Positronium cooling into nanopores and nanochannels by phonon scattering

Mariazzi, S.; Salemi, Alessandro; Brusa, R. S.

doi:10.1103/physrevb.78.085428

Cited by 50 publications

(41 citation statements)

References 32 publications

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“…Despite being interconnected, the voids in mesoporous films have a relatively narrow distribution of radii, which means that collisional cooling via Ps interactions with the walls is an efficient process, but also that there is an intrinsic lower limit to the energy of atoms emitted into vacuum because of quantum confinement. That is, the zero-point energy of confined atoms is converted into kinetic energy when they are emitted into vacuum, setting a lower limit to the attainable Ps energy that depends on the average pore size [109,247,286].…”

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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Section: Ps Productionmentioning

confidence: 99%

Experimental progress in positronium laser physics

2018

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“…In pores with size larger than 5 nm an increase of pick-off was again pointed out [3]. The authors of the present communication, have indicated [6] that these experimental deviations from RTE model could be due to oPs confining in small pores and to a longer oPs thermalization time in largest pores. Both the effects give a longer permanence of oPs in excited states where the pick-off rate is higher.…”

mentioning

confidence: 73%

“…In this work we discuss and further develop the hypothesis reported in Ref. [6] taking also into account the effect of the temperature on the interaction of oPs with the walls of the pores.…”

mentioning

confidence: 95%

“…[6] it was discussed the possibility that the experimental deviations from RTE predictions could be due to the oPs thermalization in the pore. Indeed this process is not considered by RTE model.…”

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confidence: 99%

“…In Ref. [6] the oPs energy loss and cooling time have been studied using an oPs-acoustic phonon scattering model at the first order. The model points out that effectively the thermalization time could be lengthened in pores smaller than few nanometers because of single-phonon scattering does not allow oPs to reach the ground state.…”

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confidence: 99%

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Dependence of ortho‐positronium pick‐off rate on sample temperature

Mariazzi

Salemi

Brusa

2009

Phys. Status Solidi (c)

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At room temperature the ortho‐positronium (oPs) lifetime in porosities is well described by the rectangular Tao‐Eldrup model (RTE) [1]. Recent experiments [2‐5] at low temperature have shown unexpected deviations from the RTE predictions. In Ref. [2] a pick‐off increase is observed below 200 K in pores with size less than 2 nm, at the contrary a decrease of pick‐off is found in pores with size around 3nm. An increase of the oPs lifetime (decrease of pick‐off) at low temperature was also observed by the authors of Ref. [3‐5] in porosities with sizes from 2.3 to 4 nm. In pores with size larger than 5 nm an increase of pick‐off was again pointed out [3]. The authors of the present communication, have indicated [6] that these experimental deviations from RTE model could be due to oPs confining in small pores and to a longer oPs thermalization time in largest pores. Both the effects give a longer permanence of oPs in excited states where the pick‐off rate is higher. In this work we discuss and further develop the hypothesis reported in Ref. [6] taking also into account the effect of the temperature on the interaction of oPs with the walls of the pores. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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