Low-energy positron interactions with krypton

Total, elastic, and inelastic cross sections for positron and electron collisions with tetrahydrofuran

“…Indeed, the discrepancy is nearly 35% at about 20 eV. We were a little surprised by this result, as previous studies by the two groups on argon, 41,71 krypton, 42,72 and xenon 73,74 had shown a quite satisfactory level of accord between their "uncorrected" TCS. Indeed, Zecca et al 69 noted that the angular discrimination of the Trento apparatus is comparable to that of the present spectrometer and since both independent measurements were conducted at the same temperature (∼24 ± 2…”

“…The methods used in the present experiment to measure those cross sections have already been described earlier by Makochekanwa et al, 42 Caradonna et al, 47 and Sullivan et al 43 We briefly summarize them here, by recalling that those measurements require an alteration to the experimental technique from that used in the case of quasi-elastic scattering.…”

“…It is worth noting here that in our experimental technique positrons scattered in the backward direction (i.e., through angles greater than 90 • ) are reflected from the potential barriers associated with the trap and other elements, and can travel back through the gas cell. 42,43 As a result, the measured cross section at any angle θ is actually folded about 90…”

“…The techniques used in the present experiment to measure the TCS, the Ps formation cross sections, the elastic DCS, and the details of the data analysis, have been presented previously. [41][42][43] In short, the various cross sections are determined by measuring specific fractions of the positron beam transmitted through the RPA with the target vapor present in the scattering cell. In a collision with a target molecule, the positron can be elastically scattered through some angle θ and lose some of its E in the process.…”

Toward a European Network of Positron Laboratories

“…Japanese positron beam in Tsukuba continues to challenge important questions, mainly in the fi eld of semiconductors [43]. The beam constructed within a national programme at the Australian National University in Canberra is dedicated mainly to atomic physics [44]. Currently operating positron beams, among others, in Helsinki [45], Halle [46], London [47], Delft [48], and Orleans [49] rarely go beyond national contexts and specialized applications, with the exception of the NEPOMUC facility, where scientists of European countries have access within the EU great facilities NI3 programme.…”