Advanced Search

2016 Vol. 33, No. 4

Nuclear Physics
Nuclear Structure Studies Based on the Lifetime Measurements of Excited States in Nuclei at the in-beam γ Terminal of HI-13 Tandem Accelerator
ZHENG Yun, WU Xiaoguangn, LI Guangsheng, LI Congbo, CHEN Qiming, ZHU Lihua, HE Chuangye, HAO Xin, WANG Lielin, YAO Shunhe, LIU Ying, LI Lihua, WANG Jinlong, ZHONG Jian, ZHOU Wenkui, DEN Litao, ZHU Baoji
2016, 33(4): 375-384. doi: 10.11804/NuclPhysRev.33.04.375
Abstract(1226) PDF (776KB)(239)
Abstract:
The significance and principle of lifetime measurements of excited states in nuclei are briefly described. By using the recoil-distance Doppler-shift method, the Doppler-shift attenuation method, and the fast-timing technique established at the in-beam γ terminal of HI-13 tandem accelerator, nuclear structure studies on topical subjects including chiral symmetries and magnetic rotation have been performed. Our experimental results indicate that 130Cs shows better chiral characteristics, however, the two candidate bands of 106Ag could not be a pair of chiral doublet bands. For magnetic rotation, the deduced B(M1) values deduced from the measured level lifetimes clearly demonstrate that the yrast positive-parity band in 106Ag and both the yrast positiveand negative-parity bands in 107Ag are magnetic rotation bands. In addition, our lifetime measurement data also provide valuable experimental evidences for the interpretation and understanding of the shape evolution, the shape coexistence, and the critical-point symmetries of shape phase transition in the different isotope chains.
Heavy-ion Fusion Probability and Nuclear Fission Rate in a Quantum Non-Ohmic Environment
ZHANG Jiaming, HAN Jie, BAO Jingdong
2016, 33(4): 385-391. doi: 10.11804/NuclPhysRev.33.04.385
Abstract(1356) PDF (432KB)(136)
Abstract:
Dynamics of heavy-ion fusion and nuclear fission system in a quantum non-Ohmic environment have been considered and a numerical simulation method to solve the corresponding c-number quantum generalized Langevin equation is proposed. The method of generating quantum colored noise with arbitrary correlation can be applied to generate noise of arbitrary non-Markov process. Calculating fusion probability of heavy nuclei with this method, the result has shown that the passing probability is enlarged (decreased) by the quantum fluctuation when the initial kinetic energy of the particle is less than (greater than) the critical initial kinetic energy. Steady passing probability of particle in non-Ohmic environment versus is nonmonotonic. Quantum fluctuation makes the maximum position of the curve drift towards right (left), when the initial kinetic energy of the particle is less than (greater than) the critical initial kinetic energy. Furthermore, nuclear fission rate is larger in super-Ohmic environment. Quantum fluctuation enlarges nuclear fission rate and makes the the maximum position of nuclear fission rate versus δ drift.
Progress of Theoretical Study on Dark Matter
LEE Xiguo
2016, 33(4): 392-408. doi: 10.11804/NuclPhysRev.33.04.392
Abstract(1541) PDF (566KB)(311)
Abstract:
A review of the evidence of the dark matter found in universe and the problems faced by the standard model. To address these issues as well as the possible relationship between the new physics beyond the standard model and dark matter, and given the selection condition of dark matter and possible candidates of the weakly-interacting massive particles (WIMPs). The correlation between the column surface density and the halo core radius of the dark matter halos of galaxies and cluster of galaxies is discussed, and the other models are compared. We find that the surface density within the halo characteristic radius r* is not an universal quantity; The new model (hidden dark matter)proposed in the study of dark matter is described. At last, the research progress of dark matter experiment in China is commented. At the end of 2016, the first batch of DAMPE data may be given;No significant excess events of WIMPS were found in the first stage of both the CDEX and PandaX experiments located in the China Jinping Underground Laboratory(CJPL). Look forward to their the next stage of these experiments in CJPL.
Scalar Meson f0(980) Photoproduction in γp→pf0(980) Reaction
ZHANG Yu, XIE Jujun, CHEN Xurong
2016, 33(4): 409-413. doi: 10.11804/NuclPhysRev.33.04.409
Abstract(1188) PDF (295KB)(157)
Abstract:
We study the scalar meson f0(980) in the γp→pf0(980) reaction within an effective Lagrangian approach. Based on previous studies, we calculate the differential cross sections of this reaction. We take two types of the propagators of vector mesons ρ and ω, one is the Regge form, the other one is the normal Feynman propagator. It is found that our theoretical results for the differential cross sections with the Feynman propagator are in agreement with the current experimental data. For the total cross sections, the results with the two types of propagator are much different. On the other hand, we predict the π+π- invariant mass distribution of the γp→pf0(980)→pπ+π- reaction. We find that the π+π- invariant mass distribution depends sensitively on the value of the coupling constant gf0KK. We hope that the future experiments can test our model calculation and give further constraints on the value of gf0KK and also the nature of f0(980).
On Correlation Functions of Two Particles at RHIC and LHC Energies
SI Ruifang, LIU Fuhu
2016, 33(4): 414-421. doi: 10.11804/NuclPhysRev.33.04.414
Abstract(1206) PDF (524KB)(128)
Abstract:
The multi-source thermal model is used in this paper to analyze the long-range azimuth correlation in deutron-gold (d+Au) collisions at center-of-mass energy per nucleon pair √sNN=200 GeV measured by the PHENIX Collaboration at the relativistic heavy ion collider (RHIC), and the short-range pseudorapidity correlation in high multiplicity event in proton-proton (p+p) collisions at center-of-mass energy √s=0.9, 2.36, 7 TeV measured by the CMS Collaboration at the large hadron collider (LHC). The modeling results are in approximately agreement with the experimental data in error ranges. Four parameters are used in the analysis of long-range azimuth correlation, which show that the parameters describe the change trend of ridge structure. The ridge structure is related to the collective effect, hydrodynamic flow effect, transverse momentum and signal of particle pair, and so forth. Three parameters are used in the analysis of the short-range pseudorapidity correlation in high multiplicity event in small system, which show that the parameters σ and c3 are related to collision energy. Large collision energy results in strong correlation due to close distance between particles.
Multiplicity Correlation of Produced Particles in 12C Induced Nuclear Emulsion Reactions at 290 AMeV
YANG Wenjin, ZHENG Suhua, GUO Guifang, ZHANG Donghai
2016, 33(4): 422-427. doi: 10.11804/NuclPhysRev.33.04.422
Abstract:
We have investigated the multiplicity correlation of particles produced in 12C-emulsion interactions at 290 AMeV. It is found that there is a strong correlation between black track particle, grey track particle and heavily ionized track particle, and finally black track particles and heavily ionized track particles tend to saturation, which is the same as the experimental results observed at high energies. The multiplicity correlation between shower particle and other particles is weaker, which is different from the experimental results observed at high energies. This discriminating character can be explained by the lower energy of projectile. The productivity of shower particle is lower at intermediate energies compared to that at high energies. The forward-backward averaged multiplicity of black track particle and grey track particle increases with the increasing target size.
Accelerator
Design and Research of Merging Experiment Based on HIAF SRing
SHEN Guodong, YANG Jiancheng, WU Bo, WANG Kedong, XIA Jiawen, MAO Lijun, CHAI Weiping, SHI Jian, YIN Dayu, SHENG Lina
2016, 33(4): 428-432. doi: 10.11804/NuclPhysRev.33.04.428
Abstract(1086) PDF (415KB)(151)
Abstract:
Vacuum decay phenomenon of superheavy nucleus is a problem of fundamental interest to verify quantum electrodynamics. As the shell electrons interfere the detection of electron-positron pairs in the fixed target experiments in the past, it's still not corroborated. A new merging experiment scheme is proposed in this paper. The interference of shell electrons is eliminated by collisions of 238U92+ in free space. According to the luminosity theory and the analyses of crossing angle, Laslett tune shift and beam-beam interaction, an optimized peak luminosity of 1.9×1024 cm -2·s -1 is achieved. It meets the requirements of merging experiment essentially.
Study of the Characteristics of Extracting Low-energy Broad Electron Beam into Air
CHAI Wandong, XIAO Jiahao, ZHANG Zimin
2016, 33(4): 433-436. doi: 10.11804/NuclPhysRev.33.04.433
Abstract(1045) PDF (317KB)(152)
Abstract:
In order to investigate the characteristics of extracting low-energy electron beam from vacuum into air, EGS5 is used to simulate the energy loss, beam loss and spatial distribution uniformity at the irradiation position, which is 5~10 cm to titanium foil with different thickness. The simulation results show that the transmittance is directly related to the incent energy of low-energy electron. When the titanium foil thickness is 10 μm, the inhomogeneity about the energy beam spatial distribution is below 5% on the treatment plane 5 cm away from the titanium foil. And totally meet the industrial needs.
Multi-physics Field Coupling Analysis of RFQ Cavity for SSC-LINAC
WANG Jing, HUANG Jianlong, ZHANG Xiaoqi, HE Yuan, YANG Yaqing, LU Yuanrong, ZHU Kun
2016, 33(4): 437-441. doi: 10.11804/NuclPhysRev.33.04.437
Abstract(1190) PDF (392KB)(186)
Abstract:
Heavy Ion Research Facility at Lanzhou(HIRFL) consists of SFC, SSC, CSRm and CSRe. A new linac injector, which will increase U34+ to 1 MeV/u, is designed for SSC to increase the beam intensity to ten times higher. The new injector, whose frequency is 53.667 MHz, is composed by a RFQ (Radio Frequency Quadrupole) cavity and four DTL(Drift Tube Linac) cavities. The RFQ cavity, whose RF power is 30 kW, is operated at CW(continuous wave) mode. The heat produced by HF (high frequency) electromagnetic will cause deformation of RFQ structure, lead to the resonant frequency shift, and reduce the focusing efficiency of the cavity. An efficient cooling system is necessary to ensure that the RFQ cavity can stably be operated at the nominal frequency. A detailed multi-physics field coupling analysis of RFQ has been finished with 3D finite elements software ANSYS. The result of the analysis shows that the water cooling system can cool the RFQ cavity fully and keep the frequency drift be in a acceptable level.
Nuclear Technology
A MCP and Au-Si SBD TOF Detection System for Mass Measurement of Fission Fragments
MENG Qinghua, WANG Taofeng, ZHU Liping, WANG Liming, HAN Hongyin
2016, 33(4): 442-448. doi: 10.11804/NuclPhysRev.33.04.442
Abstract(1455) PDF (458KB)(124)
Abstract:
In order to separate the mass number of fragments in the fission reactions, it is essential to develop a good time-of-flight (TOF) method. The purpose of this article is to set up a TOF detector system including a microchannel plate (MCP) and a Au-Si surface-barrier detector (SBD). The TOF system shows a detection efficiency of 39% for α-particles released from 241Am and 98% for fragments in the spontaneous fission of 252Cf. The experimental results show that the time resolutions of (224:1±6:1) ps for the heavy fragments (Ek=78 MeV, AH=138~148 u) and (154:5±5:8) ps for the light fragments (Ek=102 MeV, AL=101~111 u) can be obtained.
Prototype Front End Electronics of T0 Detector in the External Experiment of CSR in HIRFL
XIA Pinzheng, ZHAO Lei, DENG Peipei, DONG Ruoshi, LIU Shubin, AN Qi
2016, 33(4): 449-454. doi: 10.11804/NuclPhysRev.33.04.449
Abstract(1316) PDF (663KB)(202)
Abstract:
A prototype front end electronics (FEE) module is designed for the T0 detector in the External Experiment in CSR (Cooling Storage Ring) of HIRFL (Heavy Ion Research Facility in Lanzhou). Based on the Time-Over-Threshold method and NINO ASIC, a total of 6 channels are integrated in the module, and both high precision leading edge discrimination and Charge-to-Time Conversion can be achieved, which satisfies the readout requirement of MRPC (Multi-gap Resistive Plate Chamber). A series of tests were also conducted in the laboratory, including time precision tests with different thresholds and output pulse width tests with different input signal amplitudes. Test results indicate that this prototype module functions well, and the time precision is better than 20 ps in the dynamic range from 100 fC to 2 pC, which is beyond application requirement. Through this work, preparation is made for the future readout system design.
Study for the Energy Calibration of the Multi-Layer CsI(Tl) Telescope at ETF in HIRFL-CSR
YAN Duo, YUE Ke, SUN Zhiyu, WANG Shitao, YU Yuhong, ZHANG Xueheng, TANG Shuwen, FANG Fang, CHEN Junling, ZHOU Yong, SUN Yu, WANG Zhaomin, SUN Yazhou
2016, 33(4): 455-460. doi: 10.11804/NuclPhysRev.33.04.455
Abstract(1461) PDF (395KB)(140)
Abstract:
A multi-layer CsI(Tl) telescope has been designed and constructed at External Target in Facility (ETF) terminal of the Cooling Storage Ring of Heavy Ion Research Facility in Lanzhou(HIRFL-CSR), and is used for identifying light charged particles. The detector consists of seven layers of CsI(Tl) crystals, and the signals of each crystal are read out by four photomultipliers at the corners. Since the response of the CsI(Tl) crystal to the heavy ions is non-linear and also depends on the species of the incident ions, the energy calibration method of the telescope must be carefully studied. With the help of the secondary beams selected by RIBLL2 in the energy ranges from 200 to 300 MeV/u, the telescope has been tested and the energy calibration method for the first-layer crystal together with the whole telescope has been investigated. In this energy region, the quench effect in the first-layer crystal can be neglected and a linear expression can be used to represent the relation between the light output and the energy deposition in the crystal. To the total light output of the telescope, an empirical formula is used for the energy calibration. The difference between the calculated results and the experiment data is globally less than 5%.
Beam Veri cation of the Large Dynamic Range Readout Design of DAMPE-PSD
ZHOU Yong, YU Yuhong, SUN Zhiyu, ZHANG Yongjie, FANG Fang, CHEN Junling, HU Bitao
2016, 33(4): 461-465. doi: 10.11804/NuclPhysRev.33.04.461
Abstract(1355) PDF (418KB)(141)
Abstract:
The Plastic Scintillator Detector (PSD) of DArk Matter Particle Explorer (DAMPE) aims for high energy e/γ identification and charge measurement for cosmic-ray ions from Z=1~20. It adopts photomultiplier tube as the readout device and extracts signals from both dynode5 and dynode8 to enlarge the readout dynamic range. A beam test on a PSD detector unit based this design has been carried out at the External Target Facility (ETF) terminal of the Cooling Storage Ring of Heavy Ion Research Facility in Lanzhou (HIRFL-CSR). The detector response to light nuclei (Z≤8) at the medium energy scale was extracted and the attenuation length was proved to be irrelevant with the impinging nuclei species. By extrapolating the result to heavy nuclei at the high energy scale and taking into account light attenuation, energy fluctuation and imping angle, the dynamic range of the output signal of PSD detector unit was estimated. The range is well within the linear range of the front-end electronics of PSD, thus verifies the large dynamic range readout design of PSD.
Research and Development of a Neutron Multi-sphere Spectrometer
FU Xin, LI Zongqiang, XU Junkui, LI Wuyuan, SU Youwu, MAO wang, YAN Weiwei, XU Chong, PANG Chengguo
2016, 33(4): 466-470. doi: 10.11804/NuclPhysRev.33.04.466
Abstract(1439) PDF (476KB)(186)
Abstract:
Neutron response of Bonner spheres which include pure polyethylene and polyethylene with auxiliary material was calculated with Monte Carlo code MCNPx, the calculated response was used as the input le of U-M-G code for neutronspectrum unfolding. A special screening of ampli cation integrated circuits was developed, which can provides high voltage 900 V working for the SP9 tube, the screening threshold is set to 0.5 V and total magni cation is 200. Neutron energy spectrum of a Pu-Be source were measured with the developed Bonner spheres spectrometer,good agreement was found in the measured result of the spectrum datasolutionand the real spectrum, which indicated that the multi-sphere spectrometer was reliable in the neutron measurement at energy region of Pu-Be neutron source.
Cross Discipline
Microbeam Application in Radiation Biology
GUO Na, DU Guanghua, LIU Wenjing, GUO Jinlong, WU Ruqun, CHEN Hao
2016, 33(4): 471-480. doi: 10.11804/NuclPhysRev.33.04.471
Abstract:
The microbeam facility can provide micrometer scale localized and predefined ionizing radiation in the life science study, and the microbeam techniques play a unique role in determining the target substances of ionizing radiation, as well as in the study of radiation sensitivity, mechanisms of radiation damage response and repair. This paper summarizes the technical developments of biological microbeam facilities and their applications in the studies of low-dose radiation effect, bystander effect and cellular signaling. This paper also introduces the recent developments at the heavy-ion microbeam facility in the Institute of Modern Physics (IMP), which can provide heavy ion microbeam irradiation with energy of 7~80 MeV/u and LET of 30~3000 keV/μm. The facility can perform radiobiological irradiation and online investigation in living cells and mice, including bystander effect study, sleeping system influence after irradiation to mice hypothalamus and the recruitment dynamics of XRCC1 protein.
BTG1 and Its Related Pathways in Cellular Response to X-ray and Carbon Ion Radiation
TIAN Ning, LI He, JIN Liangliang, HUA Junrui, MA Yingchun, HE Jinpeng, WU Xin, WANG Jufang
2016, 33(4): 481-487. doi: 10.11804/NuclPhysRev.33.04.481
Abstract(1078) PDF (461KB)(104)
Abstract:
BTG1, an important anti-proliferative gene, plays critical roles in cellular response to stresses, including ionizing radiation (IR). However, the long term expression of BTG1 induced by IR and its upstream/downstream signal pathways have not been elucidated clearly until now. The qRT-PCR results showed that the expression level of BTG1 in 786-O cells was rapidly elevated by IR in a short time, and then decreased slowly. In addition, upregulation or downregulation by transfection of BTG1 overexpression vector or siRNA could significantly affect the carbon ion radiation-induced genomic instability. Further study indicated that IRinduced BTG1 expression may be regulated by NF-B-mediated activation of SKA2 indirectly; On the other hand, expression of BTG1 may cause epigenetic changes by activating PRMT1, and subsequently influence the genomic stability, cell cycle regulation and apoptosis.
Study on Low-cadmium Rice Mutants Induced by 12C6+ Ion Beam
LIN Yuanyuan, CHEN Huiru, LIU Binmei, YE Yafeng, WU Yuejin
2016, 33(4): 488-493. doi: 10.11804/NuclPhysRev.33.04.488
Abstract(1238) PDF (320KB)(142)
Abstract:
Screening low-cadmium rice cultivar is the most directly and effective way to control cadmium content in rice grain. We screened low-cadmium rice mutant of M2 generation exposed in different Cd concentration (the pool contaminated with 19.8 mg Cd·kg-1 and the paddy field contaminated with 2.721 mg Cd·kg-1) from rice mutants(9311, Oryza sativa L) induced by 12C6+ ion beam, and explored the mutation rate of 12C6+ ion beam irradiation and the screening efficiency of different Cd concentration exposed, all of the detections were carried out by Graphite Furnace Atomic Absorption Spectrum(GFAAS). The results showed that the mutation rate is 3:398%±0:009(P<0:05) and high Cd concentration exposed has more efficiency in screening low-Cd rice mutant. Correlation analysis show significant correlation of Cd in rice grain between M2 and M3 generations, r=0:8210(P<0:01); We obtained 23 mutant strains with significant Cd concentration difference and they had a great genetic stability. Among them, three strains' Cd concentrations were lower than the national standard (0.2 mg·kg-1). They can used for further study on cultivating new rice varieties of low Cd accumulation in rice gain.
Research on Contemporary Damage Effects of Carbon Ion Beams with Different LET Irradiation on Dry Seeds of Arabidopsis thaliana
CHEN Yuze, DU Yan, YU Lixia, LUO Shanwei, FENG Hui, MU Jinhu, SI Huaijun, LI Wenjian, ZHOU Libin
2016, 33(4): 494-499. doi: 10.11804/NuclPhysRev.33.04.494
Abstract(1086) PDF (368KB)(129)
Abstract:
Aimed to study the biological effects of carbon ion beams with different linear energy transfer (LET) values provided by Heavy Ion Research Facility in Lanzhou (HIRFL), dry seeds of Arabidopsis thaliana (Columbia-WT) were irradiated and a series of biological effects of postembryonic development, such as survival rate, primary root length, hypocotyls length and number of seeds per silique, were investigated. The results showed that, under the radiation condition of the same LET value, the survival rate, root length, hypocotyls length and number of seeds per silique were decreased with the increasing dose. In addition, under the radiation conditions with different LET values, but same dose, the extent of the decline of the survival rate, root length, hypocotyls length and number of seeds per silique were reinforced with the increasing LET. It was also found that high LET radiations inhibited the subsequent growth and development of Arabidopsis thaliana severely. In brief, it was suggested that the optimum dose of carbon ion beam with 50 keV/μm value on Arabidopsis thaliana dry seeds was 200 Gy. This research complemented the preliminary theoretical foundation for the comparative study of the highest mutation efficiency of carbon ion beam irradiations at IMP, CAS(Institute of Modern Physics, Chinese Academy of Sciences).
Combining Logistic Regression and Markov Chain Monte-Carlo Describe the Relationship between Exposure to a Given Dose of Radiation and its Effect on Clostridium tyrobutyricum Strains
ZHOU Xiang, JIANG Tingting, XU Dan, YANG Zhen, LIANG Jianping, WANG Liang
2016, 33(4): 500-505. doi: 10.11804/NuclPhysRev.33.04.500
Abstract(1193) PDF (440KB)(199)
Abstract:
Using the Markov Chain Monte-Carlo method to estimate the parameters in the Logistic regression model, we constructed a non-periodic irreducible Markov Chain with the posterior distribution of the parameters as stationary distribution, and then used the sample points extracted from the stationary distribution to calculate the Monte-Carlo integral. The above theoretical method can solve the difficult problem of classical logistic regression modeling because of the existence and limitation of the experimental sample data and the multicollinearity. In the classical regression setup with a continuous response, the predicted values can range over all real numbers. Therefore, a different modelling technique is needed. In this work, the results describe in detail a previously unknown lethality trend following 12C6+ heavy-ion irradiation of Clostridium tyrobutyricum. By Markov Chain Monte-Carlo can calculate the model fit for a randomly selected subset of the chain and calculate the predictive envelope of the model. The grey areas in the plot correspond to 50%, 90%, 95%, and 99% posterior regions. More importantly, although this study focused on the use of the method in heavy-ion irradiation of microbial, its results are broadly applicable.
Velocity Map Imaging Spectrometer for Studying the Atomic Cluster Thermodynamics
ZHANG Xujie, SHI Fudong, QIAN Dongbin, ZHANG Dacheng, ZHU Xiaolong, YANG Jie, LI Xinzhong, MA Xinwen
2016, 33(4): 506-512. doi: 10.11804/NuclPhysRev.33.04.506
Abstract:
Excitation temperature of fragmenting atomic clusters can been extracted from the initial kinetic energies of ionic products. To improve the accuracy of the temperature measurements, we have designed an ionic velocity map imaging spectrometer with high kinetic energy resolution. Firstly, based on the simulations using Simion8.0 software, the high resolution is obtained by adjusting the structure of the electrostatic lenses and collimation of molecular beam. According to theoretical analysis, it is proved that the spectrometer has a well defined kinetic energy resolution. Then, we have studied the delay ionization processes of C60 induced by nanosecond laser. A series of narrowed two-dimensional time-sliced velocity images of the C60+ with increasing the delayed time were recorded. Analysis revealed that Coulomb force between C60+ clusters in same laser shots will broadening the transverse distribution of 2D image. Considering the influence of Coulomb force on initial kinetic energy of C60+ clusters, the high resolution has been proved by analysing the negative relationship between Coulomb force and delayed time. It indicates that the establishment of the spectrometer builds up a good basis for next experiments on the studies for molecular thermodynamics in atomic clusters.
Orientation Effect in Transfer Ionization Processes of 50 keV/u Ne8+ Impact on CO
GAO Yong, ZHANG Shaofeng, ZHU Xiaolong, YAN Shuncheng, FENG Wentian, ZHANG Ruitian, GUO Dalong, LI Bin, WANG Hanbing, HUANG Zhongkui, HAI Bang, ZHANG Min, MA Xinwen
2016, 33(4): 513-517. doi: 10.11804/NuclPhysRev.33.04.513
Abstract(1063) PDF (350KB)(123)
Abstract:
The fragmentations of CO2+ are studied in transfer ionization processes of 50 keV/u Ne8+ impact on CO with reaction microscopes. The 3D momenta of C+ and O+ were measured, and the kinetic energy release (KER) of dissociative(CO2+) was obtained accordingly. The peaks resulted from the metastable states of 1Σ+, 1Π and 3Π, of 3Σ+, and of 1Σ(II)+ are identified in KER spectrum. Meanwhile, the repulsive state of 3Σ- was also observed, which forms a broad peak lying between the peaks of 3Σ+ and 1Σ(II)+. In the CO2+ dissociations from 3Σ- state, the orientation effect of CO molecular axis was observed for the first time.
Nuclear Energy and Nuclear Data
Measurements of Decay Data of 173Lu and 174gLu
SHI Quanlin, BAI Tao, LIU Jie, SHANG Jianbo, ZHANG Xiaolin, DAI Yihua
2016, 33(4): 518-523. doi: 10.11804/NuclPhysRev.33.04.518
Abstract(1364) PDF (337KB)(142)
Abstract:
175Lu(n,2n)174m,gLu(n,2n)173Lu are important neutron reactions to monitor the high energy neutron fluxes and the residual nuclei, 174m,gLu and 173Lu, are usually measured by a HPGe spectrometer conveniently so that the decay data such as half lives and gamma-ray emission probabilities of 174m,gLu and 173Lu must be accurate. There are evaluated decay data only in ENDF/B 7.1 and JEFF 3.1.1 among the major evaluated nuclear data libraries, where the most data are almost same besides the gamma-ray emission probabilities of 173Lu are higher in ENDF/B 7.1 than that in JEFF 3.1.1. Yb metal as a target was irradiated by 20 MeV proton beams on a tandem accelerator in CIAE to produce 174m,gLu and 173Lu, and 176Lu isotopic dilution methods based upon a laser resonance ionization mass spectrometer (LRIMS) and a thermal surface ionization mass spectrometer (TIMS) were employed to determine the numbers of nuclides of 174Lu and 173Lu in a solution containing the irradiated target. Several radioactive sources made from the solution had been measured by a HPGe detector during the past 7 years and the peak intensities of the characteristic gamma-rays from 174gLu and 173Lu were analyzed to determine the half lives and gamma-ray emission probabilities. According to the measurements, the half life of 173Lu is 1.45 a, which is about 6.1% longer than the evaluated 1.37 a, and the gamma-ray emission probabilities of 173Lu is also different from the evaluated data, especially the emission probability of 636.1 keV gamma-ray of 173Lu is 7% higher than the value in ENDF/B 7.1. The half life of 174gLu is 3.37 a, about 1.8% longer than the evaluated 3.31 a, and the emission probabilities of 76.5 keV and 1 241.8 keV gamma-rays of 174Lu are 1.87% and 12.8% lower than the evaluated data in ENDF/B 7.1, respectively.