Positronium in low temperature mesoporous films

Fischer, Christoph; Weber, Marc H.; Wang, CL; McNeil, S. P.; Lynn, Kelvin G.

doi:10.1103/physrevb.71.180102

Cited by 30 publications

(22 citation statements)

References 20 publications

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“…For the C sample the discrepancy is less than 10% but for the F sample the measured value is 30% lower suggesting that the pick-off rate increases. Deviations from the RTE model were already observed in previous measurements using the 2 to 3γ ratio technique [58,59] and in a measurement using PALS [60]. Different factors could be responsible for that as pointed out in those papers and deserves further studies.…”

Section: A Pals Measurementsmentioning

confidence: 59%

Measurement of the orthopositronium confinement energy in mesoporous thin films

et al. 2010

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In this paper, we present measurements of the ortho-positronium (ortho-Ps) emission energy in vacuum from mesoporous films using the time-of-flight technique. We show evidence of quantum mechanical confinement in the mesopores that defines the minimal energy of the emitted Ps. Two samples with different effective pore sizes, measured with positron annihilation lifetime spectroscopy, are compared for the data collected in the temperature range 50-400 K. The sample with smaller pore size exhibits a higher minimal energy (73 ± 5 meV), compared to the sample with bigger pores (48 ± 5 meV), due to the stronger confinement. The dependence of the emission energy with the temperature of the target is modeled as ortho-Ps being confined in rectangular boxes in thermodynamic equilibrium with the sample. We also measured that the yield of positronium emitted in vacuum is not affected by the temperature of the target.

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Section: A Pals Measurementsmentioning

confidence: 59%

Measurement of the orthopositronium confinement energy in mesoporous thin films

et al. 2010

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“…This work has also led to the use of thin mesoporous films that can be used as Ps converters [109,110,[246][247][248][279][280][281][282][283][284]. These materials produce Ps in a similar way to the powders discussed previously [35,36].…”

Section: Ps Productionmentioning

confidence: 99%

Experimental progress in positronium laser physics

2018

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Abstract. The field of experimental positronium physics has advanced significantly in the last few decades, with new areas of research driven by the development of techniques for trapping and manipulating positrons using Surko-type buffer gas traps. Large numbers of positrons (typically ≥10 6 ) accumulated in such a device may be ejected all at once, so as to generate an intense pulse. Standard bunching techniques can produce pulses with ns (mm) temporal (spatial) beam profiles. These pulses can be converted into a dilute Ps gas in vacuum with densities on the order of 10 7 cm −3 which can be probed by standard ns pulsed laser systems. This allows for the efficient production of excited Ps states, including long-lived Rydberg states, which in turn facilitates numerous experimental programs, such as precision optical and microwave spectroscopy of Ps, the application of Stark deceleration methods to guide, decelerate and focus Rydberg Ps beams, and studies of the interactions of such beams with other atomic and molecular species. These methods are also applicable to antihydrogen production and spectroscopic studies of energy levels and resonances in positronium ions and molecules. A summary of recent progress in this area will be given, with the objective of providing an overview of the field as it currently exists, and a brief discussion of some future directions.

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“…Groups working on this problem were encouraged by the unique advantages of this technique, e.g., the ability to characterize closed porosity [1][2][3] or the ability to perform measurements in situ (e.g., at various temperatures [4][5][6][7], mechanical pressures [8] or in the presence of a pore filling gas/liquid [9][10][11][12]). These capabilities are owed to the properties of positronium (Ps), which is used by PALS as a probe of material structure.…”

Section: Introductionmentioning

confidence: 99%