Crystal Channelling in Accelerators

Crystal lattice can trap and channel particle beams along major crystallographic directions. In a bent crystal, the channelled particles follow the bend. This makes a basis for an elegant technique of beam steering by means of bent channelling crystals, experimentally demonstrated from 3 MeV to 1 TeV. This technique was strongly developed in recent studies at CERN, FNAL, IHEP, and BNL, and can lead to interesting applications also at the LHC, such as crystal collimation making a collider cleaner by an order of magnitude. We review recent developments in the field and show outlook for the future.Comment: Invited talk at 10th European Particle Accelerator Conference (EPAC 06), Edinburgh, UK, 26-30 Jun 200

Calibration of CMS calorimeters with LHC proton beam deflected by crystal

Calibration of the forward CMS hadron calorimeters in situ by the LHC beam is proposed. Simulations show that bent crystal channeling technique is feasible at the LHC, and report the experience of IHEP Protvino in bending 70 GeV protons by 9 degrees (150 mrad) during 10 years in 1994-2004 experiments. Practical realization of calibration scheme based on simulations and previous experience is proposed.Comment: Presented at CARE-HHH-APD Mini-Workshop on Crystal Collimation in Hadron Storage Rings (CC-2005), Geneva, Switzerland, 7-8 Mar 200

Channeling of high-energy particles in a multi-wall nanotube

Channeling of high-energy particles in straight and bent multi-wall nanotubes (MWNT) has been studied in computer simulations and compared to the channeling properties of single-wall nanotubes (SWNT) and bent crystal lattices. It is demonstrated that MWNT can efficiently channel positively-charged high-energy particles trapped between the walls of MWNT. Bending dechanneling in MWNT has been computed as a function of the particle momentum to nanotube curvature radius ratio, $pv/R$. It is found that a bent MWNT can steer a particle beam with bending capabilities similar to those of bent silicon crystal lattice and to those of best (i.e. the narrowest) SWNT. In view of channeling applications at particle accelerators, MWNT appear favored as compared to SWNT, because MWNT can be produced quite straight (and in aligned array), while SWNT is typically very curved, thus posing a severe problem for channeling applications. Therefore, we suggest that MWNT provide a better candidate for channeling than SWNT.Comment: 16 pages, 6 figures, to appear in Phys. Lett.