A positron plasma in the laboratory—how and why

Surko, C. M.; Leventhal, M.; Passner, A.; Wysocki, F.J.

doi:10.1063/1.37614

Cited by 5 publications

(7 citation statements)

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“…For alkanes, Z,ir/Z increases from 10 for methane to 2 x 10 for hexadecane. These anomalously high values of Z,e/Z might be explained by long-lived resonances [11]. We note that Z,a/Z does not increase between dodecane and hexadecane.…”

Section: B Inorganic Moleculesmentioning

confidence: 59%

“…For earlier studies, only a small number of positrons were available, and consequently, uncertainties of a factor of two are possible in the measured values of Z,g [11].…”

Section: Discussionmentioning

confidence: 99%

“…Recently, we began more comprehensive studies of the energy spectra of annihilation radiation in a variety of molecules, including hydrocarbons and perQuorocarbons [61]. These studies suggest that, for the case of hydro-25 E, (eV) 12 11 carbons, including benzene, the positrons are localized at the C -H bond, while for the perfluorocarbons, they reside on the fIuorine atoms. These studies are now being extended to include many of the compounds reported in this paper, and it is expected that these data will help in understanding the processes involved in positronmolecule interactions and the resulting annihilation.…”

Section: Discussionmentioning

confidence: 99%

“…[11] and [13], the RRKM theory has not been applied to positron-molecule resonance collisions. For the case of the positron-molecule resonances described here, we envision that the incoming positron transfers its kinetic energy to the vibrational modes of the molecule.…”

Section: Positron-matter Interactionsmentioning

confidence: 99%

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Measurements of positron-annihilation rates on molecules

et al. 1995

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Measurements are presented for the annihilation rates of thermalized positrons in a variety of substances, including noble gases, simple inorganic molecules, hydrocarbons, substituted hydrocarbons, and aromatics. The measurements were performed using trapped clouds of room-temperature positrons, into which substances under test were introduced as low-pressure gases, so that only two-body interactions were involved. These data are compared with other values in the literature, and a compilation of annihilation rates is presented. The measurements illustrate the importance of both chemical composition and the vibrational modes of excitation of the molecules in determining the annihilation rates. The anomalously high annihilation rates observed for large molecules provide evidence for the existence of long-lived resonances. The nature of these resonances is not yet understood, and the data presented are expected to provide useful constraints for the development of theoretical models.

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Section: B Inorganic Moleculesmentioning

confidence: 59%

“…For earlier studies, only a small number of positrons were available, and consequently, uncertainties of a factor of two are possible in the measured values of Z,g [11].…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Positron-matter Interactionsmentioning

confidence: 99%

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Measurements of positron-annihilation rates on molecules

et al. 1995

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“…. 2.5 Extracted from [32] This stacked assembly sits inside 2 nd stage. The azimuthally segmented 'rotating wall' electrode is visible near the bottom right.…”

Section: Phillip Thomas John Swansea June 8 2023mentioning

confidence: 99%

A Preliminary Study of the Effect of the Chirped Rotating Wall on a Positron Cloud

John¹

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The density of the positron cloud is a crucial parameter in many applications of accumulated positrons. Previous work has shown that adjusting the frequency of the rotating wall potential following positron accumulation can be used to control the density of positron clouds. In this work, positron clouds were studied after being compressed using a linear rotating wall frequency sweep under a selection of rotating wall drive amplitudes and cooling gas pressures following an initial static frequency compression. This was performed for SF 6 , CF 4 , and briefly for CO. The effect of changing the cooling gas appears congruent to that shown by the static frequency case. The results are in qualitative agreement with previous work by Deller et al., and compare briefly but favourably to a simplistic numerical model. i I suppose I will keep this brief. When I embarked on this journey of postgraduate study, my life, my home, and indeed the world was a very different place. Whilst the Covid-19 pandemic, which started shortly after my studies began has greatly effected me and my efforts and motivations, I cannot write this work and forget to mention my wife, Elinor, who has kept me sane these recent years. Since the start of these studies we have had many firsts, moving into a home together, getting married finally after pandemic-delay, getting a cat, and many others. Despite the rocky road however, the experiences, the knowledge I have attained, and the people I have met, are truly invaluable to me, and will remain so for the rest of my life. Finally, I must mention my late father. He was with me when I began my undergraduate degree and in many ways, he is still with me today.

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