Absolute calibration of a time-of-flight spectrometer and imaging plate for the characterization of laser-accelerated protons

Abstract

A proton energy spectrometer system is composed of a time-of-flight spectrometer (TOFS) and a Thomson parabola spectrometer (TPS), and is used to characterize laser-accelerated protons. The TOFS detects protons with a plastic scintillator, and the TPS with a CR-39 or imaging plate (IP). The two spectrometers can operate simultaneously and give separate time-of-flight (TOF) and Thomson parabola (TP) data. We propose a method to calibrate the TOFS and IP by comparing the TOF data and the TP data taken with CR-39 and IP. The absolute response of the TOFS as a function of proton energy is calculated from the proton number distribution measured with CR-39. The sensitivity of IP to protons is obtained from the proton number distribution estimated with the calibrated TOFS. This method, based on the comparison of the simultaneously measured data, gives more reliable results when using laser-accelerated protons as a calibration source. The calibrated spectrometer system can be used to measure absolutely calibrated energy spectra for the optimization of laser-accelerated protons.

Response functions of Fuji imaging plates to monoenergetic protons in the energy range 0.6–3.2 MeV

“…The reading was done with a scanner Fuji BAS-1800 II. Data from Choi et al 7 are higher by one order of magnitude. The authors explained this difference as due to the different scanners used.…”

“…Mančić et al 6 and Choi et al 7 data were obtained using laser-accelerated protons. In the work of Mančić et al 6 the number of protons was counted using radiochromic films (RCF) and a magnetic spectrometer in which track detectors (CR-39) in conjunction with IPs were used as detectors.…”

“…The IP reading was done with a scanner Fuji BAS-1800 II. In the experiment of Choi et al 7 the number of protons was determined using a time of flight spectrometer and a Thomson parabola with IPs or CR39 as detectors. The reading was done with a scanner Fuji BAS-5000.…”

“…4,5 Imaging plates (IPs) are ionizing particle sensitive detectors well suited for the characterization of laser-accelerated proton beams. [6][7][8] They are used in experiments where a spatial resolution of tens of μm, 8 a sensitivity to a few protons or a detector insensitive to the electromagnetic fields accompanying a laser shot, are needed. However IPs were originally developed for imaging techniques 9 only and quantitative experimental data are still needed to determine absolute proton fluxes.…”

“…Although previous work [6][7][8] has been carried out to determine the response function of Fuji TR IPs to laser accelerated protons, response values extrapolated from the different response functions vary by at least one order of magnitude. Therefore, we have conducted an experiment based on a new technique with a 3.5 MV proton accelerator.…”