2009 Vol. 26, No. 2
Display Method:
2009, 26(2): 85-92.
doi: 10.11804/NuclPhysRev.26.02.085
Abstract:
One of the major tasks of studying isospin physics via heavy ion collisions with neutron rich nuclei, is to explore the isospin dependence of in medium nuclear effective interactions and the equation of state of neutron rich nuclear matter, i.e., the density dependence of nuclear symmetry energy. Because of its great importance for understanding many phenomena in both nuclear physics and astrophysics, the study of the density dependence of nuclear symmetry nergy has been the main focus of the intermediateenergy heavy ion physics community during the last decade. Nowadays significant progress has been achieved in studying the low density behavior of nuclear symmetry energy, but the high density behavior of nuclear symmetry energy is still very uncertain. Theoretically, a number of observables have been proposed as sensitive probes to the high density behavior of nuclear symmetry energy. With new opportunities provided by the various radioactive beam facilities being constructed around the world, studies of the high density behavior of nuclear symmetry energy is expected to be one of the main forefront research areas in nuclear physics in the near future. In this report, based on the transport model IBUU we have reviewed the major progress achieved in studying the high density behavior of nuclear symmetry energy and discussed future challenges in this field.
One of the major tasks of studying isospin physics via heavy ion collisions with neutron rich nuclei, is to explore the isospin dependence of in medium nuclear effective interactions and the equation of state of neutron rich nuclear matter, i.e., the density dependence of nuclear symmetry energy. Because of its great importance for understanding many phenomena in both nuclear physics and astrophysics, the study of the density dependence of nuclear symmetry nergy has been the main focus of the intermediateenergy heavy ion physics community during the last decade. Nowadays significant progress has been achieved in studying the low density behavior of nuclear symmetry energy, but the high density behavior of nuclear symmetry energy is still very uncertain. Theoretically, a number of observables have been proposed as sensitive probes to the high density behavior of nuclear symmetry energy. With new opportunities provided by the various radioactive beam facilities being constructed around the world, studies of the high density behavior of nuclear symmetry energy is expected to be one of the main forefront research areas in nuclear physics in the near future. In this report, based on the transport model IBUU we have reviewed the major progress achieved in studying the high density behavior of nuclear symmetry energy and discussed future challenges in this field.
2009, 26(2): 93-101.
doi: 10.11804/NuclPhysRev.26.02.093
Abstract:
In this article， three models with different isospin and momentum dependence are used to study the thermodynamical properties of asymmetric nuclear matter. They are isospin and momentumdependent MDI interaction constrained by the isospin diffusion data of heavy ion collision， the momentumindependent MID interaction and the isoscalar momentumdependent eMDYI interaction. Temperature effects of symmetry energy，mechanical and chemical instability and liquidgas phase transition are analyzed. It is found that for MDI model the temperature effects of the symmetry energy attribute from both the kinetic and potential energy， while only potential part contributes to the decreasing of the symmetry energy for MID and eMDYI models. We also find that the mechanical instability， chemical instability and liquidgas phase transition are all sensitive to the isospin and momentum dependence and the density dependence of the symmetry energy.
In this article， three models with different isospin and momentum dependence are used to study the thermodynamical properties of asymmetric nuclear matter. They are isospin and momentumdependent MDI interaction constrained by the isospin diffusion data of heavy ion collision， the momentumindependent MID interaction and the isoscalar momentumdependent eMDYI interaction. Temperature effects of symmetry energy，mechanical and chemical instability and liquidgas phase transition are analyzed. It is found that for MDI model the temperature effects of the symmetry energy attribute from both the kinetic and potential energy， while only potential part contributes to the decreasing of the symmetry energy for MID and eMDYI models. We also find that the mechanical instability， chemical instability and liquidgas phase transition are all sensitive to the isospin and momentum dependence and the density dependence of the symmetry energy.
2009, 26(2): 102-106.
doi: 10.11804/NuclPhysRev.26.02.102
Abstract:
We studied the Efimov effect in a threebody system by solving the Faddeev equations. Different models and interactions were considered. The occurrence of Efimov states was discussed. The possible Efimov state was clearly presented and its properties were investigated.
We studied the Efimov effect in a threebody system by solving the Faddeev equations. Different models and interactions were considered. The occurrence of Efimov states was discussed. The possible Efimov state was clearly presented and its properties were investigated.
2009, 26(2): 107-111.
doi: 10.11804/NuclPhysRev.26.02.107
Abstract:
A possible way to synthesize superheavy element (Z=117) by using 48Ca+249Bk reaction is studied with two step model. The fusion process is divided into two steps: the sticking process that the projectile approaches to the target to get contacted with the target by passing over the Coulomb barrier， and the formation process that the dinuclear system evolves from contact into compound nuclear state. Combined with the statistical evaporation model， the formation cross section of 297117 is calculated. The result shows that the residue for 3 neutron evaporation is 0.34 pb at excitation energy E*=31 MeV， which is detectable in laboratory.
A possible way to synthesize superheavy element (Z=117) by using 48Ca+249Bk reaction is studied with two step model. The fusion process is divided into two steps: the sticking process that the projectile approaches to the target to get contacted with the target by passing over the Coulomb barrier， and the formation process that the dinuclear system evolves from contact into compound nuclear state. Combined with the statistical evaporation model， the formation cross section of 297117 is calculated. The result shows that the residue for 3 neutron evaporation is 0.34 pb at excitation energy E*=31 MeV， which is detectable in laboratory.
2009, 26(2): 112-116.
doi: 10.11804/NuclPhysRev.26.02.112
Abstract:
The α decay halflives of the superheavy nuclei in the mass region （Z≥104） were calculated by ViolaSeaborg formula with three sets of parameters. The calculated results show that all the three sets of parameters caused rather large deviations from the experimental data. To solve this problem， we have done a parameter fitting in the regions of heavy nuclei and superheavy nuclei respectively， with the least squares method. With the new sets of parameters， the calculated α decay halflives are in much better agreement with the experimental data. In particular， the results calculated with the new parameters in the region of superheavy nuclei are even better.
The α decay halflives of the superheavy nuclei in the mass region （Z≥104） were calculated by ViolaSeaborg formula with three sets of parameters. The calculated results show that all the three sets of parameters caused rather large deviations from the experimental data. To solve this problem， we have done a parameter fitting in the regions of heavy nuclei and superheavy nuclei respectively， with the least squares method. With the new sets of parameters， the calculated α decay halflives are in much better agreement with the experimental data. In particular， the results calculated with the new parameters in the region of superheavy nuclei are even better.
2009, 26(2): 117-122.
doi: 10.11804/NuclPhysRev.26.02.117
Abstract:
We characterize the spatial dimension of pionemitting source in highenergy heavy ion collisions with the radius of rootmeansquared of twopion relativedistance Rrmst. Based on the imaging technique， one can calculate Rrmst modelindependently. Applying this method to the Core-Halo model and comparing the results with that of Gaussian fitted， the results indicate that due to the effects of longlived resonance decay， the values of Rrmst show a larger spatial size of pionemitting region. Meanwhile， for the chaotic source the chaoticity factors calculated by imaging technique are larger than that of Gaussian fitted.
We characterize the spatial dimension of pionemitting source in highenergy heavy ion collisions with the radius of rootmeansquared of twopion relativedistance Rrmst. Based on the imaging technique， one can calculate Rrmst modelindependently. Applying this method to the Core-Halo model and comparing the results with that of Gaussian fitted， the results indicate that due to the effects of longlived resonance decay， the values of Rrmst show a larger spatial size of pionemitting region. Meanwhile， for the chaotic source the chaoticity factors calculated by imaging technique are larger than that of Gaussian fitted.
2009, 26(2): 123-126.
doi: 10.11804/NuclPhysRev.26.02.123
Abstract:
Beam matching relationship between the two cyclotrons(SFC and SSC) of HIRFL is briefly discussed, and the frequency band of the new RF cavity is obtained. The new cavity is simulated with the threedimensional electromagnetic calculation code MAFIA, and the parameters of it such as frequency, Q value, shunt impedance and voltage distribution are worked out and discussed. The simulation results show that the new RF cavity can fully meet the requirements of physics design and space configuration.
Beam matching relationship between the two cyclotrons(SFC and SSC) of HIRFL is briefly discussed, and the frequency band of the new RF cavity is obtained. The new cavity is simulated with the threedimensional electromagnetic calculation code MAFIA, and the parameters of it such as frequency, Q value, shunt impedance and voltage distribution are worked out and discussed. The simulation results show that the new RF cavity can fully meet the requirements of physics design and space configuration.
2009, 26(2): 127-135.
doi: 10.11804/NuclPhysRev.26.02.127
Abstract:
The gasjet recoil transport technique is developed and improved as a new rapid and effective online and off beam method following “rabbit” apparatus in the study of short lives nuclei. It can transport the short halflife nuclear reaction products far from high radioactive area for collection and measurement at low background area. This technique has been widely used in the researches with accelerator and reactor. It is indispensable basic experimental technology and tool applied to nuclear reaction， spectroscopy， as well as synthesis and identification of new elements and nuclei. The basic principle， structure， design requirement and main characteristics of gasjet system are described in this paper， especially the mechanism of gas dynamics and the effect of several parameters on the system properties are discussed. Finally， the applications of this technique in several fields such as nuclear physics， nuclear chemistry and massspectroscopy etc. are comprehensively represented. Several typical applications are also illustrated.
The gasjet recoil transport technique is developed and improved as a new rapid and effective online and off beam method following “rabbit” apparatus in the study of short lives nuclei. It can transport the short halflife nuclear reaction products far from high radioactive area for collection and measurement at low background area. This technique has been widely used in the researches with accelerator and reactor. It is indispensable basic experimental technology and tool applied to nuclear reaction， spectroscopy， as well as synthesis and identification of new elements and nuclei. The basic principle， structure， design requirement and main characteristics of gasjet system are described in this paper， especially the mechanism of gas dynamics and the effect of several parameters on the system properties are discussed. Finally， the applications of this technique in several fields such as nuclear physics， nuclear chemistry and massspectroscopy etc. are comprehensively represented. Several typical applications are also illustrated.
2009, 26(2): 136-139.
doi: 10.11804/NuclPhysRev.26.02.136
Abstract:
The light output of the BC501A liquid scintillation detector for γrays was calibrated by serial monoenergetic γray sources. The Monte Carlo simulation method to confirm Compton edge was described briefly. The result was compared with that obtained by the semiheight method. The γray esponse matrix of BC501A liquid scintillation detector was calculated by the Monte Carlo code PHRESP from PTB. The method of using response function matrix and recoil electron spectrum to unfold γray energy spectrum was introduced and the error of unfolding spectrum was also briefly discussed.
The light output of the BC501A liquid scintillation detector for γrays was calibrated by serial monoenergetic γray sources. The Monte Carlo simulation method to confirm Compton edge was described briefly. The result was compared with that obtained by the semiheight method. The γray esponse matrix of BC501A liquid scintillation detector was calculated by the Monte Carlo code PHRESP from PTB. The method of using response function matrix and recoil electron spectrum to unfold γray energy spectrum was introduced and the error of unfolding spectrum was also briefly discussed.
2009, 26(2): 140-145.
doi: 10.11804/NuclPhysRev.26.02.140
Abstract:
The simulation of the Auger electron emissions in scanning probe electron energy spectrometer (SPEES) is reported. By simulating the trajectory of Auger electrons, we systematically investigate the dependence of the emission efficiency of Auger electrons on the shape of tip， the biasing voltage， and the distance between the tip and sample surface， as well as the intensity distributions of Auger electrons at the edge of tipsample region. The results will be the significant reference for improving the sensitivity， spatial and energy resolutions of SPEEs.
The simulation of the Auger electron emissions in scanning probe electron energy spectrometer (SPEES) is reported. By simulating the trajectory of Auger electrons, we systematically investigate the dependence of the emission efficiency of Auger electrons on the shape of tip， the biasing voltage， and the distance between the tip and sample surface， as well as the intensity distributions of Auger electrons at the edge of tipsample region. The results will be the significant reference for improving the sensitivity， spatial and energy resolutions of SPEEs.
2009, 26(2): 146-149.
doi: 10.11804/NuclPhysRev.26.02.146
Abstract:
The Au atomic Mα characteristic Xray spectrum has been measured for the slow highly charged ions Arq+ (q= 7—14) impacting on Au surface. The result shows that as long as the charge state of projectile is higher（q=11）， the characteristic Xrays of heavy atomic can be effectively excited even though the ionic beam is very weak(nA magnitude)， and the single ionic Xray yield is in the order of 10-8 and increases with potential energies of projectiles.
The Au atomic Mα characteristic Xray spectrum has been measured for the slow highly charged ions Arq+ (q= 7—14) impacting on Au surface. The result shows that as long as the charge state of projectile is higher（q=11）， the characteristic Xrays of heavy atomic can be effectively excited even though the ionic beam is very weak(nA magnitude)， and the single ionic Xray yield is in the order of 10-8 and increases with potential energies of projectiles.
Analytic Potential Energy Functions for Hydrogen Isotopic Diatomic Molecules Based on Nuclear Effect
2009, 26(2): 150-153.
doi: 10.11804/NuclPhysRev.26.02.150
Abstract:
Based on the correction of the electron energy under BornOppenheimer approximation using nuclear motion effect， the parameters of potential energy functions for hydrogen isotopic diatomic molecules (H2， HD，HT，D2， DT，T2) are calculated with QCISD (T) method and aug-cc-pvqz basis set，and those potential energy functions that indicate the differences from the masses of hydrogen isotopic atoms are obtained. The force constants and spectroscopic data of those molecules are calculated as well. The potential energy functions， force constants， and spectroscopic data of the isotopic diatomic molecules OH， OD，and OT are also derived using QCISD method and aug-cc-pvtz basis set.
Based on the correction of the electron energy under BornOppenheimer approximation using nuclear motion effect， the parameters of potential energy functions for hydrogen isotopic diatomic molecules (H2， HD，HT，D2， DT，T2) are calculated with QCISD (T) method and aug-cc-pvqz basis set，and those potential energy functions that indicate the differences from the masses of hydrogen isotopic atoms are obtained. The force constants and spectroscopic data of those molecules are calculated as well. The potential energy functions， force constants， and spectroscopic data of the isotopic diatomic molecules OH， OD，and OT are also derived using QCISD method and aug-cc-pvtz basis set.
2009, 26(2): 154-157.
doi: 10.11804/NuclPhysRev.26.02.154
Abstract:
A modified solution method，successive ionic layer adsorption and reaction(SILAR)，was applied to prepare transparent zinc oxide(ZnO) film on glass substrate at (125±5) ℃ in mixed ion precursor solution. The surface morphology and crystallizations of films were analyzed by field emission scanning microscopy(FESEM) and Xray diffraction(XRD)， respectively. The optical properties of the films were studied by ultraviolet visible(UVVis)spectroscopy. The results show that the obtained samples are polycrystalline films of hexagonal wurtzite structure，with the preference of [002\] orientation. The asdeposited films exhibit uniform and compact surface morphology， with the film thickness of 550 nm， and have high transmittance in the visible band(＞80％).
A modified solution method，successive ionic layer adsorption and reaction(SILAR)，was applied to prepare transparent zinc oxide(ZnO) film on glass substrate at (125±5) ℃ in mixed ion precursor solution. The surface morphology and crystallizations of films were analyzed by field emission scanning microscopy(FESEM) and Xray diffraction(XRD)， respectively. The optical properties of the films were studied by ultraviolet visible(UVVis)spectroscopy. The results show that the obtained samples are polycrystalline films of hexagonal wurtzite structure，with the preference of [002\] orientation. The asdeposited films exhibit uniform and compact surface morphology， with the film thickness of 550 nm， and have high transmittance in the visible band(＞80％).
2009, 26(2): 158-162.
doi: 10.11804/NuclPhysRev.26.02.158
Abstract:
To investigate the effect of low dose 12C6+ preirradiation on the cell cycle progression and DNA damage in mouse thymus and spleen， KunMing strain mice were wholebody irradiated with 0， 0.05， 0.1， 0.25 or 0.5 Gy of 12C6+ ions as the preexposure dose， and were then irradiated with 4 Gy of 12C6+ ions as a challenging dose at 4 h after perexposure. At 12h after irradiation， cell cycles of thymus and spleen were analyzed by FACS， and the frequencies of cells with tail moment and the tail lengths were determined by the single cell gel electrophoresis. The results showed that compared with highdose exposure group， the percentages of S phase cells on thymus and the percentages of G0/G1 phase cells on spleen significantly decreased via pre exposure to lowdose 12C6+ ions. Moreover， the lowdose preexposure significantly reduced length of the tails and the number of cells with tail， especially at the 0.1 Gy preexposure. The data suggested that preexposure to lowdose heavy ion can alleviate S phase arrest in thymus cells and the G1 phase arrest in spleen cell， and the degree of DNA damage.
To investigate the effect of low dose 12C6+ preirradiation on the cell cycle progression and DNA damage in mouse thymus and spleen， KunMing strain mice were wholebody irradiated with 0， 0.05， 0.1， 0.25 or 0.5 Gy of 12C6+ ions as the preexposure dose， and were then irradiated with 4 Gy of 12C6+ ions as a challenging dose at 4 h after perexposure. At 12h after irradiation， cell cycles of thymus and spleen were analyzed by FACS， and the frequencies of cells with tail moment and the tail lengths were determined by the single cell gel electrophoresis. The results showed that compared with highdose exposure group， the percentages of S phase cells on thymus and the percentages of G0/G1 phase cells on spleen significantly decreased via pre exposure to lowdose 12C6+ ions. Moreover， the lowdose preexposure significantly reduced length of the tails and the number of cells with tail， especially at the 0.1 Gy preexposure. The data suggested that preexposure to lowdose heavy ion can alleviate S phase arrest in thymus cells and the G1 phase arrest in spleen cell， and the degree of DNA damage.
2009, 26(2): 163-167.
doi: 10.11804/NuclPhysRev.26.02.163
Abstract:
Depending on their unique physical properties， proton and heavy ions have taken an irreplaceable role in modern means of tumor treatment. Onestep process and twostep process physical models were employed to explain the mechanism of ion energy loss. The transport process of proton and 12C in water was simulated by Geant4 toolkit to study the physical properties of ion beam. The calculation results were discussed， which showed the advantages and disadvantages of proton and 12C in the medical application.
Depending on their unique physical properties， proton and heavy ions have taken an irreplaceable role in modern means of tumor treatment. Onestep process and twostep process physical models were employed to explain the mechanism of ion energy loss. The transport process of proton and 12C in water was simulated by Geant4 toolkit to study the physical properties of ion beam. The calculation results were discussed， which showed the advantages and disadvantages of proton and 12C in the medical application.
2009, 26(2): 168-171.
doi: 10.11804/NuclPhysRev.26.02.168
Abstract:
To explore the effects of different linear energy transfer(LET）of 12C6+ ion Beam irradiation on BJ1, survivals and biocontrol effects were cultured and treated with LET＝40 and 60 keV/μm at the doses of 50, 100, 200, 400 and 600 Gy, respectively. The results showed more mutations and biocontrol charts and higher survivals were obtained with high LET(60 keV/μm） irradiations at lower dose, which was useful to screen good positive mutations. Based on the results above, it could be concluded that the condition of high LET(60 keV/μm） had obvious mutagenic effects than that of low LET(40 keV/μm）.
To explore the effects of different linear energy transfer(LET）of 12C6+ ion Beam irradiation on BJ1, survivals and biocontrol effects were cultured and treated with LET＝40 and 60 keV/μm at the doses of 50, 100, 200, 400 and 600 Gy, respectively. The results showed more mutations and biocontrol charts and higher survivals were obtained with high LET(60 keV/μm） irradiations at lower dose, which was useful to screen good positive mutations. Based on the results above, it could be concluded that the condition of high LET(60 keV/μm） had obvious mutagenic effects than that of low LET(40 keV/μm）.
2009, 26(2): 172-176.
doi: 10.11804/NuclPhysRev.26.02.172
Abstract:
MicroRNAs(miRNAs) are one kind of small noncoding RNAs of 19—24 nucleotides that transcriptionally regulate the expression of target genes by binding to their mRNA and thus play a central role in gene regulation in a wide arrange of biological processes. In this paper， we reviewed the clone and identification of novel miRNAs， summarized recent work on novel human miRNA recognization， and proposed a potentially feasible way to discover more human miRNAs.
MicroRNAs(miRNAs) are one kind of small noncoding RNAs of 19—24 nucleotides that transcriptionally regulate the expression of target genes by binding to their mRNA and thus play a central role in gene regulation in a wide arrange of biological processes. In this paper， we reviewed the clone and identification of novel miRNAs， summarized recent work on novel human miRNA recognization， and proposed a potentially feasible way to discover more human miRNAs.
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