The energetic bremsstrahlung photons up to 100 MeV produced in heavy ion collisions can be used as a sensitive probe for short-range correlation in atomic nuclei. The energy of the γ-rays can be measured by collectin...The energetic bremsstrahlung photons up to 100 MeV produced in heavy ion collisions can be used as a sensitive probe for short-range correlation in atomic nuclei. The energy of the γ-rays can be measured by collecting the Čerenkov light in the medium induced by the fast electrons generated in the Compton scattering or electromagnetic shower of the incident γray. Two types of detectors based on pure water and lead glass as sensitive materials were designed for this purpose. The γresponse and optical photon propagation in the detectors were simulated based on electromagnetic and optical processes in Geant4. The inherent energy resolutions of 0.022(4) + 0.51(2)∕E^(1/2)_(γ) for water and 0.0026(3) + 0.446(3)∕E^(1/2)_(γ) for lead glass were obtained. The geometry sizes of the lead glass and water were optimized to 30 cm × 30 cm × 30 cm and 60 cm × 60 cm ×120 cm, respectively, to detect high-energy γ-rays at 160 MeV. The Hough transform method was applied to reconstruct the direction of the incident γ-rays, providing the ability to experimentally distinguish the high-energy γ-rays produced in the reactions on the target from random background cosmic-ray muons.展开更多
We report a reconstruction method for fast-fission events in 25 MeV/u^(86)Kr +^(208)Pb reactions at the Compact Spectrometer for Heavy Ion Experiment(CSHINE). The fission fragments(FFs) are measured using three large-...We report a reconstruction method for fast-fission events in 25 MeV/u^(86)Kr +^(208)Pb reactions at the Compact Spectrometer for Heavy Ion Experiment(CSHINE). The fission fragments(FFs) are measured using three large-area parallel-plate avalanche counters, which can deliver the position and arrival timing information of the fragments. The start timing information is provided by the radio frequency of the cyclotron. Fission events were reconstructed using the velocities of the two FFs. The broadening of both the velocity distribution and azimuthal difference of the FFs decreases with the folding angle, in accordance with the picture that fast fission occurs. The anisotropic angular distribution of the fission axis also consistently reveals the dynamic features of fission events.展开更多
基金This work was supported by the Ministry of Science and Technology(No.2020YFE0202001)by the National Natural Science Foundation of China(Nos.11961141004 and 12205160)Tsinghua University Initiative Scientific Research Program.
文摘The energetic bremsstrahlung photons up to 100 MeV produced in heavy ion collisions can be used as a sensitive probe for short-range correlation in atomic nuclei. The energy of the γ-rays can be measured by collecting the Čerenkov light in the medium induced by the fast electrons generated in the Compton scattering or electromagnetic shower of the incident γray. Two types of detectors based on pure water and lead glass as sensitive materials were designed for this purpose. The γresponse and optical photon propagation in the detectors were simulated based on electromagnetic and optical processes in Geant4. The inherent energy resolutions of 0.022(4) + 0.51(2)∕E^(1/2)_(γ) for water and 0.0026(3) + 0.446(3)∕E^(1/2)_(γ) for lead glass were obtained. The geometry sizes of the lead glass and water were optimized to 30 cm × 30 cm × 30 cm and 60 cm × 60 cm ×120 cm, respectively, to detect high-energy γ-rays at 160 MeV. The Hough transform method was applied to reconstruct the direction of the incident γ-rays, providing the ability to experimentally distinguish the high-energy γ-rays produced in the reactions on the target from random background cosmic-ray muons.
基金supported by the National Natural Science Foundation of China(Nos.11875174,11961131010,and 11961141004)the Polish National Science Center(No.2018/30/Q/ST2/00185)。
文摘We report a reconstruction method for fast-fission events in 25 MeV/u^(86)Kr +^(208)Pb reactions at the Compact Spectrometer for Heavy Ion Experiment(CSHINE). The fission fragments(FFs) are measured using three large-area parallel-plate avalanche counters, which can deliver the position and arrival timing information of the fragments. The start timing information is provided by the radio frequency of the cyclotron. Fission events were reconstructed using the velocities of the two FFs. The broadening of both the velocity distribution and azimuthal difference of the FFs decreases with the folding angle, in accordance with the picture that fast fission occurs. The anisotropic angular distribution of the fission axis also consistently reveals the dynamic features of fission events.
