Performance of short and long bent crystals for the TWOCRYST experiment at the Large Hadron Collider

This study investigates the performance of bent silicon crystals intended to channel hadrons in a fixed-target experiment at the Large Hadron Collider (LHC). The phenomenon of planar channelling in bent crystals enables extremely high effective bending fields for positively charged hadrons within compact volumes. Particles trapped in the potential well of high-purity, ordered atomic lattices follow the mechanical curvature of the crystal, resulting in macroscopic deflections. Although the bend angle remains constant across different momenta (i.e., the phenomenon is non-dispersive), the channelling acceptance and efficiency still depend on the particle momentum. Crystals with lengths in the range of 5 to 10 cm, bent to angles between 5 and 15 mrad, are under consideration for measurements of the electric and magnetic dipole moments of short-lived charmed baryons, such as the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mi>Λ</mml:mi> <mml:mi>c</mml:mi> <mml:mo>+</mml:mo></mml:msubsup> </mml:math> . Such large deflection angles over short distances cannot be achieved using conventional magnets. The principle of inducing spin precession through bent crystals for magnetic dipole moment measurements was first demonstrated experimentally in the 1990s. Building on this concept, experimental layouts are now being explored for implementation at the LHC. The feasibility of such measurements depends, among other factors, on the availability of crystals that exhibit the required mechanical properties to reach the necessary channelling performance. To address this, a dedicated machine experiment - TWOCRYST - has been installed in the LHC to carry out beam tests in the TeV energy range. The bent crystals for TWOCRYST were fabricated and tested using both X-ray diffraction and high-momentum hadron beams at 180 GeV/c at the CERN Super Proton Synchrotron (SPS) extraction lines. Two crystals based on established technologies were included in this test. In addition, a crystal bent via anodic bonding was tested for the first time with high-energy hadrons to assess its potential for future accelerator applications. This paper presents an analysis of the performance of the three tested crystals and, where possible, outlines key differences in their properties attributed to the respective bending techniques.

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Publication Details

Journal
The European Physical Journal C
Published
2025-12-02
DOI
https://doi.org/10.1140/epjc/s10052-025-15092-y
Primary Topic
Crystallography and Radiation Phenomena
Type
article
Field-Weighted Citation Impact
0.00

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article

Performance of short and long bent crystals for the TWOCRYST experiment at the Large Hadron Collider

D. Marangotto, V. Guidi, A. Merli, Pascal Hermes et al.
The European Physical Journal C
Crystallography and Radiation Phenomena
article

Performance of short and long bent crystals for the TWOCRYST experiment at the Large Hadron Collider

D. Marangotto, V. Guidi, A. Merli, Pascal Hermes, S. Cesare, D. De Salvador, D. Mirarchi, R. Cai, A. Selmi, Kay Dewhurst, M. Romagnoni, A. Mazzolari, P. Monti-Guarnieri, C. E. Montanari, Lorenzo Malagutti, Chiara Maccani, L. Bandiera, S. Redaelli, P. Gandini, R. Negrello, G. Lezzani, G. Tonani, S. Carsi, D. Veres, M. D’Andrea, M. Zielińska, N. Néri, F. Zangari, E. Vallazza, M. Prest
article en

Abstract

This study investigates the performance of bent silicon crystals intended to channel hadrons in a fixed-target experiment at the Large Hadron Collider (LHC). The phenomenon of planar channelling in bent crystals enables extremely high effective bending fields for positively charged hadrons within compact volumes. Particles trapped in the potential well of high-purity, ordered atomic lattices follow the mechanical curvature of the crystal, resulting in macroscopic deflections. Although the bend angle remains constant across different momenta (i.e., the phenomenon is non-dispersive), the channelling acceptance and efficiency still depend on the particle momentum. Crystals with lengths in the range of 5 to 10 cm, bent to angles between 5 and 15 mrad, are under consideration for measurements of the electric and magnetic dipole moments of short-lived charmed baryons, such as the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mi>Λ</mml:mi> <mml:mi>c</mml:mi> <mml:mo>+</mml:mo></mml:msubsup> </mml:math> . Such large deflection angles over short distances cannot be achieved using conventional magnets. The principle of inducing spin precession through bent crystals for magnetic dipole moment measurements was first demonstrated experimentally in the 1990s. Building on this concept, experimental layouts are now being explored for implementation at the LHC. The feasibility of such measurements depends, among other factors, on the availability of crystals that exhibit the required mechanical properties to reach the necessary channelling performance. To address this, a dedicated machine experiment - TWOCRYST - has been installed in the LHC to carry out beam tests in the TeV energy range. The bent crystals for TWOCRYST were fabricated and tested using both X-ray diffraction and high-momentum hadron beams at 180 GeV/c at the CERN Super Proton Synchrotron (SPS) extraction lines. Two crystals based on established technologies were included in this test. In addition, a crystal bent via anodic bonding was tested for the first time with high-energy hadrons to assess its potential for future accelerator applications. This paper presents an analysis of the performance of the three tested crystals and, where possible, outlines key differences in their properties attributed to the respective bending techniques.

The European Physical Journal CVol. 85(12)
Warsaw University of Technology (PL), Goethe University Frankfurt (DE), University of Insubria (IT), University of Padua (IT), University of Trieste (IT), University of Milan (IT), University of Ferrara (IT), University of Manchester (GB), Istituto Nazionale di Fisica Nucleare, Sezione di Padova (IT), Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara (IT), Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro (IT), Istituto Nazionale di Fisica Nucleare, Sezione di Milano (IT), Istituto Nazionale di Fisica Nucleare, Sezione di Milano Bicocca (IT), Istituto Nazionale di Fisica Nucleare, Sezione di Trieste (IT), École Polytechnique Fédérale de Lausanne (CH), European Organization for Nuclear Research (CH), University of Cumbria (GB)
CERN, European Commission, Generalitat Valenciana, Politechnika Warszawska, Narodowym Centrum Nauki, Università degli Studi di Ferrara, University of Chinese Academy of Sciences, Istituto Nazionale di Fisica Nucleare, Agencia Estatal de Investigación, Nuclear Physics, Commissione Scientifica Nazionale 5, Instituto Nazionale di Fisica Nucleare
Openalex Percentile: Top 76%
Crystallography and Radiation Phenomena
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