Matter and Methods at Low Temperatures

Pobell, F.

doi:10.1007/978-3-662-03225-1

Cited by 125 publications

(75 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since this cooling mechanism does not depend on the internal structure of the species (unlike laser cooling), buffer gas cooling can be applied to nearly any atom or small molecule [4], and certain large molecules [57]. Helium maintains a sufficient vapor pressure down to a few hundred mK [4,58], and the typical helium-molecule elastic cross section [4] of ∼ 10 −14 cm 2 allows buffer gas cool- ing and trap loading to be realized with modest cell sizes (few × few × few cm 3 ). Buffer gas cooling (using both helium and neon) has been used to create beams, load magnetic traps, and perform spectroscopy in a cold buffer gas cell [4].…”

Section: B Buffer Gas Cooling and Beam Productionmentioning

confidence: 99%

“…Fortunately there is a solution, which is to use activated charcoal as a cryopump [58]. When cooled to 10 K, activated charcoal becomes a cryopump for helium with up to several l s −1 pumping speed per cm 2 of charcoal, and can hold almost 1 STP liter of helium per gram (though these values are highly dependent on temperature, and other parameters [58]).…”

Section: Cryopumpsmentioning

confidence: 99%

See 1 more Smart Citation

The Buffer Gas Beam: An Intense, Cold, and Slow Source for Atoms and Molecules

2012

View full text Add to dashboard Cite

Section: B Buffer Gas Cooling and Beam Productionmentioning

confidence: 99%

Section: Cryopumpsmentioning

confidence: 99%

The Buffer Gas Beam: An Intense, Cold, and Slow Source for Atoms and Molecules

2012

View full text Add to dashboard Cite

“…These are mostly associated with its low thermal conductivity. Below the λ-point LHe is a nearly perfect thermal conductor [14], therefore there is no thermal convection or boiling, so the laser beam going through it is undisturbed. Normal liquid helium, however, is a very poor thermal conductor (κ ≈ 2×10 −4 W/cm·K).…”

mentioning

confidence: 99%

Kerr Effect in Liquid Helium at Temperatures Below the Superfluid Transition

et al. 2004

View full text Add to dashboard Cite

The electro-optical Kerr effect induced by a slowly-varying applied electric field in liquid helium at temperatures below the λ-point is investigated. The Kerr constant of liquid helium is measured to be (1.43±0.02 (stat) ±0.04 (sys) )×10 −20 (cm/V) 2 at T = 1.5 K. Within the experimental uncertainty, the Kerr constant is independent of temperature in the range T = 1.5 K to 2.17 K, which implies that the Kerr constant of the superfluid component of liquid helium is the same as that of normal liquid helium. Our result also indicates that pair and higher correlations of He atoms in the liquid phase account for about 23% of the measured Kerr constant. Liquid nitrogen was used to test the experimental set-up, the result for the liquid nitrogen Kerr constant is (4.38±0.15)×10 −18 (cm/V) 2 . The knowledge of the Kerr constant in these media allows the Kerr effect to be used as a non-contact technique for measuring the magnitude and mapping out the distribution of electric fields inside these cryogenic insulants.

show abstract

“…If this identification is appropriate, it would be related to the thermal boundary resistance and heat capacity C by t 2 = R C B , where R B is the thermal boundary resistance. The thermal boundary resistance between copper and solid 4 He is taken as [54] / , where A is the contact surface area. The solid line in Fig.…”

Section: Dynamic Thermal Responsementioning

confidence: 99%

“…The calculated t 2 captures the qualitative but not the detailed temperature dependence. Since the thermal boundary resistance at the copper/solid 4 He interface is smaller than at the copper/ He II interface [54] by a factor of seven, t 2 is expected to be smaller when the cell is filled with solid 4 He (the heat capacity of solid 4 He is greater than that of He II by only a factor of two). This discrepancy has not been resolved.…”

Section: Dynamic Thermal Responsementioning

confidence: 99%

Search for fourth sound propagation in supersolid He4

Aoki

Kojima

Lin

2008

Low Temperature Physics

View full text Add to dashboard Cite

A systematic study was carried out to search for fourth sound propagation solid 4 He samples below 500 mK down to 40 mK between 25 and 56 bar using the techniques of heat pulse generator and titanium superconducting transition edge bolometer. If solid 4 He is endowed with superfluidity below 200 mK as indicated by recent torsional oscillator experiments, theories predict fourth sound propagation in such supersolid state. If found, fourth sound provides a convincing evidence for superfluidity and a new tool for studying the new phase. To search for a fourth sound-like mode, the response of the bolometers to heat pulses traveling through cylindrical samples of solids grown with different crystal qualities. Bolometers with increasing sensitivity were constructed. The heater generator amplitude was reduced to the sensitivity limit to search for any critical velocity effects. The fourth sound velocity is expected to vary as µ r r s / . Searches were made for signature in the bolometer response with such characteristic temperature dependence. The measured response signal has not so far revealed any signature of new propagating mode within the temperature excursion of 5 mK from the background signal shape. Possible reasons for this negative result are discussed. Prior to the fourth sound search, the temperature dependence of heat pulse propagation was studied as it transformed from «second sound» in the normal solid 4 He to the transverse ballistic phonon propagation. Our work extended the studies by Narayanamurti and Dynes [Phys. Rev. B12, 1731(1975] to higher pressures and to lower temperatures. The measured transverse ballistic phonon propagation velocity remained constant, within 0.3% scatter of data below 100 mK at all pressures and revealed no indication for an onset of supersolidity. The overall dynamic thermal response of solid to heat input was found to depend strongly on the sample preparation procedure.

show abstract

Matter and Methods at Low Temperatures

Cited by 125 publications

References 0 publications

The Buffer Gas Beam: An Intense, Cold, and Slow Source for Atoms and Molecules

The Buffer Gas Beam: An Intense, Cold, and Slow Source for Atoms and Molecules

Kerr Effect in Liquid Helium at Temperatures Below the Superfluid Transition

Search for fourth sound propagation in supersolid He4

Contact Info

Product

Resources

About