf ( < 6 MV/m) § B= 1. 5 to 2. 0 T ? Ø Use ASOL for rotator + Cooler (and/or H 2 cavities) § 12 MV/m rf Rotator § 15 MV/m cooler § 0. 75 half-cells Ø Simulation: fairly good acceptance § Lose some low energy mu’s • bunch train shortened § ~0. 25 μ/24 p after 60 m H 2 cooling § ~0. 19 μ/24 p after 60 m Li. H cooling 10

Change cavity material-Palmer Ø Be windows do not show damage at MTA § no breakdown? Ø Model: Energy deposition by electrons crossing the rf cavity causes reemission on the other side Ø less energy deposition in Be § higher rf gradient threshold Ø ~2× gradient possible with Be cavities ? ? § calculated in model § extrapolation to 200 MHz ? B electrons 11 2 R

Variant: “ 88” MHz Front end Ø Drift ~90 m Ø Buncher ~60 m § 166→ 100 MHz, 0→ 6 MV/m Ø Rotator ~58. 5 m § 100→ 86 MHz, 10. 5 MV/m Ø Cooler ~100 m § 85. 8 MHz, 10 MV/m § 1. 4 cm Li. H/cell ASOL p π→μ FE Tar get Solenoid 10 m Drift ~80 m Buncher ~60 m Rotator 60 m Cooler ~100 m 12

88 MHz example Ø Performance seems very good § ~0. 2 μ/p 24 Ø smaller number of bunches § > ~80% in best 10 bunches Ø Gradients used are not huge, but probably a bit larger than practical § up to ~10 MV/m § ~2 T magnetic fields Ø With 10 MV/m (0. 75 m cells) probably not free of breakdown problems Ø redo with realistic gradients § 6 MV/m ? 13

Plan for IDS Ø Need one design likely to work for Vrf/B-field § rf studies are likely to be inconclusive Ø Hold review to endorse a potential design for IDS § – likely to be acceptable (Vrf/B-field) § April 2010 ? Ø Use reviewed design as basis for IDS engineering study 14

Cooling for first muon collider Ø Important physics may be obtained at “small” initial luminosity μ+μ- Collider Ø μ+ + μ- -> Z* , HS § L > 1030 cm-2 s-1 Ø Start with muons fron neutrino factory front end: Ø 3 × 1013 protons/bunch § 1. 5× 1011 μ/bunch • ~12 bunches – both signs! § εt, rms, normalized ≈ 0. 003 m εL, rms, normalized≈ 0. 034 m Ø Accelerate and store for collisions Ø Upgrade to high luminosity 15

Proton Source: X -> ν-Factory/μ-Collider Ø Project X based proton driver Ø 8 Ge. V SRF linac , 15 Hz § 1. 2× 1014/cycle 8 Ge. V Linac Accumulator Buncher Ø H- inject full linac pulse into new “Accumulator” § “small” dp/p § Large εN 6π =120π mm-mrad Ø Bunch in harmonic 4 § adiabatic OK !! (2 k. V) Ø Transfer into new “Buncher” § § 100 k. V h=4 1250 turns (2 ms) short ~1 m bunches !! 3× 1013/bunch • • BF = 0. 005 δν = 0. 4 16

Large Emittance Muon Collider Proton Linac 8 Ge. V Accumulator, Buncher Hg target Drift, Bunch, Cool 200 m Linac RLA s Detector Collider Ring Use only initial “front-end” cooling Accelerate front-end bunch train; collide in ring Parameter Symbol Value Proton Beam Power Pp 2. 4 MW Bunch frequency Fp 60 Hz Protons per bunch Np 3× 1013 Proton beam energy Ep 8 Ge. V Number of bunches n. B 12 +/-/ bunch N 1011 Transverse emittance t, N 0. 003 m Collision * * 0. 05 m Collision max * 10000 m Beam size at collision x, y 0. 013 cm Beam size (arcs) x, y 0. 55 cm Beam size IR quad max 5. 4 cm E +, E _ 1 Te. V (2 Te. V total) Nt 1000 L 0 4× 1030 Collision Beam Energy Storage turns Luminosity 17

Must be upgradeable to “high-luminosity” Ø MEMC Upgrades § reduce εt to 0. 001 m • initial part of HCC § 1300 MHz rf § combine 12 -> 1 bunch § L -> 3 1032 Ø High luminosity § Cool to 0. 000025 Parameter Symb ol HEMC MEMC LEMC Value Proton Beam Power Pp 2. 4 MW 4 MW Bunch frequency Fp 60 Hz 60 Hz 15 Hz Protons per bunch Np 3× 1013 5× 1013 4× 1013 Proton beam energy Ep 8 Ge. V 50 Ge. V Number of bunches n. B 12 1 1 +/-/ bunch N 1011 1. 5× 1012 2× 1012 Transverse emittance t, N 0. 003 m 0. 001 m 0. 000025 Collision * * 0. 06 m 0. 04 0. 01 x, y 0. 013 c m 0. 0063 cm 0. 0005 cm Beam size (arcs) x, y 0. 55 cm 0. 32 cm 0. 05 cm Beam size IR quad max 5. 4 cm 3. 2 cm 0. 87 cm Collision Energy E +, E _ 1 Te. V (2 Te. V total) 1 Te. V Luminosity turns nt 1000 Luminosity cm-2 s-1 L 0 18 34 4× 103 2. 7× 103 1. 5× 10 Beam size collision at 0 2

Other cooling uses- not just high-energy muons! Ø. Stopping beam § (for 2 e, etc. ) § C. Ankenbrandt, C. Yoshikawa et al. , Muons, Inc. Ø For BCNT neutron source § Y. Mori - KURRI Ø For beta-beam source (d. E/ds)/ E= g. L(dp/ds)/p § C. Rubbia et al Ø… 19

Revisit Use of NF/MC Front End to Stop Muons with Momentum-dependent HCC μ± & π± from 100 k POT MERIT-like targetry C Yoshikawa P(Me. V/c) end of NF/MC drift region 170 μ−’s stopped Virtual detector 25 r=3 m … Mu-’s at end of HCC. Displayed is 5398/100 k, but stopping rate is 3519/100 k. HCC matching (not done) 100 k Mu-’s w/ Bent Sol Spread at start of HCC. Mu-’s midway to end of HCC (20, 836/100, 000) Potential to enhance yield via P vs. y correlation in bent solenoid. 20

FFAG-ERIT neutron source (Mori, KURRI) Ø Ionization cooling of protons/ ions is unattractive because nuclear reaction rate energy-loss cooling rate Ø But can work if the goal is beam storage to obtain nuclear reactions § Absorber is beam target, add rf Ø ERIT-P-storage ring to obtain neutron beam (Mori-Okabe, FFAG 05) Ø 10 Me. V protons (β = v/c =0. 145) target for neutrons § 5µ Be absorber, wedge (possible) § δEp=~36 ke. V/turn § 10 Be Ø Ionization cooling effects increase beam lifetime to ~ 1000 turns § not actually cooling 21

Observations of “Cooling”-PAC 09 Ø ERIT ring has been operated Ø Beam lifetime longer than without energy-recover rf § agrees with ICOOL simulation Ø Beam blowup is in agreement with simulation § multiple scattering heating in agreement with ICOOL 22

β-beam Scenario (Rubbia et al. ) Ø β-beam – another e source § Produce accelerate, and store unstable nuclei for -decay § Example: 8 B 8 Be + e++ν or 8 Li 8 Be + e+ ν* Ø Source production can use ionization cooling § Produce Li and inject at 25 Me. V § nuclear interaction at gas jet target produces 8 Li or 8 B • • e 7 Li + 2 H 8 Li + n 6 Li + 3 He 8 B + p § Multiturn storage with ionization “cooling” maximizes ion production § 8 Li or 8 B is ion source for β-beam accelerator • C. Rubbia, A. Ferrari, Y. Kadi, V. Vlachoudis, • Nucl. Inst. and Meth. A 568, 475 (2006). D. Neuffer, NIM A 583, p. 109 (2008) 23

β-beams example: 6 Li + 3 He 8 B + n Ø Beam: 25 Me. V 6 Li+++ § PLi =529. 9 Me. V/c Bρ = 0. 59 T-m; v/c=0. 094 Jz, 0=-1. 6 Ø Absorber: 3 He -gas jet ? § d. E/ds = 110. 6 Me. V/cm , Ø If gx, y, z = 0. 13 (Σg = 0. 4), β┴ =0. 3 m at absorber § § Must mix both x and y with z εN, eq= ~ 0. 000046 m-rad, σx, rms= ~2 cm at β┴ =1 m σE, eq is ~ 0. 4 Me. V Ø Could use 3 He as beam § 6 Li target ( foil or liquid) 24

β-beams alternate: 6 Li+3 He 8 B + n Ø Beam: 12. 5 Me. V 3 He++ § PLi =264 Me. V/c Bρ = 0. 44 T-m; v/c=0. 094 Ø Absorber: 6 Li - foil or liquid jet § d. E/ds = 170 Me. V/cm, LR=155 cm • at (ρLi-6= 0. 46 gm/cm 3) Ø Space charge 2 smaller Ø If gx = 0. 123 (Σg = 0. 37), β┴ =0. 3 m at absorber § εN, eq= ~ 0. 000133 m-rad § σx, rms= 2. 0 cm at β┴ =0. 3 m, § σx, rms= 5. 3 cm at β┴ =2. 0 m Ø σE, eq is ~ 0. 3 Me. V § ln[ ]=5. 34 25

Cooling Ring for Beta-Beams Ø Assume He-3 beam § Bρ=0. 44 T-m, β=0. 094 Ø Cooling ring parameters § C =12 m (? ) Ø Absorber § 0. 01 cm Li wedge § βt = ~0. 3 m, η= ~0. 3 m rf Ø rf needed § 2 MV rf Ø Injection Solenoid 1. 38 T-m Cooling wedge β=0. 3 m, η=0. 3 m § charge strip He+ to He++ (? ) Ø Extraction § kicker after wedge Ø Nu. FACT 09 § miniworkshop: July 27 -29 26

Summary Ø Rf in magnetic field problem must be addressed § Need rf configuration that can work with high confidence Ø Need to establish scenario § Use as basis for engineering study Ø Further meetings/studies § Nu. FACT 2009 § miniworkshop at Fermilab (July 27 -28) § front end and beta-beam cooling • 9 -11 am WH 3 NE • 1: 30 -4 PM § Front End Review • April 2010? 27

Future Funding … ? ? 28