Studies and application of bent crystals for beam steering at 70-GeV IHEP accelerator

This report overviews studies accomplished in the U70 proton synchrotron of IHEP-Protvino during the recent two decades. Major attention is paid to a routine application of bent crystals for beam extraction from the machine. It has been confirmed experimentally that efficiency of beam extraction with a crystal deflector of around 85% is well feasible for a proton beam with intensity up to 1012 protons per cycle. Another trend is to use bent crystals for halo collimation in a high energy collider. New promising options emerge for, say, LHC and ILC based on the "volume reflection" effect, which has been discovered recently in machine study runs at U70 of IHEP (50 GeV) and SPS of CERN (400 GeV).Comment: 12 pages, 14 figure

Crystal collimation experiment on 70-GeV proton accelerator

The first proof-of-principle experiment on "crystal collimation" was performed with 70-GeV protons on IHEP accelerator. A bent crystal installed in the ring as a primary element upstream of a collimator has reduced the radiation levels downstream in the accelerator by a factor of two. The measurements agree with Monte Carlo predictions

Proton Extraction from IHEP Accelerator Using Bent Crystals

IHEP Protvino has pioneered the wide practical use of bent crystals as optical elements in high-energy beams for beam extraction and deflection on permanent basis since 1989. In the course of IHEP experiments, crystal channeling has been developed into efficient instrument for particle steering at accelerators, working in predictable, reliable manner with beams of very high intensity over years. Crystal systems extract 70 GeV protons from IHEP main ring with efficiency of 85% at intensity of 1.E12, basing on multi-pass mechanism of channeling proposed theoretically and realised experimentally at IHEP. Today, six locations on the IHEP 70-GeV main ring of the accelerator facility are equipped by crystal extraction systems, serving mostly for routine applications rather than for research and allowing a simultaneous run of several particle physics experiments, thus significantly enriching the IHEP physics program. The long successful history of large-scale crystal exploitation at IHEP should help to incorporate channeling crystals into accelerator systems worldwide in order to create unique systems for beam delivery. We report recent results from the research and exploitation of crystal extraction systems at IHEP.Comment: Invited talk at the International workshop "Relativistic Channeling and Related Coherent Phenomena", Frascati (Rome) 23-26 March 200

Crystal collimation as an option for the Large Hadron Collider

We present a study in which we propose using a bent crystal and the channeling mechanism for halo collimation in hadron colliders. Experimental results carried out at IHEP with 70 GeV protons and detailed Monte Carlo calculations highlight that a crystal may well resist the highly radioactive environment of a large hadron collider and can be profitably used to steer halo protons out of the main stream. A crystal, integrated in a collimation system may serve either as a diagnostic tool for precise alignment of a traditional massive collimator, made of amorphous dense material or directly as a primary scraper. In this second option, simulations performed specifically in the case of the CERN large hadron collider (LHC) show that the halo intensity would fall off by more than an order of magnitude with respect to a standard collimation system

First Results of Investigation of Radiation from Positrons in a Crystalline Undulator

The sensing properties of titanium oxide have been tailored through doping with niobium and dispersion of nanosized Au particles. The microstructural features of the gold-titania composite system were investigated by transmission electron microscopy and the electronic properties of Au nanoparticles were specifically investigated by electron holography. Holography provides quantitative determination of the mean inner potential with the high spatial resolution attained by transmission electron microscopy. Large increase of the mean inner potential has been measured for ultra small Au particles arising from the nano-scale assembling. Electrical tests were performed at low operating temperatures and demonstrated the considerable enhancement of CO sensitivity owing to the extremely high catalytic activity of gold particles

Preliminary results on the study of radiation from positrons in a periodically deformed crystal

In the present experiment, the radiation from positrons moving in a periodically deformed crystal was observed for the first time. The spectra of radiation are measured in a wide range of energy. The experimental indication showing the existence of an undulator peak in radiation was obtained at a qualitative level and was confirmed by calculations. Crystal undulators provide an equivalent magnetic field of 1000 T and periods in the submillimeter range and consequently can be applied to the generation of X-rays and gamma-rays, of energies a hundreds times higher than the radiation in usual undulators

High-efficiency beam extraction and collimation using channeling in very short bent crystals

silicon crystal was used to channel and extract 70 GeV protons from the U-70 accelerator with an efficiency of 85.3±2.8%, as measured for a beam of ∼1012 protons directed towards crystals of ∼2 mm length in spills of ∼2 s duration. The experimental data follow very well the prediction of Monte Carlo simulations. This demonstration is important in devising a more efficient use of the U-70 accelerator in Protvino and provides crucial support for implementing crystal-assisted slow extraction and collimation in other machines, such as the Tevatron, RHIC, the AGS, the SNS, COSY, and the LHC

Advances in the investigation of the extraction of a proton beam from the U-70 accelerator with the aid of bent single crystals

The efficiency of the extraction of a beam from an accelerator is radically improved owing to the application of short crystals of length up to 1.8 mm bent through a small angle of about 1 mrad. This success is due to an increase in the multiplicity of particle transmission through the crystal used. A record efficiency of the extraction of 70-GeV protons in excess of 80% is achieved experimentally, this result being in agreement with theoretical predictions. It is shown that the crystal can efficiently operate at the injection energy of 1.3 GeV