1,161 research outputs found
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, . 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.
Verification of crystal collimation model in experiment
The studies of crystal collimation in the experiments at Relativistic Heavy
Ion Collider and Tevatron and in computer simulations reveal strong coherent
effects observed in a very broad angular range. Our theory explains the effects
by coherent scattering on the potential of bent crystal atomic planes, which
amplifies beam diffusion in accelerator by orders of magnitude. This coherent
scattering in bent crystal is being studied in a CERN SPS experiment. We
present Monte Carlo predictions for the SPS and Tevatron experiments, and show
the implications of the coherent scattering effect for crystal collimation in
the Large Hadron Collider.Comment: 7 pages, 4 figure
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