2012 Vol. 29, No. 3
Display Method:
2012, 29(3): 217-223.
doi: 10.11804/NuclPhysRev.29.03.217
Abstract:
The spontaneous fission halflives of the actinides are calculated by the WKB approximation and the potential barriers are constructed by a General Liquid Drop Model (GLDM) including the proximity energy， the mass and charge asymmetry， and an accurate nucleus radius. The microscopic shell correction which plays a key role for the spontaneous fission barrier is considered for the first time. The twoparameter quasimolecular shape and the proximity are described in details within the GLDM. The effects of the microscopic shell correction and proximity energy for fission barrier are discussed separately. The calcula ted spontaneous fission halflives for the actinides reasonably accord with the experimental data， implying the present GLDM combined with the microscopic shell correction can be used to study the spontaneous fission properties of heavy nuclei successfully.
The spontaneous fission halflives of the actinides are calculated by the WKB approximation and the potential barriers are constructed by a General Liquid Drop Model (GLDM) including the proximity energy， the mass and charge asymmetry， and an accurate nucleus radius. The microscopic shell correction which plays a key role for the spontaneous fission barrier is considered for the first time. The twoparameter quasimolecular shape and the proximity are described in details within the GLDM. The effects of the microscopic shell correction and proximity energy for fission barrier are discussed separately. The calcula ted spontaneous fission halflives for the actinides reasonably accord with the experimental data， implying the present GLDM combined with the microscopic shell correction can be used to study the spontaneous fission properties of heavy nuclei successfully.
2012, 29(3): 224-229.
doi: 10.11804/NuclPhysRev.29.03.224
Abstract:
The proton radiative capture reactions of C and N nuclei are important for the energy production and nucleosynthesis in the CNO cycle， and the neutron radiative capture reactions of C， N and O nuclei are key reactions for the inhomogeneous Big Bang nucleosynthesis as well as for the neutron induced CNO cycle in AGB stars. So far， most of these reactions have been measured except some reactions of the unstable nuclei， such as 13N(p， γ)14O and 16N(n， γ)17N. While the direct measured reactions， such as the 12C(p， γ)13N， 13C(p， γ)14N and 15N(p， γ)16O key reactions in CNO cycle， have not reached down to the stellar energies. In addition， the large uncertainties still exist in the measured neutron capture reactions such as 13C(n， γ)14C，15N(n， γ)16N and 18O(n， γ)19O. Thus it is significant to determine their astrophysical reaction rates via the indirect measurements. In this paper， the research status and feasibility of the indirect measurements for these reactions are discussed.
The proton radiative capture reactions of C and N nuclei are important for the energy production and nucleosynthesis in the CNO cycle， and the neutron radiative capture reactions of C， N and O nuclei are key reactions for the inhomogeneous Big Bang nucleosynthesis as well as for the neutron induced CNO cycle in AGB stars. So far， most of these reactions have been measured except some reactions of the unstable nuclei， such as 13N(p， γ)14O and 16N(n， γ)17N. While the direct measured reactions， such as the 12C(p， γ)13N， 13C(p， γ)14N and 15N(p， γ)16O key reactions in CNO cycle， have not reached down to the stellar energies. In addition， the large uncertainties still exist in the measured neutron capture reactions such as 13C(n， γ)14C，15N(n， γ)16N and 18O(n， γ)19O. Thus it is significant to determine their astrophysical reaction rates via the indirect measurements. In this paper， the research status and feasibility of the indirect measurements for these reactions are discussed.
2012, 29(3): 230-234.
doi: 10.11804/NuclPhysRev.29.03.230
Abstract:
The collision of different neutron/proton ratio， intermediate mass reaction systems(76Zn+76Zn， 76Ge+76Ge，76Se+76Se and 76Kr+76Kr) at the beam energy of 30~200 MeV/u are studied by using isospindependent quantum molecular dynamics(IQMD) model. It is found that there exists a strong relationship between nuclear stopping and the ratio of different direction kinetic energy， and nuclear stopping can be replaced by the square root of the ratio of perpendicular and parallel total kinetic energy of fragments， and it can be used to extract information of isospindependent in medium nucleonnucleon cross section. This physical quantity can be easily measured in nuclear reaction experiments， and it is a better probe.
The collision of different neutron/proton ratio， intermediate mass reaction systems(76Zn+76Zn， 76Ge+76Ge，76Se+76Se and 76Kr+76Kr) at the beam energy of 30~200 MeV/u are studied by using isospindependent quantum molecular dynamics(IQMD) model. It is found that there exists a strong relationship between nuclear stopping and the ratio of different direction kinetic energy， and nuclear stopping can be replaced by the square root of the ratio of perpendicular and parallel total kinetic energy of fragments， and it can be used to extract information of isospindependent in medium nucleonnucleon cross section. This physical quantity can be easily measured in nuclear reaction experiments， and it is a better probe.
2012, 29(3): 235-237.
doi: 10.11804/NuclPhysRev.29.03.235
Abstract:
The Projected Shell Model(PSM) is used to study the low energy scheme of the neutronrich normaldeformed isotopes of oddodd nuclei 102， 104Nb. The quasiparticle configuration is assigned. The theoretical calculations of the energy band of 102,104Nb could well reproduce the experimental data. It is shown that PSM is a valid method for studying the low energy scheme of heavy nuclei.
The Projected Shell Model(PSM) is used to study the low energy scheme of the neutronrich normaldeformed isotopes of oddodd nuclei 102， 104Nb. The quasiparticle configuration is assigned. The theoretical calculations of the energy band of 102,104Nb could well reproduce the experimental data. It is shown that PSM is a valid method for studying the low energy scheme of heavy nuclei.
2012, 29(3): 238-243.
doi: 10.11804/NuclPhysRev.29.03.238
Abstract:
The production of the low transverse momentum (PT) dileptons induced by semicohe rent twophoton interaction is calculated. The numerical results are compared with the experimental data from the PHENIX， the modification of the semicoherent twophoton interaction is remarkable in the low transverse momentum region for different mass bins. We find that the contribution of semicoherent twophoton processes is more evident in the large dilepton mass region.
The production of the low transverse momentum (PT) dileptons induced by semicohe rent twophoton interaction is calculated. The numerical results are compared with the experimental data from the PHENIX， the modification of the semicoherent twophoton interaction is remarkable in the low transverse momentum region for different mass bins. We find that the contribution of semicoherent twophoton processes is more evident in the large dilepton mass region.
2012, 29(3): 244-247.
doi: 10.11804/NuclPhysRev.29.03.244
Abstract:
The preliminary test of the superconducting solenoid for ADS injectorⅡhas been carried out in order to measure its performances. A vertical dewar with height 1 600 mm and outer diameter 510 mm was employed for this test. The magnet was energized by a cryogenic sms superconducting magnet current source. The axial magnetic distribution and leakage field were also tested through hall probes. The center field can be excited up to 8.20 T and the relative diviation between the measured value and the calculated value of the stray and leakage field is less than 10%. The measurements of the strain and stress status of the magnet skeleton show that the distortion is small and the mechanical performance is robust.
The preliminary test of the superconducting solenoid for ADS injectorⅡhas been carried out in order to measure its performances. A vertical dewar with height 1 600 mm and outer diameter 510 mm was employed for this test. The magnet was energized by a cryogenic sms superconducting magnet current source. The axial magnetic distribution and leakage field were also tested through hall probes. The center field can be excited up to 8.20 T and the relative diviation between the measured value and the calculated value of the stray and leakage field is less than 10%. The measurements of the strain and stress status of the magnet skeleton show that the distortion is small and the mechanical performance is robust.
2012, 29(3): 248-252.
doi: 10.11804/NuclPhysRev.29.03.248
Abstract:
In order to ensure that the beam quality is well enough， we need to precisely control the frequency， amplitude and phase of cavity electric field. Traditional control system consists of amplitude loop and phase loop. And these two loops control amplitude and phase stability respectively. The digital low level radio frequency (LLRF) system， which uses advanced digital control technology， needs only one feedback loop to control amplitude and phase stability. The phase control precision and stability of the system are higher than the traditional control system. The LLRF system is based on field programmable gate array (FPGA) and digital signal processing (DSP)， and implemented by direct digital frequency synthesis (DDS) and digital orthogonal modulation and demodulation (I/Q) technology. The digital LLRF system has been tested in a longterm stability and highpower experiments. The amplitude deviation is lower than ±1%， and phase control accuracy is within ±1°.
In order to ensure that the beam quality is well enough， we need to precisely control the frequency， amplitude and phase of cavity electric field. Traditional control system consists of amplitude loop and phase loop. And these two loops control amplitude and phase stability respectively. The digital low level radio frequency (LLRF) system， which uses advanced digital control technology， needs only one feedback loop to control amplitude and phase stability. The phase control precision and stability of the system are higher than the traditional control system. The LLRF system is based on field programmable gate array (FPGA) and digital signal processing (DSP)， and implemented by direct digital frequency synthesis (DDS) and digital orthogonal modulation and demodulation (I/Q) technology. The digital LLRF system has been tested in a longterm stability and highpower experiments. The amplitude deviation is lower than ±1%， and phase control accuracy is within ±1°.
2012, 29(3): 253-258.
doi: 10.11804/NuclPhysRev.29.03.253
Abstract:
The X/γ detectors in the field of national stratagem， such as astronautical technology， have very broad and important application. These detectors， however， will play their role properly only after accurate calibrations in effective energy region. For the shortage of continuously adjustable and quasimonochromatic γ source in China， it is impossible for the detector employed in aerospace to achieve an accurate calibration so that development of such detector has encountered a big obstacle (or a bottleneck). Therefore， we propose to upgrade the original LCS device to an adjustable photon energy by changing incident angle of laser beam， monochromatic， and polarized subMeV~MeV LCS γ source(SIMAPIII) ， in order to explore the new applications of LCS γ source in aerospace as well as to establish a platform for a multifunctional of γ source.
The X/γ detectors in the field of national stratagem， such as astronautical technology， have very broad and important application. These detectors， however， will play their role properly only after accurate calibrations in effective energy region. For the shortage of continuously adjustable and quasimonochromatic γ source in China， it is impossible for the detector employed in aerospace to achieve an accurate calibration so that development of such detector has encountered a big obstacle (or a bottleneck). Therefore， we propose to upgrade the original LCS device to an adjustable photon energy by changing incident angle of laser beam， monochromatic， and polarized subMeV~MeV LCS γ source(SIMAPIII) ， in order to explore the new applications of LCS γ source in aerospace as well as to establish a platform for a multifunctional of γ source.
2012, 29(3): 259-265.
doi: 10.11804/NuclPhysRev.29.03.259
Abstract:
The research on PET detector is a very active and highly innovative field. The main research interests of PET detector include improving performances of scintillation crystal detectors， investigating new detectors being suitable for multimodality imaging (e.g.， PET/CT and PET/MRI)， meeting needs of TOF and DOI technologies in order to promote their development and application. In this paper， new developments in PET detector technology about scintillation crystal， photodetector and semiconductor detector are introduced and the most potential detector design scheme in the future is brought forward.
The research on PET detector is a very active and highly innovative field. The main research interests of PET detector include improving performances of scintillation crystal detectors， investigating new detectors being suitable for multimodality imaging (e.g.， PET/CT and PET/MRI)， meeting needs of TOF and DOI technologies in order to promote their development and application. In this paper， new developments in PET detector technology about scintillation crystal， photodetector and semiconductor detector are introduced and the most potential detector design scheme in the future is brought forward.
2012, 29(3): 266-271.
doi: 10.11804/NuclPhysRev.29.03.266
Abstract:
The idea of using synchrotron radiation as a Mössbauer source experienced a breakthrough in 1985， followed by steady development for more than 20 years. Synchrotron Mössbauer spectroscopy consists of two areas. The first one is the so called time domain Mössbauer spectroscopy based on coherent nuclear resonant scattering which permits determination of hyperfine interactions and other Mössbauer parameters such as fLM and δSOD. The other is incoherent nuclear resonant inelastic Xray scattering， which provides vibration information of atoms in a solid， i.e.， the phonon density of states. All the experiments have better accuracy than that obtained in conventional Mssbauer spectroscopy.
The idea of using synchrotron radiation as a Mössbauer source experienced a breakthrough in 1985， followed by steady development for more than 20 years. Synchrotron Mössbauer spectroscopy consists of two areas. The first one is the so called time domain Mössbauer spectroscopy based on coherent nuclear resonant scattering which permits determination of hyperfine interactions and other Mössbauer parameters such as fLM and δSOD. The other is incoherent nuclear resonant inelastic Xray scattering， which provides vibration information of atoms in a solid， i.e.， the phonon density of states. All the experiments have better accuracy than that obtained in conventional Mssbauer spectroscopy.
2012, 29(3): 272-278.
doi: 10.11804/NuclPhysRev.29.03.272
Abstract:
Applications of wavelet analysis and neutral networks in the field of nuclear physics and engineering are reviewed. The principle of these two methods are introduced briefly, and then the applications of multiresolution analysis technique in the smoothing of γray spectroscopy, and in nuclear power plant monitoring are discussed in detail. Applications of the continuous wavelet analysis method in γray spectroscopy analysis, in particle identification , and in nuclear reactor safety monitoring are also talked over. In addition, the applications of neutral networks in above fields are introduced. Finally, the trends of the future development for these two methods are prospected.
Applications of wavelet analysis and neutral networks in the field of nuclear physics and engineering are reviewed. The principle of these two methods are introduced briefly, and then the applications of multiresolution analysis technique in the smoothing of γray spectroscopy, and in nuclear power plant monitoring are discussed in detail. Applications of the continuous wavelet analysis method in γray spectroscopy analysis, in particle identification , and in nuclear reactor safety monitoring are also talked over. In addition, the applications of neutral networks in above fields are introduced. Finally, the trends of the future development for these two methods are prospected.
2012, 29(3): 279-284.
doi: 10.11804/NuclPhysRev.29.03.279
Abstract:
In the framework of the timedependent localdensity approximation (TDLDA)，which applied to valence electrons， coupled nonadiabatically to molecular dynamics of ions， the microscopic mechanisms of collisions between energetic protons and ethylene are studied. Not only the amount of energy lost of the projectile， but also the electron and vibration excitations of the target are identified. In addition， the influences of the collision orientation on the energy loss of the proton and excitation dynamics of ethylene are discussed. It is found that the ionization is enhanced and more electrons are captured by the proton when the proton with the impact energy less than 250 eV moves perpendicularly to the molecular plane. A strong relation between the proton energy lost and the impact orientation is obtained when the impact energy is larger than 250 eV.
In the framework of the timedependent localdensity approximation (TDLDA)，which applied to valence electrons， coupled nonadiabatically to molecular dynamics of ions， the microscopic mechanisms of collisions between energetic protons and ethylene are studied. Not only the amount of energy lost of the projectile， but also the electron and vibration excitations of the target are identified. In addition， the influences of the collision orientation on the energy loss of the proton and excitation dynamics of ethylene are discussed. It is found that the ionization is enhanced and more electrons are captured by the proton when the proton with the impact energy less than 250 eV moves perpendicularly to the molecular plane. A strong relation between the proton energy lost and the impact orientation is obtained when the impact energy is larger than 250 eV.
2012, 29(3): 285-289.
doi: 10.11804/NuclPhysRev.29.03.285
Abstract:
To detect Yeast β-glucan’s protective effect on mice’s immune system after C ion beam radiation， mice were used as the test model. We observed the weight， hair color and behavior of mice everyday within a 7 d period of time after irradiation. Meanwhile， the content of white blood cell， on the 2nd and 7th day after irradiation was detected. We detected the thymus and spleen SOD， GSHPX activity and MDA content of the mice on the 8th day. The results showed that yeast βglucan could reduce the rapid weight loss of mice， increase white blood cell content， increase thymus and spleen SOD， GSHPX activity， decrease MDA content of thymus and spleen. These results indicate that yeast βglucan can protect mice’s immune system against C ion beam radiation damage.
To detect Yeast β-glucan’s protective effect on mice’s immune system after C ion beam radiation， mice were used as the test model. We observed the weight， hair color and behavior of mice everyday within a 7 d period of time after irradiation. Meanwhile， the content of white blood cell， on the 2nd and 7th day after irradiation was detected. We detected the thymus and spleen SOD， GSHPX activity and MDA content of the mice on the 8th day. The results showed that yeast βglucan could reduce the rapid weight loss of mice， increase white blood cell content， increase thymus and spleen SOD， GSHPX activity， decrease MDA content of thymus and spleen. These results indicate that yeast βglucan can protect mice’s immune system against C ion beam radiation damage.
2012, 29(3): 290-293.
doi: 10.11804/NuclPhysRev.29.03.290
Abstract:
In order to study the cytogenetic effects of lowenergy nitrogen ion irradiation, broad bean seed embryo was irradiated by different doses of nitrogen ions. Micronucleus rate, mitotic index and chromosome aberration in roottip cells were analyzed. The results showed that the injection of ions inhibited mitosis of root tip cells, interfered the normal process of mitosis, caused aberrations of chromosome structure, behavior and number. The frequency of micronucleus and chromosomal aberrations increased with the increasing radiation dosage, while mitotic index decreased.
In order to study the cytogenetic effects of lowenergy nitrogen ion irradiation, broad bean seed embryo was irradiated by different doses of nitrogen ions. Micronucleus rate, mitotic index and chromosome aberration in roottip cells were analyzed. The results showed that the injection of ions inhibited mitosis of root tip cells, interfered the normal process of mitosis, caused aberrations of chromosome structure, behavior and number. The frequency of micronucleus and chromosomal aberrations increased with the increasing radiation dosage, while mitotic index decreased.
2012, 29(3): 294-299.
doi: 10.11804/NuclPhysRev.29.03.294
Abstract:
Garlic has beneficial effects to protect against many diseases. It can not only protect normal cells from lesion， but also prevent tumorigenesis， proliferation， adhesion， invasion and metastasis. In this paper， the mechanisms of these functions of garlic were summarized and compared with radioprotector and radiosensitizer. We presented that garlic has both radioprotective effect on normal cells and radiosensitive effect on tumor cells. By right of its superiority， garlic can improve biological effect in the therapy of heavy ion. Therefore， it has potential value in clinical practice. That is worth for us to explore whether garlic has radioprotective and radiosensitive effect or not.
Garlic has beneficial effects to protect against many diseases. It can not only protect normal cells from lesion， but also prevent tumorigenesis， proliferation， adhesion， invasion and metastasis. In this paper， the mechanisms of these functions of garlic were summarized and compared with radioprotector and radiosensitizer. We presented that garlic has both radioprotective effect on normal cells and radiosensitive effect on tumor cells. By right of its superiority， garlic can improve biological effect in the therapy of heavy ion. Therefore， it has potential value in clinical practice. That is worth for us to explore whether garlic has radioprotective and radiosensitive effect or not.
2012, 29(3): 300-304.
doi: 10.11804/NuclPhysRev.29.03.300
Abstract:
The research progress of tumor cells radiosensitivity associated protein Siah, HIF,NF-κB and DNA-PK are summarized and reviewed. The recent works of our laboratory on tumor cells radiosensitivity associated proteins such as BRCA1 are demonstrated. In the present review, we focused on discussions about the advantages of heavy ion therapy and its possible application in the research of radiosensitivity associated proteins. At the end of this review, we highlighted the future trend and potential targets in the study of tumor cells radiosensitivity associated proteins.
The research progress of tumor cells radiosensitivity associated protein Siah, HIF,NF-κB and DNA-PK are summarized and reviewed. The recent works of our laboratory on tumor cells radiosensitivity associated proteins such as BRCA1 are demonstrated. In the present review, we focused on discussions about the advantages of heavy ion therapy and its possible application in the research of radiosensitivity associated proteins. At the end of this review, we highlighted the future trend and potential targets in the study of tumor cells radiosensitivity associated proteins.
2012, 29(3): 305-309.
doi: 10.11804/NuclPhysRev.29.03.305
Abstract:
3D evaluation algorithm instead of 2D evaluation method of clinical dose verification is highly needed for dose evaluation in Doseguided Radiotherapy. 3D evaluation algorithm of three evaluation methods， including Dose Difference， Distance ToAgreement and γ Analysis， was realized by the tool of Visual C++ according to the formula. Two plans were designed to test the algorithm: plan 1 was radiation on equivalent water using square field for the verification of the algorithm’s correctness; plan 2 was radiation on the emulation head phantom using conformal field for the verification of the algorithm’s practicality. For plan 1， the dose difference， in the tolerance range has a pass rate of 100%， the DistanceToAgreement and γ analysis was of a pass rate of 100% in the tolerance range，and a pass rate of 99±1% at the boundary of range. For plan 2， the pass rate of algorithm were 88.35%， 100%，95.07% for the three evaluation methods， respectively. It can be concluded that the 3D evaluation algorithm is feasible and could be used to evaluate 3D dose distributions in Doseguided Radiotherapy.
3D evaluation algorithm instead of 2D evaluation method of clinical dose verification is highly needed for dose evaluation in Doseguided Radiotherapy. 3D evaluation algorithm of three evaluation methods， including Dose Difference， Distance ToAgreement and γ Analysis， was realized by the tool of Visual C++ according to the formula. Two plans were designed to test the algorithm: plan 1 was radiation on equivalent water using square field for the verification of the algorithm’s correctness; plan 2 was radiation on the emulation head phantom using conformal field for the verification of the algorithm’s practicality. For plan 1， the dose difference， in the tolerance range has a pass rate of 100%， the DistanceToAgreement and γ analysis was of a pass rate of 100% in the tolerance range，and a pass rate of 99±1% at the boundary of range. For plan 2， the pass rate of algorithm were 88.35%， 100%，95.07% for the three evaluation methods， respectively. It can be concluded that the 3D evaluation algorithm is feasible and could be used to evaluate 3D dose distributions in Doseguided Radiotherapy.
2012, 29(3): 310-315.
doi: 10.11804/NuclPhysRev.29.03.310
Abstract:
The neutron leakage spectrum were measured at 40° by timeofflight method for polyethylene slabs with the thicknesses of 4.5， 9，18 and 27 cm，respectively. The experimental results were compared with the MCNP-4C simulations， which carefully considered many effects， such as the angle and energy distributions of the source neutrons，the width of the beam pulse，the detection efficiency and the effective measured area. The sample out and collimatorfilled spectra were measured as the background， and the results showed that C/E values were larger than 1 when using the sample out background spectra，but smaller than 1 when using the collimatorfilled background spectra. Combine these two different background spectra， a new method was used to calculate the background spectrum，and the results have a better agreement with the simulations.
The neutron leakage spectrum were measured at 40° by timeofflight method for polyethylene slabs with the thicknesses of 4.5， 9，18 and 27 cm，respectively. The experimental results were compared with the MCNP-4C simulations， which carefully considered many effects， such as the angle and energy distributions of the source neutrons，the width of the beam pulse，the detection efficiency and the effective measured area. The sample out and collimatorfilled spectra were measured as the background， and the results showed that C/E values were larger than 1 when using the sample out background spectra，but smaller than 1 when using the collimatorfilled background spectra. Combine these two different background spectra， a new method was used to calculate the background spectrum，and the results have a better agreement with the simulations.
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