Studies on low crossing angle bumps for the LHC luminosity upgrade G. Sterbini Accelerator Technology Department Magnet and Superconductors Group CERN, 23 th March 2006

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA2 The basic idea Motivations for considering a new bump scheme The synthesis of new bumps scheme (MAD-X) Using two kickers at 2 meters from IP1/IP5 Using two kickers at 9 meters from IP1/IP5 The analysis of the new bumps scheme (BBTRACK) How to compare the new bumps with the nominal one The technological challenges Conclusions. Contents

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA3 The basic idea…

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA4 Nominal bumps’ scheme Nominal bumps’ scheme New bumps’ scheme New bumps’ scheme TRIPLETSD1TRIPLETSD1 TRIPLETSD1TRIPLETSD1 285 urad

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA5 Motivations LHC LUMINOSITY UPGRADE 1.Increase the peak luminosity of a factor 10 Increase the particles in the bunch 2.Increase the integrated luminosity Keep the same beam lifetime : minimize the interaction between the beams Increase the number of bunches Lowering the β at the IPs In the nominal bumps scheme there is a sort of coupling between the PEAK LUMINOSITY and the INTEGRATED LUMINOSITY due to the crossing angle. It is not possible to exploit all the potential peak luminosity of the machine! SOLUTION: USE AN OTHER BUMP SCHEME

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA6 Putting the numbers… We gain a factor ! With zero crossing angle With nominal crossing angle

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA7 Putting the numbers… We gain a factor 1.138! With zero crossing angle With nominal crossing angle

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA8 Putting the numbers… We gain a factor 1.069! With zero crossing angle With nominal crossing angle

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA9 A more realistic view of the problem… Nominal bumps scheme at IP5 [meters] [meters] [meters] 194 mm m

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA10 New bumps scheme at IP5 A more realistic view of the problem… [meters] [meters] [meters] 194 mm m

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA11 A more realistic view of the problem… Nominal bumps scheme at IP1 [meters] [meters] [meters] 194 mm m

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA12 A more realistic view of the problem… New bumps scheme at IP1 [meters] [meters] [meters] 194 mm m

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA13 The LHC ultra-relativistic beams share a common beam pipe. Each beam see the field product by the other: this kind of interaction is the so called beam-beam force Head-on beam-beam effect Long-range beam-beam effect The beam-beam effect

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA14 The effect is NON LINEAR! We need tracking. Arbitrary units

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA15 Using the matching module of MAD_X we tried to maintain the same mean normalized distance to maintain the same aperture in the triplets to have the first parasitic encounter at relative high distance Tracking with BBTRACK we tried to define a quantity sensitive to the beam-beam effect (diffusive aperture) to maintain or improve the diffusive aperture

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA16 The nominal condition

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA17 1st scenario: putting the kicker before the first parasitic encounter

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA18

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA19 ≈ 4 Tm

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA20 BBTRACK results

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA21 2nd scenario: putting the kickers before the third parasitic encounter ≈ 4 Tm

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA22 BBTRACK results

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA23 Technological challenges Is there enough room in the detectors? The dipoles have not to interfere with particles (ironless) Good mapping of the total field Minimize the outer field produced by the dipoles (high field can be a problem for the silicon trackers) Radiation problem Mechanical problem Evaluate the torque produces by the static fields interaction Evaluate the force during the transients due to the dB/dt.

Studies on low crossing angle bumps for the LHC luminosity upgrade 23 March 2006Guido Sterbini, AT-MAS-MA24 We can use new bumps scheme for solving the coupling between peak luminosity and integrate luminosity We derive two possible scenarios: Kickers at 2 meters from IPs Zero crossing angle At nominal β* we need Tm Halving the β*, we need about 8 Tm Maintaining the nominal diffusive aperture we gain a factor 2 in luminosity! Kickers at 9 meters from IPs Full crossing angle of urad At nominal β* we need Tm Halving the β* we need about 8 Tm Maintaining the nominal diffusive aperture we gain a factor 1.9 in luminosity! We have to challenge several technological issues. Conclusions