Primary yields of protons measured using CR-39 in laser-induced deuteron–deuteron fusion reactions

Abstract

Investigating deuteron–deuteron (DD) fusion reactions in a plasma environment similar to the early stages of the Big Bang is an important topic in nuclear astrophysics. In this study, we experimentally investigated such reactions, using eight laser beams with the third harmonic impacting on a deuterated polyethylene target at the ShenGuang-II Upgrade laser facility. This work focused on the application of range-filter (RF) spectrometers, assembled from a 70 μm aluminum filter and two CR-39 nuclear track detectors, to measure the yields of primary DD-protons. Based on the track diameter calibration results of 3 MeV protons used to diagnose the tracks on the RF spectrometers, an approximate primary DD-proton yield of $$(8.5\pm 1.7)\times 10^6$$ was obtained, consistent with the yields from similar laser facilities worldwide. This indicates that the RF spectrometer is an effective way to measure primary DD-protons. However, due to the low yields of $${\hbox {D}}^{3}{\mathrm {He}}$$-protons and its small track diameter, CR-39 detectors were unable to distinguish it from the background spots. Using other accurate detectors may help to measure these rare events.