2019 Vol. 36, No. 3
Display Method:
2019, 36(3): 273-277.
doi: 10.11804/NuclPhysRev.36.03.273
Abstract:
Recent heavy ion experiments (HypHI, STAR) announced surprisingly short lifetime for Λ3H mesonic weak decay (MWD), which is difficult to interpret given the fact that Λ3H is a very loosely bound system. This intriguing issue is known as hypertriton lifetime puzzle. In order to test the lifetime of the hypertriton with different experimental methods, we propose to use the K-beam of J-PARC to measure the lifetime of the hypertriton through the reaction channel of K-+ 3He → Λ3H + π0. In this article, we will summarize the situation and introduce some recent activities aiming at solving this puzzle. Our method will not suffer from the track reconstruction efficiency as the heavy ion based experiments; thus provide an important test for the hypertriton lifetime puzzle with comparable precision.
Recent heavy ion experiments (HypHI, STAR) announced surprisingly short lifetime for Λ3H mesonic weak decay (MWD), which is difficult to interpret given the fact that Λ3H is a very loosely bound system. This intriguing issue is known as hypertriton lifetime puzzle. In order to test the lifetime of the hypertriton with different experimental methods, we propose to use the K-beam of J-PARC to measure the lifetime of the hypertriton through the reaction channel of K-+ 3He → Λ3H + π0. In this article, we will summarize the situation and introduce some recent activities aiming at solving this puzzle. Our method will not suffer from the track reconstruction efficiency as the heavy ion based experiments; thus provide an important test for the hypertriton lifetime puzzle with comparable precision.
2019, 36(3): 278-288.
doi: 10.11804/NuclPhysRev.36.03.278
Abstract:
In ultra-relativistic heavy-ion collisions, the strong electric field can be produced by the colliding nuclei. The magnitude of the electric field E is on the order of eE~mπ2 at the early stage of the collision. In quark gluon plasma (QGP), such a strong electric field can have a significant impact on the evolution of charmonia. We employ the time-dependent Schrödinger equation to study the evolution of charmonium states in the strong electric field generated by the moving charges. The electric field can result in transitions between charmonium states with different angular momenta. In order to see this effect, we make comparisons between the yields of J/ψ, ψ' and χc with and without the electric field. The results show that the electric field generated by the moving heavy ions induces dissociation of J/ψ. In the meantime, χc is generated via the transition from J/ψ by the electric field.
In ultra-relativistic heavy-ion collisions, the strong electric field can be produced by the colliding nuclei. The magnitude of the electric field E is on the order of eE~mπ2 at the early stage of the collision. In quark gluon plasma (QGP), such a strong electric field can have a significant impact on the evolution of charmonia. We employ the time-dependent Schrödinger equation to study the evolution of charmonium states in the strong electric field generated by the moving charges. The electric field can result in transitions between charmonium states with different angular momenta. In order to see this effect, we make comparisons between the yields of J/ψ, ψ' and χc with and without the electric field. The results show that the electric field generated by the moving heavy ions induces dissociation of J/ψ. In the meantime, χc is generated via the transition from J/ψ by the electric field.
2019, 36(3): 289-293.
doi: 10.11804/NuclPhysRev.36.03.289
Abstract:
The online γ-rays and activity decay of 24Na residual produced in the 12C+13C reaction are both measured using thick and thin targets in the center-of-mass energy of 4~6 MeV. The total fusion cross section is derived from the γ-ray yields using the theoretical correction calculated by TALYS. Comparing the cross sections obtained by different methods in previous experiments, the systematic errors in the total cross section determination by branching the online γ-ray yields and the 24Na channel cross section are both determined to be 14%.
The online γ-rays and activity decay of 24Na residual produced in the 12C+13C reaction are both measured using thick and thin targets in the center-of-mass energy of 4~6 MeV. The total fusion cross section is derived from the γ-ray yields using the theoretical correction calculated by TALYS. Comparing the cross sections obtained by different methods in previous experiments, the systematic errors in the total cross section determination by branching the online γ-ray yields and the 24Na channel cross section are both determined to be 14%.
2019, 36(3): 294-304.
doi: 10.11804/NuclPhysRev.36.03.294
Abstract:
Nuclear mass data of N=Z nuclei is crucial for the investigation of the rp-and the νp-processes. In addition, access to the nuclei on the N=Z line will help us solve key questions relating to many open questions of nuclear structure. Isochronous mass spectrometry (IMS) combined with a fragment separator is a very fast, efficient and high resolution mass measurement tool. Since the m/q values of the N=Z nuclei are very close, the current storage ring mass spectrometers CSRe/IMP and ESR/GSI cannot realize the identification of the N=Z ions of different species via revolution time spectrum, so it is impossible to realize mass measurements on them. An IMS using a newly constructed storage ring named the ‘Rare-RI Ring’ (R3) has been implemented at the RIKEN Nishina Center to determine the masses of short-lived rare nuclei with a relative precision of the order of 10-6. With the R3 operated as an IMS coupled to the high-resolution beam-line BigRIPS employed as a fragment separator, high-resolution particle identification of the N=Z nuclei on an event-by-event basis with the beam-line before their injection to R3 makes the mass measurements possible. Monte Carlo simulation studies of beam tracking, high-resolution particle identification and selection of the secondary beams have been carried out with a dedicated ion-optics design. The results show that the revolution time of all the N=Z nuclei are independent of momentum dispersion in the storage ring when we set one species of N=Z nucleus in an isochronous condition. The mass calibration method for the N=Z nuclei has also been discussed in this report based on the simulation.
Nuclear mass data of N=Z nuclei is crucial for the investigation of the rp-and the νp-processes. In addition, access to the nuclei on the N=Z line will help us solve key questions relating to many open questions of nuclear structure. Isochronous mass spectrometry (IMS) combined with a fragment separator is a very fast, efficient and high resolution mass measurement tool. Since the m/q values of the N=Z nuclei are very close, the current storage ring mass spectrometers CSRe/IMP and ESR/GSI cannot realize the identification of the N=Z ions of different species via revolution time spectrum, so it is impossible to realize mass measurements on them. An IMS using a newly constructed storage ring named the ‘Rare-RI Ring’ (R3) has been implemented at the RIKEN Nishina Center to determine the masses of short-lived rare nuclei with a relative precision of the order of 10-6. With the R3 operated as an IMS coupled to the high-resolution beam-line BigRIPS employed as a fragment separator, high-resolution particle identification of the N=Z nuclei on an event-by-event basis with the beam-line before their injection to R3 makes the mass measurements possible. Monte Carlo simulation studies of beam tracking, high-resolution particle identification and selection of the secondary beams have been carried out with a dedicated ion-optics design. The results show that the revolution time of all the N=Z nuclei are independent of momentum dispersion in the storage ring when we set one species of N=Z nucleus in an isochronous condition. The mass calibration method for the N=Z nuclei has also been discussed in this report based on the simulation.
2019, 36(3): 305-312.
doi: 10.11804/NuclPhysRev.36.03.305
Abstract:
The latest developments of measurements and corrections of the transition energy of the cooling storage ring CSRe at the Lanzhou are reviewed in this paper. The principle of the method used to measure the transition energy of the storage ring CSRe is introduced. This method was used to investigate the influence of dipole magnetic fields, quadrupole magnetic fields and sextupole magnetic fields on the transition energy curve. Experimental results show that the transition energy curve can be horizontally, vertically shifted as well as rotated, by varying dipole magnetic fields, quadrupole magnetic fields and sextupole magnetic fields, respectively. With the corrections of the quadrupole magnets and sextupole magnets at the CSRe, the mass resolving power R for the target nuclei was improved from R=3.15(9)×104 (relative error of revolution time σT/T=7.3(2)×10-6) to 1.72(4)×105 (σT/T=1.34(3)×10-6).
The latest developments of measurements and corrections of the transition energy of the cooling storage ring CSRe at the Lanzhou are reviewed in this paper. The principle of the method used to measure the transition energy of the storage ring CSRe is introduced. This method was used to investigate the influence of dipole magnetic fields, quadrupole magnetic fields and sextupole magnetic fields on the transition energy curve. Experimental results show that the transition energy curve can be horizontally, vertically shifted as well as rotated, by varying dipole magnetic fields, quadrupole magnetic fields and sextupole magnetic fields, respectively. With the corrections of the quadrupole magnets and sextupole magnets at the CSRe, the mass resolving power R for the target nuclei was improved from R=3.15(9)×104 (relative error of revolution time σT/T=7.3(2)×10-6) to 1.72(4)×105 (σT/T=1.34(3)×10-6).
2019, 36(3): 313-321.
doi: 10.11804/NuclPhysRev.36.03.313
Abstract:
To study the four-dimensional (4D) emittances of the ion beams extracted from a highly charged ion source, so as to improve the ion beam coupling efficiency to downstream accelerators, a Pepper Pot type emittance probe PEMiL (Pepper pot Emittance Meter in Lanzhou) has been developed at Institute of Modern Physics (IMP). Based on the application requirements, the typical parameters of PEMiL have been refined. In the development, we utilized a quartz glass target sprayed uniformly with KBr powder as the scintillator instead of the traditional CsI scintillator to mitigate the overlapping effect of ion beam spot images, which has been validated with the measured results that the beam spot overlapping error vanishes and clear boundary spots has been obtained. For this 4D emittance probe, corresponding data processing and analyzing code has also been developed, so as to give the detailed transverse beam quality information of the incident beam in 4D phase space. In this paper, we will present the technical details about the structure design, fabrication and data processing of PEMiL. The preliminary test results of a 75 keV, 170 eμA O5+ beam emittance will also be measured. The analysis results show that beam emittance measured by PEMiL reveals a high reliability, the emittance difference that was caused by the charge accumulation effect of scintillator is lower than 25%, and PEMiL can be used as an efficient meter for the ECR ion source extracted beam property diagnostic.
To study the four-dimensional (4D) emittances of the ion beams extracted from a highly charged ion source, so as to improve the ion beam coupling efficiency to downstream accelerators, a Pepper Pot type emittance probe PEMiL (Pepper pot Emittance Meter in Lanzhou) has been developed at Institute of Modern Physics (IMP). Based on the application requirements, the typical parameters of PEMiL have been refined. In the development, we utilized a quartz glass target sprayed uniformly with KBr powder as the scintillator instead of the traditional CsI scintillator to mitigate the overlapping effect of ion beam spot images, which has been validated with the measured results that the beam spot overlapping error vanishes and clear boundary spots has been obtained. For this 4D emittance probe, corresponding data processing and analyzing code has also been developed, so as to give the detailed transverse beam quality information of the incident beam in 4D phase space. In this paper, we will present the technical details about the structure design, fabrication and data processing of PEMiL. The preliminary test results of a 75 keV, 170 eμA O5+ beam emittance will also be measured. The analysis results show that beam emittance measured by PEMiL reveals a high reliability, the emittance difference that was caused by the charge accumulation effect of scintillator is lower than 25%, and PEMiL can be used as an efficient meter for the ECR ion source extracted beam property diagnostic.
2019, 36(3): 322-328.
doi: 10.11804/NuclPhysRev.36.03.322
Abstract:
In order to meet the high requirement of beam intensity in a short time, a new injection method named two-plane multiturn injection is proposed for HIAF/BRing. This method is different from the traditional single-plane multiturn injection, and it has no practical operation experience. This will be the first time to be used in a practical project. Therefore, it is necessary to verify the feasibility of the two-plane multiturn injection scheme through program simulation. In order to simulate and study the injection process in detail, and to overcome the disadvantages of existing programs such as slow tracking speed and inconvenient modification of injection parameters, the injection model and TPIS (Two-Plane multiturn Injection Simulation) program are developed. By comparing with the simulation results of ORBIT program, it proves that the TPIS program is correct to simulate the two-plane multiturn injection process. On this basis, particle swarm optimization algorithm is added into the TPIS program, and the injection parameters are optimized. The results show that the TIPS program can be used for injection parameter optimization. After the optimization, the injection beam loss is reduced by 28%, and the final accumulate particle number can meet the requirement of design beam intensity. It also verifies the feasibility of two-plane multiturn injection.
In order to meet the high requirement of beam intensity in a short time, a new injection method named two-plane multiturn injection is proposed for HIAF/BRing. This method is different from the traditional single-plane multiturn injection, and it has no practical operation experience. This will be the first time to be used in a practical project. Therefore, it is necessary to verify the feasibility of the two-plane multiturn injection scheme through program simulation. In order to simulate and study the injection process in detail, and to overcome the disadvantages of existing programs such as slow tracking speed and inconvenient modification of injection parameters, the injection model and TPIS (Two-Plane multiturn Injection Simulation) program are developed. By comparing with the simulation results of ORBIT program, it proves that the TPIS program is correct to simulate the two-plane multiturn injection process. On this basis, particle swarm optimization algorithm is added into the TPIS program, and the injection parameters are optimized. The results show that the TIPS program can be used for injection parameter optimization. After the optimization, the injection beam loss is reduced by 28%, and the final accumulate particle number can meet the requirement of design beam intensity. It also verifies the feasibility of two-plane multiturn injection.
2019, 36(3): 329-335.
doi: 10.11804/NuclPhysRev.36.03.329
Abstract:
Thermionic RF gun-based electron accelerators can produce ultrashort electron beams. The alpha magnet is used for bunch compression. The transmission process of electron bunch in the alpha magnet is complicated. The research results described in the related literature were based on the ideal model, and the study of beam transmission in an alpha magnet which have an entrance hole in the mirror plate was important for the use of alpha magnet. The design model of alpha magnet is presented, which is the important part of high energy electron radiography facility. The beam transport properties between the ideal model and the alpha magnet are compared by beam dynamics simulation. It is verified that the designed alpha magnet model can effectively compress the electron bunch length. The beam dynamics under the optimization injection angle and space charge effects was discussed. It was found that the effects of the mirror plate entrance hole can be compensated by reducing the injection angle. The multi-bunch simulation results were also reported. The beam emittances and bunch sizes can be optimized by installing some quadrupole magnets between the thermionic RF gun and the alpha magnet.
Thermionic RF gun-based electron accelerators can produce ultrashort electron beams. The alpha magnet is used for bunch compression. The transmission process of electron bunch in the alpha magnet is complicated. The research results described in the related literature were based on the ideal model, and the study of beam transmission in an alpha magnet which have an entrance hole in the mirror plate was important for the use of alpha magnet. The design model of alpha magnet is presented, which is the important part of high energy electron radiography facility. The beam transport properties between the ideal model and the alpha magnet are compared by beam dynamics simulation. It is verified that the designed alpha magnet model can effectively compress the electron bunch length. The beam dynamics under the optimization injection angle and space charge effects was discussed. It was found that the effects of the mirror plate entrance hole can be compensated by reducing the injection angle. The multi-bunch simulation results were also reported. The beam emittances and bunch sizes can be optimized by installing some quadrupole magnets between the thermionic RF gun and the alpha magnet.
2019, 36(3): 336-342.
doi: 10.11804/NuclPhysRev.36.03.336
Abstract:
Several Multi-Gap Resistive Plate Chambers (MRPCs) was used to construct a Time of Flight (TOF) system in the Compressed Baryonic Matter (CBM) experiment. According to the requirements of the CBM experiment, the CBM-TOF wall is composed of 6 different types of super module. Each module contains five MRPC detectors, providing 320 electronic channels with data rates up to 6 Gbps for a single module. To evaluate the quality of CBM-TOF super module, in this paper, a data readout module based on Gigabit Ethernet technology was developed. The readout module accepts digitized time data from the front-end electronics using Altera SoC FPGAs and sends the data to the DAQ software in parallel via Gigabit Ethernet. Laboratory test results show that the overall data transfer rate of a single data transmission path can reach up to 550 Mbps, which can be used for CBM-TOF Super Module quality evaluation.
Several Multi-Gap Resistive Plate Chambers (MRPCs) was used to construct a Time of Flight (TOF) system in the Compressed Baryonic Matter (CBM) experiment. According to the requirements of the CBM experiment, the CBM-TOF wall is composed of 6 different types of super module. Each module contains five MRPC detectors, providing 320 electronic channels with data rates up to 6 Gbps for a single module. To evaluate the quality of CBM-TOF super module, in this paper, a data readout module based on Gigabit Ethernet technology was developed. The readout module accepts digitized time data from the front-end electronics using Altera SoC FPGAs and sends the data to the DAQ software in parallel via Gigabit Ethernet. Laboratory test results show that the overall data transfer rate of a single data transmission path can reach up to 550 Mbps, which can be used for CBM-TOF Super Module quality evaluation.
2019, 36(3): 343-350.
doi: 10.11804/NuclPhysRev.36.03.343
Abstract:
In this paper, a new type of start-time detector is developed. The sensitive area of the detector is 60 mm×60 mm, which is divided into two layers of dislocation tightly arranged by 120 plastic scintillating fibers with a diameter of 1mm, and three adjacent fibers are used as one detecting unit that uses the silicon phtotmultiplier to read signals. The work uses 90Sr radiation source to test the performance of a single scintillating fiber, the results show that the propagation speed of light in the fiber is about 17 cm/ns, and the corresponding time resolution is better than 600 ps. Besides the test using 90Sr source, the detector's performance has also been inspected through the 15N secondary beam of 240 MeV/u provided by the second radioactive beam line at Lanzhou (RIBLL2) of Institute of Modern Physics, Chinese Academy of Sciences. The in-beam test results show that the time resolution and vertical position resolution of the detector are (150±15) ps and (1.8±0.2) cm respectively. Combined with the detector and other detectors on the RIBLL2 External Target Facility, various isotope particles of 5 ≤ Z ≤ 8 generated in the experiment can be well identified.
In this paper, a new type of start-time detector is developed. The sensitive area of the detector is 60 mm×60 mm, which is divided into two layers of dislocation tightly arranged by 120 plastic scintillating fibers with a diameter of 1mm, and three adjacent fibers are used as one detecting unit that uses the silicon phtotmultiplier to read signals. The work uses 90Sr radiation source to test the performance of a single scintillating fiber, the results show that the propagation speed of light in the fiber is about 17 cm/ns, and the corresponding time resolution is better than 600 ps. Besides the test using 90Sr source, the detector's performance has also been inspected through the 15N secondary beam of 240 MeV/u provided by the second radioactive beam line at Lanzhou (RIBLL2) of Institute of Modern Physics, Chinese Academy of Sciences. The in-beam test results show that the time resolution and vertical position resolution of the detector are (150±15) ps and (1.8±0.2) cm respectively. Combined with the detector and other detectors on the RIBLL2 External Target Facility, various isotope particles of 5 ≤ Z ≤ 8 generated in the experiment can be well identified.
2019, 36(3): 351-356.
doi: 10.11804/NuclPhysRev.36.03.351
Abstract:
Aimed to the Multipurpose Reflectance spectrometer device(MR) physics requirements, which is that the active area with 200 mm×200 mm, the detection efficiency with more than 50% and the position resolution with better than 2 mm, for China Spallation Neutron Source (CSNS) in Dongguang, China. A 3He two-dimensional multi-wire proportional chamber position sensitive neutron detector has been developed by the Institute of High Energy Physics of the Chinese Academy of Sciences (IHEP, CAS). The high-pressure two-dimensional multiwire proportional chamber neutron detector filled with 3He/C3H8(6 atm/2.5 atm) mixture gases and the multiwire technology. Firstly, the detection uniformity was tested using the Am/Be neutron source in IHEP and the uniformity could reach to 95.1%. After assembled at #20 beam station in CSNS, the performance of the detector were studied under the neutron beam. Under the selection neutron beam with 2.8Å by the time of flight (TOF), the two-dimensional position resolution and two-dimensional imaging of the detector were measured. The position resolution is 0.99 mm in the X direction (perpendicular to the direction of the anode wire), 1.36 mm in the Y direction (parallel to the direction of the anode wire) and the two-dimensional imaging is clear to identity. The results show that the detector has a good resolution and two-dimensional imaging capability, and it could meet the physics requirements of Multipurpose Reflectance spectrometer device in CSNS.
Aimed to the Multipurpose Reflectance spectrometer device(MR) physics requirements, which is that the active area with 200 mm×200 mm, the detection efficiency with more than 50% and the position resolution with better than 2 mm, for China Spallation Neutron Source (CSNS) in Dongguang, China. A 3He two-dimensional multi-wire proportional chamber position sensitive neutron detector has been developed by the Institute of High Energy Physics of the Chinese Academy of Sciences (IHEP, CAS). The high-pressure two-dimensional multiwire proportional chamber neutron detector filled with 3He/C3H8(6 atm/2.5 atm) mixture gases and the multiwire technology. Firstly, the detection uniformity was tested using the Am/Be neutron source in IHEP and the uniformity could reach to 95.1%. After assembled at #20 beam station in CSNS, the performance of the detector were studied under the neutron beam. Under the selection neutron beam with 2.8Å by the time of flight (TOF), the two-dimensional position resolution and two-dimensional imaging of the detector were measured. The position resolution is 0.99 mm in the X direction (perpendicular to the direction of the anode wire), 1.36 mm in the Y direction (parallel to the direction of the anode wire) and the two-dimensional imaging is clear to identity. The results show that the detector has a good resolution and two-dimensional imaging capability, and it could meet the physics requirements of Multipurpose Reflectance spectrometer device in CSNS.
2019, 36(3): 357-366.
doi: 10.11804/NuclPhysRev.36.03.357
Abstract:
The calculation of energy level structures is still a challenge for atomic Cu. In the present work, based on the multiconfiguration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction (RCI) methods, three large-scale correlation models have been used to calculate the energies and wavefunctions of the singly excited state 3d104p 2P1/2, the doubly excited states 3d94s(3D)5s 4D3/2,1/2, 3d94s(3D)5s 2D3/2, 3d94s(1D)5s 2D3/2 and the ionic state 3d10 1S0. The results show that the calculated level structures of copper are very sensitive to the choice of finite configuration space. All of the energy differences are less than the existing experimental results by about -0.4 eV between the doubly excited states 3d94s(3D)5s 4D3/2,1/2, 3d94s(3D)5s 2D3/2, 3d94s(1D)5s 2D3/2 and the ionic state 3d10 1S0 with the singly excited state 3d104p 2P1/2, but the calculated resonant electron energies agree well with the experimental results. In addition, according to the radiative and nonradiative transition matrix elements, the Fano parameters q have been calculated for the doubly excited states. Then, the total photoionization cross sections of singly excited state 3d104p 2P1/2 of copper is obtained, where the interference effects can be considered between direct photoionization and photoexcitation autoionization. The resonances 3d94s(3D)5s 4D3/2,1/2, 3d94s(3D)5s 2D3/2, 3d94s(1D)5s 2D3/2 have obvious asymmetrical Fano profiles, which indicates that the interference between photoionization and photoexcitation autoionization has an extremely important influence on the photoionization cross sections near the doubly excited resonances.
The calculation of energy level structures is still a challenge for atomic Cu. In the present work, based on the multiconfiguration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction (RCI) methods, three large-scale correlation models have been used to calculate the energies and wavefunctions of the singly excited state 3d104p 2P1/2, the doubly excited states 3d94s(3D)5s 4D3/2,1/2, 3d94s(3D)5s 2D3/2, 3d94s(1D)5s 2D3/2 and the ionic state 3d10 1S0. The results show that the calculated level structures of copper are very sensitive to the choice of finite configuration space. All of the energy differences are less than the existing experimental results by about -0.4 eV between the doubly excited states 3d94s(3D)5s 4D3/2,1/2, 3d94s(3D)5s 2D3/2, 3d94s(1D)5s 2D3/2 and the ionic state 3d10 1S0 with the singly excited state 3d104p 2P1/2, but the calculated resonant electron energies agree well with the experimental results. In addition, according to the radiative and nonradiative transition matrix elements, the Fano parameters q have been calculated for the doubly excited states. Then, the total photoionization cross sections of singly excited state 3d104p 2P1/2 of copper is obtained, where the interference effects can be considered between direct photoionization and photoexcitation autoionization. The resonances 3d94s(3D)5s 4D3/2,1/2, 3d94s(3D)5s 2D3/2, 3d94s(1D)5s 2D3/2 have obvious asymmetrical Fano profiles, which indicates that the interference between photoionization and photoexcitation autoionization has an extremely important influence on the photoionization cross sections near the doubly excited resonances.
2019, 36(3): 367-372.
doi: 10.11804/NuclPhysRev.36.03.367
Abstract:
Total ionizing dose (TID) and single event effect (SEE) are both the main threats to nano-SRAMs devices in space application. With the development of CMOS technology, some new phenomena were observed during studying the synergistic effect between TID and SEE on nano-SRAMs. γ ray and heavy ion irradiations were performed to investigate the impact of total ionizing dose on single event upset (SEU) sensitivity of SRAMs. The influence of irradiation parameters, test modes and data patterns on synergistic effect were studied. The results showed that γ ray irradiation led to the decrease of threshold voltage and the increase of leakage current of inverters, which reduced the SEU hardness of SRAMs. Meanwhile, the SEU cross section increased compared with that of non-TID irradiated devices. There was no significant change in the percentage of multiple-bit upset (MBU). No "imprint effect" was observed. Data pattern applied in TID and SEE tests had no influence on the test results of SEU cross section.
Total ionizing dose (TID) and single event effect (SEE) are both the main threats to nano-SRAMs devices in space application. With the development of CMOS technology, some new phenomena were observed during studying the synergistic effect between TID and SEE on nano-SRAMs. γ ray and heavy ion irradiations were performed to investigate the impact of total ionizing dose on single event upset (SEU) sensitivity of SRAMs. The influence of irradiation parameters, test modes and data patterns on synergistic effect were studied. The results showed that γ ray irradiation led to the decrease of threshold voltage and the increase of leakage current of inverters, which reduced the SEU hardness of SRAMs. Meanwhile, the SEU cross section increased compared with that of non-TID irradiated devices. There was no significant change in the percentage of multiple-bit upset (MBU). No "imprint effect" was observed. Data pattern applied in TID and SEE tests had no influence on the test results of SEU cross section.
2019, 36(3): 373-378.
doi: 10.11804/NuclPhysRev.36.03.373
Abstract:
In this paper, the radiosensitizing effects of gadolinium based nanoparticles to X-ray and carbon ion beams were studied by using gadolinium oxide nanoparticles (GON). Firstly, the particle size of GON was measured by transmission electron microscopy, the hydration radius and Zeta potential of GON were measured by dynamic light scattering (DLS), and the stability of gadolinium nanoparticles in the medium was confirmed by ultraviolet absorption spectrum. It was found that GON with 10.0 μg/mL gadolinium concentration enhanced the hydroxyl radical productivity by 1.13 times in aqueous solution under 30 keV/μm carbon ion beam irradiation. In addition, GON had no obvious toxicity to A549 lung cancer cells and normal MRC-5 lung cells. The uptake of gadolinium in human lung cancer A549 cells enhanced with the increase of co-culture GON concentration, and the uptake of gadolinium was 0.73 pg/cell when the co-culture concentration of GON was 10.0 μg/mL. Most importantly, the radiosensitizing effect of GON on A549 cells irradiated with X-rays and carbon ions was assessed with the clonogenic survival assay. Our experimental results indicated that obviously radiosensitizing effect of GON on A549 cells was observed. The radiation enhancement ratio of GON on A549 cells exposed to X-rays and carbon ions was 15.5% and 10.1% at 10% survival level. Since gadolinium has been widely used for magnetic resonance imaging (MRI), the obtained GON is expected to be an ideal material for the diagnosis and treatment of cancer using X-ray and carbon ions radiotherapy.
In this paper, the radiosensitizing effects of gadolinium based nanoparticles to X-ray and carbon ion beams were studied by using gadolinium oxide nanoparticles (GON). Firstly, the particle size of GON was measured by transmission electron microscopy, the hydration radius and Zeta potential of GON were measured by dynamic light scattering (DLS), and the stability of gadolinium nanoparticles in the medium was confirmed by ultraviolet absorption spectrum. It was found that GON with 10.0 μg/mL gadolinium concentration enhanced the hydroxyl radical productivity by 1.13 times in aqueous solution under 30 keV/μm carbon ion beam irradiation. In addition, GON had no obvious toxicity to A549 lung cancer cells and normal MRC-5 lung cells. The uptake of gadolinium in human lung cancer A549 cells enhanced with the increase of co-culture GON concentration, and the uptake of gadolinium was 0.73 pg/cell when the co-culture concentration of GON was 10.0 μg/mL. Most importantly, the radiosensitizing effect of GON on A549 cells irradiated with X-rays and carbon ions was assessed with the clonogenic survival assay. Our experimental results indicated that obviously radiosensitizing effect of GON on A549 cells was observed. The radiation enhancement ratio of GON on A549 cells exposed to X-rays and carbon ions was 15.5% and 10.1% at 10% survival level. Since gadolinium has been widely used for magnetic resonance imaging (MRI), the obtained GON is expected to be an ideal material for the diagnosis and treatment of cancer using X-ray and carbon ions radiotherapy.
2019, 36(3): 379-387.
doi: 10.11804/NuclPhysRev.36.03.379
Abstract:
In this paper, the effects and characteristics of several main irradiated pretreatment methods for lignocellulose are compared and summarized comprehensively. The mechanism of lignocellulose pretreated by microwave, ultraviolet, gamma ray, X ray, electron beam and ion beam were expounded. In particular, the transformation of polymorphys in lignocellulose (Iα → Iβ) caused by pretreatment with heavy ion beams irradiation was discussed. The crystallinity index of lignocellulose was strongly correlated with enzyme digestibility. The pretreatment of heavy ion beam radiation can destroy the lignin and hemicellulose partially, resulting in an increase in its relative crystallization, which enhances the accessibility of cellulase and lignocellulose, also increase the enzymatic hydrolysis yield. Therefore, the biotransformation efficiency of enzyme to lignocellulose and the yield of reducing sugar can be significantly improved at the appropriate dose of heavy ion beam radiation pretreatment, which provides the theoretical guidance for radiation pretreatment to improve the comprehensive utilization of lignocellulose.
In this paper, the effects and characteristics of several main irradiated pretreatment methods for lignocellulose are compared and summarized comprehensively. The mechanism of lignocellulose pretreated by microwave, ultraviolet, gamma ray, X ray, electron beam and ion beam were expounded. In particular, the transformation of polymorphys in lignocellulose (Iα → Iβ) caused by pretreatment with heavy ion beams irradiation was discussed. The crystallinity index of lignocellulose was strongly correlated with enzyme digestibility. The pretreatment of heavy ion beam radiation can destroy the lignin and hemicellulose partially, resulting in an increase in its relative crystallization, which enhances the accessibility of cellulase and lignocellulose, also increase the enzymatic hydrolysis yield. Therefore, the biotransformation efficiency of enzyme to lignocellulose and the yield of reducing sugar can be significantly improved at the appropriate dose of heavy ion beam radiation pretreatment, which provides the theoretical guidance for radiation pretreatment to improve the comprehensive utilization of lignocellulose.
2019, 36(3): 388-393.
doi: 10.11804/NuclPhysRev.36.03.388
Abstract:
The measurement and control system of particles heat transfer experiment was designed for the particles heat exchange platform. Based on the EPICS (Experimental Physics and Industrial Control System) architecture design, this system integrates NI hardware platform, infrared thermal imager equipment and Oracle database to realize the online collection, monitoring, control and real-time storage of particles heat exchange platform. The infrared thermal imager was applied to measure the temperature of particles at the outlet of heat exchanger in the measurement and control system for its advantages in high sensitivity, wide range of temperature measurement and non-contact measurement. In this paper, the SDK (Secondary Development Kit) was employed to integrate infrared thermal imager into the EPICS system. Infrared images and the data were obtained to present the real-time temperature distribution of the particles more intuitively. By comparing the data with the measured results of the thermocouple, the feasibility of using the infrared camera as a real-time temperature measuring device for particles was further tested. The experimental results show that the integrated infrared camera operating software can obtain and store the temperature values of the infrared image in real time. And the measurement and control system of particles heat transfer experiment designed and developed by EPICS architecture can fully meet the data acquisition and storage requirements of the particles heat exchange platform.
The measurement and control system of particles heat transfer experiment was designed for the particles heat exchange platform. Based on the EPICS (Experimental Physics and Industrial Control System) architecture design, this system integrates NI hardware platform, infrared thermal imager equipment and Oracle database to realize the online collection, monitoring, control and real-time storage of particles heat exchange platform. The infrared thermal imager was applied to measure the temperature of particles at the outlet of heat exchanger in the measurement and control system for its advantages in high sensitivity, wide range of temperature measurement and non-contact measurement. In this paper, the SDK (Secondary Development Kit) was employed to integrate infrared thermal imager into the EPICS system. Infrared images and the data were obtained to present the real-time temperature distribution of the particles more intuitively. By comparing the data with the measured results of the thermocouple, the feasibility of using the infrared camera as a real-time temperature measuring device for particles was further tested. The experimental results show that the integrated infrared camera operating software can obtain and store the temperature values of the infrared image in real time. And the measurement and control system of particles heat transfer experiment designed and developed by EPICS architecture can fully meet the data acquisition and storage requirements of the particles heat exchange platform.
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