58Co Reaction Research Articles

Determination of (n, charged particle) reaction cross sections for frt-relevant materials

Abstract Helium gas production cross sections for elemental nickel and molybdenum, deduced from the isotopic data, are reported. Cross sections for 58Ni (n,d) 57Co and 10B (n,t)2α reactions were measured. Excitation function of triton emission reaction on aluminium was determined via activation in diverse neutron fields and unfolding code calculations.

Precise measurement of cross sections for the reactions 59-Co(n, 2n)58-Co and 59-Co(n,p)59-Fe around 14 MeV

Abstract The cross sections for the reactions 59-Co(n,2n)58m+g-Co and 59-Co(n,p)59-Fe were measured at neutron energies of 13.5, 13.9, 14.5 and 14.8 MeV relative to the well-known cross sections for the reaction 27-A1(n,α)24-Na using the activation technique. To make the 59-Co(n,2n)58-Co reaction a reliable and handy fluence monitor for long-term 14 MeV neutron experiments, special emphasis was placed on accuracy. The (n,2n) isomeric cross section ratio was measured at the energy 13.9 MeV.

The gamma decay of g9/2and d5/2analogue resonances in57Co

An investigation of the gamma decay of the g9/2 and d5/2 analogue states in 57Co has been performed using the 56Fe(p,p' gamma ) and the 56Fe(p, gamma )57Co reactions. Excitation functions in the energy range Ep=3694-3855 keV reveal resonances at the energies Ep=3720, 3727, 3774 and 3793 keV. For the first two resonances their decay scheme along with angular distributions indicate that they are fragmented analogues of the Ex=2455 keV, Jpi =9/2+ parent state in 57Fe. The Ep=3774 and 3793 keV resonances are identified as the fragmented analogue resonances of the Ex=2506 keV, Jpi =5/2+ parent state in 57Fe. The Ex=2611 and 4586 keV states in 57Co are uniquely determined as 7/2- and 9/2+ respectively.

Proton beam monitoring via the Cu(p, x) 58Co, 63Cu(p, 2n) 62Zn and 65Cu(p, n) 65Zn reactions in copper

Cross sections for the Cu(p, x) 58Co, 63Cu(p, 2n) 62Zn and 65Cu(p, n) 65Zn reactions were measured in the energy region from 4 to 33 MeV. The excitation functions for 58Co, 62Zn and 65Zn were determined and compared with the published data. The experimental cross sections have been used as reference data for proton beam monitoring in the energy range of 13–33 MeV.

Neutron-Induced Reactions on58Ni

Using activation techniques, the excitation functions for the 58Ni(n,2n)57Ni and 58Ni(n,np + pn + d)57Co reactions were measured in the neutron energy range from 12.7 MeV, close to the (n,2n) thres...

Proton-hole states in 57Co studied with the 58Ni(d, 3He) 57Co reaction at 78 MeV

The 58Ni(d, 3He) 57Co reaction was measured at a bombarding energy of 78 MeV. Energy levels up to 7.0 MeV excitation energy in 57Co were studied. Angular distributions of the 3He particles, corresponding to transitions to the ground state and to 42 excited states in 57Co, were analyzed in the range of θ lab = 2.7° to 25°. Exact finite-range DWBA calculations were employed to extract l-values and spectroscopic factors. Shell-model calculations were carried out in an fp-shell model space. In addition, calculations of the energy levels in 57Co were performed in the SU(6) particle-vibration model (PTQM). Satisfactory agreement is observed between the experimental results and both theoretical predictions.

Investigation of the58Ni(n,p)58Co reaction at 18.5 MeV

The differential cross sections for the 58Ni(n,p)58Co reaction are measured at 18.5 MeV. The angular distribution for the possible transitions to the parent analogue states of the E1 GDR has been compared with DWBA calculations based on the Jensen-Steinwedel form factor. Agreement between the experimental data and the L=1 transitions have been obtained, including also an isotropic contribution. The M1 GDR transitions have been correlated with the 1+ analogue states in 58Ni. The proton emission 58Ni(n,p) cross section has been estimated.

Investigation of the 59Co(n, γ)60Co reaction with unpolarized and polarized neutrons

Abstract Capture of 24 keV neutrons and polarized as well as unpolarized thermal neutrons in 59 Co has been investigated. Of the 350 γ-rays observed 335 could be placed in a 60 Co level scheme containing 144 levels. The reaction Q -value amounts to 7491.92(8) keV. The χ 2 analysis of the circularly polarized γ-rays results in 31 unambiguous spin assignments for 60 Co levels. The fraction of the J = 4 − channel in the thermal capture was determined to be (80 ± 1)%. An average γ-ray multiplicity of 2.3 gammas per neutron capture was observed. The resulting level scheme is compared to shell-model predictions. Possible reaction mechanisms are discussed.

Energy levels of 56Co studied by the 58Ni( [formula omitted], α) 56Co reaction near 0°

Tensor analyzing powers, T 20, of outgoing α-particles in the 58Ni( d , α) 56Co reaction at detection angles near 0° have been measured for excited states in 56Co for beam energies of 6.75, 7.0, 7.5, 9.0 and 9.5 MeV. Thirty-seven spin-parity combinations for 56Co excited states have been deduced. Previous J π ambiguities for 11 of these states have been eliminated, and results in conflict with existing assignments for the levels at 3.235 and 3.378 MeV have been obtained. A search for 0 + states was carried out from angular distribution measurements at forward angles of the unpolarized (d, α) reaction. The combined results from this and previous experiments were found to be in reasonable agreement with calculated level schemes.

The indirect production of no-carrier-added 57Co via the 59Co(p,3n) 57Ni→ 57Co reaction

A method for the production of 57Co (271.65) for medical applications using metallic 59Co as a target, and the 59Co(p,3n) 57Ni→ 57Co reaction was explored. Excitation functions for proton-induced reactions in the 40- to 10-MeV energy region, as well as thick-target and cumulative yields for the directly-produced 57Ni (35.99h) and indirectly-produced 57Co were also measured and then compared to previously reported values. A radiochemical purification procedure based on anion-exchange chemistry is also reported. 57Co with >99.9% radionuclidic purity was obtained. The indirectly-produced 57Co yield in the 40- to 24-MeV energy region was measured as 2μCi/μAh.

Investigation of the reactions 58Ni(d, α) 56Co and 50Ti(d, α) 48Sc with vector and tensor polarized deuterons

Angular distributions of the cross section, and vector and tensor analyzing powers have been measured for the 58Ni(d, α) 56Co and 50Ti(d, α) 48Sc reactions at E d = 16 MeV. The L- and J-dependence of the vector and tensor analyzing powers allows J π assignments for some low-lying states in the final nuclei. Using optical potentials with matching geometry good DWBA descriptions of all observables could be achieved.

Cross sections and thermonuclear reaction rates for the 28Si(α, p)31P and 54Fe(α, p)57Co reactions

Absolute cross sections for the 28Si(α, p)31P and 54Fe(α, p)57Co reactions have been measured for laboratory bombarding energies over the range 5.52 ≤ Eα ≤ 12.00 MeV, using targets of approximately 4-keV thickness. Ground state reaction rates were then deduced from these cross sections and stellar rates were deduced by multiplying by the ratio of stellar-to-ground state rates obtained from statistical model calculations. Stellar rates for the reverse reactions have been determined and are fitted by a parametric equation for ease of interpolation. The experimental cross sections and rates have been compared with statistical model calculations and are in reasonable agreement for the 54Fe(α, p)57Co reaction but deviate by as much as a factor of three for the 28Si(α, p)31P reaction.

Observation of isospin mixing for the isobaric analog state in 56Co through the 56Fe(p, n) 56Co reaction

The reaction 56Fe(p, n) 56Co has been studied at E p = 17 MeV by employing the time-of-flight technique. Two prominent peaks observed at E x = 3.51 and 3.59 MeV are assigned to be J π = 0 + states from the angular distribution measurement, and interpreted as the splitting of the isobaric analog state into the nearby T <, 0 + state through the isospin-mixing Coulomb interaction. A shell-model calculation has been carried out to find such a 0 + state, which may yield a Coulomb matrix element 〈J = 0 2 + (T = 1)¦V coul ¦J = 0 3 +(T = 2, IAS)〉 of the order of 10 keV.

55Co]- and [ 64Cu]DTPA: New radiopharmaceuticals for quantitative tomocisternography

The diethylenetriaminepentaacetic acid (DTPA) complexes of the convenient half-life positron emitters 55Co and 64Cu have been prepared for quantitation of cerebrospinal fluid (CSF) kinetics in different areas of the brain using positron emission tomography. The radionuclides are prepared by proton bombardment of natural nickel ( 58Ni(p,α) 55Co and 64Ni (p,n) 64Cu reactions). The chemical separation of the radionuclides from the target is described, and the production yields, radionuclidic purities and specific activities are given.

7Li + 54Fe Single-nucleon stripping reactions at E = 48 MeV

Angular distributions have been measured for the 54Fe( 7Li, 6Li/ 6He) 55Fe, 55Co reactions at E( 7Li) = 48 MeV . Exact finite-range DWBA calculations for both reactions, employing Woods-Saxon real and imaginary potentials to generate the distorted waves, reproduce the shape of the f-state angular distributions but not the rate of fall-off with increasing angle for p-states. Using real potentials constructed by double-folding a microscopic nucleon-nucleon potential with a Woods-Saxon shaped imaginary potential to generate the distorted waves did not change the calculations. The forward angle ( 7Li, 6He) data allowed the 2 p 1 2 states in 55Co to be located and the determination of the single-particle centroid energies. The 55Co spectroscopic factors are in good agreement with those from the (d, n) reaction but are generally 25 % lower than those from average ( 3He, d) results. The 55Fe spectroscopic factors are in good agreement with (d, p) results.

Analysing powers of the [formula omitted] and [formula omitted] reactions

The differential cross sections and analysing powers of the 54Fe( 3He, d) 55Co and 54Fe( 3He, α) 53Fe reactions were measured for strong transitions populating both T < and T > states of the final nuclei using a 33 MeV polarized 3He beam. The sensitivity of the analysing powers to the total angular momentum transfer allowed model-independent determination of spins for all levels observed. The main features of the experimental data could be reproduced satisfactorily by the DWBA formalism only with certain combinations of the optical-model potentials. The analysing power of the indirect transition, when compared with coupled-reaction calculations, show a marked sensitivity to the reaction mechanism.

Ion Beam Methods Applied to Interior Ballistic Studies

High temperature, pressure and velocity gases produced during the interior ballistic cycle of a gun firing are responsible for considerable damage to the steel surfaces of a gun bore. This damage is studied by exposing steel samples to the erosive flows of burning propellant gases in a modified 37mm gun chamber where pressures of 200 MPa and flame temperatures of 3000°K are typical. Ion beam methods are used to characterize the composition of the steel surfaces by combined nuclear reaction (NR) and elastic backscattering (EBS) analysis and thin layer activation (TLA) is used to measure surface wear rates. Combined fits to the EBS and NR distributions yield concentrations and depth profiles of carbon, nitrogen and oxygen as well as iron and other heavier elements. Hydrogen concentrations have also been measured on some of the samples. The results of these experiments show the presence of two different erosion mechanisms. In one, the surface is softened by thermo-chemical processes prior to removal by the shear forces of the gas flow while in the other surface layer melting occurs prior to removal. TLA using the 56Fe(p,n)56Co reaction has been used to measure wear from a 20 mm barrel and is being instrumented for larger barrels. EBS is being used to characterize the interfaces between steel substrates and coatings designed to reduce erosion.

Thermal Annealing Behavior of the Recoil 57Co Produced by the 58Nί (ϒ, p)57Co Reaction in Some Nickel Complexes

Thermal Annealing Behavior of the Recoil ⁵⁷Co Produced by the ⁵⁸Nί (ϒ, p)⁵⁷Co Reaction in Some Nickel Complexes

Measurement of Cross Sections for the 63Cu(n, α)60Co Reaction from Threshold to 10 MeV

Measurement of Cross Sections for the ⁶³Cu(<i>n</i>, α)⁶⁰Co Reaction from Threshold to 10 MeV

A study of some resonances in the 54Fe(p, γ) 55Co reaction

Excitation functions for the 54Fe(p, γ) 55Co reaction have been recorded in the energy region E p = 1100–1760 keV. The decay schemes and branching ratios of ten resonances have been investigated. Angular distributions of primary γ-rays have been measured for three resonances to establish resonance spins. Resonance strengths for six resonances and gamma widths for three resonances have been determined. The isobaric analogues of the ground ( J π = 7 2 −) and 1919 keV J π = 3 2 −) states of the parent nucleus 55Fe have been identified at 4722 and 6712 keV respectively in 55Co. The Coulomb displacement energies of the observed analogue pairs (0–4722 keV) and (1919–6712 keV) have been obtained. The strengths of the possible analogue-antianalogue transitions for the proton capture state at E p = 1679 keV have also been determined.