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Radiative double-electron capture by fully stripped and one-electron ions in gas and thin-foil targets
Radiative double-electron capture (RDEC), in which two-electron capture is accompanied by simultaneousemission of a single photon, was investigated for fully stripped and one-electron projectiles colliding withgaseous and thin-foil targets. RDEC can be considered the inverse of double photoionization by a single photon.For the gaseous targets, measurements were done for 2.11 MeV/uF9+and F8+ions interacting with N2and Ne,while for the thin-foil target the measurements were done for 2.11 MeV/uF9+and F8+and 2.19 MeV/uO8+andO7+ions striking thin C targets. Reports on this work were already published separately in shorter accounts by LaMantiaet al.[Phys. Rev. Lett.124, 133401 (2020)for the gas targets andPhys.Rev.A102, 060801(R) (2020)forthe thin-foil targets]. The gas targets were studied under single-collision conditions, while the foil targets sufferedunavoidable multiple collisions. The measurements were carried out by detecting x-ray emission from the targetat 90◦to the beam direction in coincidence with outgoing ions undergoing double, single, and, in the caseof the foil targets, no charge change inside the target. Striking differences between the gaseous and foil targetswere found from these measurements, with RDEC for the gaseous targets occurring only in coincidence with q-2outgoing projectiles as expected, while RDEC for the foil targets was seen in each of the outgoing q-2, q-1, and nocharge-change states. The no charge-change more »
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NSF-PAR ID:
10293823
Journal Name:
Physical review
Volume:
104
ISSN:
1550-2368
2. Abstract The quest for making a triplet positronium (Ps) Bose–Einstein condensate confined in a micron-sized cavity in a material such as porous silica faces at least three interrelated problems: (1) About $$10^7$$ 10 7 spin polarized Ps atoms must be injected into a small cavity within a porous solid material without vaporizing it. (2) It is known that Ps atoms confined in 30–100 nm diameter cavities in porous silica do not remain in the gas phase, but become stuck to the cavity walls at room temperature (Cooper et al., Phys. Rev. B 97:205302, 2018). (3) Cooling a gas of Ps atomsmore »