Search

The SHELS velocity filter originated upon reconstruction of the VASSILISSA electrostatic separator used for investigations of heavy nuclei produced in complete fusion reactions. The goals of this modernization were to increase the transmission of products of asymmetric reactions and to extend the region of reactions to be investigated up to symmetric combinations. The first tests of the set-up were performed with the beams of accelerated 22 Ne, 40 Ar, 48 Ca, and 50 Ti ions. [ABSTRACT FROM AUTHOR]

We report here a determination of the asymptotic normalization coefficient of the valence neutron in 8Li from a measurement of the angular distribution of the 7Li(8Li,7Li)8Li reaction at 11 MeV. Using isospin symmetry the 8B ANC has also been calculated and used to infer a value for S17(0) of 20.2 ± 4.4 eV b. [ABSTRACT FROM AUTHOR]

The 40Ca(α,γ)44Ti reaction is believed to be the main production channel for the radioactive nuclide 44Ti in core-collapse Supernovae. Radiation from decaying 44Ti has been observed so far for two supernova remnants, and precise knowledge of the 44Ti production rate may help improve supernova models. The 40Ca(α,γ)44Ti astrophysical reaction rate is determined by a number of narrow resonances. Here, the resonance triplet at Eα = 4497,4510, and 4523 keV is studied both by activation, using an underground laboratory for the γ counting, and by in-beam γ spectrometry. The target properties are determined by elastic recoil detection analysis and by nuclear reactions. The strengths of the three resonances are determined to be ωγ = (0.92 ± 0.20), (6.2 ± 0.5), and (1.32 ±0.24) eV, respectively, a factor of 2 more precise than before. The strengths of this resonance triplet may be used in future works as a point of reference. In addition, the present new data directly affect the astrophysical reaction rate at relatively high temperatures (above 3.5 GK). [ABSTRACT FROM AUTHOR]

Given the importance of Gamow-Teller (GT) transitions in nuclear structure and astrophysical nuclear processes, we have studied Tz = +3/2 → +1/2, GT transitions starting from the 47Ti nucleus in the (3He,t) charge-exchange reaction at 0° and at an intermediate incident energy of 140 MeV/nucleon. The experiments were carried out at the Research Center for Nuclear Physics (RCNP), Osaka, using the high-resolution facility with a high-dispersion beam line and the Grand-Raiden spectrometer. With an energy resolution of 20 keV, individual GT transitions were observed and GT strength was derived for each state populated up to an excitation energy (Ex) of 12.5 MeV. The GT strength was widely distributed from low excitation energy up to 12.5 MeV, where we had to stop the analysis because of the high level density. The distribution of the GT strengths was compared with the results of shell model calculations using the GXPF1 interaction. The calculations could reproduce the experimental GT distributions well. The GT transitions from the ground state of 47Ti and the M1 transitions from the isobaric analog state in 47V to the same low-lying states in 47V are analogous. It was found that the ratios of GT transition strengths to the ground state, the 0.088-MeV state, and the 0.146-MeV state are similar to the ratios of the strengths of the analogous M1 transitions from the isobaric analog state (IAS) to these states. The measured distribution of the GT strengths was also compared with those starting from the Tz = +3/2 nucleus 41K to the Tz = +1 /2 nucleus 41Ca. [ABSTRACT FROM AUTHOR]

Abstract: Resonance-parameter covariance matrix (RPCM) evaluations in the resolved resonance regionwere done at the Oak Ridge National Laboratory (ORNL) for the chromium isotopes, titanium isotopes, 19F, 58Ni, 60Ni, 35Cl, 37Cl, 39K, 41K, 55Mn, 233U, 235U, 238U, and 239Pu using the computer code SAMMY. The retroactive approach of the code SAMMY was used to generate the RPCMs for 233U. For 235U, the approach used for covariance generation was similar to the retroactive approach with the distinction that real experimental data were used as opposed to data generated from the resonance parameters. RPCMs for 238U and 239Pu were generated together with the resonance parameter evaluations. The RPCMs were then converted in the ENDF format using the FILE32 representation. Alternatively, for computer storage reasons, the FILE32 was converted in the FILE33 cross section covariance matrix (CSCM). Both representations were processed using the computer code PUFF-IV. This paper describes the procedures used to generate the RPCM and CSCM in the resonance region for ENDF/B-VII.1. The impact of data uncertainty in nuclear reactor benchmark calculations is also presented. [Copyright &y& Elsevier]

The relatively short-lived radionuclide 44Ti is of considerable importance for the interpretation of nucleosynthesis in core-collapse supernova environments. Production is predominantly through the 40Ca(α,γ)44Ti reaction, which has been studied in this work over the energy range Ecm = 2.73--4.18 MeV, via direct γ counting and the 4π-summing technique, utilizing a previously characterized 12 inch × 12 inch single Nal crystal. The inferred reaction rate is compared here to both current experimental measurements and theoretical model calculations [ABSTRACT FROM AUTHOR]

The mass distributions of the fission fragments were measured in reactions induced by 48Ti beams on 144,154Sm, 162Dy, 174Yb, 186W, 192Os, ,196Pt, 200Hg, and 208Pb targets at near-barrier energies. The systematic tendencies of the mass widths have been explored. For the reactions with the lighter or spherical target nuclei, the mass widths increase with increasing bombarding energy, a behavior expected for fusion-fission. For the heavier and statically deformed nuclei, the mass widths increase rapidly as energies fall close to and below the capture barriers. Well above the barrier energies, the mass widths and estimated minimum quasifission contributions increase smoothly with increasing fissility of the composite nucleus. The observed behavior is a complex function of the rissility. deformation, and energy with respect to the capture barrier. Comparisons with dynamical quasifission model calculations for these reactions will be a good test of models of fusion in heavy-element formation reactions. [ABSTRACT FROM AUTHOR]

The nuclear-physical properties of Ti (half-life 3.08 h, 85% β-decay, 15% electron capture, daughter isotope Sc) make it suitable for positron emission tomography. Ti can be produced at a small cyclotron in a high yield, 450 MBq μA h, using the Sc( p,n)Ti nuclear reaction on a natural scandium target. The excitation functions for the Sc( p,n)Ti reaction were calculated by ALICE/91, ALICE/ASH, and TALYS-1.2 codes and compared to the existing data. Deposition of ScO on a Cu substrate was carried out by two sedimentation methods for the production of Ti, and a simple method for radiochemical separation of radiotitanium was suggested. The targets were examined by SEM and subjected to thermal shock test. The optimal thicknesses of target was substantiated, and the production yield for the Sc( p,n)Ti reaction was calculated. [ABSTRACT FROM AUTHOR]

The reactions 48Ti+40Ca at 600, 450 and 300 MeV were employed at the Laboratori Nazionali di Legnaro (LNL) to investigate the charged particles and the Giant Dipole Resonance (GDR) decay of hot rotating 88Mo nuclei. Some preliminary results about Light Charged Particles (LCP) distribution in coincidence with Evaporation Residues (ER) and fusion-fission events selection are shown. [ABSTRACT FROM AUTHOR]

The role of the entrance channel in the formation of the reaction products is discussed. The excitation functions of evaporation residues for the 50Ti+249Cf and 54Cr+248Cm reactions are compared. [ABSTRACT FROM AUTHOR]

Abstract: Independent and cumulative production cross-sections for the natTi(p,x)48V, 43,44m,44g,46,47,48Sc nuclear processes are reported here, for the energy region of 4–38MeV by using a stacked-foil activation technique. Measured data were critically compared with the earlier reported values, and also with the theoretical data from the TALYS and ALICE-IPPE codes. The measured natTi(p,x)48V reaction is important for charged particle beam monitoring purposes, whereas the 43,44,47Sc radionuclide have various practical applications in nuclear medicine. [Copyright &y& Elsevier]

Abstract: Results are presented from a one-neutron knockout reaction at relativistic energies on 56Ti using the GSI FRS as a two-stage magnetic spectrometer and the Miniball array for gamma-ray detection. Inclusive and exclusive longitudinal momentum distributions and cross-sections were measured enabling the determination of the orbital angular momentum of the populated states. First-time observation of the 955(6) keV -hole state in 55Ti is reported. The measured data for the first time proves that the ground state of 55Ti is a state, in agreement with shell-model calculations using the GXPF1A interaction that predict a sizable gap in 54Ca. [Copyright &y& Elsevier]

Abstract: The excitation functions of proton induced reactions on Sc targets (100% 45Sc), leading to the formation isotopes 43K, 43Sc, 44mSc, 44gSc and 44Ti were studied by the stacked foil activation technique up to 37MeV. High-resolution gamma-spectrometry measurements were performed on an HPGe detector in order to determine the activity of the irradiated Sc2O3 pellets and Ti monitor foils. The reaction cross-sections were measured from their respective thresholds up to E p =36.4MeV and were compared with previous values reported in literature. Possible batch yields and optimal irradiation parameters for generator 44Ti –44gSc in high current accelerators are discussed. [Copyright &y& Elsevier]