In-beam γ-ray Spectroscopy of Level Structure in ^134Ba

Excited states of ^134Ba, populated via the heavy-ion induced ^128Te(^10B, 1p3n)134Ba reaction at 46 MeV beam energy, have been studied to medium and high spins by in-beam γ-ray spectroscopy techniques. The experiment was performed at the tandem accelerator laboratory in the University of Tsukuba, Japan. The target is an isotopically enriched ^128Te metallic foil of 2.3mg/cm^2 thickness with a 3mg/cm^2 gold backing. Nine anti-Compton HPGe detectors were employed for the measurements of γ-γ-t coincidences. The level scheme of ^134Ba, deduced from this study, was shown in Fig.1.     

Commissioning of electron cooling in CSRe

The 400 MeV/u 12C6＋ ion beam was successfully cooled by the intensive electron beam near 1 A in CSRe.The momentum cooling time was estimated near 15 s.The cooling force was measured in the cases of difierent electron beam profiles,and the difierent angles between the ion beam and electron beam.The lifetime of the ion beam in CSRe was over 80 h.The dispersion in the cooling section was confirmed as positive close to zero.The beam sizes before cooling and after cooling were measured by the moving screen.The beam diameter after cooling was about 1 mm.The bunch length was measured with the help of the signals from the beam position monitor.The difiusion was studied in the absence of the electron beam.     

High-Spin States in Odd-Odd ^140Pr Nucleus

High-spin level structure of doubly odd nucleus ^140Pr has been investigated via the ^130Te(^14N,4n)^140Pr reaction at beam energies from 55 to 65 MeV. Measurements of γ-ray excitation functions, γ-ray singles and γ-γ-t coincidences were performed with twelve BGO(AC)HPGe detectors. The level scheme of ^140Pr, including 27 new levels and 42 new γ rays, has been established for the first time. The level structure is compared with those in the neighbouring odd-odd nuclei, and interpreted qualitatively.     

Simulation and analysis of 13N+p elastic resonance scattering

The ^13 N＋p elastic resonance scattering has been studied at the secondary radioactive beam facility of CIAE in inverse kinematics via a thick-target method. The excitation function for the ^13N（p,p） scattering was obtained in the energy interval of Ecru ≈0.5-3.2 MeV with a ^13 N secondary beam of （47.8±1.5） MeV. Careful analysis of the secondary beam components and extensive Monte-Carlo simulations enable the resolution of the experimental proton spectra. The resonance parameters for five low-lying levels in ^14 O were deduced by Rmatrix fitting calculations with MULTI7 and SAMMY-M6-BETA. The present results show general agreement with those from a recent similar work, and thus confirm the observation of a new 0^- level at 5.7 MeV in 140 with an improved width of 400（45） keV.     

Largely Deformed Dinuclear System Formed in ^19F ＋^27Al Dissipative Collision

Excitation functions are measured for different charge products of the ^19F＋^27AI reaction in the laboratory energy range 110.25-118.75MeV in steps of 250keV at θlab=57°,31° and -29°. The coherence rotation angular velocities of the intermediate dinuclear systems formed in the reaction are extracted from the cross section energy autocorrelation functions. Compared the angular velocity extracted from the experimental data with the ones deduced from the sticking limit, it is indicated that a larger deformation of the intermediate dinuclear system exists.     

Search for the Halo Effect in the ^1H（^6He,^6Li）n Reaction

The angular distributions of the charge exchange reaction ^1H(^6He,^6Li)n were measured in reverse kinematics with a secondary ^6He beam at the energy of 4.17 A MeV.The data were analysed in the context of a microscopic calculation.It is shown that both the ground state of ^6He and the second excited state of ^6Li(3.563MeV,0^ ) have a halo structure.     

Negative Parity Bands and Signature Splitting Inversion in ^80Rb

High spin states in ^80Rb were studied via the ^65Cu ^19F, ^66Zn ^180 and ^68Zn ^160 reactions. The 75-MeV ^19F,76-MeV ^180 and 80-MeV ^160 beams were provided by the CIAE HI-13 Tandem accelerator and the JAERI Tandem accelerator. The prompt γ-γ coincidence and the directional correlation from oriented nuclei (DCO)were measured by the detector arrays in CIAE and JAERI. Twenty-three new states with 28 new transitionshave been assigned to ^80Rb. The states were observed up to spins of 20^ and 22^- in the α= 0 branch for thepositive and negative parity yrast bands respectively. The negative parity non-yrast bands were significantlyextended up to spins of 22^- and 15^-. The band crossings with frequencies 0.51 MeV and 0.61 MeV in the α= 0cascade were observed for the first time. The signature splitting was observed in both negative parity bands. Thesignature inversions at spins of about 7h and 15h were observed.     

Study of 1／2 [660] （π^i13／2） Rotation Band in ^179Au

High-spin states in ^179Au have been studied experimentally by using the ^149Sm(^35C1, 5n) reaction at beam energies of 164,~180 MeV. The ^35C1 beam was provided by the tandem accelerator at the Japan Atomic En-ergy Research Institute (JAERI). The target is an isotopically enriched ^149Sm metallic foil of 1.5 mg/cm^2 thickness with a 5.0 mg/cm^2 Pb backing. Measurements of γ-ray excitation functions, X-γ coincidences and γ-γ-t coincidences were performed with 13 HPGe‘s with BGO anti-Compton shields and three LOAX detectors.     

Structure of the Semi—decoupled π 1／2[411] Band in Odd Proton Nucleus ^169Ta

High spin states of the odd proton-nucleus ^169Ta have been populated in the reaction ^155Gd(^19F,5n) with beam energies of 97MeV,Rotational band based on d3/2 proton 1/2[411]Nilsson state has been pushed up to 39/2^ in the α=1/2 decay sequence.Its signature partner,the α=-1/2 decay sequence with four link transitions has been established and 1/2[411] band in ^169Ta was reassigned to be a semi-decoupled band.The systematics of the signature splitting in the K=1/2 bands in the rear-earth region and the accidental degeneracy conclusion given by the angular projection shell model were discussed.     

New Astrophysical Reaction Rates for ^18F（P,α）^15O and ^18F（P,γ）^19Ne

The rates of the thermonuclear ^18F(P,α)^15O and ^18F(P,γ)^19Ne reactions in hot astrophysical environments are needed to understand gamma-ray emission from nova explosions. The rates for these reactions have been uncertain due to discrepancies in recent measurements, as well as to a lack of a comprehensive examination of the available structure information in the compound nucleus ^19Ne. We have examined the latest experimental measurements with radioactive and stable beams, and made estimates of the unmeasured ^19Ne nuclear level parameters, to generate new rates with uncertainties for these reactions. The rates are expressed as numerical values over the temperature range relevant for stellar explosions, as well as analytical expressions as functions of temperature in a format suitable for use in astrophysical simulations. Comparisons with the previous rate calculations are carried out, and the astrophysical implications are briefly discussed.     

High-spin States in Odd-odd ^140Pr Nucleus

The high-spin level structures of doubly odd nucleus ^140Pr have been investigated by means of the ^130Te(^14N,4n)^140Pr reaction. The ^14N beam was obtained from the HI-13 tandem accelerator of China Institute of Atomic Energy, Beijing. The target is an enriched ^130Te metallic foil of 1.67mg/cm^2 thickness with a 10.37mg/cm^2 Pb backing. Measurements of γ-ray singles, γ-γ-t coincidences and γ-ray excitation function were performed with twelve BGO(AC)HPGe detectors. Based on detailed analysis of γ-γ coincidence relationships, γ-ray     

No Anomaly of the B（E2） Value Around the Backbend in ^130Ce

The lifetime measurements of the high-spin states in the yrast band of ^130Ce have been performed using the Doppler shift attenuation method in conjunction with the reaction ^116Sn(^16O,2n)^130Ce at a projectile energy of 73MeV.The reduced transition probabilities B(E2) deduced from these measurements show a great reduction in the vicinity of the backbending region.The previously reported anomalously high B(E2) value was not observed in the present experiment.This result is in agreement with theoretical prediction based on a realistic nucleon-nucleon interaction.     

Optical Potential Parameters for Halo Nucleus System ^6He＋^12C from Transfer Reaction ^11B（^7Li, ^6He）^12C

The optical potential parameters for the halo nucleus system ^6He＋^12C are extracted from fits to the measured angular distributions of ^11B（^7Li, ^6He）12C reaction at energies of 18.3 and 28.3MeV with distorted-wave Born approximation analysis. The characters of the obtained optical potentiM parameters are basically consistent with the results extracted from the fits to the elastic-scattering angular distributions in the literature.     

Decay of the 67-μs Isomer in ^142Pm

Excited states in ^142pm are investigated via the ^12sTe(^19F, 5n)^142pm reaction at beam energies from 75 to 95 MeV by using techniques of in-beam γ-ray spectroscopy. Measurements of γ-ray excitation function, X-γ and γ-γ-t coincidences are performed with 10 BGO(AC)HPGe detectors. Decay of the previously known 67-μs isomer in     

Modeling process of the neutral beam re-ionization loss

The basic process of re-ionization loss was studied.In the drift duct there are three processes leading to re-ionization loss：the collision of neutral beam particles with the molecules of background gas,similar collisions with released molecules from the inner wall of the drift duct and the ferret-collisions among particles with different energy of the neutral beam.Mathematical models have been developed and taking EAST-NBI parameters as an example,the re-ionization loss was obtained within these models.The result indicated that in the early stage of the neutral beam injector operation the released gas was quite abundant.The amount of re-ionization loss owing to the released gas can be as high as 60%.In the case of a long-time operation of the neutral beam injector,the total re-ionization loss decreases from 13.7% to 5.7%.Then the reionization loss originating mainly from the collisions between particles of the neutral beam and the background molecules is dominant,covering about 92% of the total re-ionization loss.The drift duct pressure was the decisive factor for neutral beam re-ionization loss.     

Asymptotic Normalization Coefficient of ^27P → ^26Si ＋ p and Radius of ^27P Halo

The asymptotic normalization coefficient of the virtual decay ^27P → ^26Si ＋ p is extracted to be 1840 ± 240 fm^-1 from the peripheral ^26Mg（d,p）^27Mg reaction using charge symmetry of mirror pair, for the first time. It is then used to derive the rms radius of the valence proton in the ground state of ^27P. We obtain the rms radius （γ^2〉^1/2 = 4.57 ± 0.36 fm, significantly larger than the matter radius of ^27P. The probability of the valence proton outside the matter radius of ^27P is found to be 73%. The present work supports the conclusion that the ^27p ground state has a proton halo structure.     

Neutron dose measurement in carbon ion radiation therapy at HIRFL （IMP）

For radiation protection purposes, the neutron dose in carbon ion radiation therapy at the HIRFL （Heavy Ion Research Facility in Lanzhou） was investigated. The neutron dose from primary ^12C ions with a specific energy of 100 MeV/u delivered from SSC was roughly measured with a standard Anderson-Broun rem-meter using a polyethylene target at various distances. The result shows that a maximum neutron dose contribution of 19 mSv in a typically surface tumor treatment was obtained, which is less than 1% of the planed heavy ion dose and is in reasonable agreement with other reports. Also the T-ray dose was measured in this experiment using a thermo luminescent detector.     

Measurement of Angular Distribution for the ^8Li（p,d）^7Li Reaction

The ^8Li（p, d）^7 Li reaction plays an important role in the inhomogeneous Big Bang nucleosynthesis and in the seed-nuclide production phase for the r-process. For the first time, its angular distribution at backward angles was measured in inverse kinematics at Ec.m.=4.0 MeV by using an ^8Li secondary beam. The result of measurement includes the contributions of ^8Li（p, d0）^7Li and ^8Li（p, d1）^7Li^＊. The ^8Li（p, d0）^7Li component is estimated to be 40%-58% in the mixture angular distribution by analysing the measured result.     

Synthesis of ^197Os

An isotope at a particular region in the chart of nuclides can be produced with a certain type ot nuclear reactions and experimental approaches. The (n, 2p) reaction is one of useful techniques for producing heavy neutron-rich nuclei in region not accessible from fission. In the present experiment, ^197Os was produced by using ^198Pt(n, 2p)^197Os reaction.     

Possible Experimental Evidence of a Moderate Proton Halo in ^29S

The total reaction cross sections (TRCSs) of^29S ^28Si have been measured at intermediate energies. An obvious enhancement in TRCS of ^29S is observed as compared with its neighbouring nuclei. The TRCSs of ^29S ^28Si arecal culated with the modified Glauber theory in the optical limit and few-body approaches. The different factor d as a possible measure of halo appearance is deduced from the experimental and theoretical data. It is well accepted that ^27p is a proton halo nucleus. Although not as anomalous as ^27p, the different factor d of ^29S is obviously larger than that of its neighbouring isotones of N = 13. This result indicates that a moderate proton halo may exist in ~9S nucleus. We calculate the total reaction cross sections for ~9S with the modified Glaubertheory as a function of incident energy and compare the results with those for 2rSi which is a core nucleus 0f29S.The measured TRCSs of 27Si4-2SSi can be described to be satisfactory by the modified Glauber theory of theoptical limit approach. Although a diffused nuclear density distribution is used, the theories still inadequatelypredict the experimental TRCSs of 29S4-2SSi, which further indicates the possibility of proton halo in 29S.