A novel high resolution ion wide angle spectrometer

Abstract

A novel ion wide angle spectrometer (iWASP) has been developed, which is capable of measuring angularly resolved energy distributions of protons and a second ion species, such as carbon C(6 +), simultaneously. The energy resolution for protons and carbon ions is better than 10% at ∼50 MeV/nucleon and thus suitable for the study of novel laser-ion acceleration schemes aiming for ultrahigh particle energies. A wedged magnet design enables an acceptance angle of 30°(∼524 mrad) and high angular accuracy in the μrad range. First, results obtained at the LANL Trident laser facility are presented demonstrating high energy and angular resolution of this novel iWASP.

Ultrashort Pulsed Neutron Source

“…A small prompt signal from the laser driven gammas arrived ~100 ns prior to the neutrons, which served as a reference for determining the neutron time of flight. The neutron spectrum from a 500 nm thick target is presented in Fig 5b. The background signal from the prompt gamma-rays (dashed blue line) was determined using the method described in [34]. The spectrum matches the expected neutron evaporation spectrum of photonuclear reactions in this energy range [35].…”

On the analysis of inhomogeneous magnetic field spectrometer for laser-driven ion acceleration

“…The trade-off is a strongly non-parallel and inhomogeneous magnetic field, such as used in a recently presented design for an ion wide angle spectrometer (iWASP). 23 Here, we present a detailed analysis of ion energy detection employing a non-parallel, inhomogeneous magnetic field and demonstrate the feasibility and high accuracy of in-situ, self-calibration of the magnetic field. We, furthermore, show that unambiguous identification of proton signal is possible in a stacked detector system consisting of image plates and nuclear track detectors.…”

Recent developments in the Thomson Parabola Spectrometer diagnostic for laser-driven multi-species ion sources

“…The lack of information about the angular dependence of the ion spectra is of particular concern in cases of highly structured beam, as often produced, for example, from the interactions of intense lasers with ultrathin foils [15,46]. Some efforts have been made in order to increase the solid angle of detection by using magnetic spectrometers with large acceptance angles, such as the Imaging Proton Spectrometer [47] and the iWASP [48], in which the pinhole is substituted by a horizontal slit. By placing a filter in front of the detector, an angularly-resolved proton spectrum can be obtained with significantly higher energy resolution than RCF stacks.…”

“…The characteristics for the dipole yoke were taken from Ref. [48] and 150 mm-long electric plates were used with E 0 = 16 kV/cm. The simulated ion traces on the detector are shown in Fig.…”