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 ...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 lm 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±1.7)×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 D^3He-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.展开更多
It is of particular interest to investigate nuclear fusion reactions generated by high-intensity lasers in plasma environments that are similar to real astrophysical conditions.We have experimentally investigated2H(d,...It is of particular interest to investigate nuclear fusion reactions generated by high-intensity lasers in plasma environments that are similar to real astrophysical conditions.We have experimentally investigated2H(d,p)3H,one of the most crucial reactions in big bang nucleosynthesis models,at the Shenguang-Ⅱlaser facility.In this work,we present a new calibration of CR-39 solidstate track detectors,which are widely employed as the main diagnostics in this type of fusion reaction experiment.We measure the dependence of the track diameter on the proton energy.It is found that the track diameters of protons with different energies are likely to be identical.We propose that in this case,the energy of the reaction products can be obtained by considering both the diameters and gray levels of these tracks.The present results would be very helpful for analyzing the2 H(d,p)3H reaction products recorded with the same batch of CR-39 solid-state track detectors.展开更多
Systematic CR-39 bulk etching experiments were conducted over a wide range of concentrations(2–30 N)of NaOH-based etchant.Critical analysis and a deep discussion of the results are presented.A comprehensive nuclear t...Systematic CR-39 bulk etching experiments were conducted over a wide range of concentrations(2–30 N)of NaOH-based etchant.Critical analysis and a deep discussion of the results are presented.A comprehensive nuclear track chemical etching data bank was developed.Three regimes of CR-39 bulk etching were identified.Regime I spans etchant concentrations from 2 to 12 N.Regime II spans concentrations from 12 to 25 N.We call this the dynamic bulk etching regime.Regime III is for concentrations greater than 25 N.In this regime,the bulk etch rate is saturated with respect to the etchant concentration.This classification is discussed and explained.The role of ethanol in NaOH-based etchants is explored and discussed.A parameter called the “reduced bulk etch rate” is defined here,which helps in analyzing the dependence of bulk etching on the amount of ethanol in the etchant.The bulk etch rate shows a natural logarithmic dependence on the density of ethanol in the etchant.展开更多
Charged particle diagnosis is an important aspect of laser–plasma experiments conducted at super-intense laser facilities. In recent years, Columbia Resin #39 (CR- 39) detectors have been widely employed for detectin...Charged particle diagnosis is an important aspect of laser–plasma experiments conducted at super-intense laser facilities. In recent years, Columbia Resin #39 (CR- 39) detectors have been widely employed for detecting charged particles in laser–plasma experiments. This is because the CR-39 polymer does not respond to electromagnetic pulses or X-rays. This study presents a method for calibrating the relationship between particle energy and track diameter in a CR-39 detector (TasTrak■) using 3-8 MeV protons, 6-30 MeV carbon ions, and 1–5 MeV alpha particles. The particle tracks were compared under the manufacturer’s recommended etching conditions of 6.25 mol/l NaOH at 98℃ and under the widely adopted experimental conditions of 6.25 mol/l NaOH at 70℃. The results show that if the NaOH solution concentration is 6.25 mol/l, then the temperature of 70℃is more suitable for etching proton tracks than 98℃ and employing a temperature of 98 ℃ to etch alpha-particle and carbon-ion tracks can significantly reduce the etching time. Moreover, this result implies that C3+ ion or alpha-particle tracks can be distinguished from proton tracks with energy above 3 MeV by controlling the etching time. This calibration method for the CR-39 detector can be applied to the diagnosis of reaction products in laser–plasma experiments.展开更多
For accurate counting of alpha tracks on the polyallyl diglycol carbonate of CR-39-type track detectors,the size distributions of both artifact tracks and alpha tracks were investigated with an automatic counting syst...For accurate counting of alpha tracks on the polyallyl diglycol carbonate of CR-39-type track detectors,the size distributions of both artifact tracks and alpha tracks were investigated with an automatic counting system. At the same temperature and etchant concentration, the numbers and sizes of alpha tracks changed significantly with the etching time, and the artifact track changes were smaller. At the etching time of 5 h, the sizes of alpha tracks were evidently larger than those of the artifact tracks, and the deviation of its size distribution was much smaller than those of longer etching time. Based on the size distribution of alpha tracks etched for 5 h, the overlap effect and uncertainty of overlap correction were studied by the Monte Carlo simulations for different track densities. It was found that the counting uncertainty of the system could be less than 6% in a density range of 10–160 tracks mm^(-2) after taking the overlap correction into account.展开更多
基金supported in part by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB160203)the National Natural Science Foundation of China(Nos.11875311 and 11421505).
文摘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 lm 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±1.7)×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 D^3He-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.
基金This work was supported by the National Key Research and Development Project(No.2016YFA0400502)the National Natural Science Foundation of China(No.11775312).
文摘It is of particular interest to investigate nuclear fusion reactions generated by high-intensity lasers in plasma environments that are similar to real astrophysical conditions.We have experimentally investigated2H(d,p)3H,one of the most crucial reactions in big bang nucleosynthesis models,at the Shenguang-Ⅱlaser facility.In this work,we present a new calibration of CR-39 solidstate track detectors,which are widely employed as the main diagnostics in this type of fusion reaction experiment.We measure the dependence of the track diameter on the proton energy.It is found that the track diameters of protons with different energies are likely to be identical.We propose that in this case,the energy of the reaction products can be obtained by considering both the diameters and gray levels of these tracks.The present results would be very helpful for analyzing the2 H(d,p)3H reaction products recorded with the same batch of CR-39 solid-state track detectors.
文摘Systematic CR-39 bulk etching experiments were conducted over a wide range of concentrations(2–30 N)of NaOH-based etchant.Critical analysis and a deep discussion of the results are presented.A comprehensive nuclear track chemical etching data bank was developed.Three regimes of CR-39 bulk etching were identified.Regime I spans etchant concentrations from 2 to 12 N.Regime II spans concentrations from 12 to 25 N.We call this the dynamic bulk etching regime.Regime III is for concentrations greater than 25 N.In this regime,the bulk etch rate is saturated with respect to the etchant concentration.This classification is discussed and explained.The role of ethanol in NaOH-based etchants is explored and discussed.A parameter called the “reduced bulk etch rate” is defined here,which helps in analyzing the dependence of bulk etching on the amount of ethanol in the etchant.The bulk etch rate shows a natural logarithmic dependence on the density of ethanol in the etchant.
基金supported in part by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB160203)the National Natural Science Foundation of China(Nos.11875311,11421505,and 11475245)
文摘Charged particle diagnosis is an important aspect of laser–plasma experiments conducted at super-intense laser facilities. In recent years, Columbia Resin #39 (CR- 39) detectors have been widely employed for detecting charged particles in laser–plasma experiments. This is because the CR-39 polymer does not respond to electromagnetic pulses or X-rays. This study presents a method for calibrating the relationship between particle energy and track diameter in a CR-39 detector (TasTrak■) using 3-8 MeV protons, 6-30 MeV carbon ions, and 1–5 MeV alpha particles. The particle tracks were compared under the manufacturer’s recommended etching conditions of 6.25 mol/l NaOH at 98℃ and under the widely adopted experimental conditions of 6.25 mol/l NaOH at 70℃. The results show that if the NaOH solution concentration is 6.25 mol/l, then the temperature of 70℃is more suitable for etching proton tracks than 98℃ and employing a temperature of 98 ℃ to etch alpha-particle and carbon-ion tracks can significantly reduce the etching time. Moreover, this result implies that C3+ ion or alpha-particle tracks can be distinguished from proton tracks with energy above 3 MeV by controlling the etching time. This calibration method for the CR-39 detector can be applied to the diagnosis of reaction products in laser–plasma experiments.
基金supported by the National Natural Science Foundation of China(No.11375048)
文摘For accurate counting of alpha tracks on the polyallyl diglycol carbonate of CR-39-type track detectors,the size distributions of both artifact tracks and alpha tracks were investigated with an automatic counting system. At the same temperature and etchant concentration, the numbers and sizes of alpha tracks changed significantly with the etching time, and the artifact track changes were smaller. At the etching time of 5 h, the sizes of alpha tracks were evidently larger than those of the artifact tracks, and the deviation of its size distribution was much smaller than those of longer etching time. Based on the size distribution of alpha tracks etched for 5 h, the overlap effect and uncertainty of overlap correction were studied by the Monte Carlo simulations for different track densities. It was found that the counting uncertainty of the system could be less than 6% in a density range of 10–160 tracks mm^(-2) after taking the overlap correction into account.
