Slow positron beam extraction from high magnetic fields

Shi, M.; Gerola, D.; Waeber, W.B.; Zimmermann, Uwe

doi:10.1016/0169-4332(94)00323-8

Cited by 15 publications

(3 citation statements)

References 2 publications

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“…Nevertheless, a number of experiments that have succeeded in taking positrons (or electrons) from a high magnetic field into a field-free region Akahane (1994); Gerola et al (1995); Greaves and Surko (2002a); Shi et al (1995). Figure 33 shows the experimental arrangement of a recent experiment in which electron plasma was tailored in a PM trap in a 5 T field, then a beam was extracted, transported to a field-free region, and then focused with an electrostatic Einzel lens .…”

Section: E Electrostatic Beamsmentioning

confidence: 99%

Plasma and trap-based techniques for science with positrons

Danielson¹,

Dubin²,

Greaves³

et al. 2015

Rev. Mod. Phys.

228

222

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In recent years, there has been a wealth of new science involving low-energy antimatter (i.e., positrons and antiprotons) at energies ranging from 10 2 to less than 10 −3 eV. Much of this progress has been driven by the development of new plasma-based techniques to accumulate, manipulate and deliver antiparticles for specific applications. This article focuses on the advances made in this area using positrons. However many of the resulting techniques are relevant to antiprotons as well. An overview is presented of relevant theory of single-component plasmas in electromagnetic traps. Methods are described to produce intense sources of positrons and to efficiently slow the typically energetic particles thus produced. Techniques are described to trap positrons efficiently and to cool and compress the resulting positron gases and plasmas. Finally, the procedures developed to deliver tailored pulses and beams (e.g., in intense, short bursts, or as quasi-monoenergetic continuous beams) for specific applications are reviewed. The status of development in specific application areas is also reviewed. One example is the formation of antihydrogen atoms for fundamental physics [e.g., tests of invariance under charge conjugation, parity inversion and time reversal (the CPT theorem), and studies of the interaction of gravity with antimatter]. Other applications discussed include atomic and materials physics studies and study of the electron-positron many-body system, including both classical electron-positron plasmas and the complementary quantum system in the form of Bose-condensed gases of positronium atoms. Areas of future promise are also discussed. The review concludes with a brief summary and a list of outstanding challenges.

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Section: E Electrostatic Beamsmentioning

confidence: 99%

Plasma and trap-based techniques for science with positrons

Danielson¹,

Dubin²,

Greaves³

et al. 2015

Rev. Mod. Phys.

228

222

View full text Add to dashboard Cite

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“…The extraction can be accomplished by passing the beam through an aperture, grid, or spokelike structure made of a material with a large magnetic permeability, as long as it is done in a time less than ϳ1 / c ͑i.e., ഛ a gyroperiod in the field from which the beam is extracted͒. 31,32 Consider, for example, a beam of initial width b =2 D that has been extracted ͑stage I͒ from a 30 K ͑i.e., 3 meV͒ plasma with density n 0 =3ϫ 10 10 cm −3 in a field of B = 4.8 T. The corresponding values of b and ⑀Ј are b =5 ϫ 10 −4 cm and ⑀Ј=3ϫ 10 −3 cm eV 1/2 . The beam is then transported adiabatically to a lower field region at B =5 ϫ 10 −4 T ͑stage II͒, and finally extracted nonadiabatically from the field ͑stage III͒ through an aperture of diameter b that is made from material with a high magnetic permeability.…”

Section: B Electrostatic Beamsmentioning

confidence: 99%

“…In this case, ⌬E Ќ can be estimated by computing the transverse velocity increase ⌬v Ќ that a particle experiences as it moves through the diverging magnetic field at the termination. In CGS units, for a rectangular grid with openings of dimensions d Ӷ b, ⌬v Ќ ϳ c d, 31 resulting in a perpendicular energy spread, i.e., ⌬E Ќ ϳ͑m / 2͒͑ c d͒ 2 , where c is the cyclotron frequency. Comparison with Eq.…”

Section: B Electrostatic Beamsmentioning

confidence: 99%

Creation of finely focused particle beams from single-component plasmas

2008

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In a recent communication ͓Danielson et al., Appl. Phys. Lett. 90, 081503 ͑2007͔͒, a nondestructive technique was described to create finely focused beams of electron-mass, charged particles ͑i.e., electrons or positrons͒ from single-component plasmas confined in a Penning-Malmberg trap. This paper amplifies and expands upon those results, providing a more complete study of this method of beam formation. A simple model for beam extraction is presented, and an expression for a Gaussian beam profile is derived when the number of extracted beam particles is small. This expression gives a minimum beam diameter of four Debye lengths ͑full width to 1 / e͒ and is verified using electron plasmas over a broad range of plasma temperatures and densities. Numerical procedures are outlined to predict the profiles of beams with large numbers of extracted particles. Measured profiles of large beams are found in fair agreement with these predictions. The extraction of over 50% of a trapped plasma into a train of nearly identical beams is demonstrated. Applications and extensions of this technique to create state-of-the-art positron beams are discussed.

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