| 1. |
- Scandale, W., et al.
(author)
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First observation of multiple volume reflection by different planes in one bent silicon crystal for high-energy protons
- 2009
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In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 682:3, s. 274-277
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Journal article (peer-reviewed)abstract
- Multiple volume reflection by different planes in a bent silicon crystal with its 〈111〉 axis orientation close to the beam direction was observed for the first time for 400 GeV/c protons at the CERN SPS. The proton beam was deflected to the side opposite to the crystal bend by an angle of about 67 μrad, which is five times larger than in a single volume reflection by the (110) bent planes. The registered efficiency of one side deflection was about 84%. It was shown that multiple volume reflection transforms to a single volume reflection when the orientation angle of the 〈111〉 axis relative to the beam direction is increased. © 2009 Elsevier B.V. All rights reserved.
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| 2. |
- Scandale, W., et al.
(author)
-
High-efficiency deflection of high-energy negative particles through axial channeling in a bent crystal
- 2009
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In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 680:4, s. 301-304
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Journal article (peer-reviewed)abstract
- Deflection due to axial channeling in a silicon crystal bent along the 〈111〉 axis was observed for 150 GeV/c negative particles, mainly π- mesons, at one of the secondary beams of the CERN SPS. The whole beam was deflected to one side with the efficiency of about 90% and with the peak position at the bend crystal angle α = 43 μrad. The deflection occurs mainly due to doughnut scattering of above-barrier particles by the atomic strings of the crystal. However, due to a high probability of particle recapture into bound states with the atomic strings their contribution to the deflection should be about 15% for our case according to simulation results. © 2009 Elsevier B.V. All rights reserved.
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| 3. |
- Scandale, W., et al.
(author)
-
Manipulation of negatively charged beams VIA coherent effects in bent crystals
- 2010
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In: IPAC 2010. - : ACFA. - 9789290833529 ; , s. 4398-4400
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Conference paper (peer-reviewed)abstract
- We review the experimental evidences we recorded with volume reflection and planar and axial channelings with negatively charged particles beam. High deflection efficiency was observed in all cases. The experiment was carried out by the UA9 collaboration in the external lines of the CERN SPS with a secondary beam of 150 GeV/c negative particles.
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| 4. |
- Scandale, W., et al.
(author)
-
Observation of channeling and volume reflection in bent crystals for high-energy negative particles
- 2009
-
In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 681:3, s. 233-236
-
Journal article (peer-reviewed)abstract
- Deflection due to planar channeling and volume reflection in short bent silicon crystals was observed for the first time for 150 GeV / c negative particles, π- mesons, at one of the secondary beams of the CERN SPS. The deflection efficiency was about 30% for channeling and higher than 80% for volume reflection. Volume reflection occurs, in spite of the attractive character of the forces acting between the particles and the crystal planes, in a wide angular range of the crystal orientations determined by the crystal bend angle. © 2009 Elsevier B.V. All rights reserved.
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| 5. |
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| 6. |
- Scandale, W., et al.
(author)
-
Deflection of high-energy negative particles in a bent crystal through axial channeling and multiple volume reflection stimulated by doughnut scattering
- 2010
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In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 693:5, s. 545-550
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Journal article (peer-reviewed)abstract
- Different kinds of deflection in a silicon crystal bent along the 〈111〉 axis was observed for 150 GeV/. c negative particles, mainly π- mesons, at one of the secondary beams of the CERN SPS. The whole beam was deflected to one side in quasi-bound states of doughnut scattering (DSB) by atomic strings with the efficiency (95.4 ± 0.2)% and with the peak position close to the bend crystal angle, α=185 μrad. It was observed volume capture of π- mesons into the DSB states with a probability higher than 7%. A beam deflection opposite to the crystal bend was observed for some orientations of the crystal axis due to doughnut scattering and subsequent multiple volume reflections of π- mesons by different bent planes crossing the axis. © 2010 Elsevier B.V.
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| 7. |
- Scandale, W., et al.
(author)
-
Observation of multiple volume reflection by different planes in one bent silicon crystal for high-energy negative particles
- 2011
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In: Europhysics letters. - : EDP Sciences. - 0295-5075 .- 1286-4854. ; 93:5
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Journal article (peer-reviewed)abstract
- Multiple volume reflection by different planes passing through the 〈111〉 axis in a bent silicon crystal was observed for the first time for 150 GeV/c negative particles, π- mesons, at one of the secondary beams of the CERN SPS. The beam of π- mesons was deflected opposite to the crystal bend by an angle of about 48 μrad, which is 4.6 times larger than in a single volume reflection by the (110) bent planes. The one-side deflection efficiency was about 65%. Multiple volume reflection transforms to a single volume reflection when the orientation angle of the 〈111〉 axis relative to the beam direction is increased. Copyright © 2011 Europhysics Letters Association.
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| 8. |
- Scandale, W., et al.
(author)
-
Multiple volume reflections of high-energy protons in a sequence of bent silicon crystals assisted by volume capture
- 2010
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In: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 688:4-5, s. 284-288
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Journal article (peer-reviewed)abstract
- Multiple volume reflections of the 400 GeV / c proton beam by the sequence of fourteen bent silicon strips has been studied at the CERN SPS. The sequence is close to be parallel that is the spread of the strip orientation angles is much smaller than their bend angle and eleven strips working coherently in the regime of volume reflections deflected the beam by 110 μrad with the efficiency 88%, which is significantly larger than the estimation based on independent reflections. The mechanism giving the efficiency increase has been studied by simulation. It appears that many particles volume captured in one of the strips take part in volume reflections in the subsequent ones. Such a crystal multi reflector can be successfully used as a primary collimator for the beam halo collimation of high-energy accelerators.
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| 9. |
- Scandale, W., et al.
(author)
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Observation of nuclear dechanneling for high-energy protons in crystals
- 2009
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In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 680:2, s. 129-132
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Journal article (peer-reviewed)abstract
- Channeling in a short bent silicon crystal was investigated at the CERN SPS using 400-GeV/c protons with an angular spread much narrower than the critical channeling angle. Particle dechanneling due to multiple scattering on the atomic nuclei of the crystal was observed and its dechanneling length was measured to be about 1.5 mm. For a crystal with length comparable to such dechanneling length, an efficiency of 83.4% was recorded, which is close to the maximum value expected for a parallel beam and exceeds the previously known limitation of deflection efficiency for long crystals. © 2009 Elsevier B.V. All rights reserved.
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| 10. |
- Scandale, Walter, et al.
(author)
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Apparatus to study crystal channeling and volume reflection phenomena at the SPS H8 beamline
- 2008
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In: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 79:2
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Journal article (peer-reviewed)abstract
- A high performance apparatus has been designed and built by the H8-RD22 collaboration for the study of channeling and volume reflection phenomena in the interaction of 400 GeVc protons with bent silicon crystals, during the 2006 data taking in the external beamline H8 of the CERN SPS. High-quality silicon short crystals were bent by either anticlastic or quasimosaic effects. Alignment with the highly parallel (8 μrad divergence) proton beam was guaranteed through a submicroradian goniometric system equipped with both rotational and translational stages. Particle tracking was possible by a series of silicon microstrip detectors with high-resolution and a parallel plate gas chamber, triggered by various scintillating detectors located along the beamline. Experimental observation of volume reflection with 400 GeVc protons proved true with a deflection angle of (10.4±0.5) μrad with respect to the unperturbed beam, with a silicon crystal whose (111) planes were parallel to the beam. © 2008 American Institute of Physics.
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| 11. |
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| 12. |
- Scandale, Walter, et al.
(author)
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Deflection of 400GeV/c proton beam with bent silicon crystals at the CERN Super Proton Synchrotron
- 2008
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In: Physical Review Special Topics - Accelerators and Beams. - 1098-4402. ; 11:6
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Journal article (peer-reviewed)abstract
- This paper presents a detailed study of the deflection phenomena of a 400GeV/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. © 2008 The American Physical Society.
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| 13. |
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| 14. |
- Fiorini, M., et al.
(author)
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Experimental study of crystal channeling at CERN-SPS for beam-HALO cleaning
- 2006
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In: EPAC 2006. - Edinburgh : European Physical Society Accelerator Group (EPS-AG). - 9290832797 ; , s. 1538-1540
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Conference paper (peer-reviewed)abstract
- An efficient and robust collimation system is mandatory for any superconducting hadron collider, in particular for the LHC, which will store a beam of unprecedented high intensity and energy. The usage of highly efficient and short primary bent-crystal collimators might be a possibility for reaching nominal and ultimate LHC intensity. Over the last years, groups in Italy (Ferrara) and Russia (St. Petersburg) have developed crystal production methods, that considerably improve the crystal quality. These developments led, in turn, to a surprising increase in the channeling efficiency and to the recent observation of the "volume reflection" mechanism. The aim of the proposed experiment is the setup of a beam test facility, directing primary protons from the SPS onto a bent silicon crystal, and the quantitative study of single-pass efficiency for all involved processes. Final goal will be the extrapolation of important information on the feasibility of a crystal collimator for halo cleaning in the LHC. The experiment will be performed in the H8 beamline at the CERN SPS where a beam with very small divergence can be provided thus representing a unique facility for tests and characterization of crystals to be used for particle channeling studies.
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