Ramsey method

If we make the simplifying assumption that the time-domain Ramsey method is used to interrogate the clock transition, then the frequency stability (two-sample Allan variance- - ) is given as... 

Another situation occurs for various space tests of general relativity and related experiments for 9G/dt. The accumulation time and the reading-data time is essentially the same. Even if we try, similarly to atomic physics, to perform brief, say, one-day measurements every year, even that would not help. The problem is that when looking for a rotation of an electron we cannot measure the phase of the rotation and deal with something related in sense of classical physics to average parameters of the orbital motion. The planetary motion allows us to look for the phase of the rotation and thus the coherence time is equal to many periods of evolution. In a sense that is similar to the Ramsey method with two coherent space-separated short measurements. As a result, the effects of the gradients are of the same importance as effects of the time dependence of conventional terms. Any interpretation of the data in such a case is indeed strongly model-dependent. 

The transit-time broadening can greatly be reduced by the optical Ramsey method of separated fields. The best resolution of the recoil splittings has indeed... 

In Sect. 2.4 we saw that the first-order Doppler effect can be exactly canceled for a two-photon transition if the two photons hcoi = fuo2 have opposite wave vectors, i.e., k = —k2. A combination of Doppler-free two-photon absorption and the Ramsey method therefore avoids the phase dependence (p Vx) on the transverse velocity component. In the first interaction zone the molecular dipoles are excited with the transition amplitude a and precess with their eigenfrequency (jl> 2 = ( 2 — E )/h. If the two photons come from oppositely traveling waves with frequency u), the detuning... 

The Ramsey principle for the interaction of an atom moving in time through different electro-magnetic fields can be also realized in a completely different way. Atoms in a collimated beam are irradiated with an equidistant pulse train from a laser beam travelling collinearly with the atomic beam (Fig. 9.64). The distance Af between successive pulses corresponds to the flight time of molecules between the separated fields in the classical Ramsey method. 

The transit-time broadening can greatly be reduced by the optical Ramsey method of separated fields. The best resolution of the recoil splittings has indeed been achieved with this technique (Sect. 14.4). The transit time can also be increased if only molecules with small transverse velocity components contribute to the Lamb dip. If the laser intensity is kept so small that saturation of the molecular transition is reached only for molecules that stay within the laser beam for a sufficiently long time, that is, molecules with small components Vx, Vy, the transit-time broadening is greatly reduced [14.11]. 

A term that is nearly synonymous with complex numbers or functions is their phase. The rising preoccupation with the wave function phase in the last few decades is beyond doubt, to the extent that the importance of phases has of late become comparable to that of the moduli. (We use Dirac s terminology [7], which writes a wave function by a set of coefficients, the amplitudes, each expressible in terms of its absolute value, its modulus, and its phase. ) There is a related growth of literatm e on interference effects, associated with Aharonov-Bohm and Berry phases [8-14], In parallel, one has witnessed in recent years a trend to construct selectively and to manipulate wave functions. The necessary techifiques to achieve these are also anchored in the phases of the wave function components. This bend is manifest in such diverse areas as coherent or squeezed states [15,16], elecbon bansport in mesoscopic systems [17], sculpting of Rydberg-atom wavepackets [18,19], repeated and nondemolition quantum measurements [20], wavepacket collapse [21], and quantum computations [22,23], Experimentally, the determination of phases frequently utilizes measurement of Ramsey fringes [24] or similar" methods [25]. 

N. F. Ramsey (Harvard) invention of the separated oscillatory fields method and its use in the hydrogen maser and other atomic clocks. 

Landy, T.D., Ramsey, J.C. and McKenna, M.J. (1983). Pulmonary physiology and inhalation dosimetry in rats Development of a method and two examples. Toxicol. Appl. Pharmacol. 

R. C. Scott, P. L. Batten, H. M. Clowes, B. K. Jones, and J. D. Ramsey. Further validation of an in vitro method to reduce the need for in vivo studies for measuring the absorption of chemicals through rat skin. Fundam. Appl. Toxicol. 19 484-492 (1992). 

Supercritical-fluid chromatography has been applied by Ramsey et al. (213) for the determination of trimethoprim, along with three steroid hormones, in swine kidney. Separation was performed on a Spherisorb 5 amino-bonded column, using carbon dioxide with methanol modifier as the mobile phase. Detection at levels greater than 10 ppm was accomplished by tandem mass spectrometry using thermospray interface. However, this method lacks the sensitivity required to detect the low ppb levels likely to occur in milk and tissues. 

This last method has been used by Ramsey and Taft"5 to prepare a series of simple alkoxymethyl cations. The nmr chemical shifts, 8, of the protons of methylated methyl acetate and formate, given by Ramsey and Taft (measured in 30% S03 in H2S04) are compared below with the figures for the corresponding protonated esters, measured in FS0 tH-SbF5-S02 H. 

Ramsey, D. A., Electronic Structures of Polyatomic Molecules, in Determination of Organic Structures by Physical Methods, Academic Press, New York, 1962. 

The apparent rate of excretion was slower after dermal exposure than after oral administration, probably due to slower absorption of the 2,4,5-T ester from the skin than 2,4,5-T acid from the gut. This is in agreement with observations made by Feldmann and Maibach for 2,4-D and other pesticides applied to the forearm of human volunteers (13). Calculations by Ramsey et al. using three methods showed that 97% of the 2,4,5-T absorbed by forest workers would be excreted in urine within 7 days following dermal exposure under typical field conditions (16). 

Ramsey, J. M., Miniature chemical measurement systems, in Widmer, E., Verpoorte, E., Banard, S. (Eds.), Proceedings of the 2nd International Symposium on Miniaturized Total Analysis Systems, Analytical Methods and Instrumentation, Special Issue pTAS 96, Basel, 1996, 24-27. 

A comparison of different mineral acids for wet digestion of plant material for AAS analysis was carried out by Dokiya et al. (1975), who concluded that nitric acid was best for the determination of Cu, Mn and Pb by flameless AAS, whereas a nitric sulphuric mixture was best for Fe, Mn, Cu and Zn by FAAS. Most literature reports dissolve plant material in nitric acid (Middleton and Stuckey, 1954) or in nitric and perchloric acids (Isaac and Johnson, 1975 Williams, 1978, Thompson and Wood, 1982). This method will not dissolve aluminium containing particles from soil or other contaminations (Pierson and Evenson, 1988 Ramsey et al., 1991) (see also Standard Reference Materials). 

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