A. Oliveira’s scientific contributions

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Publications (3)


A Magnetic Field Cloak For Charged Particle Beams
  • Preprint

July 2017

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2 Reads

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A. Tishelman-Charny

Shielding charged particle beams from transverse magnetic fields is a common challenge for particle accelerators and experiments. We demonstrate that a magnetic field cloak is a viable solution. It allows for the use of dipole magnets in the forward regions of experiments at an Electron Ion Collider (EIC) and other facilities without interfering with the incoming beams. The dipoles can improve the momentum measurements of charged final state particles at angles close to the beam line and therefore increase the physics reach of these experiments. In contrast to other magnetic shielding options (such as active coils), a cloak requires no external powering. We discuss the design parameters, fabrication, and limitations of a magnetic field cloak and demonstrate that cylinders made from 45 layers of YBCO high-temperature superconductor, combined with a ferromagnetic shell made from epoxy and stainless steel powder, shield more than 99% of a transverse magnetic field of up to 0.45 T (95 % shielding at 0.5 T) at liquid nitrogen temperature. The ferromagnetic shell reduces field distortions caused by the superconductor alone by 90% at 0.45 T.


A Magnetic Field Cloak For Charged Particle Beams

July 2017

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76 Reads

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19 Citations

Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment

Shielding charged particle beams from transverse magnetic fields is a common challenge for particle accelerators and experiments. We demonstrate that a magnetic field cloak is a viable solution. It allows for the use of dipole magnets in the forward regions of experiments at an Electron Ion Collider (EIC) and other facilities without interfering with the incoming beams. The dipoles can improve the momentum measurements of charged final state particles at angles close to the beam line and therefore increase the physics reach of the experiments. In contrast to other magnetic shielding options (such as active coils), a cloak requires no external powering. We discuss the design parameters, fabrication, and limitations of a magnetic field cloak and demonstrate that cylinders made from 45 layers of YBCO high-temperature superconductor, combined with a ferromagnetic shell made from epoxy and stainless steel powder, shield more than 99% of a transverse magnetic field of up to 0.45 T (95% shielding at 0.5 T) at liquid nitrogen temperature. The ferromagnetic shell reduces field distortions caused by the superconductor alone by 90% at 0.45 T.


Figure 1: Diagrams the principle of magnetic cloaking, field lines shown in red [4]. 
Figure 2: Phosphor screens and calibration grid. From top to bottom: screen made using light-bulb phosphor, screen made zinc sulfide and silver, commercial phosphor screen, calibration grid with 0.1 in interval. 
Table 2 : Summary of Fit Results
Figure 3: Preliminary results from run 1 (lithium-7 run). Room temperature beam deflection measurements shown in red; cryogenic measurements shown in blue. Diamonds indicate data points that were excluded from linear fit calculations as part of the beam had been deflected from the screen, resulting in the downward skewing of the displacement measurements. Fits are shown in the same color as their respective data sets. 
Figure 4: Preliminary results from run 2 (oxygen-16 run). Room temperature beam deflection measurements shown in red; cryogenic measurements shown in blue. Diamonds indicate data points that were excluded from linear fit calculations as part of the beam had been deflected from the screen, resulting in the downward skewing of the displacement measurements. Fits are shown in the same color as their respective data sets. 
Magnetic Cloaking of Charged Particle Beams
  • Conference Paper
  • Full-text available

January 2017

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185 Reads

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1 Citation

In order to measure the momentum of particles produced by asymmetric collisions in the proposed Electron Ion Collider, a magnetic field should be introduced perpendicular to the path of the beam to increase momentum resolution without bending or depolarizing it. A magnetic cloak consisting of a superconducting magnetic shield surrounded by a ferromagnetic layer is capable of shielding the interior from a magnetic field – thereby protecting the beam – without distorting the field outside of the cloak – permitting detector coverage at high pseudorapidity.

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Citations (2)


... As mentioned in Sec. 2, such a time dependence above a certain threshold field is an expected behavior for HTS shields.Figure 10shows the magnetic field shielding performance of the 1 m long, 2-layer HTS shield in the Vandesteering dipole field B a , both at room temperature (superconductor does not shield field) and at liquid nitrogen temperature (superconductor shields field). The superconducting shield reduces the beam deflection by about 94% (see[18]for a comparison of our 7 3 Li 3+ and 16 8 O 3+ results). The bottom panel shows the field measured with a Hall sensor in the center of the shield as a function of steering dipole fields. ...

Reference:

A Magnetic Field Cloak For Charged Particle Beams
Magnetic Cloaking of Charged Particle Beams

... Due to the development of novel devices such as magnetic cloaks [3,4], concentrators [5,6], enhanced sensors [7] and artificial magnetic wormholes [8], new possibilities appeared. Nowadays one can improve the measurement range of magnetic field probes [9], simultaneously ensure the effective shielding and 'hide' objects [10], absorb power nearly perfectly in the energy harvesting systems [11] and minimize the influence of a device under test and an environment on each other [12]. Many extraordinary metamaterial properties were achieved through their ability to exhibit diamagnetic behavior and also due to anisotropy of the effective permeability and/or permittivity [13]. ...

A Magnetic Field Cloak For Charged Particle Beams
  • Citing Article
  • July 2017

Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment