H.Burkhardt, DIS 2008, Future Facilities WG Tue 08/04/2008. LHeC Ring-Ring. early stage : all rather preliminary!

Transcription

1 H.Burkhardt, DIS 2008, Future Facilities WG Tue 08/04/2008 LHeC Ring-Ring early stage : all rather preliminary LHeC : LHC Proton-Ion Ring + Electron Ring (or Linac, see next talk) Introduction - baseline assumptions Layout Bypass Tunnels Power considerations Injectors re-using LEP injectors? alternatives - LINAC and scaled CERN based on original plans : E. Keil, LHC ep option, LHC-Project-Report-093 March 1997 more recently : J. B. Dainton, M.Klein, P. Newman, E.Perez, and F. Willeke, hep-ex/ here mostly : discussions and material from my CERN colleagues and in particular Oliver Brüning, John Jowett, Kurt Hübner, John Andrew Osborne, Brennan Goddard, Volker Mertens, Trevor Linnecar, Hans Braun, Werner Herr 1

2 Introduction 2 LHeC : existing LHC 7 TeV Proton and Ion Ring + new ~ GeV Electron Ring or Linac - see next talk for ~ TeV collisions in c.m.s Ring-Ring : starting point and baseline Original plan : electron storage ring - could become an energy recovery ring Here mostly : looking at layout, integration, simple estimates and scaling with in particular bypasses around ATLAS / CMS idea : allow to run the LHC and LHeC as much as possible in parallel install LHeC without need for very long LHC shutdown tunneling speed about 10 m / week : 250 m tunnel pieces in 1/2 y shutdown

3 Layout LHC 3 P Z 3 3 RZ3 3 RE 38 UJ 3 2 UJ 3 3 RE 32 P M3 2 TZ3 2 P o in t 3.3 P o in t 3.2 UJ 4 3 RE 42 Point 4 RA4 3 UA4 3 P Z4 5 UX4 5 UJ 4 4 UL4 4 P M4 5 US 4 5 UW 4 5 P X4 6 TX4 6 UL4 6 UJ 4 6 RA4 7 UA4 7 UJ 4 7 RE 48 RE 52 RR 53 UJ 5 3 UL 54 UP 5 3 RZ5 4 UXC5 5 P M5 4 US C5 5 UJ CMS Point 5 P X5 6 P M5 6 UJ 5 6 UL5 6 TU5 6 UJ 5 7 RE 58 RE 62 RR 57 UP 62 Point 6 UD 62 TD 62 P M6 5 P X6 4 P Z6 5 UJ 62 RA6 3 TX6 4 UJ 63 UA6 3 UX6 5 UJ 6 4 UL6 4 UJ 6 6 RA6 7 UL6 6 UW 6 5 US 6 5 UA6 7 UJ 6 7 UJ 6 8 TD6 8 UD6 8 N RE 68 UP 68 RE 28 Point 7 RE 72 UJ 2 7 UA2 7 Point 2 P M7 6 P GC2 RA2 7 UL 26 P M2 5 UP 2 5 UJ 2 6 US 2 5 P X2 4 UL 24 UX2 5 ALICE UJ 2 4 RA2 3 RH2 3 UJ 2 2 UW 2 5 UA2 3 UJ 23 TI 2 RE 22 PMI 2 RE 18 P o in t 1.8 PM 18 P X1 6 UJ 1 8 RR1 7 UJ 1 7 UL1 6 RT 18 TI 1 8 UJ 1 6 S P S Point 1 US A1 5 P M1 5 P X1 5 P X1 4 US 1 5 UL1 4 UJ 1 4 UX1 5 ATLAS TT 40 PGC 8 LS S 4 TJ 8 TI 8 UJ 88 UJ 1 3 RE 12 RE 88 RR1 3 UJ 12 TI 1 2 RT1 2 Point 8 PM 85 UW 8 5 P X8 4 P Z8 5 UL 84 US 85 UA8 7 UL 86 UJ 8 7 UJ 86 RA 87 RH 87 TX8 4 UX 85 LHCB UA 83 RA8 3 UJ 8 4 RE 78 RE 82 UJ 83 UJ 8 2 TZ7 6 LEP LHC RR7 7 UJ 7 6 RR7 3

4 Layout LHeC P Z 3 3 RZ3 3 RE 38 UJ 3 2 UJ 3 3 RE 32 P M3 2 TZ3 2 P o in t 3.3 P o in t 3.2 UJ 4 3 RE 42 Point 4 RA4 3 UA4 3 P Z4 5 UX4 5 UJ 4 4 UL4 4 P M4 5 US 4 5 UW 4 5 P X4 6 TX4 6 UL4 6 UJ 4 6 RA4 7 UA4 7 UJ 4 7 RE 48 RE 52 RR 53 UJ 5 3 UL 54 UP 5 3 RZ5 4 UXC5 5 P M5 4 US C5 5 UJ CMS Point 5 P X5 6 P M5 6 UJ 5 6 UL5 6 TU5 6 UJ 5 7 RE 58 RE 62 RR 57 UP 62 Point 6 UD 62 TD 62 P M6 5 P X6 4 P Z6 5 UJ 62 RA6 3 TX6 4 UJ 63 UA6 3 UX6 5 UJ 6 4 UL6 4 UJ 6 6 RA6 7 UL6 6 UW 6 5 US 6 5 UA6 7 UJ 6 7 UJ 6 8 TD6 8 UD6 8 N RE 68 UP 68 RE 28 Point 7 RE 72 UJ 2 7 UA2 7 Point 2 P M7 6 P GC2 RA2 7 UL 26 P M2 5 UP 2 5 UJ 2 6 US 2 5 UX2 5 e p RF RF P X2 4 UL 24 UJ 2 4 RA2 3 RH2 3 UJ 2 2 UW 2 5 UA2 3 UJ 23 TI 2 RE 22 PMI 2 RE 18 P o in t 1.8 PM 18 P X1 6 UJ 1 8 RR1 7 UJ 1 7 UL1 6 RT 18 TI 1 8 UJ 1 6 S P S Point 1 US A1 5 P M1 5 P X1 5 P X1 4 US 1 5 UL1 4 UJ 1 4 UX1 5 ATLAS Point 8 PM 85 TT 40 UW 8 5 P X8 4 UA 83 PGC 8 P Z8 5 LS S 4 UL 84 US 85 TJ 8 UA8 7 UL 86 RA8 3 TI 8 UJ 8 7 UJ 88 UJ 1 3 UJ 8 4 RR1 3 RE 12 RE 88 TX8 4 UJ 86 RA 87 UX 85 RH 87 TI 1 2 UJ 12 RT1 2 e-injector e p RF RF RE 78 RE 82 UJ 83 UJ 8 2 TZ7 6 LEP LHC LHeC RR7 7 UJ 7 6 RR7 3 4

5 LHeC Ring-Ring : Summary Table for Extra Tunnels 5 Point 1 ATLAS Point 5 CMS Point 2 and/or 8 RF Point 3 Collimators Point 7 Collimators Type Bypass Experiment Bypass Experiment Bypass ; allow for space for e - ring RF Bypass Collimation Bypass Collimation Approximate Tunnel length 500 m 500 m 500 m 500 m 500 m 2500 m m Diameter 4.40 m 3.80 m 5.50 m 4.20 m 3.80 m Distance to p- Ring axis m m based on layout and integration considerations, very prelim.

6 LHeC Typical Cross Section through CMS &'"'$(%% 2"#$%% New beam in Survey Gallery (UPS54) )"*+(%% ##"$#(%% RR53 UPS54 UPS56 RR57 from J.A. Osborne CERN/TS 6

7 LHeC UPS 54 Survey Gallery from J.A. Osborne CERN/TS 7

8 LHeC View from UPS54 Survey Gallery into CMS Cavern on Walkways from J.A. Osborne CERN/TS 8

9 Ring Layout and Optics Considerations 9 well known starting point : LEP with its FODO lattice, matching the tunnel and LHC layout. basic LEP numbers : 73 % of circumference in arcs, 88 % of arcs with dipoles 79 m long cells ; bending angle of half cell mrad from m long dipoles dipole bending radius ρ = m 31 cells per octant; in total 8 31 = 244 cells

10 Equal Circumference of p and e Rings? 10 Needed? Maybe : for abort or rather ion-instability cleaning gap same C allows synchronisation with p-abort gap and fixed bunch pairing for collisions otherwise : packman bunch effects, mixed pairing with increased heating of p- beam, ---> beam-beam simulations to be more quantitative Possible? Yes : a bypass adds little in circumference the 10 m bypass shown later adds only Δ = 0.42 m in C, can be compensated by decrease in e-ring radius of Δ/4π = 6.7 cm

11 Bypass Layout Study - based on LEP lattice - no extra bends 11 schematic layout Dainton / Willeke et al. LEP lattice Point θ θ s IP5, m QD24.L QF23.L QD22.L QF21.L QD20.L QF19.L QL18.L QL17.L QL16.L QL15.L QL14.L QL13.L QL12.L QL11.L QL m QL11 22 m 10 m LEP Bypass QL11 QL

12 Compact Bypass with extra bends # 2 sin # /2 #/2 s = # Figure 16: Ideal compact bypass " "/2 = 2 sin 2 # /2 4.6 Compact Bypass See the old mad8 physics manual on page 62 for definition of the bending angle. "/2 = 2 sin 2 # /2 See Fig. 16. Separation by compact #/2bypass =4ρ sin 2 α 2 2 sin # /2 " (4 lateral separation =4ρ sin 2 α 2 Total path length in bends by summing up the 4 bending pieces total length in bends in bypass s =4ρα (4 21 using standard LEP bends, ρ = 3026 m, we would need α = 57 mrad to get Δ = 10 m separation by 4 x 176 m of bends. This would add 3.6% in the total energy loss. In absolute, the loss in such a bypass is 1.8 MW at 70 GeV for 70 ma beam current. With 2x stronger bends in bypass : 4 x m long bends, adding 5.1% in power 12

13 LHeC Electrons ; Intensity / Power considerations frev = Hz given by LHC circumference #bun = 2800 high collision frequency f = #bun frev = 31.5 MHz and high beam current beam current I = n e f e = As Ring : loss in SynRad U0 = Cγ E 4 /ρ ρ = 2997 m LEP had ρeff = m LINAC : beam power P = V I machine N / bun #bun Ntot / beam I beam V [GV] Pacc= V I [MW] U0 [GeV] Psyn [MW] LEP E E ma LHeC, ring-e 1.40E E ma ultimate LHeC 1 power needed in case of direct Linac, several GigaWatt 13

14 Luminosity Ring-Ring Max Klein - ECFA 30/11/2007 Luminosity: Ring-Ring " pn = 3.8µm N p =1.7 #10 11 L = N p" 4#e$ pn % I e & px & py = % I e 50mA m & px & pn cm '2 s '1 $ p(x,y ) = $ e(x,y ) % px =1.8m % py = 0.5m I e = 0.35mA " P MW " # 100GeV & % ( $ ' E e I e = 100 ma likely klystron installation limit Synchrotron rad can be reached in RR E e = GeV & P = 5-60 MW. HERA was cm -2 s -1 huge gain with SLHC p beam F.Willeke in hep-ex/ : Design of interaction region for : 50 MW, 70 GeV May reach with ERL in bypasses, or/and reduce power. R&D performed at BNL/eRHIC Plenary ECFA, LHeC, Max Klein, CERN cf also A.Verdier 1990, E.Keil

15 LEP injectors 15 what we had, with electron energy range and what is left LIL 600 MeV ; gone ; replaced by CLIC PS GeV ; nothing left for e-acceleration - old machine - not very reasonable to re-upgrade for leptons SPS GeV ; 8 MV 200 MHz TW cavities not ok for leptons ; had extra cavities for leptons, removed for impedance reduction ; Impedance issue - no increase wanted rather needs further reduction for LHC ultimate LEP injectors were all removed. Rebuilding them is not really an option. Parts and components could be re-used in new injectors (kickers, parts and components of transfer lines)

16 new LHeC injectors 16 basic parameters : about 20 GeV injection energy be able to fill reasonably fast - say within 10 min low intensity / bunch could do without accumulation many (2800) bunches, 25 ns spacing, total intensity electrons injection scheduling : analog to protons ( 3-4 batches of nominally 72 bunches ) e+ and e- : no principle problem - needs extra e+ source and possibility to change polarities

17 direct about 20 GeV 17 low energy Linac, e- and e+ conversion GeV ), EPA like e+ acc. ring accelerate with synchrotron ; same principle as we had of LEP what about 20 GeV Linac based on CLIC? clictable2007.html high gradient 100 MV/m in 85% of LINAC ; L = 235 m to reach 20 GeV N = 3.72e9 / bun; k = 312 bun/train ; Linac repetition rate of 50 Hz : 5.83e13 Elec/ sec. Significant overhead for drive beam generation - probably not very economic for a relatively short LINAC 20 GeV SC Linac, inspired by ILC gradient 31.5 MV/m ( ILC BCD ) in 85% of LINAC : L = 747 m N = 2e10 / bun, k = 2820 bun /train ; repetition rate of 5 Hz : 2.82e14 Elec/secs modify to match LHC batch structure or

18 EUROPEAN CERN CERN NuPECC CERN Dec EUROPEAN LABORATORY FOR PARTICLE PHYSICS NUCLEAR PHYSICS EUROPEAN COLLABORATION COMMITTEE Table 1: ELFE performance parameters. Top energy 25 GeV Beam current on target 100 µa Beam power on target 2.5 MW Injection energy 0.8 GeV Number of passes 7 Energy gain per pass 3.5 GeV Relative r.m.s. momentum spread at top energy 10 3 Emittance at top energy 30 nm Bunch repetition time on target 2.8 ns E L F E Editor: H. Burkhardt Conceptual Design Report S C I E N C E E S F I O N F O U N D A T A Table 2: Estimated capital expenditure for the construction of ELFE at CERN. System MCHF MCHF MCHF Injection RF system Cryogenics Magnets Vacuum Beam diagnostics Power converters Control system Accelerator components Electrical power distribution Civil engineering Experimental hall(s) Cooling, ventilation, etc Access control, etc Conventional construction Total with LEP RF for free 18

19 1081 m modified ELFE as LHeC injector ELFE@CERN frf = 352 MHz, gradient 8 MV / m Vrf = 3.5 GV, 72 rf-modules 7 passes (last at 21.5 GeV) L = 3924 m of which Linac 1081 m ρ = 56.9 m LHeC injector frf ~ 1 GHz, gradient 31.5 MV/m Linac L = 150 m 7 shorter Vrf = 4 GV, 5 passes ; last 16 GeV ρ = (16/21.5)^ m = 17.5 m or 3.3 shorter significantly downscaled L 600 m and simplified (5 passes) version of ELFE@CERN 150 m 300 m 100 m 4 GeV recirculating LINAC more cost effective (?) than single LINAC + extra phys. potential 19

20 ( my ) conclusion 20 p-ring - e-ring (both storage rings ) as baseline option proven technology -- no fundamental problems expected issues : mostly layout - integration cost and time effective bypass design -- with possible synergy with energy recovery rings RF and injectors

21 Backup Slides

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23 from Oliver Brüning, April 2008, on potential collaborators: General machine design and beam dynamics (lattice and magnets): DESY PSI EPFL BNL FERMILAB SLAC John Adams Institute (Ted Wilson) JAI Royal Holloway Crockcroft From Louis Rinofli I got the following list of interested collaborators for the source development: i. Polarized electron source design 1. JLAB (M. Polker), Mainz (K. Aulenbacher) 2. LOA (V. Malka), RAL (G. Hirst) 3. LAL (R. Roux), CEA (F. Orsini) ii. Unpolarized positron source design 1. LAL (A. Variola) 2. LNF (M. Ferrario), CEA (F. Orsini) 3. Cockcroft Institute (I. Bailey), SLAC (J. Sheppard) 4. LAL (A. Variola), IPNL (R. Chehab) iii. Polarized positron source design 1. LAL (R. Roux), DESY (S. Schriber) 2. LOA (V. Malka), RAL (G. Hirst) 3. LNF (M. Ferrario), CEA (F. Orsini) 4. KEK (Omori) Ukraine (E. Bulyak) 5. LAL (F. Zomer), KEK (J. Urakawa) 6. Cockcroft Institute (I. Bailey), SLAC (J. Sheppard) 7. LAL (A. Variola), IN2P3 (R. Chehab) Concerning the polarized positron, we have the POSIPOL group including CERN, LAL, KEK, Hiroshima University, BNL, ANL, SLAC, DESY, Ukraine University, Cockcroft, etc... The POSIPOL group could be contacted and informed about such proposal. 23