Helium physical constants

The accurate study of some atoms (hydrogen, deuterium, muonium, helium and hydrogen-like carbon) and some free particles (electron, proton, muon) provides us with new highly accurate values of the fundamental physical constants which are important far beyond the physics of simple atoms. 

Table 7. Contributions to the total ionization energies for the S-states of helium. The values used for the physical constants are Roo = 3289841960.389 MHz, a-1 = 137.035 9895 and p/M = 1.370745620 x 10-4. Units are MHz...

The idea that the cosmos is in some sense biocentric has been supported over the past several decades by the discovery of biocentric fine-tuning of the fundamental physical constants (see also the contributions of other authors in this volume), the so-called cosmic coincidences (Car and Rees, 1979 Davies, 1982 Barrow and Tipler, 1986). One such coincidence is the lucky fact that the nuclear resonances of and O are exactly what they need to be if carbon is to be synthesized and accumulate in any quantity in the interior of stars. The energy levels of these resonances ensure that is first synthesized in stellar interiors from collisions between Be and helium nuclei and that the carbon synthesized is not depleted later. This discovery was made by Hoyle in 1953 while working at Caltech with William Fowler (Hoyle, 1964). An intriguing aspect of the discovery is, as Hoyle later pointed out (1994, p. 256), that it was a prediction from the Anthropic Principle. From the cosmic abundance of carbon, Hoyle inferred probable coincidences in the nuclear resonances that facilitated and promoted the synthesis of carbon (Barrow and Tipler, 1986, pp. 250-5). Hoyle s discovery was widely acclaimed, not only as a major scientific discovery, but also as evidence for the biocentricity of nature. 

The choice of carrier gas will also be dependent on the type of columns you will use. For capillary columns the two most popular carrier gases are helium and hydrogen. When using packed columns, most analysts choose between nitrogen and helium. A van Deemter equation allows the comparison of efficiencies obtainable with carrier gases (4-9). The van Deemter equation (Equation 10.1) expresses the extent a component band spreads as it passes through the column in terms of physical constants and the velocity of the mobile phase ... 

Precision spectroscopy of helium has not, in general, been of importance for fundamental constants with the single conspicuous exception of optical spectroscopy of ionized helium. Taking advantage of the zero spin nucleus, E. Kessler was able to accomplish the last definitive Rydberg measurement before the advent of Doppler-free spectroscopy [20]. Beyond this, when two electrons are present, the physical constants and the QED effects are joined by the problem of how the two electrons learn to live with one another. This subject is rich and diverse and is treated to some extent in the contribution of Professor Fano to this Conference. 

In practice, different thermometer approaches are used at very high temperatures one uses the laws of thermal radiation (refer to Chapter 6.6) at average temperatures— the thermal expansion of hydrogen or helium at constant pressure and at low temperatures— the characteristics of solids according to the laws of quantum physical statistics (refer to Chapter 9.3) are used. 

II is a function of hydrodynamic parameters of the model. Unfortunately, these parameters which describe the effect of hydrodynamics do not correspond to any physical quantity nor can they be Independently evaluated. For some models, the value of w is a constant. For example, the penetration and surface renewal models (Danckwerts, 31) predict w 0.5, while for the boundary layer model w 2/3. The film-penetration model, on the other hand, predicts that w varies between 0.5 and 1 (Toor and Marchello, 32). Knowledge of the effect of dlffuslvlty on k Is needed in evaluating the various mass transfer models. Calderbank (13) reported a value of 0.5 Linek et al. (22) used oxygen, Helium and argon. The reported diffusion coefficients for helium and similar gases vary widely. Since in the present work three different temperatures have been used, the value of w can be determined much more accurately. Figure 4... 

The fine structure constant a can be determined with the help of several methods. The most accurate test of QED involves the anomalous magnetic moment of the electron [40] and provides the most accurate way to determine a value for the fine structure constant. Recent progress in calculations of the helium fine structure has allowed one to expect that the comparison of experiment [23,24] and ongoing theoretical prediction [23] will provide us with a precise value of a. Since the values of the fundamental constants and, in particular, of the fine structure constant, can be reached in a number of different ways it is necessary to compare them. Some experiments can be correlated and the comparison is not trivial. A procedure to find the most precise value is called the adjustment of fundamental constants [39]. A more important target of the adjustment is to check the consistency of different precision experiments and to check if e.g. the bound state QED agrees with the electrical standards and solid state physics. 

The excellent agreement between experiment and theory is used to deduce a constraint on the assumed mass Mp and charge Qp of antiproton. While the cyclotron frequency of p measured by Gabrielse et al. [22] sets a severe constraint on the ratio Mp/Qp, the antiprotonic helium gives a constrant on the p Rydberg constant MpQ a la Hughes and Deutch [23]. Combining these two physical quantities we obtain Mp and Qp independently. The constraints thus obtained are shown in Fig. 7. 

P. Cancio et al. Fine structure constant a and precision laser spectroscopy of Helium . In Recent advances in Metrology and Fundamental constants, Proceedings of the International School of Physics Enrico Fermi , ed. By S. Leschiutta, T.J. Quinn (SIF, Bologna) in press... 

We are now in a position to discuss the physical properties of surface state electrons. We choose liquid helium for the dielectric. According to H. L. Anderson (1989) the dielectric constant for liquid helium is given by... 

Properties. — The constants for the principal physical properties of helium are given in the table on page 21. The properties which make helium most interesting are its lightness, its close approach to a perfect gas, its close relationship to the radioactivity and the composition of atoms, and its absolute chemical inactivity. 

Marin and Cruz [16] also computed some properties of physical interest for the CHA, such as the Fermi contact term [30,34,35,38], diamagnetic screening constant [30,34,35], polarizability [30,34,35,44,45,57-61,63] and pressure [1,30,34,35]. In addition, they studied the hydrogen and helium atom in penetrable boxes, and the hydrogen atom between parallel hard walls [16]. 

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