Figures of merit for focusing mega-electron-volt ion beams in biomedical imaging and proton beam writing

Abstract

Articles you may be interested inA simple double-focusing electrostatic ion beam deflector Rev. Sci. Instrum. 81, 063304 (2010); 10.1063/1.3433485Focusing of laser-generated ion beams by a plasma cylinder: Similarity theory and the thick lens formula Phys. Plasmas 13, 063103 (2006); Characteristics of focused beam spots using negative ion beams from a compact surface plasma source and merits for new applications A figure of merit ͑FOM͒ has been developed for focusing quadrupole multiplet lenses for ion microand nanobeam systems. The method which is based on measurement of the central peak of the two-dimensional autocorrelation function of an image provides separate FOM for the horizontal and vertical directions. The approach has been tested by comparison with the edge widths obtained by nonlinear fitting the edge widths of a Ni grid and found to be reliable. The FOM has the important advantage for ion beam imaging of biomedical samples that the fluence needed is considerably lower than for edge fitting.

Angular and lateral spreading of ion beams in biomedical nuclear microscopy

“…This is consistent with our direct-STIM observations where features, on a scale of 50-70 nm width could be observed [1,2]. The implication is that for high lateral resolution work protons give the best intrinsic resolution, however, the smaller stopping force for protons degrades thickness resolution compared to 4 He ions. There is no obvious fundamental reason why MeV proton and He ion beams cannot be focused to spot sizes of 10 nm, or even less, which implies that using direct-STIM, sub-50 nm resolution measurements of cells are very feasible.…”

“…2 and 3 present the FWHM of the intrinsic PSF contribution resulting from scattering from different estimates for 2 MeV protons and 4 He ions, respectively. The differences between the MSBW [8,22], Amsel et al's tabulated values [9] and the SRIM2008 [13] estimates were $25% for both 2 MeV protons and 4 He ions.…”

“…There are considerable uncertainties in both analytical and SRIM2008 estimates for the spreading FWHMs for 2 MeV protons and 4 He ions in dry tissue with the nominal composition of C 3 H 7 NO. …”

“…Recently, a number of NM sytems are being developed for in-situ cell imaging and single-cell irradiation studies where the beam passes through a 4-10 lm, or so thick vacuum-atmosphere window before entering the living cells [3]. The resolution in NM is governed by the point spread function (PSF) [4,5]. For imaging using a scanned beam, the PSF is the convolution of an extrinsic contribution from the beam spot profile [4], S(x, y), with an intrinsic contribution, Gðt; qÞ, that originates from the spatial spreading of the ion beam as it traverses the sample of thickness, t, (Fig.…”

Advanced time-stamped total data acquisition control front-end for MeV ion beam microscopy and proton beam writing

“…1. In addition provision is made to control the lens current power supplies from the spare digital to analogue converters (DACs) to allow auto-focussing of the beam [5,6].…”