Double volume reflection of a proton beam by a sequence of two bent crystals

The doubling of the angle of beam deflection due to volume reflection of protons by a sequence of two bent silicon crystals was experimentally observed at the 400 GeV proton beam of the CERN SPS. A similar sequence of short bent crystals can be used as an efficient primary collimator for the Large Hadron Collider

Analysis on the Issue of East Financial Integration

在1997年金融危机发生后，东亚各国和地区意识到过分依赖外国的资金存在着巨大的风险。因此，为了避免对外国资金的过分依赖防止危机再次发生，东亚各国和地区通过完善金融体系，加强金融合作以推进金融一体化。 在此背景下，本文对东亚金融的一体化程度做出分析。本文对东亚各国和地区金融一体化的必要前提：东亚货币金融合作，东亚各国和地区资本市场放松管制情况、各国和地区的资本流动以及各国和地区股票及债券市场的发展进行了定性分析和描述，同时对各国投资与储蓄的相关性、各国消费者通过金融市场分散风险的程度、各国股票市场以及各国债券市场与两大国际市场间的联系，对东亚各国和地区金融市场一体化程度进行了实证分析。本文的研...East Asia has realized that it has great risk to depend on the foreign capital, after 1997 financial crisis. East Asia tried to improve the financial system and strengthen financial cooperation, so as to avoid the recurrence of financial crisis. This thesis tries to address the issue of the financial integration of East Asia. First of all, the basis of financial integration of East Asia was anal...学位：经济学博士院系专业：经济学院国际贸易系_世界经济学号：2005140292

Channeling radiation of multi-GeV positrons in single crystals

The process of radiation of 120 GeV positrons moving in a channeling regime in (011) plane of a single crystal was considered. At the beginning on the basis of the theory of nonlinear oscillations, the trajectory of moving positrons at different initial conditions was derived. Then taking into account the nonlinearity of motion, the distribution function over oscillation amplitudes of channeling particles was found. After this, the intensity of radiation at different initial conditions was calculated with the help of two various methods. These results may be useful for comparison with experimental data at positron energies from 100 and more GeV

Experimental study on crystal channeling at CERN-SPS for beam halo collimation

We recently suggested using short bent crystals as primary collimators in a two stage cleaning system for hadron colliders, with the aim of providing larger impact parameters in the secondary bulk absorber, through coherent beam-halo deflection. Tests with crystals a few mm long, performed with 70 GeV proton beams at IEHP in Protvino, showed a channeling efficiency exceeding 85 %. We also observed disturbing phenomena such as dechannelling at large impact angle, insufficient bending induced by volume capture inside the crystal, multiple scattering of non-channeled protons and, for the first time, a proton flux reflected by the crystalline planes. Indeed, protons with a tangent path to the curved planes somewhere inside the crystal itself are deflected in the opposite direction with respect to the channeled particles, with an angle almost twice as large as the critical angle. This effect, up to now only predicted by computer simulations, produces a flux of particles in the wrong direction with respect to the absorber, which may hamper the collimation efficiency if neglected

Crystal collimation studies at the Tevatron (T-980)

Bent-crystal channeling is a technique with a potential to increase beam-halo collimation efficiency in high-energy colliders. First measurements at the Tevatron in 2005 have shown that using a thin silicon crystal to deflect the 1-TeV proton beam halo onto a secondary collimator improves the system performance by reducing the machine impedance, beam losses in the collider detectors and irradiation of the superconducting magnets, all in agreement with simulations. Recent results, obtained with an improved goniometer and enhanced beam diagnostics, are reported here for dedicated beam studies and first full collider stores along with simulation results and plans for substantial enhancement of the T-980 experimental setup

Double volume reflection of a proton beam by a sequence of two bent crystals

The doubling of the angle of beam deflection due to volume reflection of protons by a sequence of two bent silicon crystals was experimentally observed at the 400 GeV proton beam of the CERN SPS. A similar sequence of short bent crystals can be used as an efficient primary collimator for the Large Hadron Collider

Deflection of a 400 GeV/c proton beam with bent silicon crystals at the CERN super proton synchrotron

This paper presents a detailed study of the deflection phenomena of a 400  GeV/c proton beam impinging on a new generation of bent silicon crystals; the tests have been performed at the CERN Super Proton Synchrotron H8 beam line. Channeling and volume reflection angles are measured with an extremely precise goniometer and with high resolution silicon microstrip detectors. Volume reflection has been observed and measured for the first time at this energy, with a single-pass efficiency as large as 98%, in good agreement with the simulation results. This efficiency makes volume reflection a possible candidate for collimation with bent crystals at the CERN Large Hadron Collider

Experimental apparatus to study crystal channeling in an external SPS beamline

For the new generation of high intensity hadronic machines as, for instance, LHC, halo collimation is a necessary issue for the accelerator to operate at the highest possible luminosity and to prevent the damage of superconductor magnets.1 We propose an experiment aimed to systematic study of the channeling phenomenology and of the newly observed volume reflection effect. This experiment will be performed for an external SPS beamline and will make use of a primary proton beam with 400 GeV/c momentum and very small ( 3c 3 \u3bcrad) divergence. The advantage of a proposed experiment is precise tracking of particles that interacted with a crystal, so that to determine the single-pass efficiency for all the processes involved. For this purpose, a telescope equipped with high-resolution silicon microstrip detectors will be used. New generation silicon crystals and an extra-precise goniometer are mandatory issues. Main goal of the experiment is to get the precise information on channeling of relativistic particles and, ultimately, on the feasibility of such technique for halo collimation at LHC. In this contribution we review the status of the setting-up of experimental apparatus and its future development in sight of the planned run in September 2006