The refraction and dispersion of neon and helium

Cuthbertson, Clive; Cuthbertson, Maude

doi:10.1098/rspa.1932.0019

Cited by 98 publications

(17 citation statements)

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“…Indeed, the polarizability varies with frequency as measured by Cuthbertson [12] cited by M.H.Edwards [13]. At the melting density (and for 514.5 nm), we found n He = 1.0339.…”

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confidence: 72%

Acoustic Crystallization and Heterogeneous Nucleation

2001

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By focusing a high intensity acoustic wave in liquid helium, we have observed the nucleation of solid helium inside the wave above a certain threshold in amplitude. The nucleation is a stochastic phenomenon. Its probability increases continuously from 0 to 1 in a narrow pressure interval around Pm + 4.7 bars (Pm = 25.3 bars is the melting pressure where liquid and solid helium are in equilibrium). This overpressure is larger by two to three orders of magnitude than what had been previously observed. Our result strongly supports the recent suggestion by Balibar, Mizusaki and Sasaki [1] that, in all previous experiments, solid helium nucleated on impurities.67. 80.-s, 64.60.-i, 43.35.+d To our knowledge, no one has ever observed that a high intensity sound wave travelling in a liquid can crystallize this liquid. Several experiments have shown that the negative pressure swings of the wave can produce cavitation, in other words nucleate bubbles or trigger the liquid-gas transition [2]. By focusing an acoustic wave in liquid helium, we have found that the positive swings can also trigger the liquid-solid transition. It occurs if the wave amplitude reaches a certain threshold which we have measured. We could also estimate the size of the crystallites formed in the wave (15 µm) and their typical growth velocity (100 ms −1 , close to the speed of sound). We believe that it is the ability of helium crystals to grow at very high speed which allowed us to make this observation. The observed threshold corresponds to a pressure 4.7 bar higher than the equilibrium pressure. This overpressure is two to three orders of magnitude larger than what had been observed in all previous experiments [3][4][5][6][7]. Our result strongly supports the recent suggestion by Balibar, Mizusaki and Sasaki [1] that, in all these previous experiments, solid helium nucleated on favourable impurities.Let us first describe our experimental method. Inside a cryostat with optical access, we have focused an acoustic wave through liquid helium 4. The acoustic focus is located on a clean glass plate which allows us to measure the local instantaneous density of liquid helium [8] (see Fig.1). The acoustic wave is emitted by a hemispherical piezoelectric transducer similar to the one we used for the study of cavitation [2]. It resonates in a thickness mode at 1.019 MHz and we pulse it with bursts of six oscillations, consequently about 6 µs wide. The focusing is achieved by the transducer geometry. Given the characteristics of our RF amplifier, we can reach a maximum acoustic power of 5 kW.cm −2 (200 dB) at the focus. The transducer is gently pressed against the glass plate. At the melting pressure, the sound velocity is 366.3 ms −1 in the liquid phase [9] , so that the acoustic wavelength is 360 µm. A lens of focal length 2 cm is located inside the experimental cell and focuses an Ar + laser beam onto the acoustic focal region. The waist of the laser beam at the focus is 30 µm, less than one tenth of the acoustic wavelength. The light spot position is c...

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“…Indeed, the polarizability varies with frequency as measured by Cuthbertson [12] cited by M.H.Edwards [13]. At the melting density (and for 514.5 nm), we found n He = 1.0339.…”

mentioning

confidence: 72%

Acoustic Crystallization and Heterogeneous Nucleation

2001

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“…In comparing our results with experiment, 16 ' 17 we shall first consider the refractive index and subsequently the excitation energies. The refractive index n(oo) for a system of noninteracting at-£7* "i.…”

Section: M'mentioning

confidence: 96%

“…2, we have presented our calculated curve for the refractive index using diagrams 1(a) through 1(e), together with the results of some earlier variational calculations, 5 ' 9 "" 12 and the experimental data of Cuthbertson and Cuthbertson (CC). 16 To enable detailed comparison, the results over the range of frequencies from 0 to 0.2 a.u. are enlarged in the insert in Fig.…”

Section: M'mentioning

confidence: 99%

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Many-Body Theory for Time-Dependent Perturbations in Atomic Systems

et al. 1969

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the same as the H maser" However, a refrigerated photocell and a He-Ne optical preamplifier should each add about 10 dB. The higher cavity Q will require greater bandwidth in the cavity stabilizing feed-back loop, but the signal-to-noise ratio should be ample. With a methane cell of four-times larger aperture, cooled to 76°K, we should closely approximate the H-maser stability.A many-body approach for the calculation of time-dependent properties of atoms is developed and applied to helium atom. The refractive indices and excitation energies so obtained are in excellent agreement with experiment.

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“…For typical glass wall materials the index of refraction, n w , is ~1.5. For Helium, n g , at 2000 atm and 20°C the index of refraction can be calculated from the data in Cuthbertson's paper 69 and is ~1.025 from 190-460 nm. Xenon doping at the 10% atomic level increases the index of refraction in this photon range up to ~1.1.…”

Section: Scintillation Detectionmentioning

confidence: 99%

Innovative high pressure gas MEM's based neutron detector for ICF and active SNM detection.

Martin¹,

Derzon²,

Renzi³

et al. 2007

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An innovative helium3 high pressure gas detection system, made possible by utilizing Sandia's expertise in Micro-electrical Mechanical fluidic systems, is proposed which appears to have many beneficial performance characteristics with regards to making these neutron measurements in the high bremsstrahlung and electrical noise environments found in High Energy Density Physics experiments and especially on the very high noise environment generated on the fast pulsed power experiments performed here at Sandia. This same system may dramatically improve active WMD and contraband detection as well when employed with ultrafast (10-50 ns) pulsed neutron sources. 4 ACKNOWLEDGMENTS[Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000.We wish to acknowledge those who have contributed to this project. This list includes but is not to

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The refraction and dispersion of neon and helium

Cited by 98 publications

References 0 publications

Acoustic Crystallization and Heterogeneous Nucleation

Acoustic Crystallization and Heterogeneous Nucleation

Many-Body Theory for Time-Dependent Perturbations in Atomic Systems

Innovative high pressure gas MEM's based neutron detector for ICF and active SNM detection.

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