LHC (SSC) Byung Yunn CASA

Parameters Type: Synchrotron Circumference: 26.659 (82.944) km Proton energy: 7.7 (20) TeV Bunch length: 7.5 (6 to 7.5) cm Energy spread: 1.05e-4 (0.5e-4) Transverse emittance: 3.75 (1.0) µm Longitudinal emittance: 2.5 (0.233) eV-s

continued Protons per bunch: 1.0e11 (7.3e9) Average beam current: 850 (73) mA Number of bunches: 4725 (17100) RF frequency: 400.8 (374.74) MHz RF voltage: 16 (20) MV Synchrotron tune: 0.00157 (0.0019) Momentum compaction: 2.94e-4 (2.23e-4)

continued Nominal full crossing angle: 200 (75) µrad Bunch spacing: 15 (16) ns Beta star: 50 (50) cm Beam-beam tune shift: 0.0032 (0.00084) Luminosity (/cm^2-s ): 1.65e34 (1.0e33) Number of interaction points: 3 (4) Synchrotron radiation power (per beam): 9.1 (9.1) kw

Injectors (LHC) 50 MeV proton linac (180 mA for 7 µs), injected into 4 PS booster rings PS booster: accelerated in one bunch up to 1.4 GeV, PS accepts eight 200 ns long bunches 26 GeV PS (1/11 of SPS): debunched and rebunched at 26 GeV to 1.0e11 protons per bunch (emittance = 3 µm, bunch length = 9 ns) 450 GeV SPS (7/27 of LHC): 36 SPS beam pulses to fill one LHC channel.

Injectors (SSC) 600 MeV H- linac: 125 m, RF Freq = 49.5 MHz (RFQ), 445 MHz (DTL), 1336 MHz (SCL) 8 GeV LEB: 250 m, RF Freq = 49.5-62.0 MHz 100 GeV MEB: 1.9 km, RF Freq = 62.5 MHz 1 TeV HEB (Superconducting): 6 km, RF Freq = 62.5 MHz Average current (mA): 3.9 (Linac), 99 (LEB), 92 (MEB), 87 (HEB)

Collider ring (LHC) Built on top (1.21 m) of LEP and has eightfold symmetry Two beam channels in the same magnet 10 Tesla dipole field (4 to 6 Tesla available) Can be used to collide ions Number of arcs: 8 Number of interaction regions: 8 (3 collision and 2 utility)

Collider ring (SSC) Two rings separated vertically (0.7 m) Dipole field: 6.6 T Quad in arcs: 212 T/m Interaction regions (IR) are arranged in 2 clusters (East and West) for cost effectiveness 4 IRs in each cluster and each IR is 2.4 km long Clusters are joined by arcs of 11.7 km radius

Lattice (LHC) Two beam channels in the same plane (18 cm separation in arcs) and cross at eight points. Eight 25 FODO cells (98 m long and phase advance of 90 deg per cell) per ring Four 9 m long dipoles and one 3 m quad in a half cell Beta in arcs: max 166 m, min 29 m Dispersion in arcs: max 1.86 m, min 0.9 m

continued Working point: (71.28, 70.31) Insertion: 886 m long and phase advance in each plane by 2.5 units Chromaticity correction: sextupoles next to the main quads, powered in 2 families Linear aperture: 4 mm

Lattice (SSC) FODO cell: 192 m long and phase advance of 60 deg Five 16.5 m long dipoles and one 3.3m arc quad in each half cell Eight 42 cells per ring Beta in arcs: max 332 m, min 111 m Dispersion in arcs: max 3.92 m, min 2.36 m Natural chromaticity: -204

continued Working point: (78.27, 78.28) Chromaticity correction: sextupoles next to the main quads, powered in 2 families Linear aperture: 5 mm

Collision IR (LHC) 40 m free space between final quad triplets Beta star: can be tuned from 0.5 m to 15 m Beta max: 4 km Beam radius at IP: 15 µm Beam divergence at IP: 30 µrad

Collision IR (SSC) 40 m free space between final quad triplets Beta star: 0.5 m Beta max: 8 km Beam crossing angle at IR: 75 µrad, but can vary from 0 to 150 µrad

Collective Effects (LHC) Beam lifetime: 26.5 h Luminosity lifetime: 11 h IBS emittance growth time: 100 h (horizontal), 60 h (longitudinal) Longitudinal microwave and transverse mode coupling instability are potential dangers. Coupled bunch instabilities require active feedback systems to control.

Collective Effects (SSC) Beam lifetime: 39000 h Luminosity lifetime: 24 h IBS emittance growth time: 126 h (horizontal), 277 h (longitudinal) Relatively safe from single bunch instabilities. Coupled bunch instabilities require active feedback systems to control.