A time-zero detector utilizing isochronous transport of secondary electrons

Zebelman, A. M.; Meyer, Wilfried; Halbach, K.; Poskanzer, A. M.; Sextro, R.G.; Gabor, George; Landis, D.A.

doi:10.1016/0029-554x(77)90637-1

Cited by 76 publications

(5 citation statements)

References 13 publications

(6 reference statements)

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“…1, was employed to select evaporation residues from the intense background of fission events. The detector, to be described fully elsewhere [13], is a development of earlier detectors [14,15] which operate chiefly on a time-of-flight principle. In our detector, recoiling residues, after multiple scattering inside the target, leave the target to strike an aluminized mylar foil, located 145 mm downstream.…”

mentioning

confidence: 99%

Electric dipole moments inU230,232and implications for tetrahedral shapes

Ntshangase¹,

Bark²,

Aschman³

et al. 2010

Phys. Rev. C

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The nuclei 230 U and 232 U were populated in the compound nucleus reactions 232 Th(α,6n) and 232 Th(α,4n), respectively. Gamma rays from these nuclei were observed in coincidence with a recoil detector. A comprehensive set of in-band E2 transitions were observed in the lowest lying negative-parity band of 232 U while one E2 transition was also observed for 230 U. These allowed B(E1; I − → I + − 1)/B(E2; I − → I − − 2) ratios to be extracted and compared with systematics. The values are similar to those of their Th and Ra isotones. The possibility of a tetrahedral shape for the negative-parity U bands appears difficult to reconcile with the measured Q 2 values for the isotone 226 Ra.

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mentioning

confidence: 99%

Electric dipole moments inU230,232and implications for tetrahedral shapes

Ntshangase¹,

Bark²,

Aschman³

et al. 2010

Phys. Rev. C

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“…However, to avoid time dispersion from the accompanying ions the detector would have to be designed to detect primary electrons only, e.g., by the introduction of a magnetic field. 36 On the other hand, more efficient detection is clearly possible by taking advantage of the much more intense ion emission.8 To minimize time dispersion, it may be possible to select a surface for which the secondary emission is dominated by a single species of ion for all projectiles. Alkali ions and small negative ions give intense peaks for light projectiles, but it appears that they are not suitable for this purpose because their relative intensity decreases with increasing projectile mass.…”

Section: Discussionmentioning

confidence: 99%

Secondary‐ion and electron production from surfaces bombarded by large polyatomic ions

Martens

Ens

Standing

et al. 1992

Rapid Comm Mass Spectrometry

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Heavy molecular ions with energies in the range 10-20 keV and masses from 276 u to 132,000 u, produced by matrix-assisted laser desorption, were used as primary projectiles to produce secondary-ion spectra from a variety of surfaces in a tandem time-of-flight mass spectrometer. In the negative mode the ratio of electron emission to secondary-ion emission was found to decrease rapidly with increasing projectile mass. Ion emission was found to dominate for primary ions larger than approximately 10,000 u. Positive or negative molecular ions and cations were observed from several organic targets of masses up to 1140 u (gramicidin S) for incident projectiles up to mass 132,000 u, i.e., for projectile speeds down to approximately 7000 m/s. Other ions characteristic of the target were also observed for these projectiles. Thus, large polyatomic ions can cause secondary-ion desorption even at very low velocity. The background ions of both polarities are similar to those found in keV particle bombardment by monatomic projectiles. The same ions are observed for all the projectiles; most can be identified with hydrocarbon background. The relative intensities of the background positive ions are largely independent of projectile, and for both polarities the ratio of the ions characterizing the target to those forming the background is approximately constant for all the projectiles. These results strongly suggest that the background ions come from the usual layer of organic impurities attached to the target surface. No direct evidence for surface-induced dissociation was observed in this mass and energy range.

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“…The E-TOF ERD set up at Sandia National Laboratories consists of two Zebelman type [13] pickup time units set 1 m apart and a conventional surface barrier detector [14]. The start and stop signals are generated by the electrons released when an ions passes throu'gh a thin C foil (about 20 nm thick in our case).…”

Section: Methodsmentioning

confidence: 99%