| Paper | Title | Page |
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| TUPEB075 | Preliminary results of the crystal collimation test in UA9 | 1695 |
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We present a detailed analysis of the beam loss data collected at the SPS during the 2009 machine developments devoted to test crystal collimation. Scintillator counters and Gas electron multiplier detectors were installed in special points to detect the effect of inelastic interaction of protons with the crystals in various orientation with respect to the beam. Clear correlations of the counting rates with the crystal positions and orientation were detected during the data-taking and were crucial to put the crystal in optimal channeling position. For one of the crystal the pattern of losses showed evidence of several planar and axial channeling conditions. |
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| THPEC080 | Fabrication of Silicon Strip Crystals for UA9 Experiment | 4243 |
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Channeling in bent crystals is a technique with high potential to steer charged-particle beams for several applications in accelerators physics. Revisited methods of silicon micromachining techniques allowed one to realize a new generation of crystals. Characterizations using x-ray diffraction, atomic force microscopy, high resolution transmission electron microscopy and ion beam analysis techniques, showed high quality of the crystals. A specifically designed holder allowed to mechanically bend a crystal at given curvature and remove unwanted torsion. Characterization of such crystals with 400 GeV at CERN H8 external line highlighted 85% single-pass efficiency. A selected crystal has been installed inside the SPS ring in the environment of the CERN experiment UA9 and successfully employed for collimation of the circulating beam. On behalf of UA9 collaboration |
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| THPEC087 | Measurement of Nuclear Reaction Rates in Crystals using the CERN-SPS North Area Test Beams | 4258 |
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A number of tests were performed by the UA9 Collaboration* in the North area of the SPS in view of investigating crystal-particles interactions for future application in hadron colliders. The rate of nuclear reactions was measured with 400 GeV proton beams directed into a silicon bent crystal. In this way the background induced by the crystal itself either in amorphous or in channeling orientation was revealed. The results provide fundamental information to put in perspective the use of silicon crystals to assist halo collimation in hadron colliders, whilst minimizing the induced loss. Crystals made of Germanium were also investigated in view of the expected increase of the collimation efficiency respect to silicon. Finally, crystals were tested in axial orientation and with incoming particles of negative charge. The collected results are presented in details. * http://greybook.cern.ch/programmes/experiments/UA9.html |
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| THPD052 | Manipulation of Negatively Charged Beams via Coherent Effects in Bent Crystals | 4398 |
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New results in coherent interaction of negatively-charged particles with bent crystals showed unprecedentedly and significantly high efficiency to manipulate such beams, in the same way as for positively charged particles. Key feature under experimental attainment was the usage of high-quality suitably thin silicon crystals. We experimentally tested crystals Vs. 150 GeV negative pions at external lines of CERN SPS. We observed planar channeling at full deflection angle 30% high single-pass efficiency and large acceptance (about 20μrad). Moreover in the axial case, we reached more than 90% deflection efficiency and larger acceptance (about 60μrad). We also observed volume reflection in a bent crystal, at more than 70% single-pass efficiency with such a wide acceptance as the bending angle. At last, volume reflection by several planes in a single bent crystal was successfully tested with very high efficiency (about 80%). In summary both channeling and volume reflection modes appear to be useful technique for the manipulation of negatively charged beams, e.g. for collimation in the new generation of high intensity accelerators. The UA9 collaboration |