Brain Gestorme: Status of the LHeC Ring-Ring / Linac- Ring Basic Parameters I appologise to talk about things you already know...

Design Parameters electron beamRRLR ERLLR e- energy at IP[GeV] luminosity [10 32 cm -2 s -1 ] polarization [%]4090 bunch population [10 9 ] e- bunch length [mm]100.3 bunch interval [ns]2550 transv. emit.  x,y [mm] 0.58, rms IP beam size  x,y [  m] 30, 1677 e- IP beta funct.  * x,y [m] 0.18, full crossing angle [mrad] geometric reduction H hg repetition rate [Hz]N/A 10 beam pulse length [ms]N/A 5 ER efficiencyN/A94%N/A average current [mA] tot. wall plug power[MW]100 proton beamRRLR bunch pop. [10 11 ]1.7 tr.emit.  x,y [  m] 3.75 spot size  x,y [  m] 30, 167  * x,y [m] 1.8, $ bunch spacing [ns]25 $ smaller LR p-  * value than for nominal LHC (0.55 m): - reduced l* (23 → 10 m) - only one p beam squeezed - IR quads as for HL-LHC RR= Ring – Ring LR =Linac –Ring ERL=energy recovery linac Tentative:

Change in Electron Energy: 70 GeV  60 GeV Beam Emittance again requiring: What do we gain in this case ? relaxed separation scheme (dominated by e-emittance) smaller crossing angle !!! keeping cool … i.e. keep σ e const relax the electron optics

the crossing angle: in the end the source of many problems First parasitic crossing: s = 3.75m F. Willeke βxβx Separation: 5σ p + 5σ e =0.35mm+ 5mm ≈5.5 mm  X-angle ≈ 1.4 mrad

the crossing angle: in the end the source of many problems First parasitic crossing: s = 3.75m F. Willeke βxβx Separation:

Luminosity Loss Factor:

sc half quadrupole: g = 127 T/m field free region (e-beam) ≈ Gauss separation required ≈ 50 mm Beam Separation at first p – Quadrupole:... a technical problem S. Russenschuck

sc quadrupole Q2: field free region (e-beam) ≈ Gauss separation required ≈ 85 mm Beam Separation at second p – Quadrupole: S. Russenschuck

complete the electron ring lattice include the IR into Miriams Arc / Dispersion suppressor geometry match the electron ring optics from β * to the periodic solution for 1 & 10 degree option determine β max at first parasitic encounter re-iterate the separation scheme -> recalculate the synchrotron light -> input for Nathan: Absorber Geometry write report Further Plans: status e-optics for IPAC 2010

Design Parameters electron beamRRLR ERLLR e- energy at IP[GeV] luminosity [10 32 cm -2 s -1 ] polarization [%]4090 bunch population [10 9 ] e- bunch length [mm]100.3 bunch interval [ns]2550 transv. emit.  x,y [mm] 0.58, rms IP beam size  x,y [  m] 30, 1677 e- IP beta funct.  * x,y [m] 0.18, full crossing angle [mrad] geometric reduction H hg repetition rate [Hz]N/A 10 beam pulse length [ms]N/A 5 ER efficiencyN/A94%N/A average current [mA] tot. wall plug power[MW]100 proton beamRRLR bunch pop. [10 11 ]1.7 tr.emit.  x,y [  m] 3.75 spot size  x,y [  m] 30, 167  * x,y [m] 1.8, $ bunch spacing [ns]25 $ smaller LR p-  * value than for nominal LHC (0.55 m): - reduced l* (23 → 10 m) - only one p beam squeezed - IR quads as for HL-LHC RR= Ring – Ring LR =Linac –Ring ERL=energy recovery linac Tentative:

IR principles for a LR Design (R.T.) The proton IP beta function is pushed down to 10 cm and head-on collisions are achieved via an IR dipole. In order to keep the proton triplet chromaticity to an acceptable level the l* (distance from IP to first quadrupole) has to be reduced from 23m (LHC nominal) to 10m. It is proposed to create a separating dipole field already very close to the IP, being embedded in the Solenoid design of the particle detector. β p =10 cm l * = 10 m “It was proposed to do a new "toy" design to get to the level of 200 keV and compare the results.”