RevModPhys.85.751

2008 nuernberg et al 2009 kirby et al 2011 rev mod

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Unformatted text preview: –June 2013 Plastic track detectors such as CR39 (Enge, 1995), which have the advantage of being insensitive to x rays and electrons, have been widely used also in multistack arrangements, e.g., by Clark et al. (2000a). CR39 layers (typically 0.25– 1 mm in thickness) require etching in a NaOH solution after exposure to ions, so that the damage tracks created by the particles can be revealed thanks to the different etching rate in ` the track compared to the undamaged bulk (Seguin et al., 2003). After etching, the single tracks can be counted, which provides a direct measurement of the number of protons hitting the detector. CR39 works better for low particle fluxes, as at high flux (typically above $108 particles cmÀ2 ) or for long etching times the tracks start to overlap, leading to saturation (Gaillard et al., 2007). The interaction of laser-driven high-energy ions with secondary targets can initiate a number of nuclear reactions (see Sec. V.E), which can been used to diagnose the beam properties with the ability to provide absolute particle numbers with a linear response and virtually no saturation at high flux. The 63 Cuðp; nÞ63 Zn reaction in copper stacks has been used to quantify the proton numbers through measurement of þ decay of 63 Zn nuclei, using a NaI detector-based coincidence counting system (Santala et al., 2001; Spencer et al., 2001). Techniques employing a single Cu layer, in which a range of isotopes resulting from proton-induced nuclear reactions is analyzed in order to reconstruct the proton spectrum, have also been used (Yang et al., 2004b). Spectral resolution is provided by a combination of filtering and known thresholds for the considered reaction. The above described approaches provide particle flux integrated over the whole beam cross section. Contact radiography of ðp; nÞ-generated isotopes in activation samples (where the activated foil is placed in contact with RCF) has been Andrea Macchi, Marco Borghesi, and Matteo Passoni: Ion acceleration by superintense laser-plasma . . . developed (Clarke et al., 2008; Offermann et al., 2010) as a way to achieve 2D images of the beam profile with high spatial resolution and extremely high-dynamic range. Neutron spectra produced through fusion reactions of the type Dðd; nÞ3 He have been used as a diagnostic of laserdriven deuterium ions inside a laser-irradiated target (Habara et al., 2003, 2004a, 2004b). Obtaining spectra with high-energy resolution requires the use of magnetic dispersion techniques. In simple magnetic spectrometers [see, e.g., H. Chen et al. (2008)] the ions, spatially selected by an entrance slit or pinhole, are dispersed along one spatial direction according to their energy by a $1 T magnetic field B. This arrangement, which discriminates particles according to their energy but not to their charge-to-mass ratio, is adequate for diagnosing the highenergy proton spectrum in ‘‘standard’’ TNSA experiments in which protons are the dominant acc...
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