Helium muonic

Discussing light muonic atoms we will often speak about muonic hydrogen but almost ah results below are valid also for another phenomenologically interesting case, namely muonic helium. In the Sections on light muonic atoms, m is the muon mass, M is the proton mass, and rUe is the electron mass. 

Transitions in Muonic Helium Ions Induced by Laser Radiation... 

An apparatus to perform a laser-stimulated 3D-3P transition in muonic helium ions (at the Single Burst Extraction Beam of the Brookhaven National Laboratory Alternating Gradient Synchrotron) is presented together with some results. 

Some years ago, at the CERN Synchro-cyclotron, a CERN-Pisa Collaboration [1] devised an experimental scheme to perform a laser-induced transition experiment on a muonic helium ion (n 4He) At that time a rather complex set-up, intimately connected with the operation of the Synchro-cyclotron itself, was installed and made to work, and the energy level differences D = 2 - 2P (see Table 1) were measured with an accuracy of 1.5 x 10 4. In Table 1 are presented the experimental results as well as the expected... 

In particular, this Collaboration has installed a set-up to measure the 3D-3P energy level differences in the muonic helium ions and here I wish to describe the apparatus, its performance, and give some of the experimental results obtained with it. 

In Fig. 1 are shown the first energy levels of the muonic helium ion together with some of their characteristics [6] in the same figure, the transition °5/2 F3/2 which is the first one to be measured, is marked with an arrow. 

In addition, this region of pressure seems to be rather important for an understanding of possible mechanisms [8, 9] through which the 2S muonic helium ion, at higher pressures, is so abundantly present after many hundreds of nanoseconds. 

A.M. Sachs, A. Blaer, J. French, M. May and E. Zavattini An experiment to measure vacuum polarization in 3D-3P transitions in muonic helium atoms. Proposal Exp. 745, Brookhaven National Laboratory. 

The two-photon-exchange spin-orbit interaction therefore decreases as r , or one power more rapidly than that arising from one-photon exchange. Applications of this result to a variety of exotic systems, such as pionium and muonic helium, are considered in Ref. [9]. 

This value is based on measurements of the Lamb shift in muonic helium, but attempts to reproduce the measurement have not proved successful, as discussed by Bracci and Zavattini [50]. The consistent, but less accurate value 1.676(8) fin has been obtained from electron scattering [51]. If the electron scattering value is used for " He, then the size of the error bars for the other helium isotopes increases in proportion, but the results do not otherwise change significantly. 

Fleming DG, Arseneau DJ, Sukhorukov O, Brewer JH, Mielke SL, Schatz GC, Garrett BC, Peterson KA, Tmhlar DG (2011) Kinetic isotope effects for the reactions of muonic helium and muonium with H2. Science 331 448... 

This paper describes experiments on muonium and neutral muonic helium. New results in this field were made possible by new types of muon beams and high-intensity accelerators. The muons produced... 

In muonic helium, three particles, the helium nucleus, the muon and the electron are bound in one system, all of them of different masses and not affected by the Pauli exclusion principle This system provides a sensitive testing ground for the 3-body SchrUdinger equation. 

The muonic helium atom was first discovered at SREL by means of the Larmor precession method Because of the very complicated formation process the residual polarisation of the muons in neutral muonic helium could not be predicted very well The y s are captured by the helium atom, and the atom looses both electrons due to Auger effect The He y" ion is highly excited (n=il4) The deexcitation is very fast and after a short time the ion is in its ground state The binding energy for electrons is like in... 

The measurements on muonium and muonic helium where done at LAMPF (USA) and SIN (Switzerland).The experiments where carried out with the following colleagues K.-P.Arnold, A.Badertscher, W.Beer, P.R.Bolton, P.O.Egan, M.Eckhause, C.J.Gardner, M.Greene,... 

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