Detection of atomic and molecular mega-electron-volt projectiles using an x-ray charged coupled device camera

Abstract

We show that an x-ray charge coupled device (CCD) may be used as a particle detector for atomic and molecular mega-electron-volt (MeV) projectiles of around a few hundred keV per atomic mass unit. For atomic species, spectroscopic properties in kinetic energy measurements (i.e., linearity and energy resolution) are found to be close to those currently obtained with implanted or surface barrier silicon particle detectors. For molecular species, in order to increase the maximum kinetic energy detection limit, we propose to put a thin foil in front of the CCD. This foil breaks up the molecules into atoms and spreads the charges over many CCD pixels and therefore avoiding saturation effects. This opens new perspectives in high velocity molecular dissociation studies with accelerator facilities.

Breakdown curves of CH2(+), CH3(+), and CH4(+) molecules

“…To avoid detection of the incident beam by the CH + y detector a thin (0.5 mm diameter) rod was placed in front of it. The detection of neutral species was done either by a planar silicon detector or by a dedicated CCD camera from Hamamatsu company (Chabot et al 2011). In this last case the planar neutral detector was placed on the very near side of the CCD to detect any fragments that might escape from the CCD.…”

Excitation, ionization, neutralization and anionic production in collisions of C+, N+and CnN+(n= 1–3) with He atoms at 2.2 a.u. velocity; cross sections and dissociation branching ratios

“…After the collision, the charge and mass of the projectile, or of its fragments, were analysed using the dedicated AGAT spectrometer composed of an electrostatic deflector for charge over mass separation and several solid-state silicon detectors for the mass determination. The problem of pile-up (several fragments impinging onto the same detector, particularly prominent for neutral fragments) was solved by using a pixelated silicon detector for neutral fragments, namely, a CCD camera combining position information and mass recognition (Chabot et al 2011). This allowed to resolve the whole fragmentation, with a very few exceptions (see tables A1, A4 and A5 in appendix A).…”