TY - JOUR

T1 - Aperture method to determine the density and geometry of antiparticle plasmas

AU - Oxley, P.

AU - Bowden, N. S.

AU - Parrott, R.

AU - Speck, A.

AU - Storry, C. H.

AU - Tan, J. N.

AU - Wessels, M.

AU - Gabrielse, G.

AU - Grzonka, D.

AU - Oelert, W.

AU - Schepers, G.

AU - Sefzick, T.

AU - Walz, J.

AU - Pittner, H.

AU - Hänsch, T. W.

AU - Hessels, E. A.

N1 - Funding Information:
We are grateful to CERN, its PS Division and the AD team for delivering antiprotons, to Ross Spencer for providing the computer code, and to J. Bollinger and R. Spencer for helpful comments. This work was supported by the NSF, AFOSR, the ONR of the US, the BMBF, MPG and FZ-J of Germany, and the NSERC, CRC, CFI and OIT of Canada.

PY - 2004/8/12

Y1 - 2004/8/12

N2 - The density and geometry of p̄ and e+ plasmas in realistic trapping potentials are required if the rate of antihydrogen formation from them is to be understood. A new measurement technique determines these properties of trapped positron (e+) and antiproton (p̄) plasmas, the latter for the first time. The method does not require the common assumption of a spheroidal plasma geometry, which only pertains for a perfect electrostatic quadrupole trapping potential. Plasma densities, diameters, aspect ratios and angular momenta are deduced by comparing the number of particles that survive transmission through an aperture, to that obtained from self-consistent solutions of Poisson's equation. For p̄ the results differ substantially from the spheroid plasmas of an ideal Penning trap. The angular momentum of the plasma emerges as smooth function of the number of particles in the plasma, independent of the depth of the potential well that confines them.

AB - The density and geometry of p̄ and e+ plasmas in realistic trapping potentials are required if the rate of antihydrogen formation from them is to be understood. A new measurement technique determines these properties of trapped positron (e+) and antiproton (p̄) plasmas, the latter for the first time. The method does not require the common assumption of a spheroidal plasma geometry, which only pertains for a perfect electrostatic quadrupole trapping potential. Plasma densities, diameters, aspect ratios and angular momenta are deduced by comparing the number of particles that survive transmission through an aperture, to that obtained from self-consistent solutions of Poisson's equation. For p̄ the results differ substantially from the spheroid plasmas of an ideal Penning trap. The angular momentum of the plasma emerges as smooth function of the number of particles in the plasma, independent of the depth of the potential well that confines them.

KW - 36.10.-k

UR - http://www.scopus.com/inward/record.url?scp=3843072989&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=3843072989&partnerID=8YFLogxK

U2 - 10.1016/j.physletb.2004.04.084

DO - 10.1016/j.physletb.2004.04.084

M3 - Article

AN - SCOPUS:3843072989

VL - 595

SP - 60

EP - 67

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

SN - 0370-2693

IS - 1-4

ER -