The precise energy spectra measurement of laser-accelerated MeV/n-class high-Z ions and protons using CR-39 detectors

Abstract

The diagnosis method, using a combination of a permanent magnet and CR-39 track detectors, has been developed to separately measure the energy spectrum of the laser-accelerated MeV/n-class high-Z ions and that of MeV protons. The main role of magnet is separating between high-Z ions and protons, not for the usual energy spectrometer, while ion energy was precisely determined from careful analysis of the etch pit shapes and the etch pit growth behaviors in the CR-39. The method was applied to laser-driven ion acceleration experiments using CO 2 clusters embedded in a background H 2 gas. Ion energy spectra with uncertainty ΔE = 0.1 MeV n −1 for protons and carbon/ oxygen ions were simultaneously obtained separately. The maximum energies of carbon/oxygen ions and protons were determined as 1.1 ± 0.1 MeV and 1.6 ± 0.1 MeV n −1 , respectively. The sharp decrease around 1 MeV n −1 observed in the energy spectrum of carbon/oxygen ions could be due to a trace of the ambipolar hydrodynamic expansion of CO 2 clusters. Thanks to the combination of the magnet and the CR-39, the method is robust against electromagnetic pulse (EMP).

Elucidation of the Two-Step Damage Formation Process of Latent Tracks in Poly(allyl diglycol carbonate), PADC: Role of Secondary Low-Energy Electrons

“…Poly­(allyl diglycol carbonate), PADC, often called CR-39 (its trade mark “Columbia Resin #39”) is considered as the most sensitive Solid State Nuclear Track Detector, SSNTD. , Unlike other SSNTDs, PADC can detect energetic protons (and neutron recoil nuclei) as well as heavy ions, in mixed radiation fields without background noise. Due to this advantage, it has been utilized in diverse applications, such as space radiation dosimetry − and laser driven ion acceleration experiments. , At least six books have been dedicated to SSNTD applications. − Beginning in the 1990s, molecular damage (i.e., loss/generation of chemical functions) within PADC has been examined using FT-IR spectrometric methods for a wide range of stopping powers, specifically from 1.2 to 12 000 eV/nm, − with a view to developing new SSNTD materials with desired track registration sensitivity from the viewpoint of molecular rearrangement. Figure (a) represents a repeat unit of PADC, which contains the radiation-sensitive moieties of an ether in the center and two carbonate esters in symmetrical positions.…”

“…Due to this advantage, it has been utilized in diverse applications, such as space radiation dosimetry (3)- (5) and laser driven ion acceleration experiments. (6), (7) At least six books have been dedicated to SSNTD applications. ( 8)- (13) Beginning in the 1990s, molecular damage (i.e., loss/generation of chemical functions) within PADC has been examined using FT-IR spectrometric methods for a wide range of stopping powers, specifically from 1.2 to 12,000 eV/nm, ( 14)- (15) with a view to developing new SSNTD materials with desired track registration sensitivity from the viewpoint of molecular re-arrangement.…”

Laser-driven multi-MeV high-purity proton acceleration via anisotropic ambipolar expansion of micron-scale hydrogen clusters

“…Since the CR-39 detectors under the same etching condition have a potential to identify the ion species, especially between protons and other heavier ions 49 , protons on the CR-39 plate can be identified with the size of the etch pit opening. Figure 1(b) shows a micrograph of the etch pits that appeared on the CR-39 plate, where the sizes of all the etch pit openings (0.2-1.5 µm 2 ) correspond to those of MeV-class protons obtained by the calibration study using conventional accelerators 46 .…”

Angularly resolved characterization of ion beams from laser-ultrathin foil interactions

“…CR-39 is insensitive to x-rays and electrons and can distinguish between different ion species (e.g. carbon ions and protons in our case), as for equal etching time, pit size varies for different ions [36][37][38].…”